Extratropical Storm Teddy (Hurricane Force)

 000

WTNT35 KNHC 230234

TCPAT5

BULLETIN

Post-Tropical Cyclone Teddy Advisory Number  43

NWS National Hurricane Center Miami FL       AL202020

1100 PM AST Tue Sep 22 2020

...POST-TROPICAL CYCLONE TEDDY FORECAST TO PRODUCE DESTRUCTIVE

WAVES, HEAVY RAIN AND STRONG WINDS FOR PORTIONS OF NOVA SCOTIA 

TONIGHT THROUGH WEDNESDAY...

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

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

LOCATION...42.8N 63.9W

ABOUT 125 MI...200 KM S OF HALIFAX NOVA SCOTIA

ABOUT 590 MI...950 KM WSW OF CAPE RACE NEWFOUNDLAND

ABOUT 465 MI...745 KM SSW OF PORT AUX BASQUES NEWFOUNDLAND

MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H

PRESENT MOVEMENT...N OR 10 DEGREES AT 18 MPH...30 KM/H

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

WATCHES AND WARNINGS

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

CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...

* South coast of Nova Scotia from Digby to Meat Cove

* Port aux Basques to Francois Newfoundland

A Tropical Storm Watch is in effect for...

* Meat Cove to Tidnish Nova Scotia

* North of Digby to Fort Lawrence Nova Scotia

* Magdalen Islands Quebec

* Prince Edward Island

A Tropical Storm Warning means that tropical storm conditions are

expected within the warning area.

A Tropical Storm Watch means that tropical storm conditions are

possible within the watch area.

Interests elsewhere in Atlantic Canada should closely monitor the

progress of Teddy.

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 Post-Tropical Cyclone Teddy

was located near latitude 42.8 North, longitude 63.9 West.  The

post-tropical cyclone is moving toward the north near 18 mph (30 

km/h), and a turn toward the north-northeast is expected by early 

Wednesday.  On the forecast track, the center will move over

eastern Nova Scotia on Wednesday, and then near or over 

Newfoundland by Wednesday night, and be east of Labrador on 

Thursday.

Maximum sustained winds have decreased to near 80 mph (130 km/h) 

with higher gusts.  Although weakening is likely tonight and 

Wednesday, Teddy should be a strong post-tropical cyclone when it 

moves near and over Nova Scotia. 

Hurricane-force winds extend outward up to 125 miles (205 km) from

the center and tropical-storm-force winds extend outward up to 540

miles (870 km).

The estimated minimum central pressure is 957 mb (28.26 inches).

HAZARDS AFFECTING LAND

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

Key messages for Teddy can be found in the Tropical Cyclone

Discussion under AWIPS header MIATCDAT5 and WMO header WTNT45 KNHC

and on the web at www.hurricanes.gov/text/MIATCDAT5.shtml.

STORM SURGE:  A dangerous storm surge is expected to produce

significant coastal flooding near and to the east of where the

center makes landfall in Nova Scotia.  Near the coast, the surge

will be accompanied by very large and destructive waves.

SURF:  Large swells generated by Teddy are affecting Bermuda, the

Lesser Antilles, the Greater Antilles, the Bahamas, 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.

WIND:  Tropical storm conditions are occurring in the Nova Scotia

warning area.  Tropical storm conditions could begin in the

watch areas by early Wednesday.  Tropical storm conditions

are expected to begin in the Newfoundland warning area on Wednesday

afternoon.

RAINFALL: Through Thursday, Teddy is expected to produce rainfall 

accumulations of 2 to 4 inches (50 to 100 mm) with isolated totals 

of 6 inches (150 mm) across sections of Atlantic Canada.

NEXT ADVISORY

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

Next intermediate advisory at 200 AM AST.

Next complete advisory at 500 AM AST.

$$

Forecaster Roberts

000

WTNT45 KNHC 230236

TCDAT5

Post-Tropical Cyclone Teddy Discussion Number  43

NWS National Hurricane Center Miami FL       AL202020

1100 PM AST Tue Sep 22 2020

Extratropical transition has been ongoing since last night, with

the cyclone's associated rain shield expanding over a great 

distance in the northern semicircle.  In addition, multiple

dropsonde observations from the Air Force Reserve hurricane hunters

and buoy data show a sharp temperature gradient of nearly 20

degrees F from northwest quadrant to the southeast, indicative of

the cyclone's involvement with the strong baroclinic frontal zone.

Accordingly, Teddy has become a strong post-tropical extratropical

cyclone.  Highest flight-level winds recorded this evening were 83

kt about 85 miles northeast of the center and the highest SFMR

surface winds were 63 kt.  A recent METOP-C scatterometer pass 

showed sustained winds no higher than 59 kt in the east quadrant.

A blend of these data yields an initial intensity of 70 kt for this 

advisory.  Further gradual weakening is forecast through the period 

as a result of the rapidly decreasing sea surface temperatures 

(less than 20C) north of the North Wall of the gulf stream.  The 

NHC forecast indicates Teddy approaching the coast of Nova Scotia 

below hurricane strength, but still as a strong post-tropical 

extratropical low.  Teddy should continue to gradually spin down as 

the cyclone moves north-northeastward toward Newfoundland.

The initial motion is estimated to be northward, or 010/16 kt.

A north-northeastward turn is forecast later tonight or early 

Wednesday in response to an approaching mid-latitude shortwave 

trough moving out of the northeast U.S.  Teddy should move over 

Nova Scotia tomorrow and near the island of Newfoundland, and the 

adjacent waters of the Gulf of St. Lawrence Wednesday night.  

Afterward, the post-tropical cyclone will likely be absorbed by an 

even larger high latitude extratropical cyclone near Greenland.  

There has been no significant changes made to the NHC forecast 

track this evening, and it's in best agreement with the HFIP 

Corrected Consensus Approach model.

Key Messages:

1. Teddy is expected to transition to a powerful post-tropical

cyclone as it moves near or over portions of Atlantic Canada

late today through Thursday. The most significant hazard expected

from Teddy is large destructive waves forecast along the southern

coast of Nova Scotia through Wednesday.

2. Very large swells produced by Teddy are expected to affect

portions of Bermuda, the Leeward Islands, the Greater Antilles, the

Bahamas, the east coast of the United States, and Atlantic Canada

during the next few days. These swells are expected to cause

life-threatening surf and rip current conditions.

3. Tropical Storm Watches and Warnings are in effect for portions

of Nova Scotia, Newfoundland, Prince Edward Island and the Magdalen

Islands, and heavy rainfall across Atlantic Canada is expected

through Thursday.

FORECAST POSITIONS AND MAX WINDS

INIT  23/0300Z 42.8N  63.9W   70 KT  80 MPH...POST-TROPICAL

 12H  23/1200Z 45.3N  62.3W   60 KT  70 MPH...INLAND

 24H  24/0000Z 49.8N  58.7W   50 KT  60 MPH...POST-TROP/EXTRATROP

 36H  24/1200Z 54.7N  54.9W   45 KT  50 MPH...POST-TROP/EXTRATROP

 48H  25/0000Z...ABSORBED BY A LARGER LOW

$$

Forecaster Roberts