Paloma nears hurricane strength

Tropical Storm Paloma continues to steadily strengthen, and is well on its way to becoming a hurricane. The latest 2:20 pm EST center fix from the Hurricane Hunters found that the pressure had fallen to 994 mb, and the surface winds had increased to 60 mph. The crew reported that Paloma has built a 20-mile diameter eyewall that is 3/4 complete, with only a gap on the southwest side. Bouy 42057 reported sustained winds of 60 mph, gusting to 74 mph, at 6:50 pm EST. Visible satellite images show that Paloma continues to grow more organized, with low level spiral bands wrapping around the center and upper level outflow expanding on all sides.


Figure 1. Microwave image of Paloma at 7:15 am EST Thursday November 6, 2008. A partial eyewall is evident on the southeast side of the center. Image credit: Navy Research Lab, Monterey.

The intensity forecast
Wind shear remains a very low 0-5 knots, and is expected to remain very low through Friday night. Wind shear will increase to 10-15 knots Friday night and Saturday, as the storm heads north, but I don't expect Paloma will stop intensifying until it crosses 20° North Latitude (between the Cayman Islands and Cuba) Saturday night, when the shear will increase to 30-50 knots. Water temperatures are warm, 29°C, and this warm water extends to great depth. These are very favorable conditions for intensification, and Paloma should be a hurricane by tonight or Friday morning. The latest (12Z, 7am EST) run of the HWRF model predicts Paloma will pass though the Cayman Islands on Saturday morning as a Category 2 hurricane. The GFDL model predicts a Category 3 hurricane, and the latest 18Z SHIPS model puts Paloma as a strong Category 1 hurricane with 95 mph winds in the Caymans. I believe Paloma will be a Category 3 hurricane by Saturday when it passes through the the Cayman Islands. Paloma will likely be a Category 1 or 2 hurricane at landfall in Cuba, and a strong tropical storm with 60-70 mph winds in the Bahamas.

The track forecast
A strong trough of low pressure approaching the U.S. East Coast is pulling Paloma to the north, and this trough should continue to pull the storm northwards and then turn it northeastward by Saturday. Several major models--the NOGAPS, UKMET, and ECMWF--continue to predict that Paloma will be torn in two by the wind shear just south of Cuba, with the low level remnants getting forced westward towards the Yucatan Peninsula. This solution seems unlikely, given the fact that Paloma is likely to grow much stronger and more resistant to wind shear than these models are predicting. I expect Paloma will follow the track of the GFDL, HWRF, and GFS models, which show the storm may pass very close to Grand Cayman Island on Saturday, then make landfall in southern Cuba on Sunday and continue on through the central Bahamas. On this track, Grand Cayman may receive a direct hit, but Little Cayman and Cayman Brac would only see top sustained winds of 50 mph. A slight deviation to the right, though, would put Little Cayman and Cayman Brac in the bulls-eye. Jamaica should see winds of just 20-30 mph from Paloma.

Links to follow
Buoy 42057
Grand Cayman airport weather
Grand Cayman weather
Wundermap for the Cayman Islands
Wundermap for 18N 83W

Historical note
This year and 2005 are the only seasons that we've had major hurricanes in the Atlantic in four separate months--July, August, September, and October. If Paloma becomes a major hurricane, it will make 2008 the first year since record keeping began in 1851 to feature major hurricanes in five separate months.

I'll have an update Friday morning.

Jeff Masters