Thursday, September 14, 2023

Hurricane Lee Update


002 

WTNT33 KNHC 150249

TCPAT3


BULLETIN

Hurricane Lee Advisory Number  39

NWS National Hurricane Center Miami FL       AL132023

1100 PM AST Thu Sep 14 2023


...TROPICAL STORM WARNINGS ISSUED FOR PORTIONS OF ATLANTIC CANADA...

...DANGEROUS SURF AND RIP CURRENT CONDITIONS AFFECTING MUCH OF THE

EAST COAST OF THE UNITED STATES...



SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION

-----------------------------------------------

LOCATION...32.9N 67.6W

ABOUT 170 MI...270 KM WNW OF BERMUDA

ABOUT 590 MI...945 KM SSE OF NANTUCKET MASSACHUSETTS

MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H

PRESENT MOVEMENT...N OR 10 DEGREES AT 14 MPH...22 KM/H

MINIMUM CENTRAL PRESSURE...957 MB...28.26 INCHES



WATCHES AND WARNINGS

--------------------

CHANGES WITH THIS ADVISORY:


The Canadian Hurricane Center has issued a Tropical Storm Warning

for New Brunswick from the U.S./Canada border to Fort Lawrence,

including Grand Manan Island, and a Tropical Storm Warning for the

coast of Nova Scotia from Fort Lawrence to Point Tupper.


SUMMARY OF WATCHES AND WARNINGS IN EFFECT:


A Hurricane Watch is in effect for...

* Stonington, Maine to the U.S./Canada border

* New Brunswick from the U.S./Canada border to Point Lepreau,

including Grand Manan Island

* Nova Scotia from Digby to Medway Harbour


A Tropical Storm Warning is in effect for...

* Bermuda

* Westport Massachusetts northward to the U.S./Canada border

* Martha's Vineyard

* Nantucket

* New Brunswick from the U.S./Canada border to Fort Lawrence,

including Grand Manan Island

* Nova Scotia from Fort Lawrence to Point Tupper


A Hurricane Watch means that hurricane conditions are possible

within the watch area.  A watch is typically issued 48 hours

before the anticipated first occurrence of tropical-storm-force

winds, conditions that make outside preparations difficult or

dangerous.


A Tropical Storm Warning means that tropical storm conditions are

expected somewhere within the warning area within 36 hours.


Interests elsewhere in the northeastern United States and Atlantic

Canada should monitor the progress of Lee.


For storm information specific to your area in the United

States, including possible inland watches and warnings, please

monitor products issued by your local National Weather Service

forecast office. For storm information specific to your area

outside of the United States, please monitor products issued by

your national meteorological service.



DISCUSSION AND OUTLOOK

----------------------

At 1100 PM AST (0300 UTC), the center of Hurricane Lee was located

near latitude 32.9 North, longitude 67.6 West. Lee is moving toward

the north near 14 mph (22 km/h), and this general motion with an

increase in forward speed is expected through Saturday.  A turn

toward the north-northeast and then northeast is forecast Saturday

night and Sunday.  On the forecast track, the center of Lee will

continue to pass west-northwest of Bermuda through tonight, 

approach the coast of New England and Atlantic Canada Friday and 

Saturday, and move across Atlantic Canada Saturday night and Sunday.


Maximum sustained winds remain near 85 mph (140 km/h) with higher

gusts.  Little change in strength is expected through Friday

afternoon.  Some gradual weakening is forecast Friday night and

Saturday, but Lee is expected to remain large and dangerous for the

next couple of days.


Lee is a very large hurricane.  Hurricane-force winds extend

outward up to 105 miles (165 km) from the center and

tropical-storm-force winds extend outward up to 345 miles (555 km).

A sustained wind of 40 mph (65 km/h) with a gust to 53 mph (85

km/h) was recently reported at the L.F. Wade International Airport

on Bermuda.


The minimum central pressure estimated from Air Force Hurricane 

Hunter observations is 957 mb (28.26 inches).



HAZARDS AFFECTING LAND

----------------------

Key messages for Lee can be found in the Tropical Cyclone Discussion

under AWIPS header MIATCDAT3 and WMO header WTNT43 KNHC and on the

web at hurricanes.gov/text/MIATCDAT3.shtml


WIND:  Tropical storm conditions will continue on Bermuda through

Friday morning.  Hurricane conditions are possible in the Hurricane

Watch areas in Down East Maine and in Atlantic Canada on Saturday.

Tropical storm conditions are expected to begin in southern New

England on Friday afternoon and spread northward within the

Tropical Storm Warning area through Saturday.  Tropical storm

conditions are expected in the Tropical Storm Warning area in

Atlantic Canada by late Friday into Saturday.


STORM SURGE:  The combination of storm surge and tide will cause

normally dry areas near the coast to be flooded by rising waters

moving inland from the shoreline.  The water could reach the

following heights above ground somewhere in the indicated areas if

the peak surge occurs at the time of high tide...


Flushing, NY to U.S./Canada border...1-3 ft

Long Island Sound...1-3 ft

Cape Cod...1-3 ft

Martha's Vineyard and Nantucket...1-3 ft

Boston Harbor...1-3 ft

Rockaway Inlet, NY to Montauk Point, NY...1-2 ft


The deepest water will occur along the immediate coast where the

surge will be accompanied by large and destructive waves.

Surge-related flooding depends on the relative timing of the surge

and the tidal cycle, and can vary greatly over short distances.  For

information specific to your area, please see products issued by

your local National Weather Service forecast office.


A dangerous storm surge will produce coastal flooding within the

wind warning areas in Atlantic Canada in areas of onshore winds.

Near the coast, the surge will be accompanied by large and

destructive waves.


SURF:  Swells generated by Lee are affecting portions of the Lesser

Antilles, the British and U.S. Virgin Islands, Puerto Rico,

Hispaniola, the Turks and Caicos Islands, the Bahamas, Bermuda, the

east coast of the United States, and Atlantic Canada.  These swells

are likely to cause life-threatening surf and rip current

conditions.  Please consult products from your local weather office.


RAINFALL: Outer rain bands from Lee may produce rainfall amounts of

1 to 2 inches, or 25 to 50 millimeters, across Bermuda overnight

and early Friday.


From Friday night through Saturday night, Lee is expected to produce

rainfall amounts of 1 to 4 inches, or 25 to 100 millimeters, across

portions of eastern New England into portions of New Brunswick and

Nova Scotia.  This may produce localized urban and small stream

flooding.



NEXT ADVISORY

-------------

Next intermediate advisory at 200 AM AST.

Next complete advisory at 500 AM AST.


$$

Forecaster Pasch


691 

WTNT43 KNHC 150250

TCDAT3


Hurricane Lee Discussion Number  39

NWS National Hurricane Center Miami FL       AL132023

1100 PM AST Thu Sep 14 2023


Observations from an Air Force Reserve Unit Hurricane Hunter

aircraft indicate that Lee's eyewall is not well defined, and this

is also suggested by geostationary satellite and microwave imagery.

Although the peak 700 mb flight-level winds reported by the plane

were near 93 kt, the highest SFMR-observed surface winds were 72 kt.

Thus the winds aloft in the hurricane are not being transported

very effectively to the surface.  This is not surprising, since the

central deep convection is no longer very strong.  The current

intensity is kept at 75 kt based on the aircraft data, which is

well above the Dvorak satellite estimates.


Lee wobbled a bit to the northeast early this evening, but the

longer-term motion appears to be just east of north, or around

010/12 kt.  The system should move generally northward at a faster

forward speed, on the west side of a mid-level ridge, during the

next day or so.  A slight bend to the left is likely late Friday as

the cyclone interacts with a mid-level trough.  By late Saturday,

Lee should begin to turn toward the north-northeast with the center

passing near or over western Nova Scotia.  Then, Lee is forecast to

turn northeastward over Atlantic Canada.  The track guidance remains

in good agreement through 72 hours, and the official forecast is

basically an update of the previous one.


South-southwesterly shear is predicted to increase significantly

over Lee during the next couple of days.  This, along with cooler

SSTs, particularly after the system moves north of 40N latitude,

should result in weakening.  However, baroclinic processes could

help the cyclone maintain its intensity, or at least slow the

weakening rate.  The official intensity forecast is above the model

guidance for this reason.  In 48 hours, simulated satellite imagery

shows an asymmetric cloud structure characteristic of an

extratropical cyclone.  Regardless of when extratropical transition

actually occurs, however, Lee should remain a very large and

dangerous cyclone through landfall.



KEY MESSAGES:


1. Tropical storm conditions, heavy rainfall, and high surf will

continue to impact Bermuda through Friday morning, and a Tropical

Storm Warning is in effect for the island.


2. Hurricane conditions and coastal flooding are possible in

portions of eastern Maine, southern New Brunswick, and western Nova

Scotia on Saturday, and a Hurricane Watch is in effect for that

area.  Tropical storm conditions and coastal flooding are expected

to begin in southern New England on Friday afternoon, and spread

northward along the coast of New England and over portions of

Atlantic Canada through Saturday where Tropical Storm warnings are

in effect.


3. Heavy rainfall from Lee may produce localized urban and small

stream flooding across eastern New England and into portions of New

Brunswick and Nova Scotia from Friday night into Saturday night.



FORECAST POSITIONS AND MAX WINDS


INIT  15/0300Z 32.9N  67.6W   75 KT  85 MPH

 12H  15/1200Z 35.0N  67.3W   75 KT  85 MPH

 24H  16/0000Z 38.4N  66.6W   75 KT  85 MPH

 36H  16/1200Z 41.6N  66.6W   65 KT  75 MPH

 48H  17/0000Z 44.3N  66.0W   60 KT  70 MPH...POST-TROP/INLAND

 60H  17/1200Z 47.0N  63.6W   45 KT  50 MPH...POST-TROP/EXTRATROP

 72H  18/0000Z 49.6N  59.1W   40 KT  45 MPH...POST-TROP/EXTRATROP

 96H  19/0000Z 54.5N  42.5W   35 KT  40 MPH...POST-TROP/EXTRATROP

120H  20/0000Z...DISSIPATED


$$

Forecaster Pasch

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