Hurricane Irene Briefing 830 AM Wed Aug 24, 2011 Rob Molleda National Weather Service Miami/South Florida Forecast Office

Early AM Satellite Image Irene over SE Bahamas. Strengthened overnight with max sustained winds now 115 mph (Cat 3). Moving WNW 9 mph. 550 miles SE of South Florida

5 AM NHC Forecast Direct South Florida impact continues to become less likely. Peripheral impacts possible Thursday and Thursday night, mainly coastal areas and offshore.

Weather Pattern H H Gap between the highs Troughs Irene likely to follow edge of Atlantic High

Forecast Pattern Thu PM H Forecast Steering Pattern Thu PM: Trough over Eastern U.S. reinforces steering to the north and northeast away from Florida. X

Model Guidance Models in very good agreement on turn to NW and N (NOTE: red line is not one of the reliable dynamical models).

Hurrevac Fcst Wind Swath Edge of Forecast Sustained TS wind field (assuming perfect forecast).

Forecast Wind Field On forecast track, Tropical Storm force winds remain miles offshore at worst. However, an unexpected shift back to the west or a larger than forecast storm could bring sustained TS force winds to portions of SE FL coast Thursday afternoon.

Graphical Cumulative TS Wind Speed Probabilities West Palm Beach: 29% Miami: 20% Naples: 8% These are ALL downward trends since last night.

Forecast Wave Heights Seas of ft in Gulf Stream Thursday and Thursday night. Rough surf and beach erosion likely, especially Palm Beach County.

Potential Impacts Tropical Storm Watch in effect for Atlantic waters off SE Florida. No watches in effect for land areas. Main impacts will be coastal and marine. Timing of impacts in Thursday to Thursday night time frame.

Potential Impacts Showers and occasional squalls beginning Thursday morning along SE FL coast and gradually shifting north through day and evening. SE Florida: Sustained winds mph. - Palm Beach: A few gusts to mph near the coast. - Broward and Miami-Dade: Gusts to 35 mph except a few gusts could reach 40 mph near the coast. Gulf coast will miss most of the rain, Lake Okeechobee area will likely see back edge of the rain with gusts to mph possible. Rough surf and beach erosion expected, most notably in Palm Beaches. Rainfall no more than 1-2 inches through Friday morning. Only minor flood impacts at worst.

Potential Wind Impact

Potential Coastal Impact

Questions? Thank you for your time! National Weather Service Miami/South Florida Forecast Office