View Full Version : Hurricane Maria Forecast Discussion Number 17

09-20-2017, 03:20 AM
Issued at 500 AM AST Wed Sep 20 2017 000WTNT45 KNHC 200858TCDAT5Hurricane Maria Discussion Number 17NWS National Hurricane Center Miami FL AL152017500 AM AST Wed Sep 20 2017Radar observations from the San Juan WSR-88D and wind data from anAir Force Reserve Unit Hurricane Hunter aircraft indicate thatMaria has just about completed an eyewall replacement. Based onthe now-dominant outer eyewall, the eye diameter has increased from10 n mi to 30 n mi. This has likely contributed to some weakening,and based on the latest observations from the Hurricane Hunters, theintensity is set at 135 kt which is at the top of category 4 range.Although there has been a slight reduction of intensity, Mariaremains an extremely dangerous hurricane. Some weakening islikely while the system crosses Puerto Rico. Later in the forecastperiod, less favorable upper-level winds should cause furtherweakening, but Maria is likely to remain a large and powerfulhurricane for the next 5 days. The official intensity forecast isnear or a little above the model consensus.Maria continues to move between west-northwest and northwest atabout 9 kt. The flow on the south side of a weak mid-level ridgeover the western Atlantic is expected to steer the hurricane on thisgeneral heading over the next couple of days. This track will bringthe center of Maria across Puerto Rico and just north of the easternDominican Republic over the next day or so. After that time abreak in the ridge, partially associated with Tropical Storm Jose,should cause Maria to turn north-northwestward, then northward bythe end of the forecast period. The track guidance remains tightlyclustered through 72 hours, giving fairly high confidence in thetrack forecast through that time. There is some increase in thespread of the models at days 4 and 5, with the latest ECMWFprediction near the western edge of the guidance envelope but withall of the reliable models well offshore of the southeast U.S. atthe end of the period. The official forecast is very close to thelatest FSU Superensemble track.KEY MESSAGES:1. Maria's core will make landfall over Puerto Rico within thenext couple of hours, bringing life-threatening wind, storm surge,and rainfall impacts to the island. Everyone in Puerto Rico shouldfollow advice from local officials to avoid life-threateningflooding from storm surge and rainfall.2. Wind speeds atop and on the windward sides of hills and mountainsand on high-rise buildings could be much stronger than thenear-surface winds indicated in this advisory.3. A Hurricane Warning is also in effect for the Virgin Islands,the northern coast of the Dominican Republic, the Turks andCaicos Islands and the southeastern Bahamas, where Maria is expectedto bring dangerous wind, storm surge, and heavy rainfall.FORECAST POSITIONS AND MAX WINDSINIT 20/0900Z 17.9N 65.6W 135 KT 155 MPH 12H 20/1800Z 18.6N 66.7W 125 KT 145 MPH...INLAND 24H 21/0600Z 19.5N 68.2W 120 KT 140 MPH 36H 21/1800Z 20.5N 69.4W 120 KT 140 MPH 48H 22/0600Z 21.5N 70.5W 115 KT 130 MPH 72H 23/0600Z 24.2N 72.0W 105 KT 120 MPH 96H 24/0600Z 27.3N 73.0W 100 KT 115 MPH120H 25/0600Z 30.5N 73.0W 85 KT 100 MPH$$Forecaster Pasch

More... (http://www.nhc.noaa.gov/text/refresh/MIATCDAT5+shtml/200858.shtml)