448
WTNT45 KNHC 211444
TCDAT5

Hurricane Erin Discussion Number 41
NWS National Hurricane Center Miami FL AL052025
1100 AM EDT Thu Aug 21 2025

Erin remains a sprawling hurricane, with its tropical-storm-force
winds extending nearly 500 n mi across. In fact, comparing Erin with
systems around the same intensity and in similar locations over the
past couple of decades indicates that it is around the 90th
percentile in size. The Air Force Hurricane Hunters indicate that
the peak winds have come down a bit, and based on their data, the
initial intensity is set at 85 kt. Although the core of Erin is
pulling away from the United States, coastal flooding and
tropical-storm-force winds continue along portions of the North
Carolina and Virginia coasts. The center of Erin passed just east of
NOAA buoy 41001 earlier this morning, and it reported a minimum
pressure of 962 mb and a maximum significant wave height of 45 ft.
The associated swells are covering nearly the entire western
Atlantic from the Bahamas to Atlantic Canada.

Erin is moving north-northeastward at 16 kt. A turn to the northeast
or east-northeast with a significant increase in forward speed
within the mid-latitude westerlies is expected to begin tonight,
taking Erin out to sea over the north Atlantic during the next
several days. The models are in good agreement, and only minor
changes were made to the previous NHC forecast.

Increasing southwesterly vertical wind shear, drier mid-level air,
and cooler SSTs should cause Erin to gradually lose strength over
the next several days. Extratropical transition is now expected to
be complete by early Saturday, when the system is forecast to
develop fronts after it crosses the north wall of the Gulf Stream.
The NHC intensity forecast follows HCCA and IVCN in the short term,
but leans toward the global model guidance during the predicted
extratropical phase.

KEY MESSAGES:

1. Erin will continue to produce life-threatening surf and rip
currents along the beaches of the Bahamas, much of the east coast of
the U.S., Bermuda, and Atlantic Canada during the next several days.
Beachgoers in those areas should follow advice from lifeguards,
local authorities, and beach warning flags.

2. Storm surge flooding and tropical storm conditions will continue
on the North Carolina Outer Banks today. The storm surge will be
accompanied by large waves, leading to significant beach erosion and
overwash, making some roads impassible.

3. Tropical storm conditions are expected today along the Virginia
coast. Wind gusts to tropical storm force are likely along
portions of the remainder of the U.S. Mid-Atlantic and southern New
England coasts today through early Friday.

4. Tropical storm conditions are possible on Bermuda this afternoon
through early Friday. Gusts to gale force are possible along the
coast of Nova Scotia on Friday and the Avalon Peninsula of
Newfoundland on Saturday.


FORECAST POSITIONS AND MAX WINDS

INIT 21/1500Z 35.4N 70.9W 85 KT 100 MPH
12H 22/0000Z 37.0N 68.6W 80 KT 90 MPH
24H 22/1200Z 39.1N 64.5W 80 KT 90 MPH
36H 23/0000Z 41.0N 59.1W 75 KT 85 MPH
48H 23/1200Z 43.2N 51.7W 70 KT 80 MPH...POST-TROP/EXTRATROP
60H 24/0000Z 46.2N 43.7W 65 KT 75 MPH...POST-TROP/EXTRATROP
72H 24/1200Z 49.4N 35.7W 60 KT 70 MPH...POST-TROP/EXTRATROP
96H 25/1200Z 54.5N 25.0W 55 KT 65 MPH...POST-TROP/EXTRATROP
120H 26/1200Z 56.9N 21.1W 45 KT 50 MPH...POST-TROP/EXTRATROP

$$
Forecaster Cangialosi


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