852
WTNT45 KNHC 190856
TCDAT5

Hurricane Erin Discussion Number 32
NWS National Hurricane Center Miami FL AL052025
500 AM EDT Tue Aug 19 2025

Moderate to strong northwesterly shear has caused Erin's structure
to become more asymmetric, with dry air infiltrating into the
northwestern part of the circulation, and a long trailing convective
band still draped to the south over the Turks and Caicos Islands.
An earlier Air Force Reserve Hurricane Hunter mission made a final
pass through the center of Erin around 1230 am and measured
flight-level winds of 97 kt, with a central pressure up to 953 mb.
Combining this information with the latest satellite estimates,
Erin's intensity is set at 100 kt, which could be a bit generous.

Erin has been moving slowly northwestward since yesterday, with an
initial motion estimated to be 325/6 kt. There is not much change
to the track forecast reasoning, with the hurricane still expected
to recurve over the western Atlantic between the U.S. east coast and
Bermuda over the next 3-4 days. The main highlight of the new
forecast is that much of the track guidance, including the consensus
aids, have shifted slightly west of the previous NHC prediction
during the first 2-3 days. The new NHC forecast is very close to
the TVCA and HCCA consensus aids during the first 48 hours, and then
closer to the TVCA aid beyond 48 hours. It should be noted that
there is still some space for additional adjustments to the track
forecast, particularly beyond 48 hours with the HCCA aid lying along
the northwestern edge of the guidance envelope.

There are mixed signals on Erin's future intensity. On one hand,
more favorable environmental shear and upper-level divergence in
24-36 hours should support some re-intensification. On the other
hand, Erin's slow motion and large size could lead to some upwelling
of cooler water, and the hurricane's broad structure could limit
significant strengthening. The official forecast only shows
fluctuations in intensity for the next 3 days, although it's
becoming more likely that Erin could just weaken very gradually
during that time. Erin is forecast to maintain hurricane strength
for the next 5 days, but it is likely to begin interacting with a
frontal boundary by Friday and become extratropical by late
Saturday.

The more important part of the forecast is that model guidance has
continued to show Erin growing in size, and the wind radii have been
made larger in the new NHC forecast. This new forecast now brings tropical-storm-force winds very close to the Mid-Atlantic and
southern New England coast later this week. Erin's expanding wind
field will result in rough ocean conditions over much of the western
Atlantic. It should be noted that the 34- and 50-kt wind speed
probabilities beyond 36 hours in the text and graphical products are
likely underestimating the risk of those winds occurring. This is
because the forecast wind field of Erin is considerably larger than
average compared to the wind field used to derive the wind speed
probability product.

KEY MESSAGES:

1. Erin is expected 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. Tropical storm conditions and coastal flooding are possible in
the North Carolina Outer Banks beginning late Wednesday or Wednesday
night where Tropical Storm and Storm Surge Watches are in effect.
Interests in along the U.S. Mid-Atlantic and southern New England
coasts and on Bermuda should also monitor the progress of Erin as
strong winds are possible Thursday and Friday.

3. Heavy rainfall from the outer bands of Erin will continue today
for the Turks and Caicos and through tonight for the Bahamas. Flash
and urban flooding are possible.

4. Tropical storm conditions are expected in the Turks and Caicos
Islands and in the southeast Bahamas for a few more hours. Tropical
storm conditions are possible in portions of the central Bahamas
today.


FORECAST POSITIONS AND MAX WINDS

INIT 19/0900Z 24.8N 72.0W 100 KT 115 MPH
12H 19/1800Z 26.1N 72.7W 95 KT 110 MPH
24H 20/0600Z 28.1N 73.5W 95 KT 110 MPH
36H 20/1800Z 30.3N 74.0W 100 KT 115 MPH
48H 21/0600Z 32.6N 73.4W 100 KT 115 MPH
60H 21/1800Z 34.6N 71.4W 95 KT 110 MPH
72H 22/0600Z 36.5N 68.4W 90 KT 105 MPH
96H 23/0600Z 39.5N 61.0W 75 KT 85 MPH
120H 24/0600Z 42.0N 53.4W 65 KT 75 MPH...POST-TROP/EXTRATROP

$$
Forecaster Berg


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