Reflections on Mesoscale Weather Briefings
Weekly weather briefings are a large
part of the coursework for the Certificate program. I wish now that I'd
remembered to save my postings from Meteo 241. Ah, well ... c'est la
Below are some of my postings with
linked graphics. The links in the postings will not be valid since they
are current conditions type of sites.
The southeast is fairly active
at the moment. Here's a radar image from Birmingham, Alabama
(1). The front is sitting east of Mississippi, as shown in the
attached Surface Analysis (2), with convection developing on its
eastern side in the baroclinic zone. Look at the dry line -
there was brief and spotty precip in central and eastern Texas
yesterday, but not today. This frontal image also shows the
precipiation in relation to the frontal boundary (3).
I've also attached a visible satellite image that clearly marks
the line of more heavily convective clouds (they almost look
edible)(4). This link, with limited shelf life, shows the
Convective Outlook, which runs along the lines that the
atmosphere is still too stable for anything extreme to form.
However, they see signs that more destabilization will occur as
the front moves toward the Carolinas.
I wanted to find a map with the lift indices, and found this
Lift Index from the e-wall, but am not sure how to read it - (5)
- there's alot of precipitable water showing up in the whole
southeast, but the lift index isn't shaded there, and shows a
line of 2 through the southern Gulf states.
Reply to this message
Unfortunately, I've reached my
bedtime (past it, actually). And staring at a computer screen
for 12 hours is hard on the eyes. I didn't get a chance to look
through all our reference links, but will give you this from our
local station weather blog. What I wanted to do was go through
and retrieve the data to either back up or refute what he's
saying about tomorrow's weather here in Kansas City, Missouri.
From Mike Thompson, Chief Meteorologist, Fox 4:
"Thursday, January 19, 2006 7:20 PM
What a day! Pleasant Hill hit 64! The record is 66 set way
back in 1906! But, what a difference 24 hours will make.
Tomorrow is an interesting situation. We have an open wave of
energy headed our way. It is positively tilted (southwest to
northeast orientation), which can accelerate the onset of
precipitation. So, we could see some sprinkles of rain
developing during the morning hours…possibly as early as 8 or 9
a.m. As the rainfall intensifies, by late morning, some sleet
may mix with the rain before it all changes over to snow after
lunch. There is a lot of dry air in place, and the saturating
process will cause some extreme evaporative cooling, which will
contribute to the rain/sleet mix. Temperatures will be above
freezing, though, most of the day…so most of the snowfall will
melt, except in some heavier bands of snowfall during the late
afternoon. That’s when we can expect some minor accumulations.
The combination of the sleet robbing snowfall, and the
relatively warm temperatures should limit total snow
accumulations to an inch or less over most of the area. Some of
you may see no accumulation at all, and in some spots the
streets might get coated briefly…but overall the streets should
remain primarily wet. The only real ice issue will come into
play overnight Friday night into Saturday morning, when the
skies clear and temperatures drop into the mid 20s. So Saturday
morning could be a bit slippery (black ice) until about 9-10
a.m. Full Sunshine Saturday will take away anything that does
Sunday night and Monday present another semi-interesting setup
for shallow cold air to slip in from the north, underneath a
southern plains storm. Weak cold advection coupled with a weak
700 millibar (10,000 foot) wave may create enough lift to form
some very light snowfall. Trace amounts are all I am talking
about now, but, this will need to be watched. If the southern
track turns a bit to the north…we could be into a bit more
Also, signs of a colder trend have been showing up in the
Arctic. At first, I think the cold intrusions will be very
short lived. But after the 4th of February, we may get some
brutally cold air start to head south toward us! There are
conflicting signals, however, in the Pacific that may limit the
extent of the Arctic outbreaks. On the contrary, I have been
studying the global patterns, and see plausible evidence that
February may continue to present with above normal temperatures
as well, albeit much closer to normal than January…so right now,
I am a bit conflicted. Give me a little more head scratching
time on this problem, and I’ll get back to you."
I can at least put the Forecast Discussion up for you. I copied
the whole thing so you could see the previous forecast and
compare. Also, I left the parts in about development in the
west, since many of you have been following that. This link
will give you the KC metro map of cities for your bearings.
Scroll down - it's on the right.
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
345 PM CST THU JAN 19 2006
THE STORM SYSTEM THAT WILL BRING OUR MUCH ADVERTISED MIXED BAG
WINTRY PRECIPITATION IS PROGRESSING THROUGH THE SALT LAKE REGION
THIS AFTERNOON. THE UPSTREAM KICKER FORMING OFF THE COAST OF
COLUMBIA SHOULD PUSH OUR STORM THROUGH QUICKLY TOMORROW. SO
FORECAST CHARTS SUGGESTING STRONG JET COUPLING...ABUNDANT LOW
MOISTURE...AND DEEP FRONTOGENETIC FORCING...THE FAST MOVING
PROGRESSION OF THE STORM SHOULD LIMIT SNOW TOTALS TO FOUR INCHES
LESS OVER OUR FORECAST AREA.
THE 12Z AND 18Z RUNS OF THE NAM AND GFS HAVE COME INTO GOOD
AGREEMENT WITH THE TRACK AND INTENSITY OF THE 500 MB TROUGH. THE
THERMAL GRADIENT OVER NORTHERN MISSOURI WILL BE TIGHT
MODEL THERMAL PROFILES ARE NEVER COMPLETELY RELIABLE 24 HOURS
BUT IT APPEARS THAT THE KANSAS CITY METRO WILL BE CLOSE TO THE
SNOW LINE ONCE PRECIPITATION BEGINS LATE TOMORROW MORNING. WITH
ABUNDANCE OF LOW LEVEL DRY AIR TO OVERCOME DURING THE
WOULD NOT BE SURPRISED TO HAVE A COUPLE OF HOURS OF SLEET AT THE
ONSET OF THE EVENT ALONG A CORRIDOR FROM KANSAS CITY TO
THAT TRANSITION ZONE WILL LIKELY SINK SOUTHWARD DURING THE
AS THE STORM INGESTS COLDER AIR AND MOVES EAST.
SNOW ACCUMULATIONS ARE TOUGH WITH A STORM MOVING THIS FAST...
ESPECIALLY SINCE STEEP MID LEVEL LAPSE RATES...AND STRONG
WILL CONTRIBUTE TO SOME CONVECTIVE BANDING IN THE AFTERNOON.
DEEP LAYER MOISTURE WILL BE INGESTED INTO THE STORM THE FURTHER
IT MOVES...SO I WOULD NOT BE SURPRISED THAT THE CORRIDOR FROM
CHILLICOTHE TO KIRKSVILLE COULD EXPERIENCE SIX HOURS OF MODERATE
OCCASIONALLY HEAVY SNOW. I DOUBT THAT ANY INDIVIDUAL HEAVY SNOW
WILL BECOME ESTABLISHED OVER ONE AREA FOR THAT ENTIRE SIX HOURS
SO...WITH A SNOW RATE AROUND AN INCH PER HOUR...UP TO FOUR
SEEMS LIKE A GOOD CONSERVATIVE FORECAST FOR NORTH CENTRAL AND
NORTHEAST MISSOURI. FURTHER WEST TOWARD KANSAS CITY AND SAINT
JOSEPH...A SHORTER DURATION AND THE POTENTIAL FOR SLEET WILL CUT
DOWN ON SNOW ACCUMULATIONS. ONE TO TWO INCHES FROM THE NORTHLAND
THE IOWA BORDER IS REASONABLE AT THIS TIME.
A BROAD TROUGH WILL BE POSITIONED ACROSS THE WESTERN STATES
THE WEEKEND. THE MEDIUM RANGE MODELS HAVE TRENDED TOWARD
A CLOSED LOW WITHIN THE TROUGH AND BRINGING IT SOUTH ALONG THE
COAST DURING THE EARLY PART OF NEXT WEEK. LATER NEXT WEEK THIS
CLOSED LOW IS FORECAST TO SWING OUT ACROSS THE CENTRAL CONUS.
SEGMENTS OF SHORTWAVE ENERGY WITHIN THE MEAN TROUGH ARE FORECAST
EJECT OUT IN ADVANCE OF THE CLOSED LOW AND REMAIN DIFFICULT TO
PINPOINT WITH MUCH CONFIDENCE. KEPT ONLY SLIGHT PRECIPITATION
CHANCES FOR THE SOUTHERN SECTIONS SUNDAY NIGHT WHERE THERE IS
POTENTIAL FOR MOISTURE RETURN TO REACH. OTHERWISE...THE COOLEST
IN THE EXTENDED TIME FRAME LOOKS TO BE MONDAY BEFORE
BEGIN TO MODERATE ONCE AGAIN DURING THE MIDDLE OF NEXT WEEK.
315 AM THU...
EARLY MORNING SURFACE ANALYSIS DEPICTED A BROAD SURFACE LOW
NEAR HILL CITY KANSAS...PLACING ALL OF MISSOURI AND EASTERN
WITHIN THE SURFACE WARM SECTOR. PROFILER/VWP DATA DEPICTED AN
SPRING-LIKE LOW LEVEL JET OF 50-60 KNOTS NOSING FROM THE
PLAINS INTO WRN MO. THIS WAS KEEPING PORTIONS OF CENTRAL AND
CENTRAL MISSOURI WELL MIXED...RESULTING IN A 25 DEGREE SPREAD IN
TEMPERATURES ACROSS THE CWA...WITH READINGS RANGING FROM THE
20S IN NW MO TO THE LOWER 50S IN THE BUTLER AND PAOLA AREAS.
FOR TODAY...SUBSIDENCE IN THE WAKE OF A DEPARTING UPPER LEVEL
DISTURBANCE AND COMPRESSIONAL HEATING AHEAD OF THE APPROACHING
FRONT WILL PROVIDE A MOSTLY SUNNY AND UNSEASONABLY WARM DAY
THE AREA. HAVE BUMPED HIGHS INTO THE 60S SOUTH OF THE MISSOURI
RIVER. FIRE WEATHER CONDITIONS HAVE BEEN HIGHLIGHTED SEPARATELY
BELOW AND ARE OF SIGNIFICANT CONCERN FOR TODAY.
THE MAIN FORECAST CHALLENGE CONTINUES TO BE WITH THE EVOLUTION
COMPACT COLD CORE SYSTEM DROPPING ACROSS INTO THE GREAT BASIN
THIS MORNING. 00Z MODEL SUITE HAS PROVIDED NO HELP IN THE WAY OF
CONSISTENCY FROM PREVIOUS RUNS...OFFERING A VARIETY OF DIFFERENT
SOLUTIONS. IN QUESTION IS NOT THE EXISTENCE OF THE SYSTEM
ITSELF...BUT ITS TRANSLATIONAL SPEED AND TIMING AS IT RELATES TO
INFLUX OF SUBTROPICAL MOISTURE AND UPPER LEVEL DYNAMICS. FOR
MUST LOOK TO THE UPSTREAM KICKER AND A SECONDARY JET STREAK IN
VICINITY OF 40N/140W. THE NAM SOLUTION HAS BEEN REJECTED DUE TO
INITIALIZATION OF SEVERAL KEY UPPER LEVEL WIND FEATURES (WHICH
CRITICAL TO THE FORECAST). OF THE OPERATIONAL GFS...UKMET AND
SOLUTIONS...THE GENERAL TREND HAS BEEN TOWARD A DEEP...BUT MORE
WAVE SYSTEM. IT IS NOTEWORTHY THAT THE GFS ENSEMBLE MEMBERS FALL
INTO TWO SCHOOLS OF THOUGHT...WITH HALF THE MEMBERS STILL
AND HOLDING THE MAIN UPPER TROUGH BACK AS THE INITIAL JET STREAK
BYPASSES THE SYSTEM TO THE SOUTH. HOWEVER...WATER VAPOR IMAGERY
SHOWS THAT THE UPSTREAM KICKER IS ALONG THE SAME LATITUDE...SO
LEANED TOWARD A BLEND OF THE OPGFS AND OUR EUROPEAN FRIENDS FOR
THE RESULT IS VERY LITTLE CHANGE WAS MADE TO THE GOING FORECAST.
RAPID MOISTURE INCREASE AND REORIENTATION OF THE SUBTROPICAL JET
NOTED OVER THE SWRN STATES EARLY THIS MORNING...AND WILL REACH
AREA EARLY FRIDAY. WITH A MORE OPEN WAVE SYSTEM...LOW-MID LEVEL
WILL NOT BE AS STRONG OR BACKED AS PREVIOUSLY THOUGHT. THIS WILL
LEND TO A WEAKER MOISTURE INFLUX AND FRONTOGENESIS...BUT PROGGED
ISENTROPIC ASCENT AND WARM/MOISTURE ADVECTION ARE STILL PLENTY
SUFFICIENT FOR PRECIPITATION TO BECOME WIDESPREAD BY MIDDAY.
RETAINED EMBEDDED THUNDER OVER SRN ZONES GIVEN FAVORABLE LAPSE
TRANSITION ZONE OF PRECIPITATION TYPE WILL BE THE PRIMARY
TOMORROW AS MID LEVEL WARM ADVECTION IS UNDERCUT BY LOW LEVEL
ADVECTION AND DIABATIC COOLING PROCESSES FROM PRECIPITATION.
ANALYSIS OF MODEL SOUNDINGS SUGGESTS THAT THERE MAY VERY WELL BE
NARROW CORRIDOR OF SLEET/FREEZING RAIN...BUT WILL NOT GET
AWAY AT THIS POINT. GENERAL TENDENCY WILL BE FOR PRECIPITATION
SLOWLY TRANSITION OVER TO SNOW FROM THE NORTHWEST AS THE SURFACE
MIGRATES ALONG THE I-44 CORRIDOR. THE SYSTEM WILL THEN LIFT OUT
FRIDAY NIGHT...BRINGING ADDITIONAL WRAPAROUND SNOWS ACROSS
AS IT STANDS...THE COMBINATION OF QPF...STORM DURATION...THERMAL
PROFILES AND MODEL TRENDS SUGGEST THAT THIS SYSTEM`S INITIAL
WILL BE BIGGER THAN ITS BITE. THINK A GENERAL 2-4 INCH SWATH
THE RESULT OVER NRN MO...SOMEWHERE ALONG A ST. JOSEPH TO
LINE. GIVEN THE UNDERLYING UNCERTAINTIES AT THIS POINT...WILL
THE DAY SHIFT PONDER ANY ADVISORIES BASED ON 12Z DATA.
SURFACE WINDS GUSTING TO 30 MPH OVER SOUTHWEST MISSOURI EARLY
MORNING POINT TO A DIFFICULT FIRE WEATHER DAY OVER CENTRAL AND
SOUTHERN MISSOURI. THESE GUSTY WINDS WILL LIKELY SPREAD INTO THE
TRUMAN LAKE REGION AFTER DAYBREAK AS DEEPER MIXING BEGINS TO TAP
INTO A VERY STRONG LOW LEVEL JET. AN APPROACHING LOW PRESSURE
WILL ALSO ENSURE THAT SOUTHERLY WINDS REMAIN UP FOR MOST OF THE
UNFORTUNATELY...THESE WINDS ARE SIMPLY DRAWING IN MORE DRY AIR
AN ALREADY PARCHED SOUTHERN PLAINS SOURCE REGION...AND WITH
FORECAST IN THE MID 60S...RELATIVE HUMIDITY VALUES WILL LIKELY
BELOW 25 PERCENT THIS AFTERNOON IN THE CLINTON AREA. CLINTON
OBSERVATION SHOWS THAT CURRENT FUEL STICK MOISTURES ARE BELOW 8
PERCENT WHICH IS CRITICALLY DRY FOR THIS TIME OF NIGHT. RED FLAG
CRITERIA WILL LIKELY BE MET...ALTHOUGH SUCH A PROGRAM DOES NOT
PRESENTLY EXIST FOR THE REGION. WILL HIGHLIGHT FIRE DANGER
IN THE MORNING HAZARDOUS WEATHER OUTLOOK.
I'm sorry - I know that was exhausting. I'll report in
periodically tomorrow on the progress of the storm.
Okay - I couldn't leave you without stuff to look at.
1 and 2 are Surface Analyses valid tomorrow morning and tomorrow
evening - look how the precip moves in. 3 is what it looks like
right now - see the position of the Low and the baroclinic
zone. So close. On 4 you can see the jet streak over KC - but
not the left-exit region. :( On 5 watch the RH "get greener" -
and it shows the dry air that's referenced in Mike Thompson's
blog above. And finally in 6 look at the 540 slush line - in a
few of these boxes it sits right on top of KC! Hence the sleet
in Mike's forecast.
Now I feel better. Goodnight.
Reply to this message
There's nothing happening here
but cold rain.
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1130 AM CST FRI JAN 20 2006
THE PRECIPITATION BAND IS ORGANIZING FROM NORTH OF TOPEKA
SOUTH CENTRAL IOWA AT THIS HOUR. MESOSCALE BANDING IS OCCURRING
ZONE UNDERGOING SIGNIFICANT DEEP LAYER FRONTOGENESIS IN A
CONVECTIVELY UNSTABLE ENVIRONMENT. SNOW AND SLEET AMOUNTS
OVER NORTHERN MISSOURI HAVE BEEN MINIMAL THUS FAR...AND THERE IS
CONCERN THAT AN ELEVATED WARM LAYER NEAR 800MB MAY BRING SLEET
FURTHER NORTH THAN PREVIOUSLY THOUGHT. SLEET HAS BEEN REPORTED
FAR NORTH AS THE IOWA BORDER. THE ENVIRONMENT OVER NORTHERN
HAS YET TO COMPLETELY UNDERGO ALL THE EVAPORATIVE AND DYNAMIC
COOLING THAT IT WILL EXPERIENCE THIS AFTERNOON...BUT 12Z MODELS
COMING IN WARMER THAN PREVIOUS RUNS (AROUND 800MB). SNOW
ACCUMULATIONS MAY NEED TO BE ADJUSTED NORTHWARD BY THIRTY OR
MILES...WITH THE MOST SIGNIFICANT ACCUMULATIONS FROM MOUND CITY
ALBANY TO PRINCETON. FOR KANSAS CITY...COLD AIR MAY NOT ARRIVE
TIME THIS AFTERNOON TO PRODUCE MUCH IN THE WAY OF SNOW
Reply to this message
Yep, sure has been.
Here's the loop from Topeka (the Pleasant Hill loop isn't
working right now) -
it looks like that bigger piece of precip in Kansas might try to
wrap around and give us something this afternoon later or
evening. But the brunt is in Iowa and Wisconsin, and moving
over Chicago right now.
Attached is the current surface analysis (1925Z) - the low is
sitting right below us (my farmhouse would sit on top of the
L). It hasn't occluded yet - it's strengthening now with the
upper midwest slated to receive the majority of the storm's
We have maintained 32-33 degrees here all day with intermittent
rain. Here's the current meteogram, but note that the airport
(KCI) is up north, so they probably are experiencing the
freezing rain and sleet.
Reply to this message
Well, where it's not going is
anywhere near here. Here's the near-noon CST Forecast
1146 AM CST TUE JAN 24 2006
MADE SOME ADJUSTMENTS TO OUR AFTERNOON TEMPERATURES. WHILE STILL
EXPECTING COLD AIR ADVECTION WITH THE STRONG NORTHWEST JET THIS
AFTERNOON...OUR QUICK RISE IN SURFACE TEMPERATURES FROM BOUNDARY
LAYER MIXING THIS MORNING SEEMS TO WARRANT ADDING A CATEGORY TO
TODAYS EXPECTED HIGHS. HOWEVER...STILL EXPECTING TO SEE THE RISE
TEMPERATURES TO FLATTEN OUT DURING THE AFTERNOON HOURS DUE TO
COLD AIR ALOFT.
We did, indeed, get to a high of 57 F, climbing of which has
leveled off and remains at 57 now at 2:30 CST. We are
experiencing windy conditions and sunny skies. See attached
meteogram  for 2:00 pm yesterday up till 2:00 pm today (30
minutes ago) - note the windshift between 13Z and 14Z, and the
subsequent gusts. This is the front mentioned in the
LOW PRESSURE SYSTEM MOVING ACROSS THE GREAT LAKES TODAY WILL
A TIGHTENING GRADIENT ACROSS NORTHEASTERN KANSAS AND NORTHERN
MISSOURI TODAY. [There's our windy conditions.]
ALTHOUGH THERE ARE SOME MID LEVEL CLOUDS ADVECTING
IN...SOUNDINGS SHOW WE SHOULD BE ABLE TO MIX UP TO NEARLY 800MB
BY 18Z. THIS WILL CREATE WARMER AND WINDY CONDITIONS ACROSS THE
FORECAST AREA. [Voila!]
NORTHEAST MISSOURI WILL BE IN THE PATH OF THE
HIGHEST WINDS ALOFT [300 mb winds attached]
...WITH THE GFS AND NAM BOTH SHOWING A CORE OF
50KTS AT H8. THE UPPER SYSTEM MOVES THROUGH QUICKLY...WITH A
WEAKENING GRADIENT BY 00Z. WILL HOIST A WIND ADVISORY FOR OUR
NORTHEAST CORNER...EXPECTING AT LEAST 35 TO 40 MPH SUSTAINED
IN THE KIRK AREA. CURRENT SURFACE MAP [Current Surf Obs
shows 57 hi, 15 DP, clear w/ NW winds 20 kts]
SHOWS STEADY/SLOWLY RISING
TEMPS WITH SOUTHWEST WINDS ALREADY 10-15 MPH. SINCE WE WILL
OUT RELATIVELY WARM THIS MORNING...HAVE RAISED HIGHS IN THE
SOUTHWEST CORNER OF THE AREA. THE COLD FRONT SAGS SOUTH DURING
DAY [4&5][Surface Analysis]
...WITH CAA DROPPING TEMPS AT H8 6 TO 8 DEGREES. NOT THAT MUCH
COOLER TEMPS AT THE SURFACE BEHIND THE FRONT...BUT HAVE LOWERED
TEMPS JUST A SMIDGE IN THE NORTHERN COUNTIES WHERE THE WARMING
SHOULD LEVEL OFF AROUND THE NOON HOUR.
WARM AIR SLOWLY ADVECTS BACK IN ON WEDNESDAY AS THE UPPER LEVEL
RIDGE MOVES TOWARDS US. SOMETHING TO WATCH ON WEDNESDAY WILL BE
AMOUNT OF MOISTURE WE CAN PULL BACK IN WHEN WINDS SHIFT TO
THE MODELS ARE GETTING PRETTY STINGY WITH THE PRECIP ON THURSDAY
[6&7][NAM valid 6:00 pm Thursday for Precip and 6:00 pm
Wednesday for RH].
LATEST GFS RUN NEVER HAS THE SURFACE TROF ARRIVE. AND EVEN THE
BRINGS THE SYSTEM FURTHER NORTH AND WEST . HAVE LOWERED THE
POPS A LITTLE. WILL LET DAY CREW GET MORE SPECIFIC WITH
AND TIMING...ANOTHER MODEL RUN SHOULD MAKE PICTURE A LITTLE
BETTER CHANCES FOR RAIN WILL BE OVER THE WEEKEND WITH SOUTHERN
I think I got them all in - a meteogram to show the wind shift
and gusts fairly currently, 300 mb winds to show the upper-level
jet mentioned in the Discussion, Surface Obs to show the
temp/DP/winds currently, a Surface Analysis showing the position
of the front at 6:00 pm this evening, and a Current Analysis
showing the position of the front now, 2 NAM progs - one for Wed
to show the RH that's lacking and one for Thurs to show the zero
precip forecast, and 2 Surface Analyses to show the next frontal
position on Saturday and Sunday, 6:00 am each.
Any forecast would be for the chance of precip Saturday/Sunday,
which they have in the forecast at present. The front passes
right through us Saturday and they've added a snow mix change
for Sunday, but the temps will be warm - 53 Sat and 46 Sun.
It's too far out right now - this will have to be monitored.
P.S. On the Surface Analysis, you can see the Michigan snow!
Reply to this message
re: Weather Briefing 3, Week of January 23
DEBRA JARVIS -
Edited 1/25/2006 02:40 PM
I'm really interested in that low tracking through
Arizona/Colorado, as it's been slated by our locals as maybe
giving us a chance of precip Sat/Sun. From the #10 prog in your
post, I see that it's holding alot of moisture, and I'm hoping
it retains that and relieves some of the drought in West Texas
and Oklahoma. Unfortunately, the prog loops all have it
petering out in 36-42 hrs as it gets to West Texas, with the
vorticity moving north of KC along the isotherms. Actually, AVN
doesn't give it much of a chance of precip in West Texas.
I've attached 3 surface analyses so we can see the projected
frontal boundary locations. In the first one, valid 6:00 am CST
Friday morning, shows the precip chance in southwest Texas (this
is roughly the location of the Marfa Mountains). The next two,
Days 3 and 4, show the Low just west of KC at 6 am CST Saturday
morning, then occluding east of us in Tennessee at 6 am CST
Sunday morning. This would put KC in the northern part of the
warm sector Saturday morning (rain) and the wraparound section
behind the occluding low on Sunday morning, which is why they
put rain and snow shower chances for Sunday.
Still pretty far out to forecast, but it will be interesting to
watch the low progress, and like I said, hopefully leave some of
that precip on West Texas. The prog in Phil's post shows a good
chance predicted for that area.
Reply to this message
I meant for them to be the loops
- that's why I gave links instead of attachments. Can you see
Lubbock, Texas has been without rain for roughly 3 months (I
believe that's what I heard). That's about the demarcation line
between West Texas and the Panhandle (Dallas and Wichita Falls
are North Texas). East Texas (east of Dallas - Tyler, Terrell,
Longview) has had rain in the past 3 months, albeit very little
(they caught a little from the fronts that have formed precip
east of the drought-line, per se). The Panhandle and Oklahoma
have suffered pretty heavily, with most of the wildfires
occurring in Oklahoma. However, the fire danger line a couple
of weeks ago was drawn around North, East, and Central Texas
(Dallas, Austin, Waco, East Texas). But on the local NWS site
for KC lately, the Fire Weather Watch coloring has been coming
up into Central Missouri (see the beige below Butler and Clinton
- at the end of last week, the boxes were bright pink and came
all the way up to Sedalia).
I was looking at West Texas because of Lubbock, but from the
attached Drought Monitor, they've put Dallas in the heart of
it. [Glad I moved away from there now - don't miss that!]
Reply to this message
Yeah, it's a fur piece across
our state, for a fact. I was born and raised in North Dallas
(Love Field). Spent a number of young adult years in Arlington.
One thing I've heard from Amarilloans is that Amarillo sits on
the caprock, giving it a higher elevation, and that whatever
comes out of Colorado off the Rockies will affect Amarillo -
they get much more snow than the rest of the state (Panhandle
and West Texas).
Amarillo covers a land area of 227.4 sq km (87.8 sq mi), with a
mean elevation of 1123 m (3683 ft).
As compared to Dallas [Elevation: 463 feet. County: Dallas. Land
342.5 square miles.] and Kansas City, MO [Elevation: 882 feet.
Land area: 313.5 square miles]
Wow - look at the difference!!!!
Reply to this message
re: Strong Storms in SE TX and Western LA
DEBRA JARVIS-FERGUSON - 1/29/2006 11:57 AM
That's quite a line of storms in
Dennis, where do you live again? It was good to see the DFW
metroplex mentioned - I would be homesick, except that's the
worst Urban Heat Island this side of NYC. :P
The storms have moved out of Mississippi, as has the frontal
boundary. Attached is the current radar (from about 10 minutes
ago) from Tallahassee, Florida (I had to hunt for the rain
reflectivity). Also attached is the current surface analysis
(valid 7:00 am EST this morning) showing the placement of the
The third image attached is the NWS national radar showing the
heaviest storms over the SE tip of LA/MS (Katrina Land). Here's
the loop to this radar image which shows the baroclinic storms
petering out along the Gulf states, the classic comma moving on
up around the eastern Great Lakes and NE regions, and some
storms erupting in Louisiana behind it all.
The Convective Outlook echoes what we're seeing in their 10:29
CST posting for today:
...SERN STATES/N FL...
PREFRONTAL CONVECTIVE BAND HAS MOVED WELL E OF COLD FRONT. IT
SHOULD CONTINUE TO WEAKEN AS IT DRIFTS FARTHER SE TODAY.
INSTABILITY AND WEAK UPR FORCING SHOULD KEEP COVERAGE OF
THUNDER ISOLATED. THE CONVECTIVE BAND MAY REJUVENATE SOMEWHAT
TONIGHT/EARLY MONDAY FROM THE NRN GULF ENE ACROSS NRN FL/S GA
PERHAPS SRN SC AS AMPLIFICATION OF UPSTREAM TROUGH ENHANCES
ADVECTION ACROSS REGION.
FARTHER W...AN AREA OF NEW CONVECTION/POSSIBLE THUNDER MAY
NEAR THE END OF THE PERIOD OVER PARTS OF LA/MS...IN ZONE OF
INCREASING FRONTOGENETIC FORCING CLOSER TO APPROACHING
LIMITED MOISTURE INFLOW SHOULD MINIMIZE ANY SEVERE THREAT
PRESENCE OF MODERATE TO STRONG CLOUD LAYER SHEAR.
And that explains the reflectivity firing up in LA behind the
frontal convective bands.
Reply to this message
re: Weather Briefing 1, Week of January 30
DEBRA JARVIS -
Edited 1/30/2006 04:24 PM
You've hit on something here. As of 2:49 CST, the MD says
they're looking at possibly extending/issuing a new watch for
further east, south, and northeast up into the Carolinas. Shear
is favorable, mid-level jet max moving southeastward toward the
southern Atlantic, and a moist boundary layer is helping to
build instability. Attached (1) is a sounding from Tallahassee,
FL valid 1200 UTC, which shows the shear and the moist boundary
layer. You can see the jet max at 500 mb on attachment (2).
Link to MD #0091:
The progs for 1200 UTC all point to some activity in the nxt
12-18 hours, with the NGM bringing the vort max right on top of
the area in 18, and the ETA and AVN bringing it slightly north
of the southern third of AL and GA. All three bring RH through
but immediately followed by dry air. And all three bring precip
for roughly the same parameters.
I attached the loops rather than the images.
Reply to this message
re: Weather Briefing 2, Week of January 30
DEBRA JARVIS-FERGUSON - 2/1/2006 10:44 AM
The projected storms for Texas/Louisiana are beginning to fire
up around Austin and San Antonio. The attached radar (1) for
Austin didn't save well, so the link is above. You can see the
showers on the meteogram for San Antonio (4), as well.
The Surface Analysis (2) shows the area in question on the warm
front side of the low pressure system moving through, with the
Current Analysis (3) showing the area slated for possible
thunderstorm activity. However, this is further south than
anticipated in yesterday's analyses.
Here are the links to the 1200Z progs from the e-wall:
The NGM and ETA both bring the vort max and precip in this
afternoon, and the humidity climbs as the rain totals increase.
The AVN is really slow in bringing the low over into Texas (it's
behind already, thus I don't think we can consider it); however,
once it gets there, look at the totals it brings, albeit further
north than than NGM and ETA (and current readings) show.
I also notice that the NGM and the ETA have the low gaining
precip intensity and heading across the southeast and up the
seaboard. However, it appears the low becomes vertically
stacked while still in Texas.
Fodder for discussion: what increases the precip as it travels
up the seaboard?
Reply to this message
Well, there's more. This from
the current SPC MD (with a 15% slgt risk for severe tstorms):
AMPLE /40+ KT/ DEEP SW TO WSWLY SHEAR WILL BE PRESENT FOR
SUPERCELLS...AND HODOGRAPHS WILL BE ENLARGED IN THE LOWER
NEAR WARM FRONT OVER SE TX AND THE UPR TX GULF CST. THUS...
POTENTIAL WILL EXIST FOR BOTH HAIL AND A FEW TORNADOES. THE
THREAT SHOULD SHIFT E/NE INTO SRN LA BY EARLY TONIGHT. FAR SRN
TRACK OF UPR VORT AND EXISTING COOL AIR MASS OVER THE N CNTRL
SUGGEST...HOWEVER...THAT THE TX STORMS LIKELY WILL EVOLVE INTO
MCS WITH EMBEDDED SUPERCELLS.
What are hodographs? And is it painful for them to be enlarged?
Reply to this message
re: Weather Briefing 5, Week of January 30
DEBRA JARVIS -
Edited 2/4/2006 02:29 PM
Mornin', Robert (except it's
12:48 pm here).
I understand from all the torrential rains in Florida yesterday
that the roof on a Bed, Bath and Beyond collapsed, and the whole
strip mall was evacuated hurriedly. Seems all employees were
accounted for, with only one injured.
At present, TWC is gearing up for a major snowstorm in the Great
Lakes region. Attached is a current surface analysis, and
meteograms for KIND, KTDZ and KDTW (Indianapolis, Toledo and
Detroit) where the rain has already changed over to snow. The
surface analysis really shows the deepeing low of 995 mb.
And from MD #122 showing the rain changeover to snow for today
through this afternoon:
1209 PM CST SAT FEB 04 2006
AREAS AFFECTED...WESTERN/CENTRAL OH AND SOUTHEAST LOWER MI
CONCERNING...PRECIPITATION TRENDS...WINTER PRECIPITATION
VALID 041809Z - 042245Z
PRECIPITATION WILL TRANSITION TO SNOW THROUGH MID AFTERNOON
WESTERN/CENTRAL OH AND SOUTHEAST LOWER MI...WITH MDT/PERHAPS
HEAVY WET SNOW DEVELOPING BY MID/LATE AFTERNOON. SNOW RATES
REACH 1 IN/HR AFTER 21Z.
MATURE CYCLONE CONTINUES TO DEEPEN OVER THE GREAT LAKES/OHIO
REGION...WITH STRONG PRESSURE FALLS MAXIMIZED EARLY THIS
IN VICINITY OF LAKE HURON AND DEEPENING 994 MB LOW PRESSURE
NEAR THE OH/WV BORDER AT 18Z. ALTHOUGH RAIN INITIALLY EXISTS
MUCH OF SOUTHEAST LOWER MI/CENTRAL OH AT MIDDAY...COMPACTING
FIELDS ON PERIPHERY OF EARLY-OCCLUDING CYCLONE WILL SUPPORT A
RELATIVELY QUICK CHANGE TO ALL SNOW BY MID AFTERNOON. SIMILAR
TREND IN AVAILABLE TAMDAR SOUNDINGS FROM NEAR
SCENARIO APPEARS WELL DEPICTED VIA 15Z RUC/12Z NAM FORECAST
PROFILES AND 09Z SREF CONSENSUS...WITH A CHANGE-OVER TO SNOW
BY 21Z FOR A DETROIT-TOLEDO-FINDLAY-COLUMBUS CORRIDOR. MID
/600-800 MB/ FRONTOGENETICAL FORCING /ESPECIALLY AS DEPICTED
GFS AND RUC/ IN PRESENCE OF WEAK STATIC STABILITY WILL BE
FOR SSW-NNE BANDING AND ENHANCED SNOW RATES BY LATE THIS
At first they (TWC) mentioned possible blizzard conditions by
this afternoon, but have since changed their tune on that one.
Reply to this message
Hey, Frank - nice setup.
Right now Lakes Erie and Ontario are experiencing lake effect
snows - see the NE Surface Plot (attachment 7) that clearly
shows the parallel winds blowing NE across the lakes (right box)
and the precip bands (upper left box).
Other than that, the SE is the place to watch this afternoon, I
think. Attachments 1-6 deal with this area.
You can see on the Current Surface Analysis (attachment 1) the
location of the Low over Louisiana, as noted in the Day 1
Convective Outlook Discussion linked above. This Low is set to
intensify as it moves NE, and the precip is occurring in
northern MS, AL, GA and southern TN (attachment 8). Attachment
3 shows the upper level winds (the flow is coming through nicely
right across this region) and attachment 4 shows the lower level
winds at 850 mb coming in strongly off the Gulf, bringing alot
of moisture to the mix. Surface Obs (attachment 5) show the
high dew points in the Gulf region, with surface winds coming in
from the Gulf in the warm sector and the NW winds coming down
from the cold sector behind the baroclinic zone. And attachment
6 is where we can see the 500 mb trough positively tilted across
the Texas Panhandle.
And one last item is the Forecast Surface Analysis (attachment
2) which shows the precip moving eastward by this evening
leaving a stray thunderstorm in LA behind the frontal boundary.
I wanted to show the slush line, but the e-wall seems to be
having a problem accessing data right now.
Reply to this message
re: Weather briefing 2, week of Feb 6
DEBRA JARVIS -
Edited 2/7/2006 05:37 PM
I'll take that Nebraska Low.
I've attached the Forecast Surface Analyses for 12 and 24 hours
which show the Low bringing snow and thundersnow down the Plains
and just skirting by KC, MO.
I've also attached the eWall NGM, ETA and AVN prog stills for 24
hours (18 hours for the AVN since the 24 hour was incomplete).
These show the vorticity moving in on the northwest flow, the
Low moving over Kansas/Missouri, and the precip starting to
trace up over the Missouri area. We just don't have much
moisture already for it to work with (see RH for the moisture it
There is no discussion, convective or mesoscale, regarding this
Low. There may be later, as it goes on in the prog loop to
bring more snow/thundersnow possibilities to the southeast.
Reply to this message
re: Weather briefing 5, week of Feb 6
DEBRA JARVIS-FERGUSON - 2/10/2006 12:38 PM
I'm going to zero in on the snow
occurring as we speak in far northern Arkansas/far southern
Missouri. [We have a cabin in far northern Arkansas just over
the Missouri border.]
This is so exciting watching these things as they happen!
The MD #129 is attached rather than linked, so I can save it.
The gist is that snow is expected/occurring in northern
AR/southern MO today due to a frontal boundary and short-wave
trough, moisture convergence, frontogenetic forcing, and a
surface wet bulb zero line running through the state of AR.
Current Surface Analysis (1) shows the location of the front and
low, and the snow symbol in AR.
300 mb winds (2) show the LLJ, and 850 mb winds (4) show the
The 500 mb trough can be seen on (3).
The 1h Composite Radar shows the precip inundating AR, LA, TX.
The eWall Progs (6) (7) (8) show the RH in relation to the
forcing for ascent, as well as precip totals - note that the
models are in fair agreement on placement and amount.
And number 9 (number 9, number 9) is the temp profile for
earlier this morning (wee hours) showing the surface 0 degree
isotherm in the AR area. There is a bit of a mix of precip
under the snow, in a small band from north-central AR to eastern
AR (saw it on TWC, can't attach it).
You'll have to read the MD to follow my illustrations.
Reply to this message
re: Weather Briefing 2, Week of Feb. 13
DEBRA JARVIS - Edited
2/14/2006 12:43 PM
Hey, Gary - and Happy Valentine's to
I see some of the fire weather warnings have crept back into far
southwestern Missouri - that's disturbing. It is dry here, but we've
had no warnings so far.
I'd like to address something they've been putting in the forecast now
since yesterday afternoon. According to the local (Fox 4 KC), TWC (for
KC proper) and WeatherBug (local for Peculiar, south of KC) forecasts,
we have a chance here in KC for rain/drizzle/freezing drizzle/sleet then
snow for Wed night through Thursday. The WeatherBug forecast and the
local indicate falling temps during Thursday afternoon, which will bring
the chance of the mix. I've attached the Day 2 and Day 3 Convective
Outlooks from SPC, which don't mention snow or any mix, but a chance of
thunderstorms. [AND I ASK WHAT OUR SOURCE WILL BE NOW THAT THEY'VE
DISCONTINUED THESE TODAY?]
Okay, bear with me as I made notes after looking at all the progs
The Surface Analysis  valid 6:00 pm CST tomorrow shows the position
of the warm front just to our south, and they've drawn us just inside
the precip field for rain and tstorm possibilities. That's the
The Surface Analysis 3Day Prog valid 6:00 am CST Thursday  shows us
still on the NW side of the warm front, the Low sitting just to our
southwest in southeastern Kansas, and a large pressure gradient to our
The Day 2 and Day 3 QPFs [3 & 4] show the precip sheild growing from
6:00 am CST Wednesday through 6:00 am CST Friday. Note that we stay in
the very light region (our local called for light for whatever we get).
The NGM prog  only goes up to 48hrs so 6:00 am Thursday is all we can
see on this one. It shows precip to our north, and low-moderate RH
The ETA and AVN progs are alot more fun. ETA is [6, 7, & 8] and AVN is
[9, 10, & 11] for 48hr, 54hr, and 60hr progs. On the AVN 54hr  and
the ETA 60hr  the 540 dekameter line runs right through the KC metro
area. I know this is not the "slosh" line but is a close cousin, and
this is where our chance for the freezing rain/sleet comes in around
noon Thursday. [I've posted in the Classroom an inquery as to whether
we can get the Temp Prog with the yellow "slosh" line for the rest of
As for precip, it's just to our north at 48hrs on the NGM . ETA
gives us light precip in the 48hr, 54hr and 60 hr progs [6, 7, & 8], and
the AVN gives us moderately light precip at 48hrs and 54hrs [9 & 10].
By 60hrs, the AVN has the precip moved out to our east .
Note that the RH stays in the white area just under the green for all
the progs listed. We're just not getting the high humidities/moisture
content to have a large precip event.
I tried to get a forecast sounding for Topeka or Springfield, but the
UOW site said they were unable to access.
On the prog loop for AVN, you can see our Low move northeasterward, and
deepening to 1000mb at 66hrs over the Great Lakes, and continuing to
deepen as it moves over the northeastern US as a 996 Low at 72-78hrs.
You'll have to go to the eWall and look for that!
Based on the models, the position of the Low, the 540 dekameter, and the
fact that the yellow "slosh" line on the Temp Prog for the eastern US
looks as if it follows on down toward our area, I believe we will start
out as rain sometime Wed evening or wee hours, and with dropping temps
coming with the CAA of the front, the chance for a bit of freezing-type
precip looks possible Thursday afternoon. This agrees with the local
and WeatherBug, agrees mostly with TWC, and doesn't quite jive with the
re: Weather Briefing 2, Week of Feb. 20
DEBRA JARVIS-FERGUSON - 2/22/2006 10:36
Cory and Frank, here's mention of your
fog in the 6:58 am Convective Outlook for today:
...E TX INTO THE DEEP S...
NRN STREAM JET AXIS ACROSS THE OH VLY EARLY WED WILL MOVE E TO THE
MID ATLANTIC CST BY THIS EVE. CORE OF ASSOCIATED SWLY LLJ WILL
CORRESPONDINGLY MOVE E OVER THE GULF CST REGION. GULF MOISTURE WILL
CONTINUE TO SPREAD N INTO VICINITY OF DEVELOPING COLD FRONT ON
LEADING EDGE OF AFOREMENTIONED HIGH PRESSURE SURGE. THIS SHOULD
MAINTAIN WIDESPREAD LOW CLOUDS AND FOG AHEAD OF BOUNDARY.
That developing low will be something for us to watch today, as they're
calling for possible development of some mild thunderstorms in the
southeast/Gulf Coast states.
A BAND OR TWO OF CONVECTION SHOULD DEVELOP FROM SE TX ENE INTO PARTS
OF LA/MS/AL AND GA LATER TODAY AS TIGHTENING OF BAROCLINIC ZONE
ENHANCES ASCENT. SEASONABLY WARM MID LEVEL TEMPERATURES AND LIMITED
SURFACE HEATING WILL MINIMIZE DESTABILIZATION. BUT SUFFICIENT
INSTABILITY MAY DEVELOP TO SUPPORT SPORADIC LIGHTNING IN STRONGER
UPDRAFTS. THE HIGHEST PROBABILITIES FOR THUNDER SHOULD EXIST ACROSS
THE LWR MS VLY WHERE MASS CONVERGENCE WILL BE GREATEST.
Attached is a Regional Surface Chart (1) that shows all the fog still
spreading over the southwest and Gulf Coast states, as well as a Radar
Composite (3) showing the precip in the clouds. Image (2) shows the
CAPE referenced in the CO - readings of 1500 in LA/MS and 2500 in OK!
The Surface Analysis (4) shows the developing low "deep in the heart of
Texas" around San Angelo.
That radar looks pretty active - if we're seeing surface conditions of
fog (and some rain, as indicated here and there amongst the fog
symbols), then I see the moisture gaining ground as the day progresses.
There's good low-level moisture coming in off the Gulf (5), but part of
those winds are bringing dry air from Mexico.
Like I said, something to watch for the day.
re: Weather Briefing 1, Week of February
DEBRA JARVIS - Edited
2/27/2006 11:01 AM
Yes, Mark, your posts are a work of
I'd like to pick up on the last part, where there is no activity in the
rest of the Conus.
First of all, I'd like to take some pieces from the SPC Fire Wx Outlook
Day 1 and Day 2 Outlook at
excerpts outline the winds, low RH and higher than avg temps we're
experiencing in the Central Plains.
0211 AM CST MON FEB 27 2006
...CRITICAL FIRE WEATHER AREA 1 - NWRN TX ACROSS OK AND INTO SWRN MO
/ NWRN AR...
PRIMARY CONDITIONS: STRONG SWLY WINDS / WARM TEMPS AND MODERATELY
FIRE THREAT WILL INCREASE TODAY DUE TO STRONG SWLY WINDS AND WARMING
TEMPERATURES. SUSTAINED WINDS OF 20-25 MPH WILL BE COMMON WITH
HIGHER GUSTS. AREA FROM SWRN MO ACROSS OK AND INTO NWRN TX MAY SEE
RH LEVELS DROP BELOW 30 PERCENT AT PEAK HEATING...LOWER THAN
FORECAST BY MOST MODELS...WITH LOWER VALUES FARTHER W INTO THE TX
PANHANDLE AND ERN NM WHERE WINDS WILL BE A BIT LIGHTER. SOME HIGH
CLOUDS MAY HAMPER HEATING IN AREAS BUT AGAIN STRONG WINDS WILL BE
THE MAIN WX PARAMETER DRIVING THE CRITICAL AREA.
0308 AM CST MON FEB 27 2006
...NEB / KS / OK/ NWRN TX...
IT WILL BE A WARM AND WINDY DAY OVER MOST OF THE CENTRAL AND SRN
PLAINS TUESDAY WITH DOWNSLOPE FLOW ALOFT AND UPPER RIDGE AXIS
OVERHEAD. WINDS WILL NOT BE AS STRONG OVER OK AS PREVIOUS DAY...WITH
SPEEDS NEAR 15 MPH WITH HIGHER GUSTS LIKELY. FARTHER N...WINDS WILL
BE SIMILAR WITH ABNORMALLY WARM TEMPERATURES INTO THE 70S OVER KS
AND WRN NEB. CRITICAL AREA OVER NM AND TX MAY BE EXPANDED FARTHER N
AND E NEXT DAY 1 IF CONDITIONS WARRANT.
At present, the middle of the country is experiencing 20-25 kt SWrly
winds, low RH/Dewpoints, and above average temps. The 850 winds CompMap
is attached, valid 9:00 am CST this morning. The focus of the alerts
are all around us in KC, but I assure you, they are relevant here as we
are experiencing the same conditions. We're looking to perhaps break
the 1932 record high of 78 degrees F tomorrow, and higher (80 is
forecast) on Wednesday, before a low-key non-precip front moves through
to cool it down for a high of only 10 degrees F above normal Thursday
(56). The Surface Analysis valid 6:00 am CST Wednesday is attached to
show the frontal position.
I looked at the prog loops, which really don't give much hope for the
The NGM prog loop shows the extremely dry conditions as noted by the low
RH. It also shows the Low moving over us then petering out at 36
hours. Of interest is the 48 hour still, which shows higher RH moving
in for the morning of March 1st. However, this is the day we're
expecting the highest temp and no frontal passage to cool us off until
late Wed/early Thurs. This bears watching for timing.
The ETA shows the Low petering out at 30 hrs, and the low RH becoming
moderate at 54 hrs and low again at 66 hrs.
The AVN prog has the Low coming in at 42 hrs and petered out by 48 hrs.
The low to moderate RH moves around more on this prog, going back and
forth, but staying relatively low up to 96 hrs, which of course is too
far out to count on.
Back to the Fire Alerts, I urge you to take a look at the graphics.
With the lack of rain and no end in sight, I expect to see the red
circled area grow to include the Kansas City metro area and perhaps
parts of Nebraska and Illinois before too long.
re: Briefing #3, Week of February 27
DEBRA JARVIS-FERGUSON - 3/1/2006 12:56 PM
Looks like today the freezing
rain threat has moved east into the Ohio Valley. See Surface
Analysis (1) for today, as well as Current Surface Analysis for
15Z (2) today.
Here is the excerpt from the Convective Outlook for the Ohio
1028 AM CST WED MAR 01 2006
VALID 011630Z - 021200Z
...NO SVR TSTM AREAS FORECAST...
...OH VALLEY AREA...
SHORTWAVE TROUGH NOW MOVING THROUGH THE NRN PLAINS WILL
ESEWD INTO THE GREAT LAKES AND MIDDLE MS VALLEY LATER TONIGHT.
LOW LEVEL JET WILL INTENSIFY IN ADVANCE OF THIS FEATURE ACROSS
TN AND OH VALLEYS. RESULTING THETA-E ADVECTION WILL CONTRIBUTE
DESTABILIZATION WITH MARGINAL MUCAPE POSSIBLE. ISENTROPIC LIFT
WARM ADVECTION ACCOMPANYING THE INTENSIFYING LOW LEVEL JET
LIKELY RESULT IN THE DEVELOPMENT OF ELEVATED
OF E-W BOUNDARY CURRENTLY EXTENDING ACROSS SRN PARTS OF THE OH
You can see the trough extending from Low to Low on the attached
12 hr Forecast Surface Analysis for 1635Z today (3). The "slush
line" (4) (0 degree C isotherm) is running through the affected
area, lowering in latitude slightly as it lowers in altitude,
showing that warmer layer for the snow to melt through, but at
2m sufficiently cold to freeze the rain on contact.
The 300 mb winds (5) show the Ohio Valley in the right entrance
region of the jet streak, allowing for divergence aloft to
foster convection. I haven't been impressed with the 850 mb
wind charts, as the models don't appear to show the LLJ picking
up over this region. However, the 850 mb Analysis (6) from the
Mesoanalysis Pages shows the WAA coming in on those winds from
the SW and WSW. The maps for Theta-e and MUCAPE didn't show me
anything yet, though.
re: SEVERE WEATHER TODAY
DEBRA JARVIS-FERGUSON - 3/8/2006 01:32 PM
The attached document is a copy of all the SPC Convective
Outlooks from yesterday evening through early this morning, as
well as our local NWS Forecast Discussion. I want to focus on
the possibility of severe storms for later this
afternoon/evening in the KC forecast area. Here is the excerpt
from the local NWS in Pleasant Hill, MO:
FOR TODAY I KEPT CATEGORICAL POPS FOCUSED ACROSS THE NORTHEAST
OF THE FORECAST AREA...WHERE 850MB THETA-E ADVECTION WILL BE
MOISTURE ACROSS THE FRONT. BOOSTED TEMPERATURES SOUTH OF THE
EXPECTED FRONTAL POSITION LATER THIS AFTERNOON. THIS WILL GIVE
STORMS THAT SPARK IN KANSAS A GOOD GROUNDING IN THE BOUNDARY
HOWEVER...BOTH THE GFS AND NAM INDICATE SOME DRY AIR WORKING ITS
IN UNDER THE 850MB LOW THIS AFTERNOON. SO THOUGHTS ARE THAT
LOCATIONS SOUTH OF I-70 WILL WARRANT ONLY CHANCE POPS BY THIS
AFTERNOON. THOUGH...ANY STORMS THAT FORM AND MAKE IT INTO
KANSAS AND WESTERN MISSOURI WILL HAVE A DECENT CHANCE AT
SURFACE LOW WILL BRING A COLD FRONT WITH IT INTO THE AREA BY THE
EVENING HOURS. ANY ACTIVITY THAT GETS GOING TO OUR WEST AND
SOUTHWEST WILL HAVE AMPLE OPPORTUNITY TO MOVE NORTHEAST ALONG
AHEAD OF THE FRONT ACROSS THE SOUTHWESTERN HALF OF OUR FORECAST
AREA. HAVE ADJUSTED CATEGORICAL POPS TO REFLECT THIS EXPECTED
PREFRONTAL ACTIVITY. SEVERE WEATHER CERTAINLY IS A
WITH LARGE HAIL AND DAMAGING WINDS THE PRIMARY THREATS.
Okay, Forecaster Cutter focuses on theta-e advection, moisture,
850 mb conditions, and hail in those two paragraphs. I have
attached some images related to those areas (pardon that they're
not numbered, but I have in mind using them if we do have a good
outbreak this evening). Before we get into the images, I've
also attached the Forecast Surface Analysis for today, as well
as the Forecast Fronts for 12 hrs and 24 hrs - we want to focus
on the 24 hr one, since it forecasts for 6:00 pm CST this
I focused on two areas: east-central Kansas and central
Missouri. I'll tell you why in a minute. Notice where the
frontal boundaries are located. The baroclinic zone of the cold
front is just on and behind the east-central Kansas position,
and the central Missouri position is under the warm front.
There isn't much theta-e illustrated on the attached graphic,
but what's there is mostly in the Kansas area. The moisture
convergence on the two attached graphics also show the most
being in the Kansas area. The 850 mb Analysis chart shows
dewpoints encompassing more of Missouri, though there is a
pretty tight dewpoint gradient just north of the east-central
Kansas area. The 850 WAA and winds is favorable for both
Now for the extras. If I'm reading it right, the deep moisture
convergence (red lines) is situated between the two areas of
concern, with convergence ongoing in the areas cited. I need to
read up on how to interpret this, so will leave it for others to
add onto (fodder for discussion).
I attached a chart of hail parameters, though we haven't covered
it in the lessons yet. It clearly shows areas of 200 marked in
red - I'm thinking these are favorable areas for hail to reach
the ground? If so, then it covers the two referenced areas
MUCAPE shows values of 1500 in both areas, but on SB-LI-CINH,
lifted indices show values only in the Kansas area. And as a
final note, the Supercell Composite addresses only the Kansas
area, as well.
What I didn't attach were all the numerous other graphics for
various levels, RH, AbsV, dewpoints, temps, shear, QPF (favored
MO), lapse rates, SLP, etc. I looked at all of these, however,
and compared KS vs. MO. Without going into detail, most of
these graphics favored activity developing in the Kansas area.
THEREFORE, based on all of that, my personal forecast is for
some strong storms to develop around the Topeka area and north
in the afternoon, with a few isolated cells perhaps developing
later in the Missouri area from the state line toward central
MO. Any line of storms will move SW to NE with the 850 mb and
300 mb winds (SW and W, respectively).
Conclusion: The KC metro area will most likely experience some
strong storms, with heavy rains and some small hail possible
this afternoon through this evening.
Is that what you were talking about, David? Now I know what
forecasters must feel like - it feels like going out on a limb
and trying to stand in the wind!
And I must add, since I've been
out of commission working through these images and on this
reply, they've issued a tornado watch for our area, which
encompasses the upper portion of both of my areas of concern and
north to include the KC metro area. Also, MD #188 puts the
reasoning behind this - I glanced before replying here, but
already see things I missed that warranted action on their part.
I'll try to address that,
Steve. First I want to say that many of the factors I cited
have changed from 14Z to 19Z. Where I saw no values or readings
in Missouri earlier, I now see that many variables on a number
of the graphics have moved over into Missouri (some have grown
to include that area, and some have moved over to that area).
Again I'll attach theta-e/advection, moisture convergence, 850
mb conditions (analysis and WAA/winds), MUCAPE, SB LI-CINH, and
Supercell, plus Temp/Td/Winds and Significant Tornado.
Man, things changed so fast! The theta-e went from nothing to a
value of 20 just SSW of KC. Impressive! We're currently
sitting at 73 degrees F, and the dewpoints have climbed this
afternoon to a reading of 62 F now. The Deep Moisture
Convection has moved out of Kansas and into Missouri and
northern Arkansas, with readings of 2-4-6 east and northeast of
KC - I'm looking at this as a part of the setup for later this
evening. The hail parameters have changed to a 200 reading more
concentrated on the KC area (just to the northwest of the
city). Surface moisture convergence now has a reading of 10
over the city and 15 where the 200 hail parameter reading is
located, with a mixing ratio of 11 around the forecast area. On
the T-Td-Winds chart, look at that reading of 80 degrees F in
Kansas just outside the western edge of the 200 hail
parameter/15 smc area! Dewpoints are still climbing, as they're
already showing higher than on this chart at 19Z. Lifted
indices of -4 in that same area, and just over the state line
southeast of KC in MO show a shift from only in Kansas earlier.
That's promising for tornadogenesis. MUCAPE of 1500 in that same
area northwest of KC and 1000 in the general forecast area look
good for severe tstorm development.
The Supercell Composite noticeably moved over onto the KC area,
showing readings of 4 and 6 - really want to know what that
means, but see it as favorable for supercell development. And
last, the Significant Tornado graphic has moved the readings and
shaded area way over to include the KC area and a good portion
of Missouri - don't know yet what these readings mean, either,
but they must be favorable - and therein lies the Tornado Watch
As to why a TDWatch was issued instead of a STstormWatch, I'm
thinking it's because they already see the favorable conditions
for possible tornadoes to develop later (the watch lasts until
8:00 pm CST), but severe tstorm watches won't go out until some
storms have formed and show rapid development toward severity.
And now the watch that included
northwestern Arkansas is gone. Only remaining watch is in north
Texas - so we go back and look at all the stuff again for that
re: Weather Briefing #2 Week of March 13
DEBRA JARVIS-FERGUSON - 3/14/2006 03:17 PM
The good news is
that the storm system that brought all the severe weather over
the Midwest and Southeast for the past few days is finally
exiting the east coast into the Atlantic. The attached Current
Surface Analysis for 15Z today shows the position of the low,
with a trough extending from the center down across the Great
The lake-effect snow occurring east of Lakes Erie and Ontario
appears to be tapering off, with snow in Pennsylvania and New
York. The attached 500 mb plot from the eWall shows mid-level
jet winds from the southwest blowing in across this area. The
third attached image shows the strong 300mb jet aligned with
these mid-level winds. I look for precip to taper off this
evening/overnight with the low exiting the region.
California has a pretty good rain cell over the San Fernando
Valley right now. There is a tornado warning just issued for
Sacramento, San Joaquin and Solano counties - a tornado has been
indicated by Doppler near the city of Walnut Grove. See
attached MD #293
the TW has not been posted on SPC yet (I got it from TWC). It
will be intersting to see how this pans out when it reaches the
Midwest. The attached AVN prog loop
shows the vort max for this low moving over the upper Midwest;
however, keep the loop going and watch the deep trough form and
bring massive precip into the weekend and next week. I know
that's too far to forecast properly, but isn't it exciting to
watch?! The NGM and ETA show the trough forming, as well,
though they don't go out as far to show its possible
Attached 4, 5 and 6 are some areal radar stills for the
southeast, northeast, and California. We should keep a watch on
that California tornado.
12 Outbreak - Preliminary Storm Reports
JARVIS-FERGUSON - 3/15/2006 10:58 AM
The NWS teams
have done their damage surveys and come up with the Fujita
classifications and number of tornadoes from Sunday's outbreak - 14: 7
F0s, 1 F1, 5 F2s, and 1 F3. There were 3 phases of outbreaks - the
morning storms that Lee noted elevated convection within, afternoon
storms, and evening after-sunset storms, which were the most severe and
I failed to catch images for due to too much lightning. ;(
I'm getting clarification from Don Harman at FOX4 on the length of the
path of the F3 - it traveled through 3 counties. I believe it's 45
miles. Also, there were 9 fatalities reported, but I only count 6 in
this report: 2 in the afternoon storms and 4 in the evening storms
(1-Sedalia, 1-Urich, 4-Renick).
In addition, Dr. Greg Forbes of TWC reported yesterday that there was
one cell that formed at the Oklahoma/Kansas border and managed to stay
intact and rejuvenate, spawning several tornadoes, all the way to
Please look at these links - this is fascinating stuff, guys, happening
right as we're studying it (just like last semester's hurricanes).
Fox 4 Weather Blog (has a couple of tornado pics!):
NWS Pleasant Hill Storm Report:
SPC Storm Report updated:
re: Weather Briefing 2, Week of March 27
DEBRA JARVIS-FERGUSON - 3/29/2006 02:53 PM
Greetings, everyone. Looks like another severe event is setting up to
occur in the midwest tomorrow. This won't be on the magnitude of the
outbreak, but hail, damaging winds, and isolated tornadoes are
possible. This from the 1630Z Day 1 Convective Outlook
GREATER THUNDERSTORM COVERAGE AND OVERALL SEVERE THREAT IS EXPECTED
TO INCREASE THIS EVENING/CONTINUING OVERNIGHT AS STRONGER UPPER
FORCING/HEIGHT FALLS SPREAD INTO THE PLAINS STATES WITH THE APPROACH
OF THE GREAT BASIN TROUGH. STRENGTHENING SLY LLJ WILL MAINTAIN NWD
TRANSPORT OF MOISTURE BENEATH STEEPENING LAPSE RATES FOR SUFFICIENT
ELEVATED INSTABILITY SUPPORTING STORM ORGANIZATION GIVEN FAVORABLE
EFFECTIVE BULK SHEAR. PACIFIC FRONT IS EXPECTED TO MERGE
WITH/OVERTAKE THE DRY LINE ACROSS WRN PORTIONS OF THE PLAINS LATE IN
THE PERIOD. HAIL WILL BE THE PRIMARY THREAT OVERNIGHT AS ONE OR TWO
MCS/S EVOLVE ACROSS THE SRN/CENTRAL PLAINS.
The eWall Progs show the 500 mb trough and low pressure center currently
on the west coast moving over the midwest by 30 and 36 hours (attached
1-6). Note how the pressure gradient gets larger with time, indicating
higher winds. After 36 hours (at 42 and 48 hours, not attached), the
progs show the low deepening and the precip becoming better organized as
it heads over the eastern U.S. and Great Lakes regions toward the
northeast. It moves pretty fast, and any severe weather that occurs
will be shortlived. I chose the 30 and 36 hr progs as they represent
the time of the forecast threat (Thursday afternoon and evening) for the
The 300mb maps (att 7&7) show the jet streak moving into place in 30
hours, and fully in place at 36 hours for the Kansas City area to be in
the favorable left front quadrant. Lifted indices (att 8) of -4 also
show favorable conditions for severe thunderstorm probability. And the
moisture flow of 850mb WAA at 40-50 kts both at 30 and 36 hours (att
9&10) brings the next important factor into play for probable severe
storms to form.
The forecast surface analysis for 36 hours, valid 00Z Mar 31 2006, or
6:00 pm CST Thursday, shows the warm front moving through and sitting
just northeast of the KC area, with severe thunderstorm potential in a
comma from eastern Nebraska and Iowa down through Missouri into
Oklahoma, clipping the northwest tip of Arkansas (att 11).
Att 12&13 are Skew-Ts for 30 and 36 hours, which show a moistening in
the boundary layer and an inversion forming at 825-800 mb (depending on
whether you look at ETA or GFS). CAPE appears to be favorable here.
We're currently at 68-70 degrees F, and forecast for higher tomorrow.
If our dewpoints rise sufficiently, we should be good to go. Our
dewpoints are currently low, but the winds, though light, are out of the
southeast from the Gulf.
In short: Low + 500mb Trough + 850mb WAA/Moisture + 500mb Vorticity +
-4 LI = severe thunderstorm probability.
re: Weather Briefing 3, Week of March 27
DEBRA JARVIS-FERGUSON - 3/30/2006 01:17 PM
It's definitely set up for possible severe activity this
afternoon. The radar shows the precip in central Kansas
developing and moving ever closer to the KC area as the morning
There are also storms firing up and eliciting warning boxes in
Oklahoma right now.
The synoptic setup is warm Gulf air, a dry line ahead of a low
pressure frontal boundary, and cold air aloft coming in on a
strong jet. The attached Composite Map shows this set up.
The local NWS Pleasant Hill Forecast Discussion gives a lovely
overview of this synoptic setup and the expectations for later
on this afternoon and this evening.
And the MD 361 gives the tornadic overview - I need to read it
more closely, but upon a glance I saw that it mentions LARGE
CLOCKWISE CURVING LOW-LEVEL HODOGRAPHS!
When Dr. Greg Forbes gets involved, things always promise to get
exciting. He has already come on TWC to show the synoptic set
up and its similarities to the March 12th Outbreak. Tornado
warning just issued for Central Kansas, NE Ellsworth County and
NW Saline County.
Convective Outlook for Day 1:
Weather Briefing 1 Week of April 2 2006
DEBRA JARVIS - Edited 4/3/2006 11:28 AM
Mornin' (I never say Good Morning because that's an oxymoron to me).
Pardon my lateness - didn't change the bedroom clock.
I'm not going into the storm reports for yesterday's potent tornado
outbreak in IL/TN/KY, as I think that's fodder for someone (maybe even
me) to do a post mortem later today. It was a big one, guys.
Attached is the Forecast Surface Analysis for today, the Current Surface
Analysis and 12 hr Forecast Surface Analysis valid 12Z today, and the 24
hr Forecast Surface Analysis valid 00Z Tues, or 8:00 pm EDT. The severe
storm area has moved toward the eastern coast, with a tornado watch in
effect for N GA/W NC/W SC until 11AM EDT (TD #145) and for NE KY/E OH/W
PA/N WV until 5PM EDT (TD #146). MD #417 and MD #418 go along with
these watches, and mention elevated tstorms in NC/SC (we need images for
water vapor, shear, ascent, lapse rates, instability, hail) and the
upper low near WV (we need images for the trough, visible satellite,
destabilization, temps aloft).
The SPC Convective Outlook has the area of moderate risk and highest
percentages of tornado/damaging wind/large hail in the Carolinas. It
mentions that the trough is moving ENEwd today, with a strong mid-level
jet and 40-50 kt effective shear (we need images for the jet and the
shear, as well as the trough). It also mentions low-topped tstorms in E
Now notice there's an occluded low coming onshore in the Northwest, with
pockets of heavy snow forecast for the mountain areas, and rain in the
lower elevations from Washington to California and over to the Rockies.
This is our next weather maker, slated to affect the midwest Thurs/Fri
with another chance of severe storms. Anyone want to take up the prog
analysis and tell us what's up for the near future for the west coast
into the midwest?
Weather Briefing 2 Week of April 2 2006
DEBRA JARVIS-FERGUSON - 4/4/2006 09:52 AM
I have to post quickly as I have a meeting in 15 minutes, but can come
back after an hour and post more in depth.
At present, the Convective Outlook lists three areas to be watching:
California (especially here, with the front coming onshore which will
affect all of us sometime during this week); Florida (the tail end of
that nasty system that wreaked havoc in Tennessee on Sunday); and a
piece of energy in the midwest connected to an 850 mb LLJ.
Though we need to pay attention to the Florida exiting system and the
possible surprise in the midwest to see if anything develops, I'd like
to focus on the west coast and large system that even as we speak is
bringing alot of precip in the whole western section of the country.
There are currently no MDs in effect and no watches or warnings. Here's
a satellite view (IR Enhanced) of the west coast and central/east coast
from GOES (attached).
When I get back, I can look at some progs and see where we're going from
here. However, feel free to jump on that bandwagon and get the wagon
train started down the trail.
Phil - I have attached an OSEI satellite image for you of the storm
system last Sunday that hit Tennessee so hard.
Be back in an hour.
Reply to this message
re: Weather Briefing 2 Week of April 2 2006
DEBRA JARVIS-FERGUSON - 4/4/2006 12:17 PM
Okay, I'm back. I see everyone waited for me. :)
I've attached the Forecast Surface Analysis for today, along
with the 12Z Current Surface Analysis and 24 hr Forecast Surface
Analysis valid at 7:00 pm CDT this evening.
The low pressure system is exiting the CONUS in the northeast,
though still bringing showers to Sarah in Maine. That's about
the longest trailing front I've ever seen, and it's about to
exit the tip of Florida. High pressure is dominiting the center
of the country at present, though I want to point out the area
of thunderstorms in central Texas. Let's take a look at that:
Looking at the SPC Comp Maps, there's a 400 helicity value in
this area, with 45-50 kt shear, a bit of 850 mb WAA coming up
from Mexico (where the dewpoints are higher than in Texas right
now), and a westerly 300 mb flow all converging over this area.
Anyone want to take this up further?
By 7:00 pm CDT this evening, the northeast exiting low is
bringing some snow to northeast Canada and Maine, and the warm
front is spreading across central Texas. Look at the west coast
- rain, rain, rain, and snow in the higher elevations. I
encourage you to look at the loops on the eWall for ETA
and for NGM
(AVN is in the process of updating
This is a potent low pressure system - it becomes a closed low
at 30-36 hours, and brings ample precip to the midwest right
about drive time for us conference attendees. This moves into
the Ohio Valley Friday (just in time for our own convergence).
I encourage someone to take up this thread and provide more in
depth images for this storm system.
Look at this loop for the 500 mb Ensemble Forecast - I wanted to
point out the huge trough and vort max that travels across the
Two things in closing, then ya'll take up the talking stick:
1. There's heavy flooding ongoing in North Dakota and Minnesota
on the Red River (Grand Forks and Fargo) and the Wild Rice River
(Abercrombie). The expected crest of the Red River is 39' (or
at least, that's what they have sandbagged for). I got this
from a live report from Moorehead, MN on TWC. And more precip
2. Updated storm reports are available at SPC's Storm Reports
We're up to 819 total storm reports, 64 tornado reports. I'll
let Phil update us on the post mortem field analysis - the
Memphis NWS site has an updated report with storm photos, but
field analysis is still ongoing.
re: Weather Briefing 2 , Week 4/10/06
DEBRA JARVIS-FERGUSON - 4/11/2006 12:41 PM
There is a good setup for tstorms this afternoon here in the
KS/MO area, but our dewpoints are a concern - and notice the low
RH on the prog you attached.
Look at the low dewpoints as of this morning at 7:00 am CDT
(1). It's currently 71 F with a dewpoint of 53 F. 16Z
Dewpoints (2 & 5) are still low, though climbing. Besides
surface obs and dewpoint, I've attached the 850 mb WAA and 300
mb winds compmaps (3 & 4) - we have a stiff wind at 20-30 mph
with higher gusts.
The slight risk area is in Nebraska/Iowa, but the numbers are
tending to favor the southwestern Wisconsin area. See the
attached MUCAPE-LPL Hgt, Effective Shear, Effective SR Helicity,
LCL-LFC RH, and the Supercell Comp Parameter for 16Z - all the
higher values are lined up on the southwestern corner of
Wisconsin. The LI for this area is a -2, with mid-level lapse
rates of 8.5.
All of that aside, there are spotty areas of convection
developing right now - a line of rain from Texas up to central
Kansas, Nebraska/Iowa border, Colorado/Nebraska border, and a
line forming to the northwest of the targeted Wisconsin area
outlined above. Oh, yes, and a little piece east of the KC
See Base Reflectivity attached (11).
re: Weather Briefing 3 - WEEK OF APRIL 17
DEBRA JARVIS-FERGUSON - 4/18/2006 06:04 PM
I think with MLCAPE of 3000 j/kg, CIN of -50, and LI of -9 in
the central Missouri area, the Tornado Watch
issued for this area and points north, east and south (alot of
east) is well warranted. Mark's right, though - we don't have a
lot of jet aloft right now. But look at the 850 mb WAA - and
the dewpoints are quite juicy!
MD#543 thinks stronger winds aloft/ascent will develop soon (I
was about to say around 4 this afternoon, but it's now 4:52
CST!). Here's their consensus:
GIVEN INCREASING MID-LEVEL FLOW ATOP SLY/SELY LOW-LEVEL FLOW...
VERTICAL SHEAR OF 35-45 KTS WILL EXIST BY LATE AFTN. COUPLED
2000-2500 J PER KG MLCAPE...STORMS SHOULD QUICKLY GROW INTO
SUPERCELLS WITH LARGE HAIL AND DAMAGING WINDS. A TORNADO OR
WILL BE POSSIBLE...PRIMARILY IN A NARROW ZONE VCNTY THE WARM
IN THE CHILLICOTHE-COLUMBIA-ST. LOUIS ZONE. TSTMS SHOULD
GROW UPSCALE INTO AN MCS BY EARLY/MID-EVENING AND DEVELOP/MOVE
ALONG THE WARM FRONT TOWARD THE LWR OH/MID-MS VLY.
Watch out, Tennessee -- again.
Notice the MLCAPE they're looking at -- it seems to have jumped
up a notch since they issued this MD.
The Current Surface Analysis from 18Z (all the other attachments
are from 21Z) shows the position of the front - we're in the
'armpit' or the triangle of the warm front, dry line, and cold
re: Weather Briefing 2, Week of April 24
DEBRA JARVIS-FERGUSON - 4/26/2006 01:05 PM
The far southeast is experiencing the last of that strong cold
front that's been leaving its mark across the country all week
(see 6 Curr Surf Anal 15Z). It just started raining in Atlanta
(info courtesy of TWC!). MD #669 from the SPC says they're
monitoring the situation for the possibility of needing a WW, as
a "more vigorous cluster of storms" is developing in the
Alabama/Florida coastal region.
The MD mentions high dew points (upper 60s), fairly high MLCAPE
(1000 j/kg), and about 2" of precipitable water (1.7-1.8), so
I've attached those charts for 16Z. The Hail Parameter chart
doesn't show much potential for hail due to low CAPE and lack of
shear vectors in the Florida Panhandle.
Last is an image of the current 1622Z radar showing the cluster
of storms in Alabama/Florida and over the Gulf. Current radar
shows little movement of this cluster to the east.
You can also see the line of storms west of Atlanta. CAPE here
is at about 100 as you move east, with shear at 45 knots on the
Hail Parameter. MLCAPE of 500 and 1.4 precip water indicates to
me that the Florida Panhandle will experience more heavy rain,
with the more severe potential (hail and damaging winds) in
northern-central Georgia and North and South Carolina.
re: Brief diversion from mesoscale to synoptic scale pattern
DEBRA JARVIS - Edited 4/28/2006 11:07 AM
It's great for us here in the heartland, too, in that we've badly needed
the rain and now, with the cut-off low sitting right on top of us by
Sunday, and vertically stacked to boot, we are in for about a day and a
half of steady showers/storms. This should help the moderate drought
condition we've been in lately.
At present, rain has moved into the area a bit earlier than
anticipated. I drove to work in a thunderstorm this morning - joy,
This should set in this afternoon and, with slight intermitence, run
through Sunday. The models are predicting 2-5+" around the area total.
I'm attaching a link to our Channel 41 weather blog, where Gary Lezak
has already posted 3 500 mb charts that outline nicely the progression
of the upper low from Baja to its vertically-stacked and closed position
over KC MO by Sunday morning. He accompanies it with the surface
pressure at Sunday morning - the surface low is sitting right on top of
us, as well.
(scroll down to April 27)
Weather Briefing - Synoptic Scale for April 28, 2006
DEBRA JARVIS-FERGUSON - 4/28/2006 12:10 PM
Greetings, fellow travelers.
We have a lovely low pressure system spinning over Arizona at the
present time (1 IR Sat and WV and 2 Curr Surf Anal). This low is
working in concert with cold air aloft and a LLJ through Texas (SW-NE)
to bring some storm activity to the Texas Panhandle area. Moore County
was put under a severe thunderstorm watch about 30 minutes or so ago.
Okay, I got a bit off on my numbering, but the titles are at least
explanatory enough. I attached 3 images of 500 mb flow showing the
progression from this morning to Saturday morning and ending at Sunday
morning. Look at that classic closed low over KC on Sunday!
Alright, moving along, I've also attached the 850 mb, 500 mb, and 300 mb
charts from the Comp Maps on SPC. I wanted to illustrate the low level
jet bringing in the high theta-e air (chart 6 attached) as well as the
upper level jet with the jet streak sitting just to the southwest of the
Texas Panhandle (favorable for strong upper-level divergence). The 500
mb Comp Map shows the trough and closed-low (already closed here) with
the mid-level flow coming in from the southwest into the TX Panhandle.
I attached the Theta-E advection chart (all Comp Maps are for 15Z) to
show the profusion of warm, moist air moving into the TX Panhandle. I'd
like someone to take it from here to show the CAPE, 0-6 km Shear, and
LI, as I looked at those and thought they looked pretty interesting.
[Lee - where do those "500 mb flow" charts with the pretty colors come
from? I took them from the weather blog because I couldn't find my