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94L may develop this weekend; Hurricane Bud intensifies near Mexico

By: Dr. Jeff Masters, 2:38 PM GMT on May 24, 2012

An area of disturbed weather (Invest 94L) over South Florida, Cuba, the Bahamas, and the Western Caribbean is bringing gusty winds heavy rains to the region, and is headed north-northeast along the east coast of Florida. Miami is under an areal flood watch today for rains of 1 - 3 inches, and rains in excess of one inch have already fallen over Key Largo today. The disturbance is generating some impressive winds this morning along the Southeast Florida coast--Fowey Rocks recorded sustained southeast winds of 33 mph at 10am EDT, and Molasses Reef on Key Largo had 31 mph sustained winds. The disturbance is under a very high 40 - 50 knots of wind shear, according that the latest SHIPS model analysis, making development very unlikely today. As 94L slides north-northeast along the coast on Friday and Saturday, wind shear is expected to decrease, and several of our reliable models predict that 94L could organize into a subtropical depression on Saturday or Sunday off the coast of North Carolina/South Carolina. NHC is giving 94L a 20% chance of developing by Saturday morning. A ridge of high pressure is expected to build in over the weekend off the East Coast, which will force 94L to the southwest back towards the coast. Heavy rains from 94L are likely to begin affecting coastal South Carolina, Georgia, and Northern Florida on Saturday and Sunday. If these rains do materialize, they would be welcome, considering the moderate to severe drought conditions in the area.

Figure 1. Morning radar image of heavy rains from Invest 94L affecting Southeast Florida.

Hurricane Bud heads towards Mexico
Hurricane Bud finally took advantage of its favorable environment of low wind shear and warm ocean temperatures and became a Category 2 hurricane this morning. Recent satellite loops show a well-organized storm with a prominent eye, cold eyewall cloud tops, and good low-level spiral banding. It is possible that Bud could attain Category 3 status later today. An Air Force hurricane hunter aircraft will investigate Bud this afternoon to gauge Bud's strength. Hurricanes are uncommon in the Eastern Pacific in May; there have been just twelve since record keeping began in 1949--an average of one May hurricane every five years. The earliest Eastern Pacific hurricane was Hurricane Alma of 1990, which became a hurricane on May 15. There have been only two major Category 3 or stronger May hurricanes. Here is a list of the twelve May hurricanes in the Eastern Pacific:

Hurricane Bud of 2012
Hurricane Adrian of 2005
Hurricane Alma of 2002 (major)
Hurricane Adolph of 2001 (major)
Hurricane Aletta of 2000
Hurricane Alma of 1990
Hurricane Agatha of 1986
Hurricane Adolph of 1983
Hurricane Aletta of 1978
Hurricane Agatha of 1971
Hurricane Adelle of 1970
Unnamed Hurricane of 1956

Figure 2. Morning satellite image of Bud.

Forecast for Bud
Bud will continue towards the coast of Mexico the next two days, pulled northwards by a trough of low pressure moving across the U.S. This trough will lift out and a ridge of high pressure will build in its place, and most of the computer models predict Bud will stall just offshore--or get pulled apart so that its low level center stays offshore, and its mid-level center moves inland. NHC is currently basing its track forecast on the ECMWF and GFS models, which were the two best performing models in both 2010 and 2011. An outer spiral band of Bud is already bringing a few heavy rain showers to the coast of Mexico near Manzanillo, and rains will increase in intensity on Friday and Saturday. The hurricane is expected to encounter more hostile condition--dry air, cooler SSTs, and higher wind shear--that will weaken the storm on Friday and Saturday. This should decrease the winds enough so that heavy rain will be the main threat from Bud. The coast where Bud is headed towards is very mountainous, and flash floods and dangerous mudslides will be a concern there. The region was not under drought conditions as of the end of April, but a number of wildfires are currently burning in the area, so Bud's rains may also do some good, by extinguishing these fires.

Jeff Masters


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