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Tropical Storm FLORENCE


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Tropical Storm Florence Discussion Number  19
NWS National Hurricane Center Miami FL       AL062018
1100 PM AST Mon Sep 03 2018

Although Florence continues to produce a fairly circular area of
deep convection, microwave images have revealed that there is a
significant southwest-to-northeast vertical tilt of the
circulation due to southwesterly shear.  The initial intensity is
held at 60 kt, using a blend of the Dvorak CI-numbers from TAFB and
SAB.  This estimate is a little below the latest automated Dvorak
values from CIMSS at the University of Wisconsin.

The strong tropical storm is moving west-northwestward, or 285
degrees, at 12 kt steered by a subtropical ridge to its north.  The
storm is expected to gradually turn northwestward with a decrease
in forward speed during the next several days as it moves
toward a persistent weakness in the subtropical ridge.  There
remains a fair amount of spread in the guidance, especially in the
3- to 5-day time period, but the consensus aids have changed little
this cycle.  Therefore, no significant changes were made to the
previous forecast, and this one lies near the middle of the guidance
envelope.

Little change in strength is expected through early Tuesday as
Florence remains over marginally warm waters and in moderate wind
shear conditions.  Slight weakening is expected during the middle
part of the week due to a gradual increase in southwesterly or
westerly shear.  Beyond that time, however, the shear is expected to
decrease and Florence will be over much warmer waters.  Therefore,
slow strengthening is shown at the end of the forecast period.
This forecast is unchanged from the previous one, and is in good
agreement with the HCCA guidance.

The 34- and 50-kt initial wind radii have been expanded outward
based on recent ASCAT passes.

FORECAST POSITIONS AND MAX WINDS

INIT  04/0300Z 18.9N  41.0W   60 KT  70 MPH
 12H  04/1200Z 19.4N  42.7W   60 KT  70 MPH
 24H  05/0000Z 20.1N  44.9W   55 KT  65 MPH
 36H  05/1200Z 21.1N  47.2W   55 KT  65 MPH
 48H  06/0000Z 22.1N  49.5W   50 KT  60 MPH
 72H  07/0000Z 24.5N  53.1W   50 KT  60 MPH
 96H  08/0000Z 26.8N  55.8W   55 KT  65 MPH
120H  09/0000Z 28.4N  57.8W   60 KT  70 MPH

$$
Forecaster Cangialosi

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