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| #1062735 (Received by flhurricane at: 10:54 PM 21.Sep.2021) TCDAT1 Tropical Depression Peter Discussion Number 14 NWS National Hurricane Center Miami FL AL162021 1100 PM AST Tue Sep 21 2021 The last visible satellite images of Peter this evening indicated that its low-level center was losing definition and becoming even more elongated. Earlier, new bursts of convection associated with Peter had become oriented along a northeast to southwest axis, a possible sign that Peter may no longer have a well-defined center and could be opening up into a trough. But the estimated center position is now obscured by convective debris, and without recent scatterometer data to prove otherwise, Peter is maintained as a sheared tropical depression for this advisory. The initial intensity of 30 kt is consistent with a UW-CIMSS ADT objective 30-kt estimate and a T2.0/30 kt Dvorak classification from SAB. It is estimated that Peter is moving northwestward, or 310/6 kt, although this is somewhat uncertain given the degraded low-level structure of the cyclone. The track reasoning remains consistent with previous advisories. Peter is forecast to turn more northward on Wednesday, and then move north-northeastward to northeastward through the end of the week as a trough to the north and northeast of Peter erodes the southern portion of the low-level steering ridge. The track consensus aids have shifted slightly to the right this cycle, and so the latest NHC track forecast has been adjusted a little to the right of the previous one. Environmental conditions are expected to remain hostile for Peter over the next couple of days. Strong vertical wind shear of 25-30 kt will persist for the next 24-36 h, and GFS and ECMWF model simulated satellite imagery suggest that Peter will be unable to sustain enough deep, organized convection to maintain its status as a tropical cyclone for much longer. Thus, the NHC forecast shows Peter becoming a remnant low in 36 h, with some additional weakening expected before dissipation by this weekend. Of course, without sufficient convection to sustain the low-level vortex, it would not be surprising if the depression degenerated into a trough even sooner than forecast. Key Messages: 1. Rainfall around the southern periphery of Peter may lead to areas of urban and small stream flooding through early Wednesday across northern Hispaniola, Puerto Rico, and portions of the Virgin Islands. FORECAST POSITIONS AND MAX WINDS INIT 22/0300Z 20.8N 65.3W 30 KT 35 MPH 12H 22/1200Z 21.6N 66.2W 30 KT 35 MPH 24H 23/0000Z 22.6N 66.8W 25 KT 30 MPH 36H 23/1200Z 23.6N 66.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 24/0000Z 24.6N 66.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 60H 24/1200Z 25.7N 65.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 25/0000Z...DISSIPATED $$ Forecaster Reinhart |
