Hurricane Paloma slowly strengthing as it approaches Grand Cayman

Hurricane Paloma is slowly strengthening. Satellite estimates of Paloma's strength suggest top winds have increased to 85 mph, making it a strong Category 1 hurricane. Visible satellite images show that Paloma continues to be well organized, and it appears an eye is ready to pop out. We haven't had a Hurricane Hunter aircraft in the eye since 3:39 am EST when a NOAA Hurricane Hunter aircraft measured a 982 mb pressure and 80 mph winds, so we don't know the strength of Paloma very well. The Hurricane Hunters noticed that the eyewall had a gap in its west side (Figure 1). This lack of a complete eyewall has slowed down Paloma's intensification, and is probably due to the 10-15 knots of wind shear currently impacting the storm.

Winds at the Grand Cayman airport were 33 mph, gusting to 47 mph at 10 am EST this morning, and heavy rain was falling. Over the past four days, about 4-5 inches of rain has fallen on Grand Cayman, with about 1.5" falling between midnight and 8 am today.

From wunderground member XL this morning:
I live about 100 yards from the sea on the northwest point of Grand Cayman. It is getting quite rough here now. It's been raining non stop for hours and is pretty windy. The sea is also getting quite rough with big swells. Hubby has just driven into work and says flooding of roadways is evident already.


Figure 1. Microwave image of Paloma at 1:57 am EST Friday November 7, 2008.The eyewall has a gap on the northwest side.

The intensity forecast
Wind shear has increased to a moderate 10-15 knots, and is expected to slowly increase to 20 knots Friday night and above 30 knots on Saturday morning. Recent infrared imagery shows that the cloud tops have not cooled in recent hours, so no rapid intensification is likely in the short term. Paloma should be able to intensify until it reaches a point near 20° North Latitude (between the Cayman Islands and Cuba) Saturday morning. I expect Paloma will be at Category 2 strength with 100 mph winds when it passes near or over Grand Cayman Island tonight, and will briefly intensify to Category 3 strength after passing Grand Cayman. This intensification will be slower if Paloma is unable to form a complete eyewall today. By Saturday morning, shear should rapidly weaken Paloma, and the hurricane will probably make landfall on Cuba Saturday afternoon or evening as a strong Category 1 hurricane. Passage over Cuba and continued high wind shear will further weaken Paloma before it arrives in the Bahamas Sunday night, and I expect Paloma will be a tropical storm with 45-55 mph winds as it blows through the Bahamas. The latest (06Z, 2am EST) run of both the HWRF and GFDL models predict that Paloma will hit Grand Cayman Island at about 9 pm EST tonight as a Category 1 hurricane with 85 mph winds. The latest 12Z SHIPS model puts Paloma as a strong Category 1 hurricane with 95 mph winds at landfall in Grand Cayman.

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 morning. Several major models 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 Paloma's current excellent organization and increasing intensity. I expect Paloma will follow the track of the GFDL, HWRF, and GFS models, which show the storm crossing Cuba and passing through the central Bahamas. It appears likely that Grand Cayman will receive hurricane force winds from Paloma, and there is a 50% chance the island will get a portion of the eyewall hitting it. Little Cayman and Cayman Brac should only see top sustained winds of 50 mph, and the west end of Jamaica should see winds of just 20-30 mph from Paloma.

Damage potential for Paloma
Grand Cayman Island is not that prone to large storm surges, since it lies in deep water, and a hurricane's surge tends to flow around the island rather than get pushed up onto shore. The main concern from Paloma is wind damage. A direct hit from a Category 2 hurricane would likely do about $100 million dollars in damage, a nasty blow for an island that just this year finished recovering from the devastating punch delivered by Hurricane Ivan of 2004. Ivan damaged or destroyed 85% of the islands buildings, and caused $1.85 billion in damage. Much of Grand Cayman still remained without power, water, or sewer services for several months after the hurricane. The latest H*Wind analysis of Integrated Kinetic Energy from NOAA's Hurricane Research Division puts the potential wind damage at 1.1 on a scale of 1 to 6, and the potential storm surge damage at 1.4 on a scale of 1 to 6. These numbers will increase later today, but Paloma should be nothing like Hurricane Ivan.

Links to follow
Grand Cayman airport weather
Grand Cayman weather
Wundermap for the Cayman Islands

Historical November tropical cyclones
Historically, only about 5% of all Atlantic tropical storm activity occurs after November 1. Between 1871 and 2007, 60 tropical storms formed in November. Of these, 29 became hurricanes, and four of these, major hurricanes. There have also been two major hurricanes that formed in October and continued on into November. On average, one tropical storm forms in November every other year, and we can expect a November hurricane about one year in five.

The six major November hurricanes were Hurricane Michelle of 2001 (Cat 4, 140 mph); Hurricane Lenny of 1999 (Cat 4, 150 mph); Hurricane Kate of 1985 (Cat 3, 120 mph); Hurricane Greta of 1956 (Cat 4, 140 mph); Hurricane 10 of 1932 (Cat 4, 135 mph); and Hurricane 7 of 1912 (Cat 3, 115 mph). There have been no major hurricanes in the months December through April.

Major hurricanes in the Atlantic by month, 1851-2008
----------------------------------------------------------------------
May 1
June 3
July 9
August 80
September 149
October 60
November 6

In the list above, if a hurricane was at major hurricane strength in two separate months, it is counted as a major hurricane for both months.

November hurricanes of note
The most extraordinary November hurricane was "Wrong-Way Lenny", which hit the northern Leeward Islands as a strong Category 4 hurricane with 155 mph winds on November 17-18, 1999. Lenny was the first storm to have an extended west-to-east track across the central and eastern Caribbean Sea in the 135-year Atlantic tropical cyclone record, and was the strongest November hurricane on record. Hurricane Gordon was the deadliest November hurricane. It claimed 1122 lives in Haiti when it passed just west of the country as a tropical storm on November 13, 1994. Lenny claimed six lives in Costa Rica, five in the Dominican Republic, two in Jamaica, two in Cuba, and eight in Florida. Property damage to the United States was estimated at $400 million (1994 dollars), and was severe in Haiti and Cuba as well.

Three November hurricanes have hit the U.S.--an unnamed 1916 Category 1 hurricane that hit the Florida Keys, an unnamed 1925 Category 1 hurricane that struck Sarasota, Florida, and Hurricane Kate, which struck the Florida Panhandle on November 22, 1985.

A new record for the hurricane season of 2008?
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 this afternoon.

Jeff Masters