531
WTNT45 KNHC 180255
TCDAT5

Hurricane Erin Discussion Number  27
NWS National Hurricane Center Miami FL       AL052025
1100 PM AST Sun Aug 17 2025

Erin appears to have successfully completed its eyewall replacement
cycle (ERC) that began yesterday. A F-16 SSMIS pass at 2314 UTC
showed just a single eyewall with Erin that also appears to be
contracting. Thus, Erin appears to be re-intensifying but now with a
larger 20 n mi radius of maximum winds. Satellite intensity
estimates, both subjective and objective, are starting to increase
again. Notably, we received a T6.0/115 kt subjective Dvorak
intensity value at 00 UTC. The DMINT value associated with that
earlier SSMIS pass was 113 kt, and given the improvement of Erin`s
structure on GOES-19 satellite imagery since that time period, the
initial intensity is being increased to 115 kt this advisory, making
Erin a Category 4 hurricane again. An Air Force Reserve
reconnaissance mission will soon be in the core of Erin to
provide updated in-situ observations of the hurricane.

It looks like Erin is beginning to turn northwestward, with the
initial motion now estimated to be 305/10 kt. The mid-level ridge
that has been steering Erin over the last few days is beginning to
split, with one ridge remaining parked over the Ohio Valley in the
United States, but another ridge becoming positioned more eastward
of Erin. This pattern will allow a weakness to form north of Erin,
enabling the large hurricane to turn northward and then
northeastward roughly between the Outer Banks of North Carolina and
Bermuda. The track guidance this cycle have not made very many
adjustments, and thus the latest NHC forecast track looks quite
similar to the prior advisory, just a little slower over the next
48 hours. This track lies roughly in between the Google Deep Mind
ensemble mean (GDMI) and HFIP corrected consensus approach (HCCA).

Now that Erin has completed its ERC, there is a short-term window
where additional intensification could occur while the hurricane
remains over warm waters near 29C and light to moderate
northwesterly shear. There are a couple of complications that make
the intensity forecast tricky beyond this time period. First,
vertical wind shear is expected to increase over Erin soon. If Erin
also then undergoes another ERC, sometime in the 24-48 h time
period, this could hasten a weakening trend, like HAFS-A/B models
have been suggesting. Second, as Erin grows in size, its footprint
of cool upwelling will also grow, and could potentially encroach on
its inner core. Several AOML/CIMAS gliders have been near the
inner core of Erin over the past 24 hours, and their in-situ
observations indicate that Erin has already cooled the waters in its
vicinity up to 1C over the past day. This rate of ocean cooling near
Erin is likely to continue increasing as the storm grows in size and
slows over the next 48-60 h. Thus, the intensity forecast shows
gradual weakening beginning after a short round of intensification,
which is a little lower than the previous NHC intensity forecast
beyond the short-term, but still not far off from the HCCA
consensus aid.

Erin`s wind radii have been growing in size, and are expected to
continue expanding 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 will linger across portions of Puerto
Rico and the Virgin Islands through tonight, but are expected to
diminish by Monday. Locally considerable flash and urban flooding,
along with landslides or mudslides, are possible.

2. Tropical storm conditions are expected in the Turks and Caicos
Islands and in the southeast Bahamas tonight and Monday.

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  18/0300Z 22.3N  69.3W  115 KT 130 MPH
 12H  18/1200Z 23.2N  70.2W  125 KT 145 MPH
 24H  19/0000Z 24.6N  71.3W  115 KT 130 MPH
 36H  19/1200Z 26.1N  72.1W  110 KT 125 MPH
 48H  20/0000Z 28.0N  72.8W  105 KT 120 MPH
 60H  20/1200Z 29.9N  73.1W  100 KT 115 MPH
 72H  21/0000Z 32.0N  72.5W   95 KT 110 MPH
 96H  22/0000Z 36.5N  67.5W   90 KT 105 MPH
120H  23/0000Z 41.4N  56.7W   80 KT  90 MPH

$$
Forecaster Papin