MUWIC Newsletter - February 2002

(Issued: February 1, 2002)

Millersville University Weather Information Center (MUWIC)

Eric J. Horst, Director

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LEAD STORY: Global Warming or "Business as Usual"?

While this winter has featured brief cold spells and a couple measurable snowfalls (locally), the late-January record warmth stands out as most remarkable. January produced multiple record highs and this has led many people--and some in the media--to the hasty conclusion that "global warming" must be at play. Let's take a look at our 88-year climatological database for Lancaster and form an objective conclusion as to how unprecedented the recent warmth really is.

January 2002 goes into the books with two record highs and a total monthly temperature departure from normal of +6.4 degrees. Based on this, January places as only the 12th warmest on record-it was also far "cooler" than the warmest January, which occurred in 1950 (+12.3 degrees above normal). Furthermore, our records show that seven other Januarys yielded multiple record highs (see table). It's interesting to note that a disproportional number of these events occurred in the first half of the twentieth century!

From this perspective, you can see that this winter's weather has been "business as usual" and definitely not extraordinary in the context of past winters here in the Lancaster area. In fact, highly variable weather is a hallmark of the mid-latitudes (regions located roughly equidistant from the equator and a pole) and, therefore, "normal weather" here exhibits significant variability.

In conclusion, while global warming cannot be discounted, you simply can't point to a few warm days, months, or even years and say "global warming is to blame." Such time periods are but a snapshot in the overall climatological scheme and any hasty conclusions could be flawed. Researchers continue to study and model the changing atmosphere, and they may have a better idea of the validity of global warming theory in the coming years. However, it may be decades or lifetimes until anyone knows for sure whether human-produced global warming is fact or fiction.

MONTH & YEAR # of REC. HIGHS

January 1916 - 3

January 1930 - 2

January 1932 - 4

January 1950 - 3

January 1951 - 2

January 1967 - 3

January 1990 - 2

January 2002 - 2

Unlisted Years - 1 or none

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EVENT OF THE MONTH

Our January Thaw peaked on the 28th and 29th with record highs being reached both days. The high of 71F on the 29th was the warmest January temperature in the Lancaster area since 1967!

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JANUARY CLIMATOLOGY (MU Weather Station)

Average High Temp: 45.4 F

Average Low Temp: 27.7 F

Average Monthly Temp: 36.6 F

(Departure from Normal: +6.4 F)

Snowfall: 7.5 inches

Total Precipitation (liquid equivalent): 2.34 inches

(Departure from Normal: -0.70)

Annual Precipitation: 2.34 inches

(Departure from Normal: -0.70)

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FEBRUARY NORMALS, RECORDS & FACTS

Normal high/low temperatures range from 37/20 during the first week of the month to 45/27 by month's end. The record high for February is 78 degrees (25th in 1930) and the record low is -17 F (7th in 1935). Normal liquid precipitation (rain and melted snow) is 2.47 inches. Average snowfall for the month is about 10 inches.

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FEBRUARY OUTLOOK

So far, this winter has packed little punch-I expect that to change in February.

Both December and January averaged over 6 degrees above normal. While each month featured some cold weather (and few below normal days), the magnitude and duration of unseasonable warmth was far more dominant. However, significant changes in the jet stream pattern are in the works, and I expect an opposite temperature trend in February. That is to say, I'm not ruling out some warm spells in February, but I expect the duration of the cold spells to be greater.

As for storminess, there will be some--just where is the big question. A split jet stream looks like it will be present for at least the first half of the month. Such a pattern is difficult for both computer models and meteorologists to forecast accurately, as it's ultimately the periodic, "lasting-minute" phasing (i.e. joining) of the jet streams that sparks large storms. However, when and where this happens are often details we (and the models) can't predict more than a couple days in the future. Therefore, while this month will likely produce two or three measurable snowfalls in the area, I suspect there will also be many rumors of storms that never materialize.