Atlantic Basin Tropical Cyclones

Tropical Storm Rose Forecast Discussion


000
WTNT42 KNHC 210837
TCDAT2

Tropical Storm Rose Discussion Number   9
NWS National Hurricane Center Miami FL       AL172021
500 AM AST Tue Sep 21 2021

Rose has lost organization over the past several hours.  Satellite
images show a fully exposed low-level center with only a small area
of deep convection lingering in the southeastern quadrant.  The
Dvorak classifications have decreased, and the initial intensity is
nudged downward to 40 kt.

Rose is moving northwestward at 17 kt.  This general heading but
with a decrease in forward speed is expected during the next couple
of days as the storm is steered by the flow on the southwest side of
a low- to mid-level ridge.  By late this week and over the weekend,
a sharp turn to the north and then the northeast is expected as
Rose becomes embedded in the flow on the south side of a broad
deep-layer trough. Although there is some spread in the guidance,
the models all show the same general theme.  The NHC track forecast
lies near the middle of the guidance envelope.

The environment is expected to become increasingly unfavorable for
Rose during the next several days with westerly shear increasing and
dry air expected to wrap into the circulation.  These conditions
should promote a weakening trend, and the cyclone is forecast to
become a remnant low by the weekend when it should be over cooler
waters and in an environment of more than 30 kt of shear.  Some of
the models suggest that Rose could become a remnant low or open into
a trough sooner than that, and if the current trend continues that
is a distinct possibility.  The new forecast is largely an update of
the previous one, but does show the storm becoming a remnant low a
day earlier.


FORECAST POSITIONS AND MAX WINDS

INIT  21/0900Z 21.0N  36.4W   40 KT  45 MPH
 12H  21/1800Z 22.4N  37.2W   40 KT  45 MPH
 24H  22/0600Z 23.8N  38.3W   35 KT  40 MPH
 36H  22/1800Z 25.0N  39.5W   30 KT  35 MPH
 48H  23/0600Z 26.4N  40.6W   30 KT  35 MPH
 60H  23/1800Z 27.7N  41.0W   30 KT  35 MPH
 72H  24/0600Z 29.0N  40.4W   30 KT  35 MPH
 96H  25/0600Z 30.7N  36.6W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  26/0600Z 32.8N  31.4W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Cangialosi



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