Alex near hurricane strength

June 29, 2010

-Last nights model runs, enhanced by upper-air data collection over the Gulf of Mexico, produced a tight spread among global forecast models.  All show Alex making landfall just south of the U.S.-Mexico border tomorrow night or Thursday morning.

-Towards the end of last night’s Hurricane Hunter mission, a westward component of motion was evident again, ending the drifting movement to the north-northeast.  Observations on the last pass showed the storm at 55 knots/65 mph.  Given its improved satellite appearance, that was adjusted upward to 60 knots/70 mph for the 4 AM advisory.

– Intensity forecast is essentially the same, showing a peak intensity of 80 knots.  Average intensity forecast error for the 48 hour period last year was 17.5 knots.  Given apparently favorable conditions, and appears that any error would involve under-forecasting storm strength.

–  Average forecast track hour at 48 hours last year was 73 nautical miles.  Keep in mind that some of that is along-track error (errors due to timing) and cross-track (errors to the left/right in the forecast).

-Biggest problem for the Texas coast, not just the lower coast near the boarder, but further north as well  may be rainfall totals.  A couple of models bring Alex ashore rather slowly.  While the peak winds might be far enough away to not be problematic for Texas the rain will not.  Dwellers of low-lying areas, take heed.

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