000 WTNT45 KNHC 260243 TCDAT5 Hurricane Maria Discussion Number 40 NWS National Hurricane Center Miami FL AL152017 1100 PM EDT Mon Sep 25 2017 Maria's deep convection continues to slowly diminish, especially over the western semicircle of the circulation, where only a few cold tops are seen. The Air Force Hurricane Hunters reported an SFMR-observed surface wind of 67 kt over the northeast quadrant, so the current intensity is maintained at 70 kt for the time being. Although vertical shear is not forecast by the dynamical guidance to increase significantly over the next few days, cooler waters and drier air are likely to cause Maria to weaken to a tropical storm by late Tuesday or Wednesday. By the end of the forecast period, global models indicate that the system will have transformed into a frontal cyclone over the northern Atlantic, and this is also reflected in the official forecast. Maria continues to move northward quite slowly, or 360/6 kt, on the western side of a subtropical high pressure area. A mid-level ridge over the northeastern United States should continue to retard the system's forward progress for another day or two. Afterward, this ridge is predicted to weaken, and Maria should begin to accelerate northeastward to east-northeastward away from the United States east coast, ahead of a broad mid-tropospheric trough. The official track forecast is very similar to the previous one and is in line with the multi-model consensus. This is also between the faster GFS and slower ECMWF tracks. KEY MESSAGES: 1. Maria 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 North Carolina coast beginning Tuesday, where a Tropical Storm Warning is in effect. 2. Storm surge flooding, especially along the sound side of the North Carolina Outer Banks, is expected beginning on Tuesday, and a Storm Surge Watch has been issued for portions of eastern North Carolina. 3. Swells generated by Maria are affecting much of the east coast of the United States from Florida through southern New England. These swells are also affecting Bermuda, Puerto Rico, the northern coast of Hispaniola, the Turks and Caicos Islands, and the Bahamas. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office for more information. FORECAST POSITIONS AND MAX WINDS INIT 26/0300Z 32.3N 73.1W 70 KT 80 MPH 12H 26/1200Z 33.2N 73.2W 65 KT 75 MPH 24H 27/0000Z 34.1N 73.2W 65 KT 75 MPH 36H 27/1200Z 35.0N 73.0W 60 KT 70 MPH 48H 28/0000Z 35.5N 72.4W 60 KT 70 MPH 72H 29/0000Z 36.5N 68.4W 60 KT 70 MPH 96H 30/0000Z 40.0N 57.5W 60 KT 70 MPH 120H 01/0000Z 47.0N 40.0W 60 KT 70 MPH...POST-TROP/EXTRATROP $$ Forecaster Pasch