Monthly Archives: June 2010

Tropical Storm Alex Gains Strength

The latest forecast discussion from the NHC:

although the cloud pattern of Alex has become a little distorted this morning…the cyclone has continued to gradually intensify. An Air Force Reserve reconnaissance plane found peak flight-level winds of 66 kt…SFMR values of 51 kt…and a decrease in pressure to 989 mb. Thus the initial intensity is increased a bit to 50 kt.

The initial motion is 330/5…to the right of previous estimates. An upper-level trough seen to the north of the storm may be contributing to the more poleward motion by causing a weakening of the ridge over the Gulf Coast. This trough is forecast to lift out of the area in a day or so…which should allow ridging to build back in slightly and steer Alex more toward the northwest. After that time…the strength of a ridge over the Central Plains should help determine whether the tropical cyclone continues a northwestward motion or makes more of a turn toward the west-northwest. The model guidance is in pretty good agreement through 48 hours…then has a bit more spread. There has been a subtle shift northward with some of the 06z guidance…and the NHC forecast has been adjusted in that direction.

Some northwesterly shear is currently affecting Alex…although this has not prevented the storm from slowly deepening. This shear is forecast to abate by tomorrow as the upper-level trough pulls out of the Gulf of Mexico…which could then allow for more significant strengthening. The statistical models continue to show more intensification of Alex than the dynamical guidance…which seems reasonable given the likely environmental conditions. The NHC forecast is close to the statistical models and the previous forecast.

Dr. Jeff Masters on the various models and the uncertainty associated with this storm – and all hurricanes for that matter:

This consensus forecast has narrowed in on the region near the Texas/Mexico border as being the most likely landfall location, with the usual cone of uncertainty surrounding it. The northernmost landfall location is Port O’Connor, as predicted by the Canadian model. The southernmost landfall location is near Tampico, Mexico, as predicted by the ECMWF model. Alex’s landfall time varies from Wednesday evening to Thursday morning. Which model should you trust? Last year, the best performing models at the 3 day forecast period were the GFS, Canadian, ECMWF, and GFDL. Three out of four of those models are predicting a landfall between Brownsville and Corpus Christi, with only the ECMWF model predicting a landfall well south of the Texas border. With steering currents relatively weak, the uncertainty in landfall location is high. The average error in an NHC 72-hour track forecast last year was 230 miles, which is about the distance from Brownsville to Port O’Connor. Consider also that the NHC cone of uncertainty is the region where 2/3 of the time (using the last 5 years of statistics) the center of a storm will go. That means that 1/3 of the time a storm will not be in the cone of uncertainty. Given the slow motion of Alex and the recent uncertainty of the computer models, people living just beyond the edge of the cone of uncertainty should not be confident yet that Alex will miss them.

In short, residents of Texas and Louisiana can’t take their eyes of Alex yet and significant uncertainty will persist for the next 36-48 hours. However, if I lived between Brownsville and Corpus Christi I’d kick my hurricane preparation into gear immediately. Watches have been issued.

Hurricane Alex? Hurricane Blogging Season Kicks Off

hurricanealex06272010 Hurricane Alex? Hurricane Blogging Season Kicks Off

Hurricane season means hurricane blogging. TD Alex shows every sign of becoming hurricane Alex soon and some of models are starting to shift towards the upper Texas coast. Dr. Jeff Masters:

While the track forecast for Alex today through Monday is fairly well-assured, the longer range forecast has become highly uncertain. An increasing number of our reliable models are now indicating Alex may take a more northerly track beginning on Tuesday, with possible landfall on the Texas coast near Galveston on Friday (according to the 8am run of the GFS model) or into western Louisiana on Wednesday (the 8am run of the Canadian model.) The key question remains how Alex will react to the trough of low pressure expected to swing down over the Eastern U.S. on Monday and Tuesday. Most of the models were predicting that the trough would not be strong enough to swing Alex to the north, and several of them continue to predict this. The 8am runs of the NOGAPS and ECMWF models, for example, take Alex into the Gulf coast of Mexico 150 miles south of Texas, on Wednesday. The GFDL and HWRF models split the difference, with the GFDL predicting a Thursday landfall in southern Texas near Brownsville, and the HWRF predicting a Thursday landfall near Corpus Christi. Morris Bender of the GFDL group has just provided me the track forecast from an improved experimental version of the GFDL that shows landfall between Corpus Christi and Galveston. So which model should you trust? Last year, the best performing models at the 3 – 4 day forecast range were the GFS and the Canadian, and these are the models that are currently calling for the more northerly track towards the upper Texas coast and Louisiana. Residents of those areas should review their hurricane preparedness plans and anticipate that Alex could make landfall as early as Wednesday in their vicinity. Residents of the Mexican coast south of Brownsville should make similar plans, as Alex could just as easily hit there.

This is an excellent time for everyone along the Gulf to start thinking about hurricane preparedness if they haven’t already.

If it does head this way I’ll blog the approach and the storm itself – as I did for Ike and storms before it. BoW HQ is relatively safe in a very secure building several stories above ground in downtown Houston. My biggest worry is usually life after the storm.

Check out the weather resources in the left sidebar and stay tuned to Blogs of War for rapid updates if this thing heads our way.