In my last blog entry, I wrote about the rapid ramp-up in activity that typically occurs the first week or two of August. It now appears that the next named storm of the 2010 season is taking shape in the eastern Gulf of Mexico. A feature that we identified as Tropical Disturbance 34 last weekend is steadily becoming better organized just west of the lower Florida Peninsula.
Although a recon plane is scheduled to investigate the disturbance this afternoon, I really don’t think that they’ll be able to find out anything that we don’t already know. The disturbance is located in an area that has plenty of good surface observation stations. These stations indicate that there is no question it has a low-level circulation center, a requirement for classification as a tropical depression. Winds around the low center are in the 20-25 mph range, too low for tropical storm strength. Thunderstorms around the low center remain a bit weak and are situated mostly south of the center, a sign of somewhat unfavorable winds aloft. But recent satellite imagery does indicate that upper-level conditions are steadily becoming more favorable for development.
The bottom line is that though this disturbance may not fully meet all of the criteria for classification as a tropical depression at present, we think that it’s well on its way to becoming a depression by tonight and the fourth named storm of the 2010 hurricane season tomorrow. Its name would be Danielle. The next questions would be where will Danielle most likely track and how strong could it get.
Below is the latest model guidance for the disturbance. Models have been in very good agreement for days now that the disturbance would track generally toward southeast Louisiana. We agree, and or track (in dark blue) is similar to most of the guidance though a bit south of guidance to start out with and a little east of guidance across eastern Louisiana. It’s a tough call as to exactly where it might move ashore. The current slow westward movement could even increase the risk that it might move inland toward the central or even southwest Louisiana coast.
As for its intensity at landfall, model guidance appears centered around maximum sustained winds of between 50 and 60 mph at landfall. Basically, a moderate tropical storm. I am concerned, though, that conditions may become quite favorable for strengthening in the last 12 hours before it reaches the Louisiana coast on Thursday. In that case, intensification could be quite rapid as it’s making landfall. So it’s not out of the question that it could reach hurricane strength as it approaches the coast. I estimate those chances at roughly 30%.
The good news is that with a limited region of moisture and favorable winds aloft, the storm is not likely to be very large. It should be average or a little below average in terms of its size as a tropical storm. If it reaches hurricane intensity, then its size would be smaller than average. More than likely, any hurricane force winds would be confined to squalls over the water rather than inland over southeast Louisiana.
Ah, I see that the recon plane just left Keesler AFB in Biloxi a few minutes ago (11:08AM CDT). With only a short distance to travel to get to the disturbance, it won’t be long before the plane is near the center.
