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.