Tropical Report

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Wed Sep 20 2017

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

The National Hurricane Center is issuing advisories on Tropical
Storm Jose, located a couple of hundred miles south of Nantucket,
Massachusetts, and on extremely dangerous Hurricane Maria, located
over Puerto Rico.

1. Showers and thunderstorms have not become any better organized
during the past several hours in association with the remnants of
Lee, located about 1000 miles east of the Leeward Islands. Although
environmental conditions are marginal for development, only a small
increase in the overall organization of the system would result in
the regeneration of Lee. This low is expected to move northward
over the central Atlantic Ocean during the next few days.
* Formation chance through 48 hours…medium…60 percent.
* Formation chance through 5 days…high…70 percent.

Additional information on the remnants of Lee can be found in High
Seas Forecasts issued by the National Weather Service, under AWIPS
header NFDHSFAT1, WMO header FZNT01 KWBC, and available on the Web
at http://www.opc.ncep.noaa.gov/shtml/NFDHSFAT1.shtml.

Forecaster Cangialosi

 

AIR FORCE HURRICANE HUNTERS INDICATE THAT JOSE IS A STRONG TROPICAL STORM… …DANGEROUS SURF AND RIP CURRENTS EXPECTED TO CONTINUE FOR SEVERAL MORE DAYS ALONG MUCH OF THE EAST COAST OF THE UNITED STATES

Tropical Storm Jose Discussion Number 61
NWS National Hurricane Center Miami FL AL122017
1100 AM EDT Wed Sep 20 2017

The Air Force Hurricane Hunters have been investigating Jose this
morning and found maximum flight-level winds of 78 kt at 5,000 feet
and peak SFMR surface winds of 56 kt. Based on these data, the
initial wind speed is set at 60 kt, which is slightly higher than
the previous estimate. Jose remains a sprawling cyclone, with
tropical storm force winds extending 180 n mi from the center.
Although Jose does not have a purely tropical appearance, it still
has a warm core and well-defined convective bands, especially to the
north of the center.

Jose is moving northeastward at 7 kt toward a mid- to upper-level
trough over eastern Canada. A slightly slower northeastward to
east-northeastward motion is expected through tonight. Thereafter,
the trough is expected to lift out, allowing a mid-level high
pressure system to build to the northwest of Jose. This will likely
cause the storm to reverse its course and drift westward or
west-southwestward. In about 3 days, however, the models suggest
that Jose will be caught in very weak steering currents, and the NHC
official track forecast now shows Jose stationary from 72 to 120
hours.

The tropical storm is moving over a tight SST gradient associated
with the north wall of the Gulf Stream current, and it will likely
remain over this gradient for the next several days. These
relatively cool SSTs and dry air should cause a slow weakening
trend, and a gradual transition to a post-tropical cyclone. The NHC
intensity forecast is not too different from the previous one and is
in best agreement with the consensus models.

KEY MESSAGES:

1. While the center of Jose is forecast to remain offshore of the
U.S. east coast, the large cyclone is expected to cause some direct
impacts in portions of New England during the next couple of days,
and a tropical storm warning is in effect for Cape Cod, Block
Island, Martha’s Vineyard, and Nantucket.

2. Minor to moderate coastal flooding is possible from Delaware to
southern New England during the next several days. Please see
products issued by local National Weather Service forecast offices.

3. Swells generated by Jose are affecting Bermuda and much of the
U.S. east coast and will likely cause dangerous surf and rip current
conditions for the next several days in these areas.

4. Jose is expected to produce additional rainfall accumulations of
1 to 2 inches over Martha’s Vineyard and Cape Cod, and 2 to 4 inches
in Nantucket as it passes offshore today into Thursday. This
rainfall could cause isolated flash flooding.

FORECAST POSITIONS AND MAX WINDS

INIT 20/1500Z 39.0N 70.0W 60 KT 70 MPH
12H 21/0000Z 39.5N 69.0W 60 KT 70 MPH
24H 21/1200Z 39.8N 68.1W 55 KT 65 MPH
36H 22/0000Z 39.6N 68.3W 45 KT 50 MPH
48H 22/1200Z 39.5N 69.0W 40 KT 45 MPH…POST-TROPICAL
72H 23/1200Z 39.3N 70.0W 40 KT 45 MPH…POST-TROPICAL
96H 24/1200Z 39.3N 70.0W 35 KT 40 MPH…POST-TROPICAL
120H 25/1200Z 39.3N 70.0W 30 KT 35 MPH…POST-TROPICAL

$$
Forecaster Cangialosi

 

DESTRUCTIVE WINDS AND FLOODING CONTINUE OVER PORTIONS OF PUERTO RICO… …CENTER OF MARIA APPROACHING THE NORTHERN COAST OF PUERTO RICO

Hurricane Maria Discussion Number 18
NWS National Hurricane Center Miami FL AL152017
1100 AM AST Wed Sep 20 2017

The last radar image from the San Juan WSR-88D was received at 0950
UTC when Maria’s eye was located only about 5 n mi off the
southeastern coast of Puerto Rico. Subsequent 1-minute imagery from
the GOES-16 satellite, as well as surface observations, indicate
that the eye made landfall a little south of Yabucoa Harbor, Puerto
Rico, around 1015 UTC. Now that the center is moving over the
mountainous terrain of the island, the eye has become cloud filled,
and the infrared satellite presentation has degraded. Without radar
velocity data, the initial intensity is incredibly uncertain, but my
best guess is 120 kt based on a typical inland decay rate. Maria’s
center is expected to move off the northern coast of Puerto Rico
soon, and an Air Force Reserve reconnaissance aircraft is scheduled
to intercept the center early this afternoon and provide a better
estimate of how much Maria has weakened.

The initial motion is northwestward, or 305/10 kt. This
northwestward motion is forecast to continue for the next 48 hours,
followed by a turn toward the north by days 4 and 5, while Maria
moves between a mid-level high centered southeast of Bermuda and a
broad trough extending from Tropical Storm Jose southwestward into
the Gulf of Mexico. The track guidance is tightly clustered this
cycle, and there were no significant changes made to the NHC
forecast track.

Once Maria moves off the coast of Puerto Rico, it will take some
time for the structure to reorganize over the warm waters of the
Atlantic Ocean. However, the shear is expected to be less than 10
kt for the next 24-36 hours, and Maria has an opportunity to
restrengthen a bit over that time period. After 36 hours, a gradual
increase in shear is likely to lead to a commensurate gradual
decrease in the hurricane’s intensity through the end of the
forecast period. Since the SHIPS model, in particular, responds to
the favorable conditions for intensification, the NHC intensity
forecast lies just above the intensity consensus through much of the
forecast period.

Since we don’t have radar imagery from San Juan, and the eye has
become cloud filled in satellite imagery, the hourly position
updates are being discontinued.

KEY MESSAGES:

1. Maria’s core is moving over Puerto Rico, with life-threatening
wind, storm surge, and rainfall impacts continuing over the
island. Everyone in Puerto Rico should follow advice from local
officials to avoid life-threatening flooding from storm surge and
rainfall. A Hurricane Warning remains in effect for the Virgin
Islands, but conditions should gradually improve there later today.

2. Wind speeds atop and on the windward sides of hills and mountains
and on high-rise buildings could be much stronger than the
near-surface winds indicated in this advisory.

3. A Hurricane Warning is also in effect for the northern coast of
the Dominican Republic, the Turks and Caicos Islands and the
southeastern Bahamas, where Maria is expected to bring dangerous
wind, storm surge, and heavy rainfall.

FORECAST POSITIONS AND MAX WINDS

INIT 20/1500Z 18.4N 66.5W 120 KT 140 MPH…OVER PUERTO RICO
12H 21/0000Z 19.2N 67.6W 120 KT 140 MPH
24H 21/1200Z 20.2N 69.0W 125 KT 145 MPH
36H 22/0000Z 21.2N 70.1W 125 KT 145 MPH
48H 22/1200Z 22.4N 71.0W 120 KT 140 MPH
72H 23/1200Z 25.3N 72.4W 110 KT 125 MPH
96H 24/1200Z 28.5N 73.0W 100 KT 115 MPH
120H 25/1200Z 31.5N 73.0W 90 KT 105 MPH

$$
Forecaster Berg