ZCZC MIATCDAT1 ALL
TTAA00 KNHC DDHHMM CCA
 
Tropical Storm Peter Discussion Number   7...Corrected
NWS National Hurricane Center Miami FL       AL162021
500 AM AST Mon Sep 20 2021

Corrected name of storm in first and second paragraphs
 
Peter is a strongly sheared tropical storm. Reconnaissance wind 
data, conventional satellite imagery, and passive microwave 
satellite data indicate that Peter's center is located just to the 
west of the deep convection. Data from the aircraft support holding 
the intensity at 45 kt for now based on 925-mb flight-level and 
SFMR winds of 53 kt and 41 kt, respectively, on their last leg when 
the aircraft came in from the northeast. The central pressure had 
also increased only slightly to 1006 mb.

Peter has continued to move west-northwestward, or 295/12 kt. There 
are no significant changes to the previous track forecast or 
reasoning. Peter is expected to move around the southwestern and 
western periphery of a subtropical ridge for the next couple of 
days, followed by a slow northward motion on days 3-5 as the 
cyclone moves through a weakness in the ridge induced by the 
southward-moving former Tropical Storm Odette. The new NHC track 
forecast is very similar to the previous advisory track, and lies 
just to the east of the tightly packed consensus track models. 
 
Some fluctuations in intensity will be possible during the next 
24-36 hours owing to 5-10 kt fluctuations in the magnitude and also 
the direction of the deep-layer vertical wind shear. However, by 48 
hours and beyond, a slow weakening trend is expected due to the 
shear increasing from the southwest and west-southwest of near 30 
kt. The new official intensity forecast is essentially just an 
update of the previous advisory, and closely follows the IVCN and 
HCCA intensity consensus models.
 
Based on the latest track, intensity, and wind radii forecasts, no
tropical storm watches or warnings are required for the northern
Leeward Islands, Virgin Islands, or Puerto Rico at this time.
However, locally heavy rain is possible on Monday and Tuesday when
Peter is expected to pass to the north of these locations.
 
 
Key Messages:

Rainfall around the southern periphery of Tropical Storm Peter may 
lead to areas of urban and small stream flooding through Tuesday 
across Puerto Rico, the Virgin Islands, and the Northern Leeward 
Islands.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/0900Z 19.1N  59.5W   45 KT  50 MPH
 12H  20/1800Z 19.7N  61.4W   40 KT  45 MPH
 24H  21/0600Z 20.4N  63.6W   40 KT  45 MPH
 36H  21/1800Z 21.4N  65.5W   35 KT  40 MPH
 48H  22/0600Z 22.4N  67.2W   35 KT  40 MPH
 60H  22/1800Z 23.2N  68.0W   30 KT  35 MPH
 72H  23/0600Z 24.2N  68.4W   30 KT  35 MPH
 96H  24/0600Z 26.2N  67.8W   25 KT  30 MPH
120H  25/0600Z 28.5N  66.8W   30 KT  35 MPH
 
$$
Forecaster Stewart
 
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