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Tropical Storm Kate Forecast Discussion Number 11
2021-08-30 22:36:04| National Hurricane Center (Atlantic)
Issued at 500 PM AST Mon Aug 30 2021 988 WTNT45 KNHC 302035 TCDAT5 Tropical Storm Kate Discussion Number 11 NWS National Hurricane Center Miami FL AL102021 500 PM AST Mon Aug 30 2021 The low-level center of Kate is exposed in visible satellite imagery this afternoon. Its deep convection collapsed late this morning, and the sheared tropical cyclone is now only producing a small area of convection over 60 n mi east of its center. A partial 1321 UTC ASCAT-B pass still showed numerous 30-kt wind vectors in the eastern semicircle, even with little to no active convection. The initial intensity is conservatively lowered to 35 kt for this advisory. The subtropical jet stream across the central Atlantic will continue to impart strong west-northwesterly vertical wind shear on Kate during the next day or so. If the struggling tropical cyclone can survive these hostile conditions, some modest strengthening could occur later this week over warm SSTs of 28 deg C or so. However, the lack of mid-level moisture in the surrounding environment may limit convective development even under these more favorable conditions, and there is no guarantee that Kate will survive that long. In fact, simulated satellite imagery from the GFS and ECMWF suggest that Kate may continue to only produce sporadic bursts of convection over the next couple of days, which jeopardizes its chances of surviving through the week. The official NHC intensity forecast has been adjusted downward based on the latest guidance trends and the uncertainties discussed above. Minor fluctuations in intensity could occur over the next 24-36 h as convective pulsing causes the cyclone's intensity to hover around tropical-storm-force strength. Kate is moving a little faster toward the north, or 355/9 kt, within a weakness in the subtropical ridge. A northward motion is expected to continue through early Tuesday. The subtropical ridge is expected to become reestablished over the central Atlantic Tuesday night into Wednesday, which should turn Kate toward the northwest through midweek. Thereafter, Kate is forecast to accelerate northward or north-northeastward ahead of an approaching deep-layer trough that will move across the western Atlantic late this week. Assuming Kate is still around by day 5, the cyclone is forecast to become absorbed by a larger extratropical low near Atlantic Canada. FORECAST POSITIONS AND MAX WINDS INIT 30/2100Z 22.7N 50.9W 35 KT 40 MPH 12H 31/0600Z 23.7N 50.7W 30 KT 35 MPH 24H 31/1800Z 24.7N 50.7W 30 KT 35 MPH 36H 01/0600Z 25.8N 51.1W 35 KT 40 MPH 48H 01/1800Z 27.0N 52.1W 35 KT 40 MPH 60H 02/0600Z 28.4N 53.5W 40 KT 45 MPH 72H 02/1800Z 30.1N 54.7W 40 KT 45 MPH 96H 03/1800Z 34.5N 55.0W 40 KT 45 MPH 120H 04/1800Z...DISSIPATED $$ Forecaster Reinhart
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