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Hurricane Maria Forecast Discussion Number 7
2017-09-18 04:49:56| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Sun Sep 17 2017 000 WTNT45 KNHC 180249 TCDAT5 Hurricane Maria Discussion Number 7 NWS National Hurricane Center Miami FL AL152017 1100 PM AST Sun Sep 17 2017 Reports from an Air Force Reserve Hurricane Hunter aircraft received just after the previous advisory indicated that Maria's maximum sustained winds had increased to 70 kt. Since that time, a large central dense overcast with cloud tops colder than -80C has formed, and data from the radar on Martinique shows 60-70 percent of an eyewall is present under the overcast. Satellite intensity estimates have increased to 75 kt, and that is the initial intensity. The initial motion is 290/11. The subtropical ridge to the north is expected to steer Maria generally west-northwestward for the next 72 h, with some decrease in the forward speed. After that time, the guidance suggests that the hurricane should turn more toward the northwest as it approaches the western end of the ridge. The track guidance remains tightly clustered, and the new forecast track, which is similar to the previous track, is in best overall agreement with the HFIP corrected consensus and ECMWF models. Analyses from CIMSS at the University of Wisconsin suggest that Maria is currently experiencing light to moderate southwesterly shear. However, all indications are that the shear should diminish during the next 24-48 h, which should allow steady to rapid strengthening. The Rapid Intensification Index of the SHIPS model forecast better than a 50 percent chance of 25-30 kt of strengthening during the next 24 h, and about a 35 percent chance of 55 kt of strengthening during the next 48 h. Based on this, the intensity forecast has been increased to show Maria becoming a major hurricane in 24 h and a category 4 hurricane in 48 h. Late in the forecast period, a combination of land interaction and increasing shear should cause some weakening. The new intensity forecast is near the upper edge of the guidance in best overall agreement with the HWRF. KEY MESSAGES: 1. Maria continues to strengthen and is expected to be at major hurricane intensity when it affects portions of the Leeward Islands over the next few days, bringing dangerous wind, storm surge and rainfall hazards. Hurricane and tropical storm warnings have been issued for portions of the Leeward Islands, and these warnings will likely be extended northward and westward on Monday. 2. Maria is likely to affect the British and U.S. Virgin Islands and Puerto Rico by mid week as a dangerous major hurricane. Hurricane watches have been issued for the U.S. and British Virgin Islands and could be extended to Puerto Rico early Monday. Interests in these areas should monitor the progress of Maria and follow any advice given by local officials. FORECAST POSITIONS AND MAX WINDS INIT 18/0300Z 14.2N 58.4W 75 KT 85 MPH 12H 18/1200Z 14.7N 59.8W 85 KT 100 MPH 24H 19/0000Z 15.4N 61.2W 100 KT 115 MPH 36H 19/1200Z 16.2N 62.6W 110 KT 125 MPH 48H 20/0000Z 16.9N 63.9W 115 KT 130 MPH 72H 21/0000Z 18.5N 67.0W 120 KT 140 MPH...OVER PUERTO RICO 96H 22/0000Z 20.0N 69.5W 115 KT 130 MPH...OVER WATER 120H 23/0000Z 22.0N 71.5W 105 KT 120 MPH $$ Forecaster Beven
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Category:Transportation and Logistics