Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 3:24 PM GMT on October 15, 2012
Tropical Storm Rafael is intensifying as it pulls away from the Lesser Antilles Islands. Data from the Hurricane Hunters and satellite loops show that Rafael has gotten more organized this morning, with a blow-up of very heavy thunderstorms near the center that have created a large Central Dense Overcast (CDO), the hallmark of an intensifying tropical storm that is near hurricane strength. Rafael is experiencing high wind shear near 20 knots, and this shear is expected to remain constant through Tuesday, which should allow Rafael to intensify into a Category 1 hurricane. Sporadic heavy rains from Rafael will gradually diminish today over the Leeward Islands, Puerto Rico, and the Virgin Islands. A tropical storm warning has been posted for Bermuda, but if Rafael follows the official NHC forecast track, tropical storm-force winds will remain just offshore from Bermuda as Rafael makes its closest pass by the island on Tuesday evening. The 11 am EDT wind probability forecast from NHC gave Bermuda a 29% chance of experiencing tropical storm-force winds between Monday night and Wednesday morning, and a 1% chance of experiencing hurricane-force winds. The models are pretty tightly clustered showing a track for Rafael to the east of Bermuda, putting the island on the weaker (left front) side of the storm.
Figure 1. Morning satellite image of Tropical Storm Rafael.
Hurricane Paul forms in the Eastern Pacific
Hurricane Paul is putting on a burst of rapid intensification, and is a strong Category 1 hurricane with 90 mph as it heads northwards towards Mexico's Baja Peninsula. Paul will have favorable conditions for intensification through Tuesday morning, when wind shear is predicted to rise to the high range, above 20 knots. Paul should be weakening quickly as it approaches the coast of Baja Tuesday night and Wednesday morning, but heavy rains from the storm will spread over Baja beginning on Tuesday night, and these rains will be capable of causing flooding problems. 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. On average, the Eastern Pacific experiences one named storm after October 15, which would bring this season's total activity to 17 named storms, 10 hurricanes, and 4 major hurricanes. An average Eastern Pacific season has 15 named storms, 8 hurricanes, and 3 major hurricanes.
Figure 2. Morning satellite image of Hurricane Paul.
A rare early-season major tropical cyclone in the Southwest Pacific
It's springtime in the Southern Hemisphere, where Category 3 Tropical Cyclone Anais is churning southwestwards towards Madgascar. 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 has moved over cooler waters, and has weakened slightly to 115 mph winds, down from the peak 120 mph it had on Sunday. Further weakening is expected over the next few days as wind shear increases and the waters beneath continue to cool, and Anais is not expected to directly impact any land areas.
Figure 3. MODIS satellite image of Tropical Cyclone Anais in the Southwest Pacific taken at 5:40 am EDT Monday October 15, 2012. At the time, Anais was a Category 3 storm with 115 mph winds, and was the strongest tropical cyclone ever observed in the Southwest Pacific so early in their hurricane season. Image credit: NASA.
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