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Tropical Storm Peter Forecast Discussion Number 12
2021-09-21 16:57:08| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Tue Sep 21 2021 000 WTNT41 KNHC 211457 TCDAT1 Tropical Storm Peter Discussion Number 12 NWS National Hurricane Center Miami FL AL162021 1100 AM AST Tue Sep 21 2021 Like the last several days, this morning's visible satellite imagery indicates that Peter has become increasingly detached from the remaining fragmented convection that is firing more than 100 n mi east of the center. An Air Force Reserve Reconnaissance aircraft has been sampling the storm this morning and so far has yet to find any flight level (925 mb) or SFMR winds above tropical storm force, although they weren't able to fly the full pattern in the northeastern quadrant. The initial intensity has been lowered to 35 kt for this advisory, though the data so far suggests this estimate is generous. After taking a jog to the west overnight, Peter appears to have resumed a slower west-northwest motion at 290/8 kt. Over the next several days, Peter is expected to continue to slow down as it gradually turns to the north and then north-northeast as a deep-layer cyclone to the north is forecast to create a weakness in the current low-level ridging. The track guidance is in general agreement with this scenario, but differences remain in how sharp this rightward turn will be. The latest NHC track forecast has elected to stay close to the track consensus models TVCN and HCCA, and is a bit right of the previous track. After holding its own against a fairly hostile upper-level wind environment during the last 24-48 hours, Peter appears to finally be succumbing to the combination of 25-30 kt of deep-layer vertical wind shear helping to import sub-50 percent mid-level relative humidity over the center. This shear is not forecast to abate for the next 36-48 hours, and it now appears likely Peter will not be able to survive this unfavorable environment. The latest NHC intensity forecast now weakens Peter to a tropical depression in 12 hours, and degenerates it to a remnant low in 48 hours. However, given the current fragile state of the low-level circulation, it is distinctly possible that Peter may open up into a trough even sooner in the next 24-48 hours. Key Messages: 1. Rainfall around the southern periphery of Tropical Storm Peter could lead to areas of urban and small stream flooding through today across northern Hispaniola, Puerto Rico, portions of the Virgin Islands, and the Northern Leeward Islands. FORECAST POSITIONS AND MAX WINDS INIT 21/1500Z 19.9N 64.7W 35 KT 40 MPH 12H 22/0000Z 20.7N 65.7W 30 KT 35 MPH 24H 22/1200Z 21.7N 67.0W 30 KT 35 MPH 36H 23/0000Z 22.7N 67.5W 25 KT 30 MPH 48H 23/1200Z 23.4N 67.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 60H 24/0000Z 24.4N 67.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 24/1200Z 25.4N 66.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 25/1200Z 27.5N 64.4W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 26/1200Z 29.8N 62.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Papin
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Category:Transportation and Logistics