Isaias Becomes A Post-Tropical Cyclone As It Moves Into Southeastern Canada

Post-Tropical Cyclone

Forecast Cone image updated at 09:45 PM
Forecast Cone image updated at 09:45 PM

Location 45 miles ESE of Montreal Quebec
Wind 45 mph
Heading NNE at 38 mph
Pressure 29.53
Coordinates 72.5W, 45.3N


At 1100 p.m. EDT (0300 UTC), the center of Post-Tropical Cyclone Isaias was located near latitude 45.3 north, longitude 72.5 west. The post-tropical cyclone is moving toward the north-northeast near 38 mph (61 km/h), and this general motion is expected with a decrease in forward speed through Wednesday night.

Maximum sustained winds have decreased to near 45 mph (75 km/h) with higher gusts, mainly over water to the southeast of the center. Continued weakening is expected, and the winds are expected to drop below tropical-storm force during the next few hours. The post-tropical cyclone is expected to dissipate over southeastern Canada Wednesday night or Thursday.

Tropical-storm-force winds extend outward up to 175 miles (280 km) to the southeast of the the center. The noaa automated station at isle of shoals, New Hampshire recently reported sustained winds of 46 mph (74 km/h) and a wind gust of 51 mph (81 km/h) at an elevation of 63 ft (19 m).

The estimated minimum central pressure is 1000 mb (29.53 inches).

Satellite image updated at 09:46 PM
Satellite image updated at 09:46 PM

Watches and Warnings

Changes with this advisory:

The tropical storm warning has been discontinued south of the merrimack river, Massachusetts.

Summary of watches and warnings in effect:

A tropical storm warning is in effect for, * merrimack river Massachusetts to stonington Maine

A tropical storm warning means that tropical storm conditions are expected somewhere within the warning area, in this case during the next few hours.

For storm information specific to your area, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office.

Models image updated at 08:10 PM
Models image updated at 08:10 PM

Land Hazards

Key messages for Isaias can be found in the tropical cyclone discussion under awips header miatcdat4, wmo header wtnt44 kNHC, and on the web atwww.hurricanes.gov/text/MIATCDAT4.shtml.

Wind: tropical-storm conditions are expected for a few more hours in the tropical storm warning area in southern new england. These winds could cause significant tree damage and power outages.

Gale-force winds are possible over portions of southeastern quebec for a few more hours. See products issued by environment Canada for more information.

Rainfall: rainfall accumulations of 1 to 3 inches are expected along and near the track of Isaias across southern quebec. Additional rainfall of up to an inch is possible across western and northern Maine overnight.

As the rainfall exits the United States, scattered minor to moderate and isolated major river flooding is ongoing or forecast across portions of the mid-Atlantic with most rivers falling below flood stage Wednesday. Quick-responding rivers in the northeast will also be susceptible to minor and possible moderate river flooding.

Tornadoes: a couple of tornadoes are possible across central and eastern Maine for the next several hours.

Surf: swells generated by Isaias will affect the mid-Atlantic and northeast coasts of the United States through tonight. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.