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| #898545 (Received by flhurricane at: 4:36 AM 16.Aug.2017) TCDAT3 Hurricane Gert Discussion Number 14 NWS National Hurricane Center Miami FL AL082017 500 AM AST Wed Aug 16 2017 Gert has strengthened a little more during the last several hours. There have been some hints of an eye in infrared satellite images overnight, and the center is embedded beneath a large area of cold cloud tops. The latest Dvorak classifications are both 4.5/77 kt from TAFB and SAB, and recent ADT values are a little higher. Based on these estimates, the initial wind speed is nudged upward to 80 kt. The hurricane is forecast to strengthen a little more during the next 12 to 24 hours while it remains over the warm waters of the Gulf Stream and in a favorable upper-level wind pattern. After that time, sharply colder waters, a significant increase in west- southwesterly shear, and drier air should end the strengthening trend and cause weakening. The models are in good agreement in showing Gert losing its tropical characteristics in 36 to 48 hours. The NHC intensity forecast is largely an update of the previous one. Gert continues to pick up speed, and it is now moving northeastward at 18 kt. The hurricane is located between a subtropical ridge to its southeast and a large deep-layer low pressure system to its northwest. Gert is expected to turn to the east-northeastward and accelerate some more during the next couple of days while it becomes embedded in the fast mid-latitude flow. Beyond a couple of days, when Gert is post-tropical, the system is forecast to slow down and move more erratically while it interacts and ultimately merges with another extratropical low. The NHC track forecast lies closest to the various consensus aids. The post-tropical portion of the track, intensity, and wind radii forecasts are based on guidance provided by NOAA`s Ocean Prediction Center. Swells from Gert are beginning to reach portions of the mid-Atlantic coast of the United States, and are expected to spread northward to New England and Atlantic Canada during the next couple of days. These swells are likely to produce dangerous surf and rip current conditions. Please consult products from your local weather forecast office for more information. FORECAST POSITIONS AND MAX WINDS INIT 16/0900Z 36.0N 68.4W 80 KT 90 MPH 12H 16/1800Z 37.7N 64.8W 85 KT 100 MPH 24H 17/0600Z 40.0N 58.2W 85 KT 100 MPH 36H 17/1800Z 43.2N 50.1W 75 KT 85 MPH 48H 18/0600Z 47.0N 42.6W 60 KT 70 MPH...POST-TROP/EXTRATROP 72H 19/0600Z 54.0N 33.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 20/0600Z 55.5N 27.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 120H 21/0600Z 57.5N 12.0W 35 KT 40 MPH...POST-TROP/EXTRATROP $$ Forecaster Cangialosi |
