On the third day (click to open) of my week as briefer I once again switched my focus back to hurricane Helene as Gordon from briefing day number two had been downgraded to a tropical storm and Helene continued to be a hurricane force system with winds of 90 kts. Since the storm was also being affected by wind shear from the US East coast I had hoped to steer the discussion in that direction, as we'll see it did go that way, but several unexpected and very good items were brought into the discussion by others as well.

The first unexpected item to hit the discussion thread was the post by Philip Lutzak immediately after the briefing post which got us our first look at real, live actual vortex data message data from a current storm system as shown below:

Philip continued in the above posting to break down and decode the vortex data message and draw the conclusion that the storm was weakening rapidly due to the dry air the system was encountering as well as the shear that I had mentioned in my briefing.

Those views were shared by Barbara DeClerck in the following post, who also introduced us (ore at least myself) to a new term - "saddle point":

"Based on the QuikScat data at 18Z on 20 Sep, both the upper level winds (Helene_mid_level_winds.gif) and lower level winds (Helene_low_level_winds.gif) indicate that the storm is moving into a saddle point (light and variable winds) in both layers.  I think this indicates that the storm will lose its punch, slowing and getting caught up in the front approaching from the west."

Which as she explained to Philip Lutzak's questioning post following it was defined as:

"A saddle point is the intersection of two ridges and two troughs.  So, a constant pressure surface looks like a saddle (high in front and back, low on each side).  It's a very descriptive term, wouldn't you agree?  Saddle points tend to be more easily identified on streamline charts and are typically characterized by light and variable winds."

An excellent posting and very descriptive definition that added a new term to my meteorology vocabulary.

Shortly after this another angle was taken on the briefing, that of cooler upwelling water caused by sea turbulence generated by the previous storm system Gordon as mentioned and shown by David Williams:

This led me to another good learning point here:

Storms can be and are affected by other systems if they are trailing them or coming across the same areas of ocean soon after.

In this case the cooler waters stirred up to the surface by Gordon were adversely affecting the strength of Helene.

Overall, day number three proved to be just as instructive for me as the previous two. Although the discussion seemed to take on a path and life of its own at times, many excellent new facts and items were brought up by fellow classmates such as:

• Always be looking for data - in this case the vortex data messages that were seen and added by Philip Lutzak.
   
• Be alert to and ready to investigate new or unfamiliar terminology such as "saddle point" as shown by Barbara DeCLerck's posting.
   
• Remember to look at and consider how other weather events may affect what you are currently observing as is the case here with the cool upwelling caused by the previous storm (Gordon) that passed over this same area a short time earlier as was shown by David Williams.

Now that day three is done, lets continue on to day number four, Thursday September 21, 2006(click to continue), or click the following link to go back to Tuesday September 19, 2006..