Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 9:18 PM GMT on August 25, 2006
The Hurricane Hunters visited Tropical Depression Five this afternoon, and at 1:30pm EDT found a surface circulation center and maximum sustained surface winds of 40 mph, making this Tropical Storm Ernesto. Visible satellite images from this afternoon show a a sheared system, with the low level circulation center completely exposed. Upper level winds from the northwest are creating 10-20 knots of shear, which is keeping all the heavy thunderstorm activity confined to the southeast (downwind) side. However, this heavy thunderstorm activity is building towards the center, and the storm has some solid spiral bands forming. The storm is intensifying in the face of the shear. Radar from Aruba shows some of the outer spiral bands.
Figure 1. Current satellite image of Ernesto.
The latest 12Z (8am EDT) model runs are in, and they portray a conflicting picture of what may happen. Three of the four major global models--UKMET, GFS, and NOGAPS--dissipate or severely weaken the storm by Monday. The Canadian model, which has been the most aggressive in making Ernesto a hurricane in the Gulf of Mexico, now keeps the system a weak tropical storm all the way to landfall in the Florida Panhandle on Tuesday. The European Center model has a similar forecast. Oddly, the large upper-level trough of low pressure over the central Caribbean is forecast by these models to move west away from Ernesto, and an upper level high pressure system to build on top of the storm. This situation should act to lower the shear and aid in intensification, and that it what the official NHC forecast is calling for. It is unusual for the models to forecast a favorable shear environment, yet dissipate a storm, and serves to show the limitations of these models in making hurricane intensity forecasts. I have very little confidence in any of the Ernesto intensity forecasts--including the official NHC forecast of a hurricane in the Gulf of Mexico on Tuesday. High wind shear could still destroy this storm on Sunday. Ernesto should slowly intensify through Saturday, but beyond that, I have no idea. It's best to prepare for the worst, and hope for the best. All portions the U.S. coast from the Florida Keys to Brownsville, Texas are at risk from this storm.
Given the high degree of uncertainty in Ernesto's intensity, those of you traveling to or from Jamaica, Cuba, the Cayman Islands, and Cancun should play "wait and see" as long as you can. At this point, it is likely that Jamaica, eastern Cuba, and southwest Haiti will get tropical storm conditions on Sunday. Jamaica's airports will probably close about 2am Sunday, and remain closed into late Sunday night. Ernesto probably does not have enough time to intensify to a hurricane before reaching Jamaica. Airports in the Cayman Islands will probably close by late morning on Sunday, and reopen Monday afternoon. Ernesto could be a Category 1 hurricane for the Caymans.
Hurricane Ioke in the Central Pacific has reached Category 5 status with 160 mph winds today. Ioke is the first hurricane in the Central Pacific since 2002. It's not a threat to any land areas, but is most impressive on satellite imagery. The 12Z GFDL has Ioke at 880mb in 5 days, the lowest forecast pressure I've seen from the GFDL model.
Figure 2. Visible satellite image of Category 5 Hurricane Ioke, 2030 GMT, 8/25/06. Image credit: Navy Research Lab.
Max Mayfield to step down
Max Mayfield announced today that he is stepping down as head of the National Hurricane Center at the end of the year, according to press reports from the Miami Herald and Florida Sun Sentinel. Mayfield, 57, admitted that the last two hurricane seasons wore him out. Ed Rappaport, the center's deputy director and a veteran forecaster may be next in line for the job, after Max steps down on January 3. Max will be missed--his expert guidance of NHC has no doubt saved many lives, and I will miss his calm and intelligent presence at the helm of NHC.
The next Hurricane Hunter mission into Ernesto is at 2am EDT Saturday morning. My next update will be Saturday morning between 9-11am, or earlier if there's something major to comment on. I don't have my model summary piece completed yet, but will do so as soon as I get it done.
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