Tuesday, September 13, 2011

Short to Medium Range Rainfall Update and Long Range Tropical Outlook...

As mentioned in a post yesterday, a widespread rain event is expected to unfold beginning later tonight through at least Saturday across portions of the Central & Southern Plains.  

The image below is the total rainfall forecast from the GFS model, valid for the same general time period:

I've taken the same image and annotated the heavier rainfall forecast totals for greater emphasis on the image below:

As you can see, a total of 2-3 inches of rain is forecast within the red shaded areas across portions of the Texas panhandle and northern Oklahoma, as well as along the Arkansas/Missouri border region.  Some of that rain will come at the tail end of the model's forecast period (Tuesday the 20th), however much of it will fall prior to that time, from Wednesday through Saturday.

Looking further into the future, it continues to appear as though much of the main body of the state of Texas will have an opportunity for at least some rainfall on Tuesday and Wednesday of next week (the 20th-21st).  The latest GFS image valid 7pm Tuesday the 20th shows widespread rain, albeit light, across a good part of Texas and Oklahoma ahead of a weak cool front:

The unfortunate fact in this latter case is that computer models continue to indicate that this disturbance will be moving rather quickly, which will limit total rainfall to likely one-half inch or less across Texas.  At this point, however, beggars can't be choosers, and I know we'll happily take whatever we can get next week...

There are some interesting signs in the longer range that suggest that portions of Texas may have a chance for more significant rainfall during the last week of September (particularly during the period from the 24th-27th).  The details on this are still not clear, but there has been increasing consistency in this possibility indicated by the last few computer model runs.  I will continue to monitor this closely and provide you with more concrete details as they become available...

Another interesting element of the longer range forecast (also for the last week of September) is the GFS model's insistence on a hurricane impacting Florida during that time period (see the latest GFS forecast model image valid 7am CDT Tuesday, 9-27-11, below):

While it's obviously way too early to tell whether or not the above scenario will come to pass, I must point out that the overall weather pattern does suggest that steering currents will be in place which favor a tropical threat across Florida or elsewhere along the Southeast U.S. coast as we approach the last week of September.  Stay tuned for updates!

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