12:40 PM | ***Winter-like pattern next couple of weeks with very impressive cold air outbreaks and snow is on the table***
Paul Dorian
12Z GFS forecast maps of 850 mb temperature anomalies from Friday morning, November 8th (hour 96) to Monday morning, November 18th (hour 336); maps courtesy NOAA, tropicaltidbits.com
Overview
November has started off colder for the nation as a whole than all but two years (1991, 2002) going back to the late 1970’s and there won’t be much let up for the eastern 2/3rds through at least the middle part of the month. The powerful frontal passage late last week in the eastern US was part of an overall pattern change and the warmth of October has transitioned to the cold of November. There will likely be multiple cold air outbreaks over the next couple of weeks that ride along in the polar jet stream from central Canada to the Mid-Atlantic/NE US. After a bit of a warm up on Tuesday, it’ll turn cooler again at mid-week, but it is the late week when another impressive cold air blast will arrive. This next shot of cold air will drop southeastward from Canada and arrive in the Mid-Atlantic/NE US in the Thursday night/Friday time period. Another cold air outbreak is destined to reach the central and eastern US early next week. Both of these cold air outbreaks may present some snow possibilities for the Great Lakes and interior NE US and even to parts of the Mid-Atlantic region.
06Z GEFS forecast map of 850 mb temperature anomalies averaged over days 1-5; maps courtesy NOAA, tropicaltidbits.com
Late week cold blast
A significant cold air outbreak appears to be headed for the Mid-Atlantic/NE US from central Canada at the end of the work week. At the same time, moisture is likely to advance to the northeast from the southern states and there is a chance for a rain-changing-to-snow type of scenario in at least interior sections of the northern Mid-Atlantic and northeastern US. Whether or not the snow materializes, the cold is coming and temperatures Friday night should be very cold for this early in the season throughout the Mid-Atlantic region and NE US.
06Z GEFS forecast map of 850 mb temperature anomalies averaged over days 6-10; maps courtesy NOAA, tropicaltidbits.com
Early next week cold blast
All signs point to another cold air outbreak for the central and eastern US early next week and this too can feature snow in the Mid-Atlantic and NE US and possibly a better shot at snow for the DC-to-Philly-to-NYC corridor in the Monday night/Tuesday time frame. Much like the late week outbreak, this cold air mass will drop southeastward across Canada and push through the Great Lakes by early next week and then into our part of the nation. Upper-level forecasts map suggest strong ridging will form over Alaska and western Canada and combine with a trough over the Great Lakes early next week allowing for the transport of the cold air mass into the Mid-Atlantic/NE US. Longer term, it appears this colder-than-normal pattern that began in the eastern US on the first day of the month may very well continue for much of the month of November. One other note, both of these cold air outbreaks may turn on the Great Lakes “snow machine” as the cold air will cross over the still relatively warm waters causing lots of instability in the lower atmosphere and downstream snow squalls/bands.
06Z GEFS forecast map of 850 mb temperature anomalies averaged over days 11-15; maps courtesy NOAA, tropicaltidbits.com
One final note, while accumulating snow during November in the Mid-Atlantic region may not be all that common, it certainly is not unprecedented. In fact, just last year there was a significant snow accumulation on the 15th of November in the Philly and NYC metro regions which led to as much as 8 inches in some suburban locations and an evening rush hour traffic nightmare in both areas.
Meteorologist Paul Dorian
Perspecta, Inc.
perspectaweather.com
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