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Hurricane Maria Forecast Discussion Number 20
2017-09-21 05:00:30| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Wed Sep 20 2017 000 WTNT45 KNHC 210300 TCDAT5 Hurricane Maria Discussion Number 20 NWS National Hurricane Center Miami FL AL152017 1100 PM AST Wed Sep 20 2017 The satellite presentation is a little better organized than a few hours ago, and Maria now has a large ragged eye. However, data from an Air Force Hurricane Hunter plane indicate that the winds are still 95 kt, while the central pressure has remained unchanged oscillating near 959 mb. Even with the current favorable low-shear environment and warm ocean, it takes in general about 24 hours for the boundary layer of the hurricane to recover from the passage over high terrain, in this case Puerto Rico. In addition, the reconnaissance plane reported two wind maxima and two concentric eyewalls in the previous penetration, and it just reported that the inner one has collapsed in the last fix. This suggest that an eyewall replacement cyclone has occurred. With this complex scenario, the NHC forecast allows for some small increase in intensity as suggested by guidance and brings Maria back to category 3 status in about 24 hours. Maria continues right on track, moving toward the northwest or 310 degrees at 8 kt. The hurricane is expected to be steered north-northwestward and northward around a subtropical ridge over the Atlantic for the next 2 to 3 days. The only change to the previous forecast is a small shift to the east by the end of the forecast period as indicated by most of the track models. By then, Maria should have reached the northwestern edge of the ridge. The NHC forecast is basically on top of the multi-model consensus and very near the HFIP corrected consensus. KEY MESSAGES: 1. Maria is moving away from the northwestern coast of Puerto Rico, and strong winds and storm surge flooding should continue to subside through early Thursday. However, heavy rainfall is expected to continue, and catastrophic flash flooding is occurring on the island, especially in areas of mountainous terrain. Everyone in Puerto Rico should continue to follow advice from local officials to avoid these life-threatening flooding conditions. 2. A Hurricane Warning is in effect for the northern coast of the Dominican Republic, the Turks and Caicos Islands, and the southeastern Bahamas, where Maria is expected to bring dangerous wind, storm surge, and heavy rainfall. FORECAST POSITIONS AND MAX WINDS INIT 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 MPH 120H 26/0000Z 32.0N 71.0W 80 KT 90 MPH $$ Forecaster Avila
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