Most Read: Local

Posted at 02:00 PM ET, 10/21/2010

Tropical Storm Richard blossoms in Caribbean

* NWS & AccuWeather: Winter less snowy | Sunny days: Full Forecast *

Welcome the 17th named storm of the 2010 hurricane season: Tropical Storm Richard. The National Hurricane Center (NHC) now expects Richard, to become Hurricane Richard by Saturday morning. The storm, about 220 miles southeast of the Cayman Islands, has maximum sustained winds of 40 mph. It is forecast to produce flooding rain of four to eight inches over Jamaica, with amounts up to a foot in the mountainous terrain.

In my post yesterday, we discussed how the swirl near the surface was divorced from the main complex of thunderstorms by more than 100 miles, and that this separation could not support the intensification of then 99L. But a cluster of very intense thunderstorms, about the size Kansas, developed last evening roughly 200 miles west of Kingston, Jamaica, very near the low-level vortex formerly called 99L.

This impressive flareup of towering storms (with tops above 60,000 feet) was not only able to help redefine the center of the circulation closer to it, it also helped to spin up 99L to tropical depression and, just today, tropical storm strength.

The environment surrounding Richard right now has not improved dramatically since yesterday, and for now remains relatively hostile to significant development. Strong westerly winds at high altitudes, carrying very dry air aloft, continue to filter in to the Western Caribbean. In fact, the dryness of the air on the northern and western periphery of Richard (indicated by the orange tint) is more notable in the satellite presentation this morning than it was yesterday.

The change in wind speed with height (vertical shearing of the wind) remains very high across all of the Gulf of Mexico and the Northern Caribbean. The yellow contours in the image below indicate that there is 20-40 knots (25-45 mph) of shear just to the north of TD19.

We may be seeing the impact of these unfriendly surroundings on Richard, as the complex of storms that helped create it last night seem to have weakened somewhat this morning.

However, and this is the big concern, there are indications that by the weekend the environmental flow will relax a bit. This is a significant reason why NHC predicts Richard will reach hurricane strength by then.

Of course, Richard will have to withstand the punishment inflicted by the dry air and wind shear during the next couple of days if it is to verify that forecast. We shall see. But perhaps more importantly, there are also signs that Richard will move northward near, or into, the Gulf of Mexico early next week, as a strong trough moves into the Central Plains and tries to pull it northward. The track forecasts are showing this possibility quite noticeably.

It is important to note that the southern Gulf of Mexico waters are still warm enough, throughout a deep enough layer, to support a major hurricane. The Capital Weather Gang will be monitoring Richard's progress very closely.

By  |  02:00 PM ET, 10/21/2010

Categories:  Tropical Weather

Read what others are saying

    © 2011 The Washington Post Company