Extended National Weather Service discussion for New York/New Jersey/Connecticut
Record cold temperatures are possible to start the new work week next to the coast in the Northeast.
Additional wintry weather could occur across the northern states during the Labor Day holiday weekend.
The potential for frost to develop by the Monday morning commute in New York and New Jersey will continue over the next several days. In fact, this potential will intensify over the next week.
Cold air across western Canada and the northern Plains will enter the region in the fall months. This is quite unlike the classic Canadian Pacific (colder) and Appalachian Mountains (warmer) air that hangs off the coast of Canada.
Temperatures on the East Coast have a tendency to start out seasonally warm in October and fall, then cool into the mid-50s (F) by November. However, the past few winters (2016-17 and 2017-18) have featured an additional cold influence over the Northeast. This could negatively impact growing season for trees and shrubs this fall.
A strong disturbance will cross the Midwest late this weekend. This will combine with warm ocean water along the Atlantic seaboard and a build-up of moisture in the atmosphere to bring showers and thunderstorms across the region.
In addition to showers, the cold air with this disturbance could rapidly become so cold during the rain or thunderstorms that urban and tree damage is possible. The cold air will likely reinforce itself onshore so areas west of New York City and west of Boston will likely get wet and windy. Showers are likely with this disturbance.
After the disturbance ends, a back dry flow of air from Canada will take its place, especially during the middle of next week as a corridor of dry air moves up into the Northeast from Canada.
This dry air will likely come from what is called a combination ridge/trough in the jet stream. This high-pressure system at the west coast of Canada will essentially line up the exact opposite of the associated low pressure over the East Coast.
A continuous flow of temperatures from Canada northward can be expected early in the season as a result of the development of the above-average setting from Canada. Temperatures along the mid-Atlantic coast will be in the mid-70s (F) from mid-September through at least October.
These conditions normally occur at the start of the season, when the eastern half of the country doesn’t see much rain or wet weather during the summer, while the northeast or interior of the country sees near-normal to very-normal rainfall during the summer.
Several computer models differ on the timing of this pattern change for September, though most agree that it will take place by early next week.
Rainfall total is expected to decline after this pattern change, with the main storm center off the coast of the Appalachians and the Ohio Valley possibly not being close enough to the coast to get a soaking. It seems there may be times when rain and at least some gusty winds could occur in the Northeast as these storms move through, while sunshine will be scarce for the next week.
A storm cell could move across the eastern seaboard during the middle of the week, with the big question being whether or not any of the storms track over the upper Great Lakes.
In the event of a high-pressure zone coming over the central Great Lakes, the jet stream will remain well west of the area, which means dry air will stream in from the Canadian Rockies and will become strongest in the southern tier of the Great Lakes.
Strong winds, rain and snow could be in store for the northern Rockies late this week and the upper Great Lakes, including the northern and central Great Lakes.
While this pattern change doesn’t seem significant for our upcoming work week, it is worth mentioning how much different the climate has been the past two years.
The cold is extreme and rainy is commonplace on the East Coast, right near the coast.