[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 131456
TCDAT4

Hurricane Margot Discussion Number  25
NWS National Hurricane Center Miami FL       AL142023
Issued by the NWS Weather Prediction Center College Park MD
300 PM GMT Wed Sep 13 2023

Margot continues to exhibit a double eyewall structure based on
a recent SAR pass over the storm, with a well-defined inner core.
GOES-16 IR data shows the inner-eye feature occasionally obscured by
clouds, but overall the organization of Margot has changed little
over the last several hours. The latest microwave data in
conjunction with the SAR pass suggests the initial intensity may be
just a tad stronger compared to continuity, and so it will be set at
80 kt for this advisory.

Margot is slowing down as it moves within the flow between a
deep-layer ridge over the eastern Atlantic and a narrow upper trough
to its west. A general north to north-northwest motion should
continue over the next day or so before the track forecast becomes
very challenging. Margot is expected to become caught in weak
steering currents, with the global models showing a blocking ridge
developing to the north of the cyclone by late week into the
weekend. There are significant differences between the GFS and ECMWF
with regards to the strength and position of this ridge, which has
large implications in the longer-range track of Margot. The overall
consensus of the guidance suggests that Margot could make a
clockwise loop as the ridge builds, and the latest NHC forecast
shows little net motion between 36-72 hrs as the cyclone meanders
over the central Atlantic. At days 4-5, most models (except for the
ECMWF) show the ridge sliding eastward, allowing for Margot to
gain latitude, and the overall track forecast confidence remains
low.

The deep-layer shear is forecast to increase during the next 24 to
36 hrs, and this coupled with a likelihood of the upwelling of
cooler waters should result in a weakening trend. Drier air
surrounding the storm will also be a factor in causing a weakening
cyclone going into the weekend. The NHC intensity forecast is close
to the previous forecast and shows gradual decrease in strength
through 72 hrs, and in good agreement with the consensus of the
intensity aids. Although this forecast keeps Margot a tropical
cyclone through day 5, simulated satellite imagery from the global
models suggests these environmental factors could cause the system
to lose organized convection and become post-tropical early next
week as the storm lingers west of the Azores.


FORECAST POSITIONS AND MAX WINDS

INIT  13/1500Z 34.1N  40.4W   80 KT  90 MPH
 12H  14/0000Z 35.0N  40.7W   75 KT  85 MPH
 24H  14/1200Z 36.0N  40.2W   75 KT  85 MPH
 36H  15/0000Z 36.8N  39.5W   70 KT  80 MPH
 48H  15/1200Z 36.9N  39.4W   65 KT  75 MPH
 60H  16/0000Z 36.5N  39.4W   60 KT  70 MPH
 72H  16/1200Z 36.3N  40.2W   50 KT  60 MPH
 96H  17/1200Z 36.0N  42.5W   45 KT  50 MPH
120H  18/1200Z 38.0N  42.5W   45 KT  50 MPH

$$
Forecaster Orrison/Blake
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