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Hurricane Maria Forecast Discussion Number 16
2017-09-20 04:45:21| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Tue Sep 19 2017 000 WTNT45 KNHC 200245 TCDAT5 Hurricane Maria Discussion Number 16 NWS National Hurricane Center Miami FL AL152017 1100 PM AST Tue Sep 19 2017 Since the previous advisory, WSR-88D radar data from San Juan Puerto Rico has shown the development of concentric eyewalls and a double-wind maximum. This has led to an increase in the size of the 50- and 64-kt wind radii. An earlier Air Force Reserve reconnaissance aircraft measured a peak flight-level wind of 157 kt and a few SFMR winds of 149-152 kt in the small inner eyewall between 2200 and 0000 UTC this evening. Based on these data, the initial wind speed was increased to 150 kt. The minimum pressure estimated from earlier dropsonde data is 909 mb, which is the tenth lowest minimum pressure recorded in an Atlantic basin hurricane. Since the outer eyewall has become better defined and the winds are increasing within the outer eyewall, it is likely that Maria's intensification will finally cease. However, Maria is expected to remain an extremely dangerous category 5 hurricane until landfall in Puerto Rico early Wednesday. The passage of the core over Puerto Rico should cause some weakening, but Maria is likely to remain a major hurricane for several more days. Increasing shear and cooler waters over the western Atlantic in the wake of hurricanes Irma and Jose will likely lead to additional weakening late in the period. Maria is moving between west-northwest and northwest at about 9 kt. A weak ridge over the western Atlantic is expected to steer the hurricane on this general heading over the next couple of days. This track will bring the center of Maria over Puerto Rico and just north of the eastern Dominican Republic over the next day or so. After that time, a break in the ridge should cause Maria to turn north-northwestward, then northward by late in the week. The track guidance is tightly clustered through 72 hours, yielding fairly high confidence in the track forecast through that time. There is some increase in the spread of the models at days 4 and 5, with the GFS and HWRF farther west and faster, while the ECMWF is along the eastern edge of the guidance and slow. For now, the NHC track forecast is between the various consensus models at 96 and 120 h. KEY MESSAGES: 1. Maria's core will pass near or over St. Croix within the next few hours and will approach the southeastern coast of Puerto Rico early Wednesday, bringing life-threatening wind, storm surge, and rainfall impacts to portions of those islands. Everyone in these areas should follow advice from local officials to avoid life-threatening flooding from storm surge and rainfall. 2. Wind speeds atop and on the windward sides of hills and mountains and on high-rise buildings could be much stronger than the near-surface winds indicated in this advisory. 3. A Hurricane Warning is also in effect for the remainder of the Virgin Islands and the northern coast of the Dominican Republic, where Maria is expected to bring dangerous wind, storm surge, and heavy rainfall. 4. A Hurricane Watch is in effect for the southeastern Bahamas and the Turks and Caicos, where Maria could bring hurricane conditions on Thursday. FORECAST POSITIONS AND MAX WINDS INIT 20/0300Z 17.3N 64.7W 150 KT 175 MPH 12H 20/1200Z 18.0N 65.8W 145 KT 165 MPH 24H 21/0000Z 18.9N 67.3W 125 KT 145 MPH 36H 21/1200Z 19.9N 68.6W 120 KT 140 MPH 48H 22/0000Z 20.9N 69.7W 115 KT 130 MPH 72H 23/0000Z 23.3N 71.4W 110 KT 125 MPH 96H 24/0000Z 26.2N 72.2W 105 KT 120 MPH 120H 25/0000Z 29.5N 72.5W 90 KT 105 MPH $$ Forecaster Brown
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