Atlantic Basin Tropical Cyclones

Tropical Depression Eight Forecast Discussion


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Tropical Depression Eight Discussion Number   1
NWS National Hurricane Center Miami FL       AL082022
Issued by the NWS Weather Prediction Center College Park MD
1100 AM AST Tue Sep 20 2022

Geostationary and microwave satellite data indicate that the system 
that NHC has been monitoring over the central Atlantic has developed 
a well-defined center and organized deep convection, and now meets 
the definition of a tropical cyclone.  The initial intensity is 
estimated to be 30 kt based on a partial ASCAT pass that showed peak 
winds in the 25-30 kt range.  The low-level center is estimated to 
be on the southern side of the main area of deep convection.

The depression is currently moving northward at 9 kt on the western 
side of a subtropical ridge.  A faster motion to the northeast is 
expected on Wednesday when the system reaches the northwestern 
periphery of the ridge, followed by a turn to the east.  By the end 
of the week, however, the depression is expected to stall in weak 
steering currents as high pressure builds near and to the north of 
the cyclone.  Over the weekend, the depression is expected to turn 
northwestward and increase its forward speed as Fiona tracks well to 
the west of this system.  The models are in fair agreement, but 
there is some cross-track spread by the end of the period with the 
GFS showing the fastest solution and ECMWF the slowest.  The NHC 
track forecast lies close to the various consensus models.

The depression is currently over relatively warm water, in a region 
of upper-level diffluence within a somewhat favorable moist 
environment. These factors should allow the system to strengthen 
slowly during the next couple of days.  However, after that time, 
much cooler SSTs, drier air, and an increase in westerly shear 
should end the strengthening trend.  The system is expected to 
become extratropical over the weekend when it moves over SSTs just 
above 20C.  The NHC intensity forecast lies a little lower than 
HCCA and IVCN consensus models. 

Interests in the Azores should monitor forecasts of the depression.

FORECAST POSITIONS AND MAX WINDS

INIT  20/1500Z 32.8N  45.7W   30 KT  35 MPH
 12H  21/0000Z 34.6N  45.0W   35 KT  40 MPH
 24H  21/1200Z 36.7N  43.2W   40 KT  45 MPH
 36H  22/0000Z 38.2N  40.6W   45 KT  50 MPH
 48H  22/1200Z 39.2N  37.8W   50 KT  60 MPH
 60H  23/0000Z 39.7N  35.3W   50 KT  60 MPH
 72H  23/1200Z 39.8N  33.7W   50 KT  60 MPH
 96H  24/1200Z 40.1N  33.7W   50 KT  60 MPH
120H  25/1200Z 42.4N  36.9W   45 KT  50 MPH...POST-TROP/EXTRATROP

$$
Forecaster Cangialosi/Pereira/Montgomery

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