[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 160855
TCDAT4

Tropical Storm Margot Discussion Number  36
NWS National Hurricane Center Miami FL       AL142023
900 AM GMT Sat Sep 16 2023

This morning, Margo's structure on satellite imagery has degraded
some. Cloud top temperatures surrounding the tropical cyclone have
been gradually warming, and there is evidence of northerly vertical
wind shear beginning to impinge on the storm due to flow from a
poleward amplifying upper-level anticyclone. The subjective
intensity estimates from TAFB and SAB have been slowly decreasing,
though the AiDT, D-PRINT, & D-MINT estimates remain a bit higher. A
compromise of these various data support a slightly weaker intensity
of 50 kt on this advisory.

Margot continues to execute a slow clockwise turn, with the
estimated motion now southwestward at 220/6 kt. A gradual turn to
the west and then northwest is anticipated over the next 24-36 hours
as the cyclone rounds the southern periphery of a mid-level ridge
shifting gradually northeast of Margot. It is interesting to note
that Margot's track evolution over the last several days appears to
have been remotely influenced by Lee, where mid-level height rises
north of the tropical storm are in part related to diabatic ridge
building downstream of Lee. Ultimately the same trough that is
phasing with post-tropical cyclone Lee will pick up Margot as well,
with the cyclone turning northeast and even eastward by the end of
the forecast. The latest track forecast is not far off the previous
forecast, but a little farther to the south and west over the first
day or so, adjusting a bit towards the reliable consensus aids.

The vertical wind shear diagnosed by SHIPS guidance is not expected
to abate much over the next 24 hours, and Margot will be moving over
its own cold wake it previously generated along its forecast track.
Thus, weakening is anticipated, and simulated satellite imagery from
both the GFS and ECMWF suggest that the cyclone may cease to produce
enough convection to qualify as a tropical cyclone sometime in the
36-48 hour period, though this is not explicitly shown. However,
most of the guidance agrees a favorable trough interaction may
result in a convective resurgence in the 60-72 h time period, and
the latest intensity forecast shows some re-intensification during
that time period. The trough is expected to ultimately leave behind
Margot, with increasing shear and cooler sea-surface temperatures
likely to result in the system becoming a post-tropical cyclone for
good in the day 4-5 day time period.


FORECAST POSITIONS AND MAX WINDS

INIT  16/0900Z 35.0N  38.3W   50 KT  60 MPH
 12H  16/1800Z 34.5N  39.4W   45 KT  50 MPH
 24H  17/0600Z 34.3N  41.1W   40 KT  45 MPH
 36H  17/1800Z 34.8N  42.5W   35 KT  40 MPH
 48H  18/0600Z 36.0N  43.3W   35 KT  40 MPH
 60H  18/1800Z 37.7N  41.9W   40 KT  45 MPH
 72H  19/0600Z 38.9N  39.3W   45 KT  50 MPH
 96H  20/0600Z 38.5N  33.0W   35 KT  40 MPH...POST-TROPICAL
120H  21/0600Z 38.5N  29.5W   30 KT  35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Papin
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