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#904402 (Received by flhurricane at: 10:53 AM 24.Sep.2017) TCDAT5 Hurricane Maria Discussion Number 34 NWS National Hurricane Center Miami FL AL152017 1100 AM EDT Sun Sep 24 2017 NOAA and Air Force Hurricane Hunter aircraft have measured 700-mb flight-level winds of 101 to 117 kt over the eastern and southeastern portion of the Maria this morning. However, surface wind estimates from the SFMR suggest that these winds are not mixing to the surface at the usual efficiency, as the highest SFMR winds on both flights have been around 80 kt. Based on a blend of the flight-level and SFMR winds the initial wind speed has been reduced to 90 kt. The initial motion estimate is 350/8 kt. A north-northwestward to northward motion is expected over the next 2 to 3 days while Maria is steered between a cut-off low/trough over the southeastern U.S. and eastern Gulf of Mexico, and a subtropical ridge over the southwestern Atlantic. Maria is predicted to slow down within the next couple of days as a high pressure ridge builds to the north of the hurricane. After 72 h, Maria should turn east-northeastward as the ridge to the north weakens and a broad mid-latitude trough begins to move eastward over the northern United States. The dynamical model guidance is in good agreement on this overall scenario, but there remains a fair amount of spread on the timing of recurvature, with the ECMWF a little farther west and slower than much of the remainder of the guidance. The updated NHC track is between the ECWMF and the various consensus aids, and very close to the previous official forecast. Since Maria is a large hurricane, the associated tropical-storm-force winds could reach a portion of the North Carolina coast by mid-week regardless of the exact forecast track. Some fluctuations in intensity could still occur during the next day or so while Maria moves over warm water and remains in a low shear environment. Later in the forecast period, cooler waters from the wake of Hurricane Jose that traversed the same area last week will likely cause a gradual decrease in intensity. KEY MESSAGES: 1. Maria`s is forecast to continue moving northward, paralleling the U.S. east coast, and it is likely that some direct impacts will occur along portions of the coast by midweek. Interests along the coast of the Carolinas and the Mid-Atlantic should monitor the progress of Maria, as tropical storm or hurricane watches may be needed for part of this area later today. 2. Swells from Maria are increasing along the coast of the southeastern United States and are expected to reach the Mid- Atlantic coast today. These swells will likely cause dangerous surf and rip currents at beaches in these areas through much of the week. For more information, please monitor information from your local National Weather Service office at www.weather.gov. FORECAST POSITIONS AND MAX WINDS INIT 24/1500Z 28.7N 72.9W 90 KT 105 MPH 12H 25/0000Z 29.7N 73.1W 90 KT 105 MPH 24H 25/1200Z 30.8N 73.2W 90 KT 105 MPH 36H 26/0000Z 31.9N 73.3W 85 KT 100 MPH 48H 26/1200Z 32.9N 73.4W 80 KT 90 MPH 72H 27/1200Z 34.4N 73.5W 75 KT 85 MPH 96H 28/1200Z 35.5N 71.8W 70 KT 80 MPH 120H 29/1200Z 36.5N 68.0W 65 KT 75 MPH $$ Forecaster Brown |