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Tropical wave 92L weakens but could bring heavy rains to Haiti

By: Dr. Jeff Masters, 2:23 PM GMT on June 20, 2010

The tropical wave (92L) that brought heavy rains of 2 - 5 inches to Puerto Rico on Saturday is continuing westward at 10 - 15 mph, but has grown very disorganized. The National Hurricane Center is no longer interested enough in this wave to classify it as an "invest" worthy of generating computer forecasts for. Today through Monday, 92L will encounter 20 - 40 knots of wind shear as it plows though a region of strong upper-level winds associated with the subtropical jet stream. The disturbance will also encounter the mountainous terrain of Hispaniola and Cuba. If there is anything left of 92L after crossing these mountains, it may have the opportunity to develop beginning on Tuesday, when it will enter a region of wind shear less than 20 knots near central Cuba. None of our reliable computer forecast models is calling for 92L to develop once it reaches this region of lower wind shear. I give 92L a 10% chance of developing into a tropical depression by Saturday. The storm could bring heavy rains of up to four inches to Haiti today and Monday. Rain of four inches are probably the lower threshold for life-threatening floods to occur in the Haiti earthquake zone, and this disturbance poses the most serious flooding threat Haiti has seen since the earthquake.

Figure 1. Radar estimated rainfall over Puerto Rico from Invest 92L.

Elsewhere in the tropics
The NOGAPS and ECMWF models call for a possible tropical depression to form in the central or western Caribbean next weekend, 6 - 8 days from now.

Wind and ocean current forecast for the BP oil disaster
Southeast to east winds less than 10 knots will blow in the northern Gulf of Mexico Monday through Thursday, according to the latest marine forecast from NOAA. The resulting weak ocean currents should cause little motion of the oil slick, according to the latest trajectory forecasts from NOAA and the State of Louisiana. The long range outlook calls for a continued summertime weather pattern of weak winds over the Gulf of Mexico during the coming two weeks.

Figure 2. Visible satellite image from NASA's MODIS instrument of the Deepwater Horizon oil slick from Saturday, June 19, 2010.

Resources for the BP oil disaster
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool allows one to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Happy Father's Day, all you fathers out there, and I'll have an update on Monday.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.