[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 140848
TCDAT4

Hurricane Margot Discussion Number  28
NWS National Hurricane Center Miami FL       AL142023
900 AM GMT Thu Sep 14 2023

The satellite structure of Margot has continued to deteriorate. The
low-level center has been partially exposed in GOES-16 proxy-visible
satellite images, and recent AMSR2 microwave data show the inner
core convection has eroded. These changes appear to be the result of
some southwesterly shear over the system and dry air intrusions into
the circulation. Presently, deep convection is limited to a couple
of curved bands that wrap around the northern portion of the system.
The objective and subjective satellite intensity estimates have
markedly decreased, and the initial intensity is lowered to 65 kt,
in best agreement with recent UW-CIMSS SATCON and TAFB Dvorak
current intensity estimates. However, this could be generous given
the rapidly degrading satellite presentation.

Margot continues to slow down this morning, and it appears the
center has recently turned north-northeastward (015/5 kt). The
cyclone is likely to stall and meander over the next couple of days
in response to a building ridge to its north and west. In general,
the track models agree that Margot will make a gradual clockwise
loop while it pivots around the ridge that is forecast to slowly
slide eastward over the weekend. However, there is still large
spread in the various model solutions while the steering currents
remain weak. The updated NHC forecast tries to reflect the latest
trends of the multi-model consensus aids and shows little movement
between 12-60 h. By early next week, the ridge should become
re-positioned to the east of Margot, allowing the system to turn
northward and become caught up in the mid-latitude westerlies.

In addition to the ongoing shear, several factors suggest Margot is
likely to continue weakening during the next several days. The
cyclone is over marginal SSTs, and the coupled atmosphere-ocean
models indicate the slow-moving storm is likely to upwell even
cooler waters while it meanders over the central Atlantic. Also,
more bouts of dry air entrainment within a drier and more subsident
environment will make it difficult for Margot to sustain convection
near its center, as suggested by the GFS and ECMWF simulated
satellite imagery. The NHC forecast shows continued weakening
through early next week with Margot becoming extratropical in 120 h
while accelerating into the mid-latitudes. Although not explicitly
forecast, it is noted that the hostile conditions could render
Margot devoid of deep convection even sooner.


FORECAST POSITIONS AND MAX WINDS

INIT  14/0900Z 35.9N  40.3W   65 KT  75 MPH
 12H  14/1800Z 36.4N  39.8W   60 KT  70 MPH
 24H  15/0600Z 36.6N  39.2W   55 KT  65 MPH
 36H  15/1800Z 36.4N  39.0W   55 KT  65 MPH
 48H  16/0600Z 35.9N  39.5W   50 KT  60 MPH
 60H  16/1800Z 35.4N  40.6W   50 KT  60 MPH
 72H  17/0600Z 35.2N  42.0W   45 KT  50 MPH
 96H  18/0600Z 37.5N  43.3W   45 KT  50 MPH
120H  19/0600Z 40.5N  39.0W   40 KT  45 MPH...POST-TROP/EXTRATROP

$$
Forecaster Reinhart
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