1. Regardless of whether it is a hurricane or a post-tropical cyclone, Dorian is expected to have a significant impact in portions of eastern Canada beginning later today. Dangerous storm surge impacts are likely in portions of the Gulf of St. Lawrence, southwestern Newfoundland and eastern Nova Scotia. Hurricane-force winds are also likely in Nova Scotia, Prince Edward Island and Newfoundland later today and tonight. Refer to information from the Canadian Hurricane Centre for more information on these hazards.

1. Regardless of whether it is a hurricane or a post-tropical cyclone, Dorian is expected to have a significant impact in portions of eastern Canada beginning during the next several hours. Dangerous storm surge impacts are likely in portions of the Gulf of St. Lawrence, southwestern Newfoundland and eastern Nova Scotia. Hurricane-force winds are also likely in Nova Scotia, Prince Edward Island and Newfoundland later today and tonight. Refer to information from the Canadian Hurricane Centre for more information on these hazards.

WHAT'S NEW:

The Canadian Hurricane Center has adjusted the warnings for Nova Scotia, Newfoundland, and the Lower North Shore Quebec.

SUMMARY OF ALERTS:

A Hurricane Warning is in effect for...
- Eastern Nova Scotia from Lower East Pubnico to Brule
- Western Newfoundland from Indian Harbour to Hawke's Bay

A Hurricane Watch is in effect for...
- Prince Edward Island
- Magdalen Islands

A Tropical Storm Warning is in effect for...
- Woods Hole to Sagamore Beach MA
- Nantucket and Martha's Vineyard MA
- East of Bar Harbor to Eastport ME
- Prince Edward Island
- Southwestern Nova Scotia from Avonport to north of Lower East Pubnico
- Fundy National Park to Shediac
- Stone's Cove to Indian Harbour
- Hawke's Bay to Fogo Island
- Mutton Bay to Mary's Harbour

A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. Preparations to protect life and property should be rushed to completion.

A Tropical Storm Warning means that tropical storm conditions are expected within the warning area in this case within the next 12 hours.

A Hurricane Watch means that hurricane conditions are possible within the watch area. Interests elsewhere along the New England coasts of the United States should monitor the progress of Dorian. 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.

WIND: [TOP] Tropical storm conditions are expected to continue in the warning area over portions of extreme southeastern Massachusetts during the next several hours. These conditions should spread into the warning area in Maine by this afternoon.

Regardless of whether Dorian is a hurricane or a post-tropical cyclone, hurricane conditions are expected in the Hurricane Warning area in Nova Scotia and Newfoundland beginning later today, and they are possible in the Hurricane Watch area by tonight. Tropical storm conditions are expected in the Tropical Storm Warning area in eastern Canada later today and tonight.

STORM SURGE: [TOP] Storm Surge is likely in the Gulf of St. Lawrence, the Southwest Coast of Newfoundland, and Eastern Nova Scotia.

RAINFALL: [TOP] Dorian is expected to produce the following rainfall totals through Saturday:

Extreme Southeastern New England and far eastern Maine...1 to 3 inches.

Nova Scotia...3 to 5 inches, isolated 7 inches.

New Brunswick and Prince Edward Island...2 to 4 inches

Newfoundland and far eastern Quebec...1 to 2 inches

This rainfall may cause life-threatening flash floods

SURF: [TOP] Large swells are increasing along the coast in Atlantic Canada, and they will continue to affect that area during the next few days. Swells along the mid-Atlantic and New England coasts of the U.S. will continue for a couple of more days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.

At 500 AM AST (0900 UTC), the center of Hurricane Dorian was located near latitude 39.7 North, longitude 68.1 West. Dorian is moving toward the northeast near 25 mph (41 km/h), and this general motion is expected through Sunday. On the forecast track, the center of Dorian should pass to the southeast of extreme southeastern New England this morning, and then move across Nova Scotia and Newfoundland later today and tonight.

Maximum sustained winds are near 85 mph (140 km/h) with higher gusts. Some slight weakening is forecast, but Dorian is expected to move over Nova Scotia with hurricane-force winds. Thereafter, Dorian is forecast to become a powerful post-tropical cyclone over eastern Canada by tonight or early Sunday.

Hurricane-force winds extend outward up to 105 miles (165 km) from the center and tropical-storm-force winds extend outward up to 310 miles (500 km). A NOAA buoy at Nantucket Shoals, Massachusetts, recently reported a sustained wind of 52 mph (83 km/h) and a gust of 76 mph (122 km/h). A Weatherflow observation on Cape Cod, Massachusetts, recently measured a wind gust of 48 mph (77 km/h).

The estimated minimum central pressure is 965 mb (28.50 inches).

Dorian is gradually becoming less organized. The cyclone is feeling some effects of southwesterly wind shear with most of its deep convection located to the north and east of the estimated center. The initial intensity is lowered a little to 75 kt, which is in good agreement with the latest Dvorak CI-numbers from TAFB and SAB. A pair of ASCAT passes from several hours ago indicate that the wind field has expanded significantly, and tropical-storm-force winds have been observed over far southeastern Massachusetts.

Dorian is racing northeastward, with the latest initial motion estimated to be 050/22 kt. The hurricane is well embedded in the fast mid-latitude flow, and it should continue to move quickly northeastward toward Nova Scotia later today. After the cyclone passes Nova Scotia, it is forecast to move through Newfoundland and Labrador before turning east-northeastward over the far north Atlantic. The NHC track forecast is largely an update of the previous one and not far from the various consensus aids.

Dorian is expected to gradually weaken due to even stronger southwesterly wind shear and much colder SSTs to the north of the Gulf Stream current. The combined influences of these cold waters and an approaching mid- to upper-level trough should cause Dorian to lose its tropical characteristics in about 24 hours. However, the post-tropical cyclone will likely still be producing hurricane-force winds as it moves through portions of eastern Canada. The global models are in good agreement that the post-tropical cyclone should slowly weaken and ultimately become absorbed by another extratropical low in 3 to 4 days. The NHC intensity forecast is in best agreement with the GFS and ECMWF models, which typically handle large extratropical lows better that than the intensity models that are made for tropical cyclones.

Satellite imagery this morning indicates that Dorian is starting extratropical transition, with cold air clouds entraining into the southwestern side of the cyclone and a developing warm front to the north and east. However, the cyclone still has persistent convection just north and northeast of the center, so it remains a hurricane on this advisory. NOAA buoy 44011 reported a minimum pressure of 955.3 mb as the center passed just to the west, so the initial central pressure is lowered to 953 mb. The initial intensity remains 75 kt based partly on recently-received WindSat data showing hurricane-force winds southwest of the center.

Dorian continues to move rapidly northeastward with an initial motion of 040/25 kt. The current motion should bring the center of Dorian over central and eastern Nova Scotia in about 12 h and near or over Prince Edward Island shortly thereafter. Subsequently, Dorian is forecast to move near or through northern Newfoundland and southeastern Labrador before turning east-northeastward over the far north Atlantic. There are no significant changes to the previous forecast, and the new forecast is again close to the various consensus aids.

Dorian is expected to complete extratropical transition during the next 24 h as it merges with a strong mid- to upper-level trough and associated surface frontal zone. The global models agree on a gradual decay of the winds after transition is complete. However, the cyclone will likely still be producing hurricane-force winds as it moves through portions of eastern Canada. The global models also agree that the post-tropical cyclone should become absorbed by another extratropical low in 2-3 days. The NHC intensity forecast again leans towards the GFS and ECMWF models, which typically handle large extratropical lows better that than the intensity models that are made for tropical cyclones.