[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT41 KNHC 130236
TCDAT1

Tropical Depression Eleven Discussion Number   6
NWS National Hurricane Center Miami FL       AL112020
1100 PM AST Wed Aug 12 2020

Conventional satellite imagery and a fortuitous ASCAT-B
scatterometer overpass indicate that the center of circulation
is a little farther south than previously estimated and remains
well to the southeast of the deep convective canopy.  The latest
UW-CIMSS shear analysis confirms modest east-southeasterly shear
impinging on the cloud pattern.  A compromise of the satellite
intensity estimates from TAFB and SAB, and the aforementioned
scatterometer pass retains the initial intensity at 30 kt.

Large-scale models and the statistical-dynamical intensity guidance
still show the shear abating soon which should result in gradual
strengthening with a peak intensity of 50 kt in 2 days.  After that
time, the cyclone is forecast to encounter moderate to strong
southwesterly shear associated with a deep-layer trough stretching
over the southwestern Atlantic.  This change in the upper wind
pattern should induce steady weakening.  A number of the global
models indicate that the cyclone will become a remnant low by day 4
and open up into a trough by day 5 which is certainly possible.
The NHC forecast is similar to the previous advisory but indicates
a more expeditious weakening trend beyond the 48 hour period in
deference to the global model solution.

The initial motion is estimated to be westward, or 275/13 kt, within
the low to mid-tropospheric easterly flow produced by a subtropical
ridge anchored to the north of the depression.  The song remains
the same...there is virtually no change to the forecast philosophy
and only a slight shift to the left of the previous track forecast
was made in response to the southward initial position adjustment.


FORECAST POSITIONS AND MAX WINDS

INIT  13/0300Z 12.5N  47.1W   30 KT  35 MPH
 12H  13/1200Z 13.0N  48.4W   35 KT  40 MPH
 24H  14/0000Z 14.2N  51.0W   40 KT  45 MPH
 36H  14/1200Z 15.7N  53.7W   45 KT  50 MPH
 48H  15/0000Z 17.0N  56.4W   50 KT  60 MPH
 60H  15/1200Z 18.3N  58.9W   45 KT  50 MPH
 72H  16/0000Z 19.7N  61.4W   40 KT  45 MPH
 96H  17/0000Z 22.5N  65.6W   35 KT  40 MPH
120H  18/0000Z 25.6N  67.5W   30 KT  35 MPH

$$
Forecaster Roberts
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