December 11-18, 2007 Idea: Milder Air Likely to Ooze into US

[donsutherland1]

The latest computer guidance and teleconnection indices appear to be conspiring to promote a trend toward gradual moderation. A big rush of Pacific air and dramatic coast-to-coast warmup is not likely. Cooler air could initiate a rear-guard action in parts of the East and Great Lakes Area (including southern Ontario). The Pacific Northwest looks to be wetter than normal.

With the vast reservoir of cold air in Canada likely to be emptying in the coming weeks, odds favor La Niña’s ultimately stamping out winter’s resistance in the East. If past experience with strong La Niñas is representative, ridging could eventually predominate in the East, while the Pacific Northwest sees the frequency and duration of colder air masses increase. Nevertheless, one should bear in mind that past moderate or strong La Niñas that saw December wind up cooler than normal in the East tended to buck the warmer scenario. So, the longer the cold holds out, perhaps the stronger the indication that perhaps an exception might be in the making. For now, odds still favor the warmer idea

Average Regional Temperature Anomalies (12/11-18):
Northeast: Below normal
Mid-Atlantic: Somewhat below normal
Southeast: Near normal
Great Lakes: Somewhat below normal
Northern Plains: Near normal to somewhat above normal
Central Plains: Near normal to somewhat above normal
Southern Plains: Near normal to somewhat above normal
Pacific Northwest: Above normal
Southwest/Rest of West Coast: Much above normal

Historical Tidbit: Winter 1801-02:
From a meteorological journal from Hartford:

December 1801: December a very warm month—Little ice in Connecticut River till about the middle of the month, when people began to walk over; some horses passed, though the ferry was kept open for the passage of the boats; farmers plowing, and good dry walking; no snow—general time of health.

January 1802: January a remarkably warm month—very little freezing weather—no snow about Hartford—very little to the northward—muddy walking; bad riding; healthy in Hartford; sickly in some places.

February 1802: The month of February was still warmer than either of those mentioned…

Toward the end of February parts of New England experienced two major snowstorms within a period of a week.

[donsutherland1]

Verification

The Pacific Northwest looks to be wetter than normal.

The Pacific Northwest saw above normal precipitation.

Average Regional Temperature Anomalies (12/11-18):
Northeast: Below normal; Actual: Below normal
Mid-Atlantic: Somewhat below normal; Actual: Near normal to somewhat above normal
Southeast: Near normal; Actual: Above to much above normal
Great Lakes: Somewhat below normal; Actual: Somewhat below normal
Northern Plains: Near normal to somewhat above normal; Actual: Above normal
Central Plains: Near normal to somewhat above normal; Actual: Below normal
Southern Plains: Near normal to somewhat above normal; Actual: Somewhat below normal to near normal
Pacific Northwest: Above normal; Actual: Near normal
Southwest/Rest of West Coast: Much above normal; Actual: Somewhat below normal to near normal