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Tropical Storm Margot Discussion Number  16
NWS National Hurricane Center Miami FL       AL142023
900 AM GMT Mon Sep 11 2023
 
This morning's satellite presentation consists of an isolated area
of deep convection near Margot's surface center and a curved band
displaced about 160 mi to the northeast beneath upper-level 
southerly diffluent flow.  This distinctive cloud pattern is a 
result of very dry mid-tropospheric air intruding from the 
southwest and wrapping around and into the northeast sector of the 
cyclone.  The Dvorak satellite intensity estimates from TAFB and 
SAB haven't changed since last night, and the initial intensity is 
held at 55 kt for this advisory.
 
The latest GFS and ECMWF sounding analyses show modest northwesterly 
shear undercutting the diffluent southerly flow aloft while drying 
and stabilizing the mid-level portion of the atmosphere.  In fact, 
the statistical-dynamic SHIPS indicates 40 to 50% relative humidity 
in the surrounding environment.  The deterministic and SHIPS models 
still indicate, however, that the upper-level trough providing these 
inhibiting conditions will lift northeastward soon, allowing 
anticyclonic upper-tropospheric flow to develop over Margot.  As a 
result, the cyclone should strengthen, and the NHC intensity 
forecast follows suit and indicates the cyclone becoming a hurricane 
in less than 24 hours while intensifying further through mid-week.  
Weakening is predicted beyond day 3 as the thermodynamic environment 
in the mid-latitudes of the central Atlantic becomes even less 
favorable.  The official intensity forecast follows the HFIP HCCA 
corrected consensus intensity model through 48 hours, then is based 
on a blend of the HCCA, Decay SHIPS, and the IVCN intensity aids.
 
Margot's initial motion during the past 12 hours has been north, or 
360/7 kt.  A mid-tropospheric subtropical ridge extending from west 
Africa to the eastern subtropical Atlantic should steer the cyclone 
in a generally northward trajectory through an amplified weakness 
over the central Atlantic over the next 72 hours.  Through the 
remaining period, Margot is expected to slow in forward speed, and 
possibly meander, in response to high pressure building to the 
north of the cyclone over the central north Atlantic.  The NHC 
forecast track is adjusted slightly to the right beyond 48 hours, 
and lies between the previous forecast and the TVCA simple average 
multi-model consensus. 

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  11/0900Z 25.3N  40.0W   55 KT  65 MPH
 12H  11/1800Z 26.6N  39.9W   60 KT  70 MPH
 24H  12/0600Z 28.6N  39.8W   70 KT  80 MPH
 36H  12/1800Z 30.8N  40.1W   75 KT  85 MPH
 48H  13/0600Z 32.7N  40.8W   75 KT  85 MPH
 60H  13/1800Z 34.0N  41.7W   75 KT  85 MPH
 72H  14/0600Z 35.0N  42.0W   75 KT  85 MPH
 96H  15/0600Z 36.7N  41.0W   70 KT  80 MPH
120H  16/0600Z 37.1N  40.9W   60 KT  70 MPH
 
$$
Forecaster Roberts
 
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