[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT41 KNHC 240241
TCDAT1

Post-Tropical Cyclone Ophelia Discussion Number  11
NWS National Hurricane Center Miami FL       AL162023
1100 PM EDT Sat Sep 23 2023

Ophelia appears to have lost its tropical characteristics.  Surface
observations show a well-defined wind shift associated with a
frontal boundary extending across eastern Virginia, and the heaviest
precipitation is now well north of the center, oriented along and
to the north of the front.  In addition, phase space diagrams based
on global model fields indicate that the system has entered the
asymmetric cold-core regime.  Therefore, Ophelia is being declared a
post-tropical cyclone.  Surface observations indicate that maximum
winds have decreased to 30 kt, mainly over the ocean well east of
the center.

With the last bit of convection having been sheared off to the
north, the center appears to have slowed down since the last
advisory, and the current estimate is northward at 360/7 kt.  The
circulation is expected to turn northeastward on Sunday, but also
become more diffuse while it moves across eastern Virginia and the
Delmarva Peninsula.  The NHC forecast now shows the low becoming
absorbed by the nearby frontal boundary by 36 hours.  Maximum winds
are likely to remain around 30 kt until dissipation, mainly in
a band to the north of the front off the coast of Long Island.

This is the last tropical cyclone discussion issued by the National
Hurricane Center on Ophelia.  Future information on Ophelia can be
found in discussions issued by the Weather Prediction Center
beginning at 500 AM EDT, under AWIPS header TCDAT1, WMO header
WTNT41 KWNH, and on the web at www.hurricanes.gov.


Key Messages:

1. Coastal flooding will continue along portions of Chesapeake Bay
and its tidal rivers through Sunday.  Refer to statements from your
local National Weather Service Forecast Office for additional
information.

2. Heavy rainfall from Ophelia may produce localized flash and
urban flooding impacts across portions of the Mid-Atlantic states
from Virginia to New Jersey through Sunday.

3. Swells generated by Ophelia will affect much of the U.S. east
coast through the weekend, likely causing life-threatening surf and
rip currents.


FORECAST POSITIONS AND MAX WINDS

INIT  24/0300Z 37.1N  77.6W   30 KT  35 MPH...POST-TROP/EXTRATROP
 12H  24/1200Z 38.2N  77.1W   30 KT  35 MPH...POST-TROP/EXTRATROP
 24H  25/0000Z 39.1N  75.7W   30 KT  35 MPH...POST-TROP/EXTRATROP
 36H  25/1200Z...DISSIPATED

$$
Forecaster Berg
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