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Ike crossing Cuba; Texas next?

By: Dr. Jeff Masters, 2:23 PM GMT on September 09, 2008

Hurricane Ike has made landfall over the western tip of Cuba, and continues its onslaught on that island nation with 80 mph winds, a 4-7 foot storm surge, and heavy rains of 6-12 inches. Key West radar shows that Ike has a tiny 10-mile wide eye, and Ike has hurricane force winds over just a small region near its center. In fact, the 8 am Hurricane Hunter flight was only able to find winds of tropical storm strength, and Ike may be weaker than advertised. Still, the storm has a central pressure of 965 mb, which is a pressure more typical of Category 2 hurricanes.

The capital of Havana reported sustained winds of 40 mph gusting to 58 mph this morning, and the worst of Ike's winds will pass well south of the city. Ike's primary threat to Cuba at this point is heavy rains. Ike killed four people in Cuba yesterday--the first hurricane deaths in Cuba this year. Cuba put in place its usual massive evacuation plan for Ike, evacuating 1.2 million residents. Considering the number of people affected and the violence of Category 4 Gustav and Category 3 Ike, Cuba's low death toll this year is a remarkable achievement.

Figure 1. Current Key West radar image.

Track forecast for Ike
A trough of low pressure is currently passing to the north of Ike, and this trough has been able to turn Ike north of due west. Ike is now moving west-northwest, and this motion is expected to continue today, taking the storm across the western tip of Cuba, where Hurricane Gustav crossed just two weeks ago. By Wednesday, Ike is expected to take a more westerly motion again, as high pressure to the north builds in. As Ike approaches Texas on Friday, a new trough of low pressure is expected to pass to the north, potentially turning Ike to the northwest.

The latest 0Z/6Z (8 pm/2 am EDT) computer models show a variety of timings and strengths for Friday's low pressure trough, resulting in a high amount of uncertainty on where Ike will make landfall. Most of the models predict the trough will arrive too late and be too weak to affect Ike, and take Ike ashore near the Texas/Mexico border. These models include the NOGAPS, GFS, and GFDL. The HWRF is bit farther north, placing landfall near Corpus Christi, and the UKMET and ECMWF are farther north still, targeting a region between Freeport and Galveston. Oddly, these two farthest north models were the southernmost ones yesterday. Suffice to say, the crystal ball is still cloudy. The entire Texas and northernmost coast of Mexico are at risk from Ike.

Intensity forecast for Ike
While Ike is over Cuba, slow weakening will occur. Significant strengthening will not occur until Wednesday morning, after the storm has recovered from its crossing of Cuba. Water temperatures are a warm 29.5°C in the Gulf of Mexico, and wind shear is expected to be modest, 10-15 knots. Ike will be crossing over two regions of high heat content associated with the Loop Current and a Loop Current eddy (Figure 2). The GFDL and HWRF models show Ike responding to these favorable conditions by intensifying to a Category 4 hurricane on Thursday. By Friday, wind shear is predicted to increase to 15-20 knots, but the heat content of the ocean remains relatively high. There is much higher oceanic heat content off the Texas coast than was present off the Louisiana coast for Gustav. Thus, it is less likely that Ike will significantly weaken as it approaches the coast. The GFDL and HWRF models predict landfall in southern Texas as a Category 3 or 4 hurricane Friday night. The SHIPS model is less aggressive, and foresees a Category 1 or 2 hurricane at landfall. So take your pick--Ike could be a Category 1, 2, 3, or 4 hurricane at landfall. Such is the state of long-range hurricane intensity forecasts. A middle of the road forecast of a Category 2 or 3 hurricane at landfall is a reasonable one at present.

Figure 2. Projected path of Ike overlaid on the current map of Tropical Cyclone Heat Potential (TCHP). TCHP is a measure of total ocean heat content, and TCHP values in excess of 80 kJ/cm^2 (yellow colors) are frequently associated with rapid intensification of hurricanes. Ike will be passing over two regions of high heat content--one associated with the Loop Current, and another associated with an eddy that broke off from the Loop Current in July. Note that heat content stays relatively high all the way to the coast of Texas, in contrast to what Gustav experienced as it approached the coast of Louisiana. Image credit: NOAA/AOML.

Elsewhere in the tropics
A area of disturbed weather has developed near 10N, 21W, about 300 miles south of the Cape Verdes Islands. This morning's QuikSCAT pass showed a sloppy circulation and some 25 mph winds in heavy thunderstorms to the south. The region is currently under about 20 knots of shear, but shear is expected to decline over the disturbance as it moves west-northwest at 10-15 mph this week. The GFS model predicts this disturbance could develop by Sunday. The disturbance will be near the northern Lesser Antilles Islands 7-8 days from now.

The remains of Tropical Storm Josephine are no longer a threat.

The tragedy in Haiti
The death toll in Haiti due to the onslaught of Hurricanes Gustav, Hanna, and Ike, plus Tropical Storm Fay, is now over 1,000 people. At least 14,000 homes have been destroyed, and 800,000 people are without food, water, and/or shelter. The death toll is sure to rise higher as rescuers reach more remote flooded areas in coming days. The economic impact of the disaster is projected to be greater than the 2004 devastation wrought by Hurricane Jeanne, which killed over 2,000 people. Haiti needs all the help it can get, and I want to thank everyone who has donated to the Lambi Fund of Haiti charity. They're an outstanding group that I've supported for a number of years, and they focus on fixing the underlying causes of poverty and natural disasters in Haiti.

Figure 3. The flooded city of Gonaives after Hurricane Hanna, September 3, 2008. Image credit: Lambi Fund of Haiti.

Tonight, at 9pm EDT, I'll make my annual appearance on the Internet Partnership Radio program, "Center of Circulation". You can listen in at http://www.ipr365.com/. I'm usually on for at least 45 minutes.

I'll have an update this afternoon.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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