Major Hurricane Lee (Category 3) Grows In Size As It Lumbers Northward

000

WTNT33 KNHC 130241

TCPAT3

BULLETIN

Hurricane Lee Advisory Number  31

NWS National Hurricane Center Miami FL       AL132023

1100 PM AST Tue Sep 12 2023

...LARGE LEE LUMBERING NORTHWESTWARD...

...TROPICAL STORM WARNING ISSUED FOR BERMUDA...

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

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

LOCATION...25.3N 66.7W

ABOUT 495 MI...800 KM SSW OF BERMUDA

MAXIMUM SUSTAINED WINDS...115 MPH...185 KM/H

PRESENT MOVEMENT...NW OR 320 DEGREES AT 7 MPH...11 KM/H

MINIMUM CENTRAL PRESSURE...946 MB...27.94 INCHES

WATCHES AND WARNINGS

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

CHANGES WITH THIS ADVISORY:

The Bermuda Weather Service has issued a Tropical Storm Warning for

Bermuda.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...

* Bermuda

A Tropical Storm Warning means that tropical storm conditions are

expected somewhere within the warning area, generally within 36

hours.

Interests in the northeastern United States and Atlantic Canada

should monitor the progress of Lee.

For storm information specific to your area, 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 25.3 North, longitude 66.7 West.  Lee is moving toward

the northwest near 7 mph (11 km/h).  Lee is forecast to turn toward

the north on Thursday and increase in forward speed.

Maximum sustained winds are near 115 mph (185 km/h) with higher

gusts.  Lee is a category 3 hurricane on the Saffir-Simpson

Hurricane Wind Scale.  Some slow weakening is forecast during the

next 48 hours, however Lee is likely to remain a large and 

dangerous hurricane for the next couple of days.

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

outward up to 125 miles (205 km) from the center and 

tropical-storm-force winds extend outward up to 240 miles (390 km).

Saildrone 1036, located about 75 miles (120 km) northwest of Lee's 

center, recently reported a wind gust to 88 mph (141 km/h).

The estimated minimum central pressure is 946 mb (27.94 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 are expected in Bermuda starting

late Wednesday or early Thursday.

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, and Bermuda.

These swells are likely to cause life-threatening surf and rip

current conditions. Dangerous surf and rip currents are affecting

portions of the southeastern U.S. coast, and these conditions are

forecast to spread northward along much of the U.S. East Coast and

Atlantic Canada during the next couple of days. Please consult

products from your local weather office.

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

1 to 2 inches, 25 to 50 millimeters, across Bermuda Thursday into

early Friday.

NEXT ADVISORY

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

Next intermediate advisory at 200 AM AST.

Next complete advisory at 500 AM AST.

$$

Forecaster Pasch

000

WTNT43 KNHC 130242

TCDAT3

Hurricane Lee Discussion Number  31

NWS National Hurricane Center Miami FL       AL132023

1100 PM AST Tue Sep 12 2023

Geostationary satellite images show that Lee has a large eye about 

40 n mi in diameter surrounded by very cold-topped central 

convection.  There are numerous convective banding features, 

especially over the northern portion of the circulation.  The 

cirrus-level outflow pattern is fairly symmetric at this time, 

suggesting that the vertical wind shear over the system is still 

low.  The intensity estimate is held at 100 kt for this advisory, 

which is a blend of subjective and objective satellite estimates 

from TAFB, SAB, and UW/CIMSS.  The objective intensity estimates 

are generally a little higher than the subjective values.  

Lee continues to move on a generally northwestward heading, with a 

motion estimate of 320/6 kt, on the southwestern side of a 

mid-level anticyclone.  Over the next couple of days, a 500-mb 

trough moving through the eastern United States should induce a 

northward turn with some increase in forward speed.  Even though 

the predicted track has the center of the hurricane passing well to 

the west of Bermuda, Lee's very large wind field should result in 

tropical storm conditions spreading over the island by late 

Wednesday or early Thursday.  In the 3 to 4 day time frame, the 

model guidance suggests just a slight leftward bend in the track 

while Lee interacts with the trough.  There has been little change 

to the NHC forecast track, which remains close to the corrected and 

simple model consensus predictions.  After 96 hours, Lee should 

turn northeastward and east-northeastward in the mid-latitude 

westerlies.

Gradual weakening is anticipated during the next few days days 

while Lee moves over cooler waters and encounters high vertical 

wind shear.  However the system is likely to remain a large and 

dangerous hurricane while it approaches the coast.  If Lee moves 

faster than forecast over the colder waters north of the Gulf 

Stream, it will likely retain more of its strength when it reaches 

land.  Around 96 hours, simulated satellite imagery from the global 

models show the appearance of an extratropical cyclone with 

decreased convection and an asymmetric cloud pattern.

It should again be noted that the 34- and 50-kt wind speed 

probabilities beyond 36 hours in the text product and graphics are 

likely underestimating the risk of those winds occurring.  This is 

because the forecast wind field of Lee is considerably larger than 

average compared to the wind field used to derive the wind speed 

probability product.

KEY MESSAGES:

1. Dangerous surf and life-threatening rip currents will affect

portions of the northern Leeward Islands, the Virgin Islands, Puerto

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

Bermuda, and most of the U.S East Coast through much of the week.

2. Tropical storm conditions, heavy rainfall, and high surf are 

expected to impact Bermuda beginning Wednesday night or early 

Thursday, and a Tropical Storm Warning has been issued for the 

island.

3. It remains too soon to know what level of additional impacts Lee

might have along the northeastern U.S. coast and Atlantic Canada

late this week and this weekend.  However, since wind and rainfall

hazards will extend well away from the center as Lee grows in size,

users should continue to monitor updates to Lee's forecast during

the next several days.

FORECAST POSITIONS AND MAX WINDS

INIT  13/0300Z 25.3N  66.7W  100 KT 115 MPH

 12H  13/1200Z 26.1N  67.2W  100 KT 115 MPH

 24H  14/0000Z 27.7N  67.8W   95 KT 110 MPH

 36H  14/1200Z 29.7N  68.2W   90 KT 105 MPH

 48H  15/0000Z 32.1N  67.9W   80 KT  90 MPH

 60H  15/1200Z 35.0N  67.1W   75 KT  85 MPH

 72H  16/0000Z 38.0N  66.6W   75 KT  85 MPH

 96H  17/0000Z 44.0N  66.4W   60 KT  70 MPH...POST-TROP/EXTRATROP

120H  18/0000Z 48.5N  62.0W   40 KT  45 MPH...POST-TROP/EXTRATROP

$$

Forecaster Pasch

000

FXUS61 KCAR 130113

AFDCAR

Area Forecast Discussion

National Weather Service Caribou ME

913 PM EDT Tue Sep 12 2023

.SYNOPSIS...

A warm front will slowly lift northward across the area late

today into tonight. A cold front will then cross the region

Wednesday night through early Thursday. High pressure returns

on Friday. Hurricane Lee approaches the area Friday night into

Saturday and moves northeast into the Canadian Maritimes

Sunday.

......LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...

Hurricane Lee will be approaching the New England and Atlantic

Canada regions through the end of the week. The exact track of

Lee still remains uncertain. Plenty of ensembles maintain the

center of Lee to our east, though some guidance, particularly

the ECMWF, suggests a further west track, with the center

reaching our area or just to the west of our area. Regardless of

the exact track of Lee, it remains true that as Lee continues to

move northward the storm will begin to expand in size, and

impacts will extend well outside of the very center of the

storm. This system will be closely monitored for trends in track

as well as impacts to our forecast area as the time draws closer

as to how much rainfall may be expected and how strong the winds

may be. For what is seen right now, the strongest winds will

likely be along the coastal Downeast region, and gradually

decreasing in speed further inland. There is also increasing

confidence in some tropical rainfall somewhere in the forecast

area, but as to whether it is the entire forecast area or more

confined to the south and east remains uncertain as well.

The uncertainty in track will depend greatly on the forward

speed of the storm and whether or not Lee interacts with the

exiting upper level trough from the middle of the week. As such,

there is timing uncertainty in when Lee will reach our general

region as well, though it will most likely be some time Friday

night into early Saturday morning.

Later this week, Lee will be chased out of the area by another

shortwave crossing across Ontario, with another round of rain

showers expected through early next week......

3:48 PM ADT Tuesday 12 September 2023

The next information statement will be issued by 9 AM ADT Wednesday.

Hurricane Lee will start moving on a more northward heading tomorrow and further enhance the tropical airmass over Atlantic Canada.  It will also have the effect of slowing the progress of a front which could increase the risk of heavy rainfall over the Maritime provinces on Thursday and Friday before the hurricane approaches.

We expect Lee's circulation to broaden significantly as it moves north and expect it to move into the Canadian marine district as a category-1 hurricane.  It is looking likely that the forward motion of the storm could slow and while doing so, winds would start to decrease, the intensity would drop below hurricane strength and it would become post-tropical.  The track of the storm centre could range anywhere from Downeast Maine to Cape Breton.  Also note that after the likely slow-down in forward motion, Lee's trajectory is expected to shift from northerly to northeasterly.  Since it will be a rather broad system, the rain, wind, waves, etc would affect most of the Maritime provinces and neighboring waters to varying extent. Lee will be much- weakened before reaching Newfoundland.   

The trend in computer model guidance has been a somewhat faster approach speed and arrival time in the region.  NOTE: If the trend continues, there would be a risk of higher winds reaching land. As of now, western Nova Scotia has the higher possibility of impacts which is worth noting since that region wasn't impacted by recent storms like Dorian and Fiona. It will be important to follow updates of this bulletin where we will articulate any shifts in the impact likelihood and of course the eventual details of impacts.

With the expanding size of the hurricane and a long trajectory northward, building surf conditions and rip currents are expected along the Atlantic coast of Nova Scotia over the coming days - particularly on Friday.

This next bulletin is planned for 9 a.m. ADT Wednesday with the CHC track and technical bulletin taking effect at that time as well..

Forecaster: Fogarty

Please continue to monitor alerts issued by the Canadian Hurricane Centre and forecasts issued by Environment Canada.

Visit the Canadian Hurricane Centre to learn more about hurricanes.