Hurricane Beta: unlucky 13

The Hurricane Season of 2005 is determined to own every major record for the Atlantic, and now has another--Beta is the 13th hurricane of the season, beating the record of 12 hurricanes set in 1969. Number thirteen will be an unlucky number for both Nicaragua and Honduras, who figure to bear the worst of this strengthening hurricane. In one respect, though, these countries have been lucky--the tropical disurbance that formed northeast of Beta yesterday is still there today, generating wind shear over Beta that is keeping it from rapidly intensifying. Had the disturbance not formed, Beta would already be a Category 2 hurricane today, and well on its way to a Category 3. As it is, the disturbance is still generating about ten knots of shear over Beta, which has allowed only a slow rise to Category 1 strength.

The disturbance has steadily weakened the past 24 hours, and so has the shear over Beta. By the time Beta makes its expected landfall near the Nicaragua-Honduras border Sunday morning, the shear will drop to five knots, which could allow rapid strengthening. There is not much time, though, for Beta to make it to Category 3 status, and the most likely strength at landfall is as a Category 2 hurricane. However, the latest microwave satellite data from NASA's TRMM satellite shows a pinhole eye--a very small 10-mile diameter eye like Wilma developed just before her rapid deepening phase. This may portend a rapid intensification cycle to Category 3 strength or higher may occur today. The hurricane hunters will be in the storm beginning at about 3 pm EDT today to check on its strength.

The island of Providencia (Columbia) received a direct hit from Beta last night and experienced sustained hurricane force winds for many hours that caused serious damage. Communications with the island were cut off at the height of the storm and have not been re-established.

The computer models are sorely missing the presence of the NOAA jet to provide detailed data on Beta's surrounding environment. Only one of the four main models--the UKMET--has correctly forecast the slow north and then northwest drift of Beta. The other three models have incorrectly been assuming the ridge to Beta's north is much stronger than it really is. The resulting forecasts of a westerly or southwesterly track across Nicaragua and into the Pacific Ocean have been incorrect for three days in a row. All indications are, though, that this ridge is unusually strong for this time of year, and Beta is not likely to turn north and threaten Cuba or Florida, at least for the next three to five days. The official NHC forecast seems reasonable.

If Beta does make landfall near the Honduras/Nicaragua border as a Category 2 storm as expected, a large storm surge of up to 15 feet is expected, since a long shallow area of Continental Shelf waters exists close to shore that will allow the storm surge waters to pile up. One would expect such a large storm surge, plus Beta's 100-mph sustained winds, to cause tremendous damage--but this is a large and very sparsely populated rainforest region. The storm surge and winds are unlikely to do significant damage. Far more dangerous will be Beta's rains, which may push inland into the mountainous regions of central Honduras where Hurricane Fifi in 1974 killed 8000, and where Hurricane Mitch in 1998 killed over 9000. Rains of up to 0.8 inches/hour are alreay affecting northeast Honduras, and Beta's slow motion will allow it to dump up to 15 inches of rain in some regions of Honduras. However, Beta is a very small storm, and its rains will affect a smaller portion of Honduras than either Fifi or Mitch did. Plus, Mitch dumped at least 30 inches of rain over much of Honduras during its rampage. These factors, along with the improved evacuation procedures that have been adopted in Honduras since 1998, give hope that Beta will not trigger a major flooding disaster in Honduras. Tune into wunderblogger Helen's blog from Roatan Island, Honduras, to follow the storm. Roatan is on the central coast of Honduras--the area Hurricane Mitch hit hardest in 1998.


Figure 2. Rainfall rate at 7:30 am EDT, taken by a NOAA polar-orbiting satellite. Image credit: Navy Research Lab.

Elsewhere in the tropics
The large tropical disturbance in the central Caribbean that is interfering with Beta's circulation has weakened and is not expected to develop through tomorrow.

A large tropical wave located about 600 miles east of the Lesser Antilles has become better organized today and has some potential for further development over the next few days as it moves west or west-northwest at 15 mph. This area of disturbed weather will bring heavy rain and gusty winds to the northern Leeward Islands on Monday and Puerto Rico on Tuesday. If a tropical storm does develop from this wave, it could threaten the Bahamas and the Southeast U.S. coast five or six days from now.

I'll be back with an update Sunday morning.

Jeff Masters