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| #981234 (Received by flhurricane at: 10:48 PM 05.Sep.2019) TCDAT3 Tropical Storm Gabrielle Discussion Number 10 NWS National Hurricane Center Miami FL AL082019 1100 PM AST Thu Sep 05 2019 The center of Gabrielle has been devoid of deep convection since late this morning, as dry air and southerly shear have taken their toll. If this trend continues, then advisories may be discontinued Friday morning. For the time being, a recent scatterometer pass showed that 35 kt winds are still occurring in association with Gabrielle`s circulation, and that will be the initial intensity for this advisory. SHIPS intensity guidance indicates strong shear will continue to affect the cyclone for the next 24 to 36 hours. If the circulation survives this, the shear will diminish. However, it appears that there will still be dry air to contend with. The forecast calls for a steady intensity through 36 hours, followed by slow strengthening as the shear becomes negligible. Late in the forecast period, the cyclone will move over cooler waters as it begins to transition to an extratropical cyclone, which should limit any non-baroclinic intensification beyond 96 hours. The intensity forecast is highly uncertain, as Gabrielle very well could become a post-tropical remnant low tomorrow. The convection will have to recover once the wind shear subsides, and I am skeptical that this will do so with any haste due to the dry air that is forecast to be in place. The official intensity forecast is similar to the previous one, and is below the various consensus aids beyond 36 hours. Gabrielle has begun to accelerate to the northwest. The forward speed will increase a little more through Friday morning as the cyclone is steered between a mid- to upper-level low to its west, and a subtropical ridge to its east. Later in the forecast period, Gabrielle will begin to turn northward then northeastward and accelerate as a mid-latitude trough approaches the cyclone. The official track forecast is very close to the previous one through 72 hours, and then was nudged slightly to the left beyond that time due to a shift in the global models and consensus guidance. FORECAST POSITIONS AND MAX WINDS INIT 06/0300Z 24.3N 36.6W 35 KT 40 MPH 12H 06/1200Z 25.7N 38.0W 35 KT 40 MPH 24H 07/0000Z 27.9N 40.2W 35 KT 40 MPH 36H 07/1200Z 29.7N 42.7W 40 KT 45 MPH 48H 08/0000Z 31.1N 45.3W 45 KT 50 MPH 72H 09/0000Z 34.3N 48.2W 55 KT 65 MPH 96H 10/0000Z 38.5N 45.5W 60 KT 70 MPH 120H 11/0000Z 44.5N 38.0W 60 KT 70 MPH $$ Forecaster Latto |
