April 16-23, 2007 Idea: The Cold Hangs Tough

[donsutherland1]

The cold that blasted eastward beginning on April 4 and produced a high temperature of just 31° on 4/5 at Pittsburgh, the coldest such maximum reading there in April since 4/5/1972, marked retreating winter’s proverbial shot across the bow of spring. The pattern that evolved to bring about this change is one that has often hung tough for a prolonged period of time.

NCEP 500 mb Mean 500 mb Anomalies at 264 hours:


Composite Historic 500 mb Anomalies:


NCEP 500 mb Mean 500 mb Anomalies at 360 hours:


Composite Historic 500 mb Anomalies adjusted forward by 120 hours from those posted above:


Composite Historic 500 mb Anomalies adjusted forward by 240 hours from those posted at the beginning of this discussion:


If the historic experience holds true, the April 16-23 period could wind up cooler than normal and also wetter than normal in the Great Lakes, Mid-Atlantic, and Northeast regions. Springlike warmth might not begin to return there, at earliest, until perhaps closing 3-5 days of April.

My thinking for the average temperature anomalies during the 4/16-23 period is as follows:

Average Regional Temperature Anomalies (4/16-23):
Northeast: Much below normal to below normal
Mid-Atlantic: Below normal
Southeast: Somewhat normal
Great Lakes: Much below normal to below normal
Northern Plains: Below normal
Central Plains: Below normal
Southern Plains: Below normal
Pacific Northwest: Somewhat below normal to near normal
Southwest/Rest of West Coast: Somewhat above normal

For the major cities from Washington, DC to Boston, the 4/16-23 period is likely to feature:

- Nights generally in the 30s in Boston and 30s and 40s in New York City, Philadelphia, and Washington, DC.
- Days mainly in the 50s in Boston and 50s and 60s in New York City, Philadelphia and Washington, DC.
- Boston could see a day with a high temperature below 50°

In the Southeast, Atlanta will likely see highs generally in the 60s and 70s. Lows should generally be in the 40s and 50s. Elsewhere, Burlington will likely see highs mainly in the 40s and 50s. Lows should be mainly in the 30s. A subfreezing night is possible.

Toronto: Most days will likely see highs in the 7.0°C to 14.0°C range (mid 40s to mid 50s). Nights will generally be in the +1.0°C to +7.0°C range (30s to lower 40s). The low temperature could fall below freezing on one or two days.

Occasional Historic Tidbit:

On April 22-23, 1993, a storm that moved from the Delmarva Peninsula into eastern New England brought heavy wet snow to portions of New York State. 22 inches fell at Malone. Binghamton picked up 10.3 inches.

[wbug1]

That's pretty cold in NA, but what catches my eye is the incredible warm anomaly over Greenland and northern Canada. Is ice melting at about an order of magnitude more than previously? I would
say... yes.