Tropical Report

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Mon Sep 25 2017

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Hurricane
Maria, located several hundred miles south-southeast of Cape
Hatteras, North Carolina, and on Hurricane Lee, located over the
central Atlantic Ocean.

Tropical cyclone formation is not expected during the next 5 days.

$$
Forecaster Beven
LEE STATIONARY OVER THE CENTRAL ATLANTIC

Hurricane Lee Discussion Number 29
NWS National Hurricane Center Miami FL AL142017
500 AM AST Mon Sep 25 2017

Lee continues to hold steady in intensity. The 10 n mi eye of the
hurricane remains quite distinct, and although the convective
pattern around the eye is fairly symmetric, the cloud tops are not
very cold. Since the Dvorak classifications remain the same as
earlier, the initial intensity is again held at 80 kt based on a
blend of the subjective and objective numbers. It is interesting
to note that Lee remains a very compact hurricane, with
tropical-storm-force winds extending only 30 n mi from the center.

Lee remains in a favorable upper-level wind pattern for
strengthening, but SSTs beneath the cyclone are marginal, in part
due to the hurricane moving over its own cool wake. Lee is expected
to move over slightly warmer waters in a day or so, and that could
allow the system to strengthen a little. Later in the forecast
period, drier air, a sharp increase in shear, and a track toward
colder water should cause weakening. Only minor changes were made
to the previous NHC intensity forecast, and this prediction is in
best agreement with the consensus models IVCN and HCCA.

The trough that had been steering Lee to the east or southeast much
of the day on Sunday has now bypassed the system leaving Lee in
weak steering currents. A ridge is expected to build to the north
of the hurricane by tonight, and that should cause the system to
begin moving west-southwestward or westward. By mid-week, a
trough is expected to approach the hurricane, and it should
cause the system to accelerate to the northeast over the central
Atlantic in 4 to 5 days. The NHC track forecast has been adjusted
to the west of the previous one to come into better agreement with
the latest guidance.

FORECAST POSITIONS AND MAX WINDS

INIT 25/0900Z 31.1N 49.4W 80 KT 90 MPH
12H 25/1800Z 30.9N 49.7W 80 KT 90 MPH
24H 26/0600Z 30.7N 50.9W 80 KT 90 MPH
36H 26/1800Z 30.8N 52.4W 85 KT 100 MPH
48H 27/0600Z 31.2N 53.6W 85 KT 100 MPH
72H 28/0600Z 32.7N 54.5W 85 KT 100 MPH
96H 29/0600Z 36.5N 51.5W 75 KT 85 MPH
120H 30/0600Z 42.5N 42.8W 55 KT 65 MPH

$$
Forecaster Cangialosi

NNNN

MARIA CONTINUES TO WEAKEN… …TROPICAL STORM WARNING ISSUED FOR PORTIONS OF THE NORTH CAROLINA COAST

Hurricane Maria Discussion Number 37
NWS National Hurricane Center Miami FL AL152017
500 AM EDT Mon Sep 25 2017

A combination of conventional satellite imagery, scatterometer
data, and reports from a NOAA Hurricane Hunter aircraft indicate
that Maria is weakening and undergoing major changes in structure as
it encounters the cool water left by Hurricane Jose. Satellite
imagery shows that the low-level center has become exposed to the
northwest of the remaining central convection, with some outer
convective banding remaining mainly in the eastern semicircle. The
scatterometer and aircraft data suggests that the inner wind core
has collapsed, with no hurricane force winds occurring in the
western semicircle. Based on the combination of these data, the
initial intensity is lowered to a possibly generous 70 kt, and the
initial and forecast wind radii have been significantly changed.

The initial motion is 355/6. Maria is being steered by the flow
between a mid- to upper-level cyclone over the southeastern U.S. and
the subtropical ridge over the southwestern Atlantic. A mid-level
ridge moving eastward across the northeastern U.S. will likely cause
Maria’s forward motion to slow some more over the next couple of
days. After that time, the mid-latitude westerlies are expected to
encroach on Maria, causing it to turn sharply to the east-
northeast and accelerate. The guidance is in good agreement on this
track scenario, and the new forecast track, which lies between the
ECMWF and the various consensus models, is an update of the
previous forecast.

The environment of cool sea surface temperatures and moderate shear
should keep Maria weakening. However, it unclear just how fast it
will weaken, as the guidance has been generally forecasting a slower
weakening than has actually occurred. The new intensity forecast
will follow the trend of the guidance and the previous forecast of
a gradual weakening, with Maria now forecast to weaken below
hurricane status after 36 h. However, an alternate scenario is
that the cyclone continues weakening at a faster rate and thus
winds up weaker than the new intensity forecast.

Maria is a large cyclone, so even if it weakens to a tropical storm
and remains well offshore it is expected to bring tropical storm
conditions to portions of the North Carolina coast during the next
couple of days.

KEY MESSAGES:

1. Maria is forecast to continue moving northward, paralleling the
U.S. east coast, and it is likely that some direct impacts will
occur along portions of the coast beginning Tuesday. A Tropical
Storm Warning has been issued for a portion of the coast of North
Carolina.

2. Storm surge flooding especially along the sound side of the
North Carolina Outer Banks is possible beginning Tuesday, and a
Storm Surge Watch has been issued for a portion of the North
Carolina Outer Banks.

3. Swells from Maria are increasing along the coast of the
southeastern United States and are expected to reach the Mid-
Atlantic coast today. These swells will likely cause dangerous surf
and rip currents at beaches in these areas through much of the
week. For more information, please monitor information from your
local National Weather Service office at www.weather.gov.

FORECAST POSITIONS AND MAX WINDS

INIT 25/0900Z 30.6N 73.0W 70 KT 80 MPH
12H 25/1800Z 31.4N 73.2W 70 KT 80 MPH
24H 26/0600Z 32.5N 73.3W 65 KT 75 MPH
36H 26/1800Z 33.5N 73.3W 65 KT 75 MPH
48H 27/0600Z 34.3N 73.2W 60 KT 70 MPH
72H 28/0600Z 35.5N 72.0W 60 KT 70 MPH
96H 29/0600Z 37.0N 66.5W 60 KT 70 MPH
120H 30/0600Z 40.0N 56.5W 60 KT 70 MPH

$$
Forecaster Beven