Tropical Report

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Wed Sep 27 2017

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

The National Hurricane Center is issuing advisories on Tropical
Storm Maria, located about 150 miles east 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 Brown

STILL AN OPPORTUNITY FOR LEE TO STRENGTHEN TODAY

Hurricane Lee Discussion Number 37
NWS National Hurricane Center Miami FL AL142017
500 AM AST Wed Sep 27 2017

Conventional satellite imagery indicates that Lee has been
undergoing some cloud structural changes during the past several
hours. The eye has nearly doubled in size to 30 miles in
diameter, the central pressure indicated in the CIMSS Objective
Dvorak technique has increased a few millibars, and an earlier 2147
UTC WindSAT overpass revealed a developing outer ring surrounding
the partially opened inner core. These aforementioned cloud pattern
alterations arguably point to an undergoing eyewall replacement
cycle, and the possibility of intensification in the short term.
The initial intensity of 95 kt remains above the subjective
T-numbers, and is close to the CIMSS ADT estimated intensity. The
official intensity forecast reflects the possibility of Lee becoming
a major hurricane later today before a weakening trend commences by
early Wednesday. The global models and the FSU Cyclone Phase
Evolution product agree that Lee will maintain tropical
characteristics through day 3. Afterward, the guidance shows the
cyclone quickly absorbed by an existing larger baroclinic
system.

The initial motion is estimated to be west-northwestward, or 285/8
kt. Lee should turn gradually northwestward later today, and
generally northward on Thursday as the cyclone is steered by the
southwestern peripheral flow of a subtropical ridge over the
east-central Atlantic. Through the remaining portion of the
forecast, Lee is forecast to accelerate northeastward within the
strong mid-latitude southwesterly flow and ultimately dissipate in
72 hours. The model guidance suite continues to trend toward the
west through the 36-hour period, and the official forecast follows
suit. Beyond that time frame, the forecast is a little faster than
the previous advisory and is nudged toward the HFIP Corrected
Consensus technique model.

FORECAST POSITIONS AND MAX WINDS

INIT 27/0900Z 30.2N 56.3W 95 KT 110 MPH
12H 27/1800Z 30.8N 57.0W 95 KT 110 MPH
24H 28/0600Z 32.1N 57.3W 90 KT 105 MPH
36H 28/1800Z 34.5N 56.5W 85 KT 100 MPH
48H 29/0600Z 37.8N 53.1W 75 KT 85 MPH
72H 30/0600Z 46.3N 39.0W 60 KT 70 MPH
96H 01/0600Z…DISSIPATED

$$
Forecaster Roberts

MARIA CRAWLING NORTHWARD OFF THE NORTH CAROLINA OUTER BANKS

Tropical Storm Maria Discussion Number 45
NWS National Hurricane Center Miami FL AL152017
500 AM EDT Wed Sep 27 2017

Maria has changed little in structure since the last advisory. A
band of deep convection attempted to wrap around the western side
of the circulation, but that has since dissipated due to continued
shear and dry air. The initial intensity remains 60 kt based on
surface winds measured by the SFMR on the previous reconnaissance
flight. Maria will likely be moving over some warm and cold eddies
associated with the Gulf Stream during the next 2 to 3 days, and
with vertical shear expected to gradually decrease during that
time, only slow weakening is anticipated. After day 3, vertical
shear increases significantly, and Maria is expected to complete
extratropical transition by day 4. The global models then indicate
that the low will be absorbed by a larger extratropical low over
the northeastern Atlantic by day 5.

Earlier reconnaissance fixes indicated that Maria’s center was
jumping around a bit, but its average motion is estimated to be
slowly northward, or 005 degrees at 4 kt. Maria is moving around
the western periphery of a mid-level ridge located over the central
Atlantic, and it should enter the mid-latitude westerlies in about
36 hours, at which point it is expected to accelerate northeastward
across the north Atlantic. Most of the model spread continues to
be in the along-track direction, highlighted by the faster GFS and
HWRF models and the slower ECMWF model. As was the case before,
the updated NHC track forecast splits the difference between these
scenarios and remains close to the multi-model consensus aids.

KEY MESSAGES:

1. Maria is forecast to slowly move away from the U.S. east coast
during the next day or so. However, tropical storm conditions are
expected to continue along portions of the North Carolina coast
through much of today.

2. Storm surge flooding, especially along the sound side of the
North Carolina Outer Banks, is expected, and a storm surge warning
and watch are in effect for portions of eastern North Carolina.

3. Swells generated by Maria are affecting much of the east coast of
the United States, Atlantic Canada, Bermuda, the Bahamas, and the
Turks and Caicos Islands. These swells are likely to cause
life-threatening surf and rip current conditions. Please consult
products from your local weather office for more information.

FORECAST POSITIONS AND MAX WINDS

INIT 27/0900Z 35.1N 72.9W 60 KT 70 MPH
12H 27/1800Z 35.7N 72.7W 55 KT 65 MPH
24H 28/0600Z 36.2N 71.7W 55 KT 65 MPH
36H 28/1800Z 36.5N 69.3W 50 KT 60 MPH
48H 29/0600Z 37.0N 65.3W 50 KT 60 MPH
72H 30/0600Z 40.5N 52.5W 50 KT 60 MPH
96H 01/0600Z 47.5N 32.5W 45 KT 50 MPH…POST-TROP/EXTRATROP
120H 02/0600Z…ABSORBED BY A LARGER EXTRATROPICAL LOW