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Rafael intensifying, but is pulling away from the Lesser Antilles

By: Dr. Jeff Masters, 3:55 PM GMT on October 14, 2012

Tropical Storm Rafael is intensifying, but is headed northwards away from the Lesser Antilles Islands, after bringing gusty winds and heavy rains to the islands over the past two days. Three-day rainfall amounts of 2 - 3" were common over the Leeward Islands, but the winds mostly stayed below tropical storm-force. Here are some of the peak wind gusts from Rafael and rainfall totals from Oct 11 through 10 am EDT October 14:

Barbados, 47 mph, 0.81"
Antigua: 37 mph, 3.66"
Martinique: 30 mph, 3.10"
St. Lucia: 39 mph, 2.07"
St. Martin: 45 mph, 2.56"
Guadaloupe: 36 mph, 2.51"
Dominica: 25 mph, 2.68"
St. Kiits: 34 mph, 3.47"

Satellite loops show that Rafael has gotten much more organized late this morning, with an impressive spiral band with very heavy thunderstorms to the east of the center. Heavy thunderstorms with cold cloud tops are forming over the center, the hallmark of an intensifying tropical storm. The Hurricane Hunters found a central pressure of 997 mb, and winds at their 5,000-foot flight level of 68 mph this morning. Rafael is experiencing a moderate 10 - 20 knots of wind shear.

Figure 1. Morning satellite image of Tropical Storm Rafael.

Forecast for Rafael
Wind shear is expected to remain in the moderate range through Tuesday, which should allow Rafael to intensify into a Category 1 hurricane. Heavy rains will continue over the Leeward Islands today and diminish on Monday. A tropical storm watch has been posted for Bermuda, which is at risk of seeing tropical storm-force winds from Rafael on Tuesday. The 11 am EDT wind probability forecast from NHC gave Bermuda a 40% chance of experiencing tropical storm-force winds between Monday night and Wednesday morning, and a 6% chance of experiencing hurricane-force winds. The models are pretty tightly clustered showing a track for Rafael to the east of Bermuda, which would put the island on the weaker (left front) side of the storm.

Tropical Storm Paul forms in the Eastern Pacific
Tropical Storm Paul formed yesterday in the East Pacific, and is headed northwards towards Mexico's Baja Peninsula. Paul's formation brings this year's tally of named storms in the East Pacific to sixteen, making 2012 just the third year since records began in 1949 that both the Eastern Pacific and Atlantic have had at least sixteen named storms. The other years were 2003 and 2008.

Figure 2. MODIS satellite image of Tropical Cyclone Anais in the Southwest Pacific taken at 2:05 am EDT Sunday October 14, 2012. At the time, Anais was a Category 3 storm with 120 mph winds, the strongest tropical cyclone ever observed in the Southwest Pacific so early in their hurricane season. Image credit: NASA.

A rare early-season major tropical cyclone in the Southwest Indian Ocean
It's springtime in the Southern Hemisphere, where an unusual tropical cyclone has formed--Tropical Cyclone Anais, which hit Category 3 strength with 120 mph winds. According to Meteo France in La Reunion Island, Anais is the earliest major hurricane to form during the Southwest Indian Ocean's tropical cyclone season, which typically runs from November to May. Anais' formation in mid-October is akin to getting a major hurricane in the Atlantic during April, something which has never occurred (the earliest major hurricane on record in the Atlantic occurred on May 21, 1951.) Anais is the second earliest hurricane of any kind to form so early in the Southwest Indian Ocean tropical cyclone season, after Tropical Cyclone Blanche of October 10, 1969. Anais may reach Category 4 strength before cooler waters and increased wind shear weaken the storm as it approaches Madagascar.

Jeff Masters


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