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| #898403 (Received by flhurricane at: 4:47 PM 14.Aug.2017) TCDAT3 Tropical Storm Gert Discussion Number 8 NWS National Hurricane Center Miami FL AL082017 500 PM EDT Mon Aug 14 2017 The satellite presentation of Gert has continued to improve today. Convective banding has increased around the center, and a large banded eye has appeared in recent visible satellite pictures. Satellite intensity estimates from TAFB, SAB, and UW-CIMSS supported an intensity of around 55 kt at 18z, but due to the continued increase in organization, the initial wind speed is set at 60 kt for this advisory. Although there is some light northerly shear over the system, it should not prevent additional strengthening during the next day or so while Gert remains over SSTs of 28 to 29 deg C. Gert is expected to become a hurricane within 12 hours, and the updated NHC intensity forecast calls for a bit higher peak intensity than before. The NHC forecast is a little above the statistical guidance and calls for peak intensity a little sooner than most of the guidance. The HWRF continues to be very bullish in bringing the system to major hurricane status, but since it shows peak intensity well after the system is expected to encounter westerly shear and cooler SSTs, less weight has been placed on that scenario. 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 has been moving more slowly than expected today while it has been rounding the western portion of the ridge. The storm is expected to turn north-northeastward and begin to accelerate Tuesday ahead of a shortwave trough approaching the northeastern United States. The track guidance continues to be in excellent agreement, but is generally slower than before. As a result, little cross-track change was required in the NHC track through 72 h, but the new forecast is slower than the previous one to account for the latest trend in the latest guidance. 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 14/2100Z 30.6N 72.3W 60 KT 70 MPH 12H 15/0600Z 31.6N 72.3W 70 KT 80 MPH 24H 15/1800Z 33.3N 71.6W 75 KT 85 MPH 36H 16/0600Z 35.6N 69.0W 80 KT 90 MPH 48H 16/1800Z 38.0N 64.0W 80 KT 90 MPH 72H 17/1800Z 44.5N 48.0W 70 KT 80 MPH...POST-TROP/EXTRATROP 96H 18/1800Z 52.0N 39.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 19/1800Z...ABSORBED BY LARGER EXTRATROPICAL LOW $$ Forecaster Brown |
