Tuesday, August 16, 2011

Could an end-of-August hurricane head for the U.S.?

Looking into the next two weeks toward the end of August, there has been indication over the last several weather computer model runs that a tropical system may move from the Atlantic through places like the Dominican Republic, Haiti and Cuba before heading toward southern Florida by August 27th (and riding inland up toward Virginia as a weakening cyclone by the 29th?). As weather forecasters right now in the CBS 6 Storm Team, we'll keep looking at each new data set from the model runs to check for "consistency" of the hurricane's existence, track, and timing. We'll also look at a suite of models for comparison to see if the various potential scenarios look similar. This far in advance if we continue to see consistency of this potential hurricane, then we can have higher confidence in the storm affecting the U.S. the last few days of August. Here is just one (GFS 06Z model run today) representation of that potential hurricane on Saturday, August 27th:

What you see there over Florida will likely in reality be different by the time we get there...but it's definitely something to which we as forecasters are already paying close attention.

Based on tropical cyclone climatology in the Atlantic Basin, you can see that late August into September is when we typically see most of our tropical activity. We are also past-due (statistically speaking) for our first hurricane of the season (See Table 1 below), which in an average season would have occurred by August 10th. As of this blog posting, we are through Tropical Storm Gert, our 7th named storm of the 2011 season (all storms of which have remained below Hurricane status).
Table 1: Progress of the average Atlantic season (1966-2009). Date upon which the following number of events would normally have occurred.

The point of formation for this potential late-August hurricane looks to be in the central or western Atlantic, which is a statistically active formation region of the Basin during that time of year:
Sea surface temperatures continue to remain highly favorable through the Atlantic, Caribbean, and Gulf regions, so no matter which way this system goes, it will encounter ample fuel for development and strengthening. Upper-level winds will continue to be our primary concern, as has been the case with every storm so far this season. Tropical Storms in many cases were inhibited from reaching Hurricane strength because of even the slightest shear. We'll need a low-wind-shear environment for this storm to get its act together.

You can learn about Virginia's long record of brushes or hits by tropical cyclones by clicking here.
Stay with CBS6, we'll keep you ahead of the storm.
--Meteorologist Carrie Rose

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