500
WTNT45 KNHC 150843
TCDAT5

Tropical Storm Erin Discussion Number  16
NWS National Hurricane Center Miami FL       AL052025
500 AM AST Fri Aug 15 2025

Erin has struggled to become better organized tonight, as the system
is still trying to establish an inner core. Convection has
diminished over the low-level center in recent hours due to some dry
air entrainment. The Air Force Reserve Hurricane Hunters have been
investigating the system this morning and found maximum flight-level
winds of 52 kt. Recent infrared satellite imagery depicts a deep
convective band becoming established in the southern semi-circle
although flight-level aircraft data found little wind within that
band. Objective satellite intensity estimates range from 55 to 67
kt. Given the latest recon data and satellite estimates, the
intensity is held at a potentially generous 60 kt. A NOAA P-3
hurricane hunter aircraft is en route to investigate the system, and
hopefully Tail Doppler Radar data will be able to better assess the
structure of the system.

Erin is moving west-northwestward at an estimated motion of 285/15
kt. A subtropical ridge to the north will continue to steer the
system west-northwestward into the weekend. A weakness in the ridge
is forecast to develop early next week, and this will result in the
system gradually turning northwestward then northward by the end of
the forecast period. The guidance is in fairly good agreement
through about 60-72 hours. After 72 hours, there are some
differences in the forward speed and cross-track spread with the
turn toward the north. The regional hurricane models lie along the
western edge of the guidance envelope with the GFS and Google
DeepMind models remaining on the eastern edge of the guidance. The
latest NHC forecast is similar to the previous one in the short
term, and was nudged slightly west beyond day 3 closer to some of
the simple consensus aids. There is still uncertainty about what
impacts Erin may bring to portions of the Bahamas, the east coast of
the United States, and Bermuda in the long range.

The storm is in a favorable environment for strengthening, and it
will likely intensify once the inner core becomes more organized.
Sea surface temperatures have warmed to about 28C and should
continue to warm to near 30C along the forecast track, with a slight
decrease in shear expected over the next day or so. Although SHIPS
guidance depicts a slight increase in shear later this weekend, the
upper-level wind pattern becomes a little more favorable with
increasing mid-level RH values. The NHC forecast is similar to the
previous with a steady rate of strengthening and lies near the
consensus aids, with Erin forecast to become a hurricane later
today, and a major hurricane late this weekend. Some of the
hurricane regional models and the Florida State Superensemble depict
a higher peak intensity than the current NHC forecast. Regardless of
the details, Erin will be a large and powerful hurricane over the
southwestern Atlantic Ocean this weekend.

KEY MESSAGES:

1. Heavy rainfall across the northernmost Leeward Islands, the U.S.
and British Virgin Islands, as well as southern and eastern Puerto
Rico, may lead to isolated flash and urban flooding, along with
landslides or mudslides this weekend into early next week.

2. Tropical storm conditions are possible for portions of the
northern Leeward Islands, where Tropical Storm Watches are in
effect, beginning on Saturday as the core of Erin passes north of
those islands.  Tropical storm conditions could also occur in
portions of the Virgin Islands and Puerto Rico later in the weekend,
and additional watches may be required later today.

3. While there is still uncertainty in what impacts might occur in
portions of the Bahamas, the east coast of the United States, and
Bermuda next week, the risk of dangerous surf and rip currents
across the western Atlantic basin next week continues to increase.


FORECAST POSITIONS AND MAX WINDS

INIT  15/0900Z 17.8N  54.4W   60 KT  70 MPH
 12H  15/1800Z 18.4N  56.9W   70 KT  80 MPH
 24H  16/0600Z 19.3N  59.9W   80 KT  90 MPH
 36H  16/1800Z 20.1N  62.5W   90 KT 105 MPH
 48H  17/0600Z 21.0N  64.8W  100 KT 115 MPH
 60H  17/1800Z 22.2N  66.9W  110 KT 125 MPH
 72H  18/0600Z 23.2N  68.5W  115 KT 130 MPH
 96H  19/0600Z 25.5N  70.5W  110 KT 125 MPH
120H  20/0600Z 28.9N  71.4W  105 KT 120 MPH

$$
Forecaster Kelly