[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 140244
TCDAT4

Hurricane Margot Discussion Number  27
NWS National Hurricane Center Miami FL       AL142023
300 AM GMT Thu Sep 14 2023

Margot's satellite depiction has become more ragged during the last
few hours. An earlier microwave pass showed that the center was
partially opened on the northern and western sides of the system.
Dry air is beginning to wrap into the center of the system, which
has caused some of the banding features to become broken. The center
has been cloud filled since the previous advisory, with overall
warming cloud tops. Satellite Dvorak current intensity estimates
were both 4.5 from TAFB and SAB. Given these estimates and the
degraded satellite depiction, the initial intensity for this
advisory is lowered to 75 kt.

Margot continues to gradually slow down as it moves within the flow
between a deep-layer ridge over the eastern Atlantic and an upper
trough to its west. A general northward motion should continue over
the next day or so. The steering pattern becomes fairly weak with a
blocking ridge to the north of the system, causing Margot to meander
over the north Atlantic and make a gradual clockwise loop over the
next 2 to 3 days. There are still some large differences in the
guidance envelope in the long term, but slightly better agreement
than 24 h ago. By the end of the period, the storm will likely
begin accelerating off to the east-northeast as it gets picked up by
the westerlies, but the overall track forecast confidence remains
low given the model spread.

Margot's convective structure has degraded this evening. The system
is entering a less favorable environment, with dry air entrainment
beginning to erode some of the structure. Deep-layer shear is also
forecast to increase, and upwelling of cooler waters due to the lack
of forward motion should result in weakening of the system through
the weekend. The NHC intensity forecast is similar to the previous
advisory and lies near the corrected consensus aids, the HCCA and
IVCN. Although the forecast keeps Margot a tropical cyclone through
day 5, simulated satellite imagery from the global models suggests
these increasingly hostile environmental factors could cause the
system to lose organized convection and become post-tropical sooner.


FORECAST POSITIONS AND MAX WINDS

INIT  14/0300Z 35.2N  40.5W   75 KT  85 MPH
 12H  14/1200Z 35.9N  40.2W   70 KT  80 MPH
 24H  15/0000Z 36.4N  39.6W   65 KT  75 MPH
 36H  15/1200Z 36.4N  39.3W   60 KT  70 MPH
 48H  16/0000Z 36.1N  39.6W   55 KT  65 MPH
 60H  16/1200Z 35.6N  40.5W   50 KT  60 MPH
 72H  17/0000Z 35.5N  41.7W   45 KT  50 MPH
 96H  18/0000Z 37.2N  43.2W   45 KT  50 MPH
120H  19/0000Z 40.4N  40.2W   45 KT  50 MPH

$$
Forecaster Kelly
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