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Tropical Depression Peter Forecast Discussion

WTNT41 KNHC 220840

Tropical Depression Peter Discussion Number  15
NWS National Hurricane Center Miami FL       AL162021
500 AM AST Wed Sep 22 2021

Peter is a disorganized tropical depression.  The low-level center 
is fully exposed and currently located a couple of hundred miles 
north of Puerto Rico.  Most of the associated thunderstorm activity 
remains displaced well east of the center due to about 30 kt of 
westerly shear.  The initial intensity is held at 30 kt based on a 
0206 UTC ASCAT-B pass that showed a swath of 25-30 kt winds about 60 
n mi north of the center. The ASCAT data also showed that the 
circulation has become quite elongated.  Since the hostile 
conditions of strong westerly shear and dry air entrainment are not 
expected to let up, a continued gradual decay of Peter is forecast.  
The system is still predicted to become a remnant low in 36 hours 
and dissipate in a few days, but both of these could occur sooner.

The depression is moving northwestward, with the latest initial 
motion estimated to be 310/10 kt.  The cyclone is expected to turn 
northward by tonight and then northeastward by the end of the week 
as the system moves in the flow on the east side of a deep-layer 
trough.  The NHC track forecast is a little to the east of the 
previous one and close to an average of the GFS and ECMWF models.

Key Messages:

1. Rainfall around the southern periphery of Peter may lead to areas 
of urban and small stream flooding through Thursday morning across 
northern Hispaniola, Puerto Rico, and portions of the Virgin 


INIT  22/0900Z 21.5N  66.1W   30 KT  35 MPH
 12H  22/1800Z 22.2N  66.7W   30 KT  35 MPH
 24H  23/0600Z 23.2N  66.9W   25 KT  30 MPH
 36H  23/1800Z 24.1N  66.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  24/0600Z 25.1N  65.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 60H  24/1800Z 26.5N  64.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  25/0600Z...DISSIPATED

Forecaster Cangialosi

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