624
WTNT45 KNHC 190234
TCDAT5

Hurricane Erin Discussion Number 31
NWS National Hurricane Center Miami FL AL052025
1100 PM EDT Mon Aug 18 2025

Erin has weakened some since the last advisory. Multiple microwave
overpasses show that the convection has eroded on the northwestern
side and that the mid-level center is displaced to the southeast
of the low-level center by northwesterly shear. Reports from NOAA
and Air Force Reserve Hurricane Hunter aircraft show that the
central pressure has risen to near 949 mb, and that flight-level
winds at 8000 and 10000 ft are in the 105-115 kt range. The
initial intensity is reduced to 110 kt for this advisory, and this
could be a bit generous. It should be noted that the wind field
has become very spread out, with flight-level winds of hurricane
force noted by the two aircraft more than 100 n mi from the center.

Erin has slowed its forward speed with the initial motion now 320/7
kt. The overall track reasoning remains unchanged, with Erin
expected to turn northward during the next day or two into a break
in the subtropical ridge, followed by recurvature into the
westerlies with some acceleration thereafter. However, there is
some spread in the track guidance in both direction and speed. The
UKMET and ECMWF are slower and on the left side of the guidance
envelope, while the GFS and Canadian are on the right side of the
guidance and faster. The new forecast track is similar in direction
to the previous track, but it is going to be slower than the
previous track in deference to the ECMWF/UKMET and the consensus
models.

The dynamical model guidance suggests that the current shear should
diminish in 18-24 h, and as that happens the upper-level winds
become divergent over the hurricane. However, due to the current
poor organization, it is unclear whether Erin will be able to take
advantage of the more favorable environment. The intensity forecast
first calls for some additional weakening due to the ongoing
shear. After that, it calls for modest re-intensification as the
upper-level winds become more favorable. Once Erin has recurved
into the westerlies, there should be substantial weakening due to
another round of shear and the onset of extratropical transition.

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. Heavy rainfall is expected into Wednesday for portions of the
southeastern Bahamas. Flash and urban flooding are possible.

2. 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
tonight 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.
Beachgoers in those areas should follow advice from lifeguards,
local authorities, and beach warning flags.

4. Tropical storm conditions and coastal flooding are possible in
the North Carolina Outer Banks beginning late Wednesday where
Tropical Storm and Storm Surge Watches are in effect. Interests in
Bermuda should also monitor the progress of Erin as strong winds are
possible beginning on Thursday.


FORECAST POSITIONS AND MAX WINDS

INIT 19/0300Z 24.4N 71.7W 110 KT 125 MPH
12H 19/1200Z 25.4N 72.3W 105 KT 120 MPH
24H 20/0000Z 27.1N 73.2W 105 KT 120 MPH
36H 20/1200Z 29.2N 73.7W 110 KT 125 MPH
48H 21/0000Z 31.4N 73.5W 110 KT 125 MPH
60H 21/1200Z 33.5N 72.5W 105 KT 120 MPH
72H 22/0000Z 35.4N 70.0W 100 KT 115 MPH
96H 23/0000Z 38.5N 62.9W 80 KT 90 MPH
120H 24/0000Z 41.1N 54.8W 65 KT 75 MPH

$$
Forecaster Beven


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