Tropical Report

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Sun Sep 24 2017

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

The National Hurricane Center is issuing advisories on Hurricane
Maria, located a few hundred miles east-northeast of Great Abaco
Island in the Bahamas, and on Hurricane Lee, located over the
central Atlantic Ocean almost a thousand miles east of Bermuda.

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

$$
Forecaster Brown

LEE CONTINUES TO RAPIDLY INTENSIFY

Hurricane Lee Discussion Number 25
NWS National Hurricane Center Miami FL AL142017
500 AM AST Sun Sep 24 2017

Since the earlier special advisory issued to make Lee a hurricane,
the eye has become much better defined in IR imagery, indicating
that the hurricane has continued to rapidly intensify. The initial
intensity has therefore been increased to 75 kt, based on an
application of the Dvorak technique to the latest IR imagery. It
should be noted that in this case, the intensity is fairly uncertain
given the lack of ground truth and the small size of the cyclone.

At this point, it is hard to judge how long this period of rapid
intensification will continue. On one hand, Lee is expected to
remain in a relatively unstable and low-shear environment for the
next several days. On the other, despite the clearing of the eye,
cloud tops have not cooled significantly overnight, and the slow
motion of Lee allows the possibility that the storm could begin to
interact with its own cold wake. The NHC forecast brings Lee to
near major hurricane strength in 24 h, and then keeps Lee around
that intensity through day 4, similar to the FSSE model. By the end
of the forecast, higher shear, due in part to the outflow of
Hurricane Maria, could cause Lee to weaken, so the NHC forecast is a
little lower at that point.

Lee is drifting southward for now, but a southeastward motion is
still forecast to begin later today. Very little change has been
made to the NHC forecast, which is mainly just an update of the
previous one. The models have come into better agreement that Lee
will be primarily steered for the next several days by a mid-level
ridge building to the northwest. By day 5, a trough associated
with Maria and the subtropical ridge should cause Lee to begin
recurving. Since the model spread has decreased, confidence in
that aspect of the forecast has increased this morning.

FORECAST POSITIONS AND MAX WINDS

INIT 24/0900Z 31.8N 50.1W 75 KT 85 MPH
12H 24/1800Z 31.6N 49.6W 85 KT 100 MPH
24H 25/0600Z 31.1N 48.9W 95 KT 110 MPH
36H 25/1800Z 30.6N 48.8W 95 KT 110 MPH
48H 26/0600Z 30.2N 49.4W 95 KT 110 MPH
72H 27/0600Z 30.5N 51.3W 90 KT 105 MPH
96H 28/0600Z 32.0N 52.5W 90 KT 105 MPH
120H 29/0600Z 34.5N 51.4W 80 KT 90 MPH

$$
Forecaster Zelinsky

NOAA HURRICANE HUNTER FINDS THAT MARIA IS SLIGHTLY WEAKER… …INTERESTS ALONG THE CAROLINA AND MID-ATLANTIC COASTS SHOULD MONITOR THE PROGRESS OF MARIA

Hurricane Maria Discussion Number 33
NWS National Hurricane Center Miami FL AL152017
500 AM EDT Sun Sep 24 2017

A NOAA Hurricane Hunter aircraft investigating Maria has reported
700-mb flight-level winds of 107 kt in the southeastern eyewall,
with surface wind estimates from the Stepped Frequency Microwave
Radiometer between 75-80 kt. The plane also reported that the
central pressure has risen to 948 mb inside a 30 n mi wide eye.
Based on these data, the initial intensity is nudged downward to
95 kt, and it is possible that this is a bit generous.

The initial motion is 355/8, with Maria currently being steered by
the flow between the Atlantic subtropical ridge and a cut-off
low/trough over the eastern Gulf of Mexico and the southeastern
United States. A general motion toward the north or north-
northwest should continue for the next 3 days or so, with some
decrease in forward speed as a mid-latitude westerly ridge moves
through the New England states to the north of the hurricane. After
72 h, the westerlies move south and erode the subtropical ridge,
which should allow Maria to recurve to the northeast. The track
guidance supports this scenario, although there is some
disagreement on the timing and the location of the recurvature.
The new forecast track lies a little to the north and west of the
previous track in best agreement with the HFIP Corrected consensus
model. However, the 72 and 96 h points lie a little to the east of
the forecasts of the GFS and ECMWF models. Regardless of where the
recurvature occurs, Maria is a large cyclone and the associated
tropical storm force winds could eventually reach a portion of the
North Carolina coast.

Fluctuations in intensity appear likely during the next 24-36 h as
Maria remains over warm water and in an environment of light or
moderate shear. After that time, the hurricane is likely to
encounter the colder water left by Hurricane Jose, which should
cause a weakening trend. The new intensity forecast follows the
overall trend of the guidance and, except for a downward nudge at
12 and 24 h, is similar to the previous forecast.

KEY MESSAGES:

1. Maria’s forecast track continues to be northward, paralleling the
U.S. east coast, and it is likely that some direct impacts will
occur along portions of the coast next week. Interests along the
coast of the Carolinas and the Mid-Atlantic should monitor the
progress of Maria, as tropical storm or hurricane watches may be
needed for part of this area later today.

2. 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 the beach through much of next week. For
more information, please monitor information from your local
National Weather Service office at www.weather.gov.

FORECAST POSITIONS AND MAX WINDS

INIT 24/0900Z 27.9N 72.7W 95 KT 110 MPH
12H 24/1800Z 28.9N 72.8W 95 KT 110 MPH
24H 25/0600Z 30.1N 73.0W 95 KT 110 MPH
36H 25/1800Z 31.2N 73.1W 90 KT 105 MPH
48H 26/0600Z 32.1N 73.2W 85 KT 100 MPH
72H 27/0600Z 34.0N 73.5W 75 KT 85 MPH
96H 28/0600Z 35.0N 72.5W 70 KT 80 MPH
120H 29/0600Z 36.0N 69.0W 65 KT 75 MPH

$$
Forecaster Beven