Wednesday, June 30, 2010

NHC best track shifts farther south, peak U.S. surge estimate reduced to 3 to 5 feet

Wednesday, June 30, 2010

Update: The NHC best track has shifted farther south since yesterday evening. The best track now places landfall about 100 nautical miles S of Brownsville, TX. Therefore, the estimate of peak U.S. surge has been lowered to 3 to 5 feet.

Peak U.S. surge estimate:
Location: South Padre Island, TX
Surge Height: 3 to 5 feet


Alex will likely make landfall about 25 miles S of the landfall location of Hurricane Emily (2005). Emily produced a 5-foot surge at S Padre Island, TX. Although Emily was stronger than Alex will be at landfall, Alex's circulation is very large, which tends to enhance surge heights. To give some idea of Alex's massive size, check out the radar picture in this blog post. Rain bands associated with Alex extend as far out as the western Florida Panhandle. Rain bands are pushing into Baton Rouge this morning, more than 600 miles from the center of circulation!

The NHC upgraded Alex to a hurricane last night around 2130 CDT and conditions are favorable for further strengthening. Alex is currently a Cat 1 and may make landfall as a Cat 2.

Onshore winds should persist in S TX today, reaching tropical storm force for perhaps 12-18 hours near S Padre Island.

This peak U.S. surge estimate is based on comparison of NHC best track and intensity forecasts to similar historical surge events. As mentioned in previous posts, the SCIPP program identified three similar surge events, which are useful in this comparison: Hurricane Emily (2005), Hurricane Gilbert (1988), and an Unnamed storm (1909).

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