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92L drenches Puerto Rico, and could develop into a TD by Wednesday

By: Dr. Jeff Masters, 4:32 PM GMT on June 19, 2010

Invest 92L continues its steady march to the west-northwest across the northern Caribbean. The storm has brought up to 4 inches of rain to Puerto Rico today, and will spread heavy rains of up to four inches over the Dominican Republic tonight and Haiti on Sunday. Rains 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. There is no evidence of a surface circulation apparent on visible satellite imagery or surface observations. Water vapor satellite loops show that there is a large amount of dry, continental air from North America in the storm's environment. With wind shear at 30 - 40 knots today and expected to be 20 - 30 knots on Sunday, 92L is not a threat to develop into a tropical depression today or Sunday. The National Hurricane Center is giving 92L a low (10% chance) of developing into a tropical depression by Monday morning, which is a reasonable forecast. You can track the progress of 92L today by looking at our wundermap for the region, with weather stations turned on.

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

92L could develop by Wednesday
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, though it appears that much of the disturbance's energy is tracking almost due west, and thus may escape disruption by these islands. If 92L manages to hold together through the high wind shear, dry air, and mountainous terrain of Hispaniola and Cuba, it may have the opportunity to develop beginning on Tuesday, when it may enter a region of wind shear less than 20 knots in the region near central Cuba. Some modest moistening of the atmosphere may also occur at that time, according to the latest SHIPS model run. The latest 12Z GFS model run indicates re-organization of 92L may occur by Wednesday over the waters near the Lower Florida Keys, but the ECMWF, NOGAPS, and UKMET models do not show this. The obstacles that 92L must overcome to become a tropical depression in the Gulf of Mexico next week are significant, and I give 92L a 20% chance of developing into a tropical depression by Friday.

Elsewhere in the tropics
The NOGAPS model is calling for a possible tropical depression to form in the central Caribbean on Friday.

Wind and ocean current forecast for the BP oil disaster
Light and variable winds less than 10 knots will blow in the northern Gulf of Mexico for the next four days, according to the latest marine forecast from NOAA. The winds will tend to have an offshore northerly component through Sunday, and an easterly component beginning on Monday. The resulting ocean currents should keep the oil near the coast from Alabama to Panama City, Florida, according to the latest trajectory forecasts from NOAA and the State of Louisiana. Ocean current forecasts for the period Monday - Wednesday show only weak flow, which would result in little transport of oil from its current location. The long range 5+ day outlook is uncertain, as we will have to see what Invest 92L does once it reaches the western Caribbean and southern Gulf of Mexico on Wednesday. If the GFS model is correct, we can expect 92L to bring strong easterly winds to the oil spill location late next week, pushing the oil towards Louisiana.

Figure 2. Visible satellite image from NASA's MODIS instrument of the Deepwater Horizon oil slick from Friday, June 18, 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

I'll have an update on Sunday or 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.