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#898330 (Received by flhurricane at: 10:50 PM 13.Aug.2017) TCDAT3 Tropical Storm Gert Discussion Number 5 NWS National Hurricane Center Miami FL AL082017 1100 PM EDT Sun Aug 13 2017 Gert continues to gradually become better organized on satellite imagery. A large curved band feature has formed in the eastern semicircle, with very deep convection. It still appears the center is on the northwest side of the convection, somewhat displaced to the north of the mid-level center. Intensity estimates are a little higher than the last advisory, so the wind speed is raised to 40 kt. Gert should remain in a light-to-moderate northerly wind shear environment for the next couple of days, with anomalously warm SSTs and increasing mid-level moisture in the forecast path. Almost all of the historically reliable guidance now show Gert becoming a hurricane in a couple of days under these moderately favorable conditions, and so does the official forecast. The latest NHC prediction is raised from the previous one but remains below the model consensus, closest to the LGEM model. Gert should rapidly weaken as it undergoes extratropical transition in 3-4 days over the cold north Atlantic waters. Gert is moving north-northwestward at 8 kt on the southwestern periphery of a subtropical ridge. A northward turn is expected on Monday while the system rounds the western side of the ridge, and Gert is expected to be about midway between Bermuda and North Carolina on Tuesday. After that time, a progressively faster motion to the northeast and east-northeast is forecast as the system becomes embedded in the mid-latitude westerlies until it dissipates in about 5 days. The guidance has shifted a little bit to the west after recurvature, so the official forecast is moved in that direction. FORECAST POSITIONS AND MAX WINDS INIT 14/0300Z 28.8N 71.9W 40 KT 45 MPH 12H 14/1200Z 30.0N 72.1W 50 KT 60 MPH 24H 15/0000Z 31.6N 72.1W 55 KT 65 MPH 36H 15/1200Z 33.6N 71.2W 60 KT 70 MPH 48H 16/0000Z 36.0N 68.5W 65 KT 75 MPH 72H 17/0000Z 41.0N 55.5W 65 KT 75 MPH 96H 18/0000Z 48.0N 41.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 19/0000Z...DISSIPATED $$ Forecaster Blake |