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Tropical Depression Kate Forecast Discussion Number 15
2021-08-31 22:31:53| National Hurricane Center (Atlantic)
Issued at 500 PM AST Tue Aug 31 2021 000 WTNT45 KNHC 312031 TCDAT5 Tropical Depression Kate Discussion Number 15 NWS National Hurricane Center Miami FL AL102021 500 PM AST Tue Aug 31 2021 Kate continues to produce small, sporadic bursts of convection near and to the east of its partially exposed low-level center this afternoon. The cyclone has moved north of the subtropical jet stream that it has been centered under for the past couple of days, so the mid- to upper-level vertical wind shear is beginning to diminish. Unfortunately, all three ASCAT passes this morning missed Kate's small circulation. The current intensity Dvorak estimates from TAFB and SAB support maintaining the initial intensity at 30 kt for this advisory. The cyclone is moving a little faster to the north, or 360/6 kt. The track forecast reasoning is largely unchanged. Kate is expected to begin moving north-northwestward tonight as a mid-level ridge builds to the east and northeast of the cyclone. This general motion should continue through early Thursday, before an approaching mid- to upper-level trough begins steering Kate more northward through Friday. The official NHC track forecast is essentially an update of the previous one and lies near the center of the guidance envelope, remaining close to the multi-model consensus aids. The intensity forecast is a bit more challenging, with mixed signals noted from the various intensity models. On the one hand, satellite imagery indicates the vertical wind shear is obviously diminishing over Kate, and the cyclone is forecast to move over SSTs of around 28.5 deg C for the next couple of days. However, the cyclone remains embedded within a dry mid-level environment that is clearly making it difficult for Kate to produce organized convection. The official NHC intensity forecast still shows no explicit intensity change and remains closest to the HFIP corrected consensus approach (HCCA) and IVDR aids. However, some short-term intensity fluctuations are certainly possible, which is notable since Kate's intensity is hovering around the tropical depression/storm threshold. By Thursday, Kate will be moving into an even drier, more subsident environment that will make it even more difficult to sustain deep convection. Thus, the NHC forecast shows Kate becoming a remnant low completely devoid of convection by Friday, with dissipation shortly thereafter ahead of an approaching frontal system. FORECAST POSITIONS AND MAX WINDS INIT 31/2100Z 24.6N 50.9W 30 KT 35 MPH 12H 01/0600Z 25.5N 51.5W 30 KT 35 MPH 24H 01/1800Z 26.9N 52.6W 30 KT 35 MPH 36H 02/0600Z 28.6N 53.5W 30 KT 35 MPH 48H 02/1800Z 30.3N 54.2W 30 KT 35 MPH 60H 03/0600Z 32.0N 54.2W 30 KT 35 MPH 72H 03/1800Z 33.7N 53.8W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 04/1800Z...DISSIPATED $$ Forecaster Reinhart
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