View Full Version : Hurricane Maria Forecast Discussion Number 20

09-21-2017, 12:16 AM
Issued at 1100 PM AST Wed Sep 20 2017 000WTNT45 KNHC 210300TCDAT5Hurricane Maria Discussion Number 20NWS National Hurricane Center Miami FL AL1520171100 PM AST Wed Sep 20 2017The satellite presentation is a little better organized thana few hours ago, and Maria now has a large ragged eye. However,data from an Air Force Hurricane Hunter plane indicate that thewinds are still 95 kt, while the central pressure has remainedunchanged oscillating near 959 mb. Even with the current favorablelow-shear environment and warm ocean, it takes in general about 24hours for the boundary layer of the hurricane to recover from thepassage over high terrain, in this case Puerto Rico. In addition,the reconnaissance plane reported two wind maxima and two concentriceyewalls in the previous penetration, and it just reported that theinner one has collapsed in the last fix. This suggest that aneyewall replacement cyclone has occurred. With this complexscenario, the NHC forecast allows for some small increase inintensity as suggested by guidance and brings Maria back to category3 status in about 24 hours.Maria continues right on track, moving toward the northwest or 310degrees at 8 kt. The hurricane is expected to be steerednorth-northwestward and northward around a subtropical ridge overthe Atlantic for the next 2 to 3 days. The only change to theprevious forecast is a small shift to the east by the end of theforecast period as indicated by most of the track models. By then,Maria should have reached the northwestern edge of the ridge. TheNHC forecast is basically on top of the multi-model consensus andvery near the HFIP corrected consensus.KEY MESSAGES:1. Maria is moving away from the northwestern coast of PuertoRico, and strong winds and storm surge flooding should continue tosubside through early Thursday. However, heavy rainfall is expectedto continue, and catastrophic flash flooding is occurring on theisland, especially in areas of mountainous terrain. Everyone inPuerto Rico should continue to follow advice from local officials toavoid these life-threatening flooding conditions.2. A Hurricane Warning is in effect for the northern coast of theDominican Republic, the Turks and Caicos Islands, and thesoutheastern Bahamas, where Maria is expected to bring dangerouswind, storm surge, and heavy rainfall.FORECAST POSITIONS AND MAX WINDSINIT 21/0300Z 19.2N 67.9W 95 KT 110 MPH 12H 21/1200Z 19.9N 68.8W 95 KT 110 MPH 24H 22/0000Z 21.0N 70.0W 100 KT 115 MPH 36H 22/1200Z 22.3N 70.8W 100 KT 115 MPH 48H 23/0000Z 23.7N 71.5W 100 KT 115 MPH 72H 24/0000Z 26.8N 72.2W 100 KT 115 MPH 96H 25/0000Z 29.5N 72.0W 90 KT 105 MPH120H 26/0000Z 32.0N 71.0W 80 KT 90 MPH$$Forecaster Avila

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