[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 100837
TCDAT4

Tropical Storm Margot Discussion Number  12
NWS National Hurricane Center Miami FL       AL142023
500 AM AST Sun Sep 10 2023

Westerly shear and a slug of dry air, which was noted in the
MET-10 water vapor imagery, impedes Margot's ability to sustain
deep convection near the surface center while most convection
remains displaced to the northeast.  A recent AMSR2 microwave pass
confirmed that the surface center has again become exposed to the
southwest of the convective canopy.  The initial intensity is held
at 45 kt and is based on the TAFB and SAB Dvorak satellite
intensity estimates.

The aforementioned moderate shear should continue to undercut the
diffluent southerly flow aloft during the next couple of days.
Afterward, the statistical-dynamic SHIPS guidance indicates that
Margot will slip under a narrow upper-level ridge, favoring
intensification.  The only inhibiting factor during the latter part
of the forecast appears to be a less conducive surrounding
thermodynamic environment, which should affect the intensity rate
some.  Therefore, only gradual strengthening is forecast and agrees
with intensity consensus models but below the HAFS-B hurricane
model, which predicts Margot as a hurricane on day 4.  For now, the
official forecast shows Margot becoming a hurricane in 48 hours in
agreement with the reliable intensity consensus aids, but this
predicted rate of intensification could be generous.

Through the early part of this week, Margot is expected to turn
north-northwestward to northward while entering a growing weakness
in the central Atlantic subtropical ridge.  Beyond day 3, Margot
will likely slow its forward motion in response to a building or
blocking high to the northwest.  There remains quite a bit of model
spread/uncertainty late in the period, with the two global model
clusters showing Margot either turning eastward or moving toward
the northwest to west.  The NHC track forecast conservatively lies
between the HFIP HCCA and simple consensus TVCA, which splits the
two model cluster solutions.



FORECAST POSITIONS AND MAX WINDS

INIT  10/0900Z 22.1N  39.6W   45 KT  50 MPH
 12H  10/1800Z 23.1N  40.1W   50 KT  60 MPH
 24H  11/0600Z 24.8N  40.5W   55 KT  65 MPH
 36H  11/1800Z 26.5N  40.7W   60 KT  70 MPH
 48H  12/0600Z 28.2N  40.8W   65 KT  75 MPH
 60H  12/1800Z 30.1N  40.9W   70 KT  80 MPH
 72H  13/0600Z 32.4N  41.0W   70 KT  80 MPH
 96H  14/0600Z 35.0N  41.6W   75 KT  85 MPH
120H  15/0600Z 36.7N  41.9W   75 KT  85 MPH

$$
Forecaster Roberts
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