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| #898430 (Received by flhurricane at: 10:48 PM 14.Aug.2017) TCDAT3 Hurricane Gert Discussion Number 9 NWS National Hurricane Center Miami FL AL082017 1100 PM EDT Mon Aug 14 2017 Satellite images show that Gert has developed an eye, although the convection is weak in the western eyewall. Still, microwave images show a healthy inner-core structure, with plenty of deep convection in the eastern eyewall. Satellite intensity estimates unanimously support making Gert a hurricane on this advisory, and the initial wind speed is set to 65 kt, close to the TAFB figure. Some light or moderate northerly shear is forecast to continue to affect Gert for the next day or so, which might limit the intensification rate. On Wednesday, however, the shear is forecast to drop off as Gert accelerates northeastward over warm waters with a large increase in upper-level divergence also noted. This is typically a favorable environment for intensification, and the official forecast is raised from the previous one, lying between the model consensus IVCN and the higher corrected consensus aids. Gert is expected to complete extratropical transition within 72 hours, then gradually weaken over the North Atlantic before it merges with a larger extratropical cyclone in 4 to 5 days. Gert continues to move northward at about 7 kt. The storm is expected to turn north-northeastward and begin to accelerate Tuesday ahead of a shortwave trough approaching the northeastern United States. Like the last cycle, the track guidance continues to be in excellent agreement, but is generally slower than before. The new forecast is on the fast side of the guidance, assuming that Gert is a strong hurricane that stays vertically coherent in the faster mid/upper-level flow. Swells from Gert are expected to spread northward along the mid-Atlantic coast of the United States during the next few days. These swells are likely to produce dangerous surf and rip current conditions. Please consult products from your local National Weather Service office. FORECAST POSITIONS AND MAX WINDS INIT 15/0300Z 31.2N 72.3W 65 KT 75 MPH 12H 15/1200Z 32.3N 72.0W 70 KT 80 MPH 24H 16/0000Z 34.3N 70.6W 75 KT 85 MPH 36H 16/1200Z 36.6N 66.9W 85 KT 100 MPH 48H 17/0000Z 39.3N 60.8W 90 KT 105 MPH 72H 18/0000Z 46.0N 46.0W 70 KT 80 MPH...POST-TROP/EXTRATROP 96H 19/0000Z 52.0N 37.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 20/0000Z...DISSIPATED $$ Forecaster Blake |
