The November 6-13, 2007 Cold Period: Some Initial Thoughts

[donsutherland1]

With October’s warmth having approached or exceeded monthly records in part of the East, the idea of a dramatic turn to below and much below normal temperatures might seem unlikely. Yet, that’s what lies ahead for much of the East in the not-too-distant future. At the height of the cold, some of the cities that have yet to see their first freeze will likely see it. Boston and New York City should see their first 32° or below readings ahead of last year’s first freeze.

First freeze in 2006:
Boston: November 21
New York City: December 4
Philadelphia: November 4
Washington, DC (DCA): November 4

The latest ensemble guidance has been remarkably good in its run-to-run continuity. The latest runs of the GFS and ECMWF are in reasonable agreement, as well. The following is the forecast 500 mb height anomalies forecast at 192 hours by the NCEP ensemble suite:



Those anomalies are reasonably similar to a composite from 1956, 1967, and 1992:


The forecast 850 mb temperature anomalies show an area of unseasonably cold air encompassing the East at 192 hours:


If one examines the individual outbreaks that comprise the composite case, one finds:

Lowest Readings:

November 9-10, 1956:
Boston: 26°
Burlington: 19°
New York City: 30°
Philadelphia: 30°
Toronto: 17° (-8.3°C)
Washington, DC (DCA): 35°

November 5-9, 1967:
Boston: 30°
Burlington: 19°
New York City: 32°
Philadelphia: 28°
Toronto: 24° (-4.4°C)
Washington, DC (DCA): 26°

November 14-16, 1992:
Boston: 30°
Burlington: 21°
New York City: 30°
Philadelphia: 28°
Toronto: 21° (-6.1°C)
Washington, DC (DCA): 27°

Summary:
The November 6-13 period will likely see Boston, New York City, Philadelphia and Washington, DC (DCA) see their lowest readings bottom out at 32° or below. Dulles International Airport (IAD) will probably see its lowest reading in the 20s. Burlington and Toronto should see the lowest reading fall to 22° (-5.6°C) or below. One or more readings of 19° (-7.2°C) or lower are possible in Burlington and Toronto.

Two additional tidbits from the composite cases: In all three cases on which the composite pattern was based, Burlington had seen some accumulation of snow during the cold period. Moreover, at the height of the cold, both Toronto and Burlington had at least one day on which their high temperature reached no higher than 38° (3.3°C).

[RL3AO]

I've been watching this in the long range GFS for a few days now. I was waiting for you to make a thread on this.


Here in Minnesota, one local station is forecasting mid 30's highs/low 20's lows in the Twin Cities with a chance of flurries middle of next week.

[PTPatrick]

Are you saying 1967, 1956 and 1992 are analog years to what we are seeing now...

[donsutherland1]

PTPatrick,

Those years only represent analogs for a specific outbreak of cold air. The composite map for November using those years was colder than normal except in the Northern Plains and West Coast. This year, I expect a much smaller area of cool anomalies in November. In my opinion, November 2007 will likely see the following anomalies:

Northeast: Below normal to near normal
Mid-Atlantic: Below normal
Southeast: Below normal
Ohio Valley: Near normal
Northern Plains: Above normal to much above normal
Central Plains: Above normal
Southern Plains: Above normal
Pacific Northwest: Above normal
California/Southwest: Above normal

After the aforementioned cold spell, a large part of the USA will likely turn warmer than normal as Pacific air begins to flood the nation.

December will probably see a transition toward the predominant winter pattern where much of the USA winds up warmer than normal. My early thinking for December is:

Northeast: Above normal
Mid-Atlantic: Above normal
Southeast: Above normal
Ohio Valley: Above normal
Northern Plains: Above normal to much above normal
Central Plains: Above normal
Southern Plains: Above normal
Pacific Northwest: Somewhat below normal to near normal
California/Southwest: Somewhat below normal

[PTPatrick]

Yeah...I agree on the Central plains. If one were to follow the GFS...Denver doesnt even really have a shot at the 540 line until almost the 15th or 16th...and pretty much no precip in what is Denver's 2nd snowiest month. Oddly enough last october was snowy but November featured very little moisture then too...and I think we are in for repeat. Looks like the 2nd half of november may redeem itself for the west...and I wouldnt be suprised to have a cold Turkeyday. Especially since Denver rarely stays one way or another for more than 2 week...the ridge has to breakdown eventually.

[pawxguy]

I am watching with anticipation the 0z model runs for the possibility of some development of an east coast low this weekend IF the trough amps a bit more than the 12z and 18z models depict. The low is there but it is at 40N/70W

Tis the season.

[pawxguy]

Quite the storm shown on the NAM this weekend . 972... that's impressive and its not that far away from clipping places like Cape Cod.

[donsutherland1]

Verification:

From 11/1:
The November 6-13 period will likely see Boston, New York City, Philadelphia and Washington, DC (DCA) see their lowest readings bottom out at 32° or below. Dulles International Airport (IAD) will probably see its lowest reading in the 20s. Burlington and Toronto should see the lowest reading fall to 22° (-5.6°C) or below. One or more readings of 19° (-7.2°C) or lower are possible in Burlington and Toronto.

Two additional tidbits from the composite cases: In all three cases on which the composite pattern was based, Burlington had seen some accumulation of snow during the cold period. Moreover, at the height of the cold, both Toronto and Burlington had at least one day on which their high temperature reached no higher than 38° (3.3°C).

Lowest Temperatures:
Boston: 28°, 11/11 (missed record of 24° set in 1901)
Burlington: 22°, 11/10
New York City: 31°, 11/11 (missed record of 28° set in 1926 and tied in 1933)
Philadelphia: 32°, 11/8, 11
Toronto: 28° (-2.5°C), 11/11
Washington, DC: DCA: 33°, 11/11; IAD: 25°, 11/8

Lowest maximum readings:
Burlington: 38°, 11/8
Toronto: 38° (3.2°C), 11/7

Additional Note:
Burlington saw no snow.

[Tampa Bay Hurricane]

wow excellent call don

[tropicana]

don never ceases to amaze me with his very insightful articles. Really pretty accurate.

-justin-

[JonathanBelles]

How cold do you think it will get late this week?

[ETXHAMXYL]

Hey Don,
My hubby is heading home to Philly on the 17th. I will be flying up on Thanksgiving Day and we will be leaving on the 27th heading back to Texas.
I know it is a bit early but can you tell me what I might expect up in Philly during this time period. This Texas Gal is still basking in 80 degree weather. I don't think I own a long sleeve anything. LOL To me 50 degrees in the daytime is downright cold.
Thanks...I regard your thoughts highly when it comes to Yankee Weather!

[donsutherland1]

Thanks Justin.

[donsutherland1]

Fact789,

I'll post my thoughts in the morning.

[donsutherland1]

ETXHAMXYL,

I'll post more details tomorrow. Much of the period (November 17-19 and November 22-27) looks to be colder than normal though there are some timing differences on the models. During the coldest days, highs will likely stay in the lower and middle 40s; some lows near or below freezing are possible.

[donsutherland1]

Fact789,

The upcoming cold shot for later this week and weekend will probably be more modest in terms of lowest temperatures than the one that produced the season's first freeze in such cities as Philadelphia and New York.

[donsutherland1]

ETXHAMXYL,

In my opinion, placing greater weight on the GFS ensembles and operational ECMWF than recent runs of the GFS, the November 17-27 period will work out as follows:

November 17-20: Below normal readings; Highs mainly in the upper 40s and lower 50s; lows in the middle 30s

November 21-23: Above normal readings. A storm tracking to the Great Lakes could bring a surge of warmth around the 22nd or 23rd. High temperatures during this period could rise into the upper 50s. A reading above 60 degrees is possible. A strong cold front will likely move across the Philadelphia area on the 24th.

November 25-27: Colder than normal readings. High temperatures could be in the middle 40s. Lows could reach the upper 20s to lower 30s.

[Ptarmigan]

Don gets it right with winter weather. Very insightful.