8am Sunday update on Debby

 Tropical Storm Debby is located in the eastern Gulf of Mexico, a little southwest of the Tampa, Florida area this Sunday morning. 

Debby continues to organize, and it has a shot of becoming a hurricane prior to a landfall early tomorrow morning in the Big Bend region of Florida.

As I was mentioning on air last week, the steering currents then collapse around Debby, and its motion will become very slow and erratic.  

As I see it, there are two basic ideas for how Debby will behave through the week. 

    1) Debby bends slowly north-northeast and crawls up near the Georgia, South Carolina, and then North Carolina coast through the work week.

    2) Debby bends to the east or northeast rather briefly, then gets pushed back westward well inland into Georgia or South Carolina and meanders through the work week. 

Either of these scenarios is plausible, but they have huge difference in the tangible weather for North Carolina. The European, most of its ensemble members, and the ICON model (ICON was very good with Beryl earlier this season) favor option 1. Below are the rain totals this week from those two models:

The GFS and the Canadian models favor the second, inland scenario. Here are the rain totals from those models this week:

I am ever-so-slightly leaning toward the up neat the coast scenario (option 1 above), but it is a slight lean and very low-confidence. We will have to continue to refine this forecast over the next couple of days. 

Below is the National Blend of Models rainfall output this week. A blend like this is the best course of action for now until we can get a better handle on the eventual track of Debby.

For the coastal Carolinas, please continue to closely monitor Debby's progress. It is well within the realm of possibility that a hurricane could work its way slowly up the coast through the work week, if option 1 is correct. 

For western and central North Carolina, if option 1 is correct, rain totals would be much more limited, and this would likely not be too big of a deal for that part of the state. However, if option 2 is correct, then flooding rains and a threat of tornadoes will be an significant issue by midweek. Stay tuned. 

Read more...