639
WTNT45 KNHC 180836
TCDAT5

Hurricane Erin Discussion Number 28
NWS National Hurricane Center Miami FL AL052025
500 AM EDT Mon Aug 18 2025

Erin is growing in size, as predicted. Data from the Air Force
Hurricane Hunters and ASCAT passes from a few hours ago showed that
the hurricane- and tropical-storm-force winds now extend up to 70 n
mi and 200 n mi from the eye, respectively. The eye of the hurricane
has also grown and is now about 30 n mi in diameter, and there is
some evidence of mesovorticies within it. There is also some
indication that Erin again has concentric eyewalls as the Hurricane
Hunters reported a double wind maximum in their last pass. The
initial intensity remains 115 kt based on a combination of the
earlier aircraft data and current satellite estimates. Erin's outer
rainbands are affecting the southeast Bahamas and the Turks and
Caicos Islands, and those locations will likely continue to
experience tropical storm conditions for several more hours.

The hurricane has wobbled to the left over the past 6 hours, but a
longer-term motion is still west-northwestward at 11 kt. Erin is
still forecast to gradually turn northward later today and Tuesday
as it moves into a weakness within the subtropical ridge. This
motion should take the core of the hurricane roughly midway between
Bermuda and the east coast of the U.S. on Wednesday and Thursday.
After that time, an approaching trough should cause Erin to
accelerate northeastward over the northern Atlantic. The NHC track
forecast has been nudged to the left of the previous one to be
closer to the various consensus models.

Deep convection has been increasing in intensity and symmetry, and
it seems likely that Erin will strengthen today. The intensification
is likely to end by tonight due to some increase in shear and a
broadening of the inner core wind field. Slow weakening seems likely
beginning Tuesday, but it should be emphasized that Erin is expected
to remain a powerful hurricane through the week. The NHC intensity
forecast is above the models in the short term, but falls near the
middle of the guidance after that.

Based on an evaluation of storm sizes of major hurricanes over the
past couple of decades in the subtropics, Erin is around the 80th
percentile. Erin's wind field is expected to keep growing over the
next few days. The 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. Bands of heavy rainfall are expected today over portions
of Hispaniola and through Tuesday for the Turks and Caicos and
portions of the southeast and central Bahamas. Flash and urban
flooding are possible.

2. Tropical storm conditions are expected in the Turks and Caicos
Islands and in the southeast Bahamas today. Tropical storm
conditions are possible in portions of the central Bahamas late
today through Tuesday.

3. 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.

4. Interests along the Outer Banks of North Carolina and Bermuda
should monitor the progress of Erin as there is a risk of strong
winds associated with the outer rainbands during the middle part of
the week.


FORECAST POSITIONS AND MAX WINDS

INIT 18/0900Z 22.8N 70.2W 115 KT 130 MPH
12H 18/1800Z 23.6N 71.2W 125 KT 145 MPH
24H 19/0600Z 25.0N 72.2W 115 KT 130 MPH
36H 19/1800Z 26.6N 72.9W 110 KT 125 MPH
48H 20/0600Z 28.6N 73.4W 105 KT 120 MPH
60H 20/1800Z 30.7N 73.4W 100 KT 115 MPH
72H 21/0600Z 32.9N 72.2W 95 KT 110 MPH
96H 22/0600Z 37.2N 66.1W 85 KT 100 MPH
120H 23/0600Z 41.6N 56.0W 75 KT 85 MPH

$$
Forecaster Cangialosi


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