MUWIC Newsletter - April 2004

(Issued: April 1, 2004)

Millersville University Weather Information Center (MUWIC)

Eric J. Horst, Director

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LEAD STORY: “March 2004: A Chameleon Month”

What has three 70-degree days and three measurable snowfalls? March 2004. The past 31 days did indeed take us on a wild weather ride, and it showed by example why March has been called the “chameleon month.”

March begin with a beautiful Spring preview, as temperatures remained above freezing for seven consecutive days and on one day reached a near record high of 70 degrees. Overall, the period of March 1^st to the 8^th averaged 11.6F degrees above normal. Then, everything changed as the jet stream flipped and winter returned to the region for the next sixteen days. March 9^th through the 24^th averaged nearly 5 degrees below normal. More notable was the snow that fell on three days—the 16th, 17th, and 19^th—which, in aggregate, represents a snowier-than-normal March. It also elevated our seasonal snowfall total to 33.5 inches (the average seasonal snowfall is about 26 inches).

The last week of March provided us with the most spectacular days of the month as deep southwest flow pushed temperatures into the 70s on consecutive days (26^th and 27^th). The last seven days of March averaged about 5 degrees above normal. In the end, however, March’s bipolar character averaged out very close to normal. Thus, March 2004 goes in the record books as just over one degree above normal (not statistically significant) with total liquid-equivalent precipitation totaling about one-and-a-half inches below normal.

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EVENT OF THE MONTH

The morning of March 19^th brought a period of heavy snow to the Commonwealth. A potent Alberta clipper dropped up to 8 inches across parts of Eastern Pennsylvania. In the Lancaster area, snowfall ranged from around 3 inches across southern and western parts of the county to as much as 6 inches on the hilltops near the Berks county border.

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MARCH CLIMATOLOGY

Average High Temp: 52.2 F

Average Low Temp: 33.4 F

Average Monthly Temp: 42.8 F

(Departure from Normal: +1.4 F)

Snowfall: 6.8 inches

(Departure from Normal: +2.4 in.)

Precipitation: 1.88 inches

(Departure from Normal: -1.5)

Annual Precipitation: 6.58 inches

(Departure from Normal: -2.28)

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APRIL NORMALS, RECORDS & FACTS

Normal high/low temperatures range from 59/37 on April 1st to 70/44 by month's end. The record high for April is 95 degrees (on 4/18/76) and the record low is 11 F (on 4/1/23). Normal liquid precipitation (rain and melted snow) is 3.47 inches. Measurable snow falls in April on an average of once every five years. The rainiest April on record occurred in 1983 (9.14 inches) while the driest April was just two years later (0.39 inches in 1985).

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APRIL OUTLOOK

April is beginning with a large upper-level closed low parked over the mid-Atlantic region while a jet stream ridge is aligned near the Continental Divide. As a result, the first few days of April will feature damp, dreary, and unseasonably cool conditions in the East, while above normal temperatures dominate in the Rockies. The current upper-level low will finally exit over the weekend, however, I have a sense that this major feature is hinting at what might be the prevailing trend during the first half of the month.

Thus, I expect that, in the mean, a jet stream trough will be located in the East through at least April 14^th. While I can’t rule out a few warm days, I do think this early part of the month will average several degrees below normal. In fact, a shot of arctic air glancing through the region on April 4^th through the 6^th may even produce some snow across the mountains of central and northern PA. Might a few stray flurries even be spotted in the Lancaster area?

Late April is a tough call. Normal temperatures warm to 70 degrees by month’s end, so it’s likely we’ll be treated to spells of nice Spring weather. However, I’m inclined to stay with the overall trend of fast jet stream flow and a trough in the East, in the mean. Therefore, there will likely be frequent April showers as well as numerous windy days. Let’s stay the month will average out a couple degrees below normal with near normal precipitation.