The latest advisory from the NHC:
RAINFALL…ALEX IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS OF 6 TO 12 INCHES OVER PORTIONS OF NORTHEASTERN MEXICO AND SOUTHERN TEXAS…WITH ISOLATED MAXIMUM AMOUNTS OF 20 INCHES. THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES…ESPECIALLY IN MOUNTAINOUS TERRAIN. RAINBANDS ASSOCIATED WITH ALEX ARE SPREADING ONSHORE IN NORTHEASTERN MEXICO AND SOUTHERN TEXAS.
WIND…TROPICAL STORM CONDITIONS ARE EXPECTED TO REACH THE COAST WITHIN THE HURRICANE AND TROPICAL STORM WARNING AREAS LATER THIS MORNING…MAKING OUTSIDE PREPARATIONS DIFFICULT OR DANGEROUS.
STORM SURGE…A DANGEROUS STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 3 TO 5 FEET ABOVE GROUND LEVEL ALONG THE IMMEDIATE COAST TO THE NORTH OF WHERE THE CENTER MAKES LANDFALL. THE SURGE COULD PENETRATE INLAND AS FAR AS SEVERAL MILES FROM THE SHORE WITH DEPTH GENERALLY DECREASING AS THE WATER MOVES INLAND. NEAR THE COAST…THE SURGE WILL BE ACCOMPANIED BY LARGE AND DESTRUCTIVE WAVES.
TORNADOES…ISOLATED TORNADOES ARE POSSIBLE OVER PORTIONS OF EXTREME SOUTHERN TEXAS TODAY.
Rain, not wind, is the biggest threat by far but the balance could shift a little for those near the eye:
VERTICAL SHEAR IS FORECAST TO REMAIN LIGHT UP UNTIL LANDFALL OCCURS IN ABOUT 24 HOURS. GIVEN THAT ALEX IS ALSO MOVING SLOWLY OVER SOME OF THE WARMEST UPPER-OCEAN HEAT CONTENT IN THAT REGION OF THE GULF OF MEXICO…STEADY STRENGTHENING RIGHT UP UNTIL LANDFALL SEEMS REASONABLE. HOWEVER…GIVEN THE RELATIVELY LOW CENTRAL PRESSURE RECENTLY MEASURED BY THE RECON AIRCRAFT…RAPID INTENSIFICATION OF AT LEAST 30 KT IN 24 HOURS IS A DISTINCT POSSIBILITY. THE OFFICIAL INTENSITY FORECAST IS A BLEND OF THE LGEM AND SHIPS MODELS.
If Alex does reach category 2 or weak category 3 status wind becomes a significant concern but flooding will impact, and kill, many more people than wind. FEMA on flooding:
The next time you hear hurricane — think inland flooding!
While storm surge has the highest potential to cause hurricane related deaths, more people died from inland flooding associated with tropical systems from 1970 to 1999. Since the 1970′s, inland flooding has been responsible for more than half of all deaths associated with tropical cyclones in the United States. Flooding from hurricanes can occur hundreds of miles from the coast placing communities, which would not normally be affected by the strongest hurricane winds, in great danger.