Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 5:36 PM GMT on October 09, 2011
A large extratropical low pressure system with heavy rain and gale-force winds is centered over the Northwest Bahamas. Water vapor satellite loops show that the center of this low is filled with dry air, and is headed northwest at 5 - 10 mph. The low will cross over the Florida Peninsula today. The west side of this low also has a large amount of dry air, which is limiting precipitation amounts along the Gulf of Mexico coast, but the east side has plenty of tropical moisture. Radar-estimated rainfall amounts since Friday are already in excess of ten inches just inland along the Central Florida coast. Melbourne, Florida had its second wettest October day in its history yesterday, with 5.68" of rain. Much of the region, including Cocoa Beach, is under a flood watch, high surf advisories, and a high wind watch for wind gusts up to 55 mph. Winds offshore from the Florida east coast are near tropical storm strength this afternoon. Buoy 41009 offshore from Cape Canaveral recorded sustained winds of 38 mph, gusting to 47 mph, at 1 pm EDT today. Several ships have reported winds in excess of 46 mph this morning along the Florida east coast. Due to the large amount of dry air near the storm's center and west side, plus the fact the track of the storm will take it over the Florida Peninsula today and into the Florida Panhandle by Tuesday night, I doubt the storm will have time to organize into a tropical or subtropical storm that gets a name. NHC is currently giving this storm a 30% chance of becoming a named tropical or subtropical storm by Tuesday morning. This large diffuse system will bring strong winds and heavy rains to a large area of the Southeast U.S. coast over the next two days.
Figure 1. Radar-estimated rainfall from the Melbourne, Florida radar as of Sunday afternoon.
Dangerous Hurricane Jova headed for Mexico
In the Eastern Pacific off the coast of Mexico, Hurricane Jova continues to slowly intensify. Recent satellite loops show the hurricane has developed a prominent eye, and low level spiral bands have become more organized. A hurricane hunter aircraft is scheduled to arrive at Jova near 11 am PDT today. The computer models have come into excellent agreement on the track of Jova, with storm expected to hit just west of Manzanillo. The big unknown is how intense Jova will be at landfall. Jova is under light wind shear of 5 - 10 knots, and shear is predicted to stay in the low to moderate range between now and landfall. Ocean temperatures are warm, 28 - 29°C, but the warm waters do not extend to great depth, limiting Jova's potential for rapid intensification. The upper atmosphere is also not cold enough to give Jova the kind of instability typically needed for rapid intensification. Nonetheless, both the GFDL and HWRF models predict Jova will intensify into a major Category 3 and Category 4 hurricane, respectively, before landfall on Tuesday on the Mexican coast. Regardless of Jova's strength at landfall, the storm will bring very heavy rains to the Mexican coast capable of causing dangerous flash floods and mudslides, beginning on Monday.
Figure 2. Afternoon visible satellite image of Tropical Storm Irwin (left) Hurricane Jova (center) and Invest 99E (right) over the East Pacific.
Figure 3. Rainfall forecast for Hurricane Jova from this morning's 2 am EDT run of the GFDL model. Image credit: Morris Bender, NOAA/GFDL.
Tropical Storm Irwin also headed for Mexico
Once Jova has made landfall, Mexico needs to concern itself with Tropical Storm Irwin, farther to the west. The computer forecast models show Irwin could make landfall as a tropical storm on the Mexican coast late in the week, along the same stretch of coast Jova will affect. If this verifies, the one-two punch of heavy rains from two tropical cyclones within a week could cause a devastating flood situation along the Mexican coast.
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