MUWIC Newsletter - March 2005

(Issued: March 2, 2005)

Millersville University Weather Information Center (MUWIC)

Eric J. Horst, Director

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LEAD STORY: “Bipolar Pattern Dominates Winter 2004-2005”

Like a scene for the movie Groundhog Day, this winter’s weather has had a propensity to repeat itself. More than any in recent memory, winter 2004-2005 displayed a remarkably bipolar personality as each month produced a definitive warm and cold spell.

The cycle began in December with a thirteen-day streak of above normal conditions, followed by a fifteen-day, below-normal spell that continued through Christmas weekend. Unseasonable warmth returned in time for New Year’s and continued for seventeen days before the pattern flipped to “cold and snowy” to conclude January. February produced a repeat performance with a thirteen-day, above-average stretch giving way to another round of cold, snowy weather that continues into early March.

Interestingly, aggregate temperature and snowfall statistics paint a nearly “normal” three-month period, while we have in fact experienced a wildly abnormal season. The table below reveals a wild weather ride to remember.

Dates Avg. Depart. from Normal Snowfall

December 1 – 13, 2004 +4.5 0

December 14 – 28, 2004 - 5.2 0

Dec. 29 – January 14, 2005 +10.6 0

Jan. 15 – February 3, 2005 -10.2 13.5”

February 4 – 16, 2005 +7.9 0.1”

February 17 – March 1, 2005 -5.6 13.6”

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STAT OF THE MONTH

If you are thinking the last ten days of February were uncommonly snowy, you are right! Three storms dropped a total of 13.5 inches in the Lancaster area, making for the snowiest close to February since 1947 (16” fell in the final week of February 1947).

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FEBRUARY CLIMATOLOGY (MU Weather Station)

Average High Temp: 42.3 F

Average Low Temp: 24.4 F

Average Monthly Temp: 33.3 F

(Departure from Normal: +0.7 F)

Snowfall: 13.7 inches

(Departure from Normal: +5.5)

Total Precipitation (liquid equivalent): 2.11 inches

(Departure from Normal: -0.36)

Annual Precipitation: 5.83 inches

(Departure from Normal: +0.35)

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MARCH NORMALS, RECORDS & FACTS

Normal high/low temperatures increase rapidly from 46/26 on March 1st to 59/36 on the 31st. The record high for March is 88 degrees (1921, 1945) and the record low is –1 F (1984). Normal liquid precipitation (rain and melted snow) is 3.38 inches. Average snowfall for the month is 3.7 inches. Spring officially arrives at 7:34 a.m. on March 20^th.

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MARCH OUTLOOK

There will be no early Spring this year. Sorry!

After three months of topsy-turvy, undulating conditions, the jet stream has finally locked into a configuration that will last more than two or three weeks. The current cold cycle began on February 17^th and will continue through at least mid-March (possibly beyond). The feature to blame for the persistent late-season chill is a large blocking jet stream ridge that has formed over Greenland. This downstream, high-latitude pooling of warm air will act as a dam that facilitates a building of unseasonably cold air over eastern Canada and the Northeastern US. This basic setup was central to some of the colder (and often snowier) Marches of the past. Remember March 1958, March 1984 or March 1993?

As a result, deep northwesterly wind flow will dominate from the Great Lakes to the Mid-Atlantic for the next two to three weeks. A parade of Alberta Clippers will trigger occasional snow showers over the mountains, as well as many windy, unseasonably cold afternoons locally. So while normal high temperatures increase from 46F on March 1^st to 51F on the 15^th, I expect highs in the coming days to average 5 to 10 degrees below these normals. The blocking pattern will eventually loosen its grip, but not before making March 2005 the coldest in the last ten years.

What about snow? If you live at elevation (say, 1000 feet or more above sea level), then I expect you will see a bit more of the white stuff. The current pattern will likely produce a couple more rounds of snow showers, although late-season light snow typically has a difficult time accumulating at lower elevations (most of Lancaster county is only 300 to 500 feet above sea level). Still, we’ll need to keep an eye on the southern branch of the jet stream. Should a southern storm phase with one of the clippers diving in from Canada, then a significant Nor’easter could develop bringing a rare March snowstorm to the Lancaster area.