MUWIC Newsletter - January 2003

(Issued: January 6, 2003)

Millersville University Weather Information Center (MUWIC)

Eric J. Horst, Director

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LEAD STORY: “The Return of Winter…The End of a Drought”

What a difference a year makes!

December 2001 was the warmest on record in Lancaster with three record highs being set and no snowfall. Conversely, December 2002 produced two new record lows and the most snowfall (for December) since 1969. A total of 16 inches of snow fell this past December, compared to the 24 inches that fell in 1969. Average snowfall for December is 2.7 inches.

Total liquid-equivalent precipitation (i.e. rain and melted ice/snow) for the month was 4.19 inches. This represents 140 percent of normal precipitation and continues the three-month trend of above normal rainfall. Consequently, the historical drought of the past two years is but a memory. In turn, the Governor further downgraded our drought classification on December 19^th. Lancaster county is presently in a “drought watch”, which is the second lowest of four possible designations. It’s quite likely the final downgraded to “normal status” will occur in the coming weeks.

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EVENTS OF THE MONTH

#1. The eight-inch, December 5th snowfall was the largest winter storm so early in the season in over 40 years. Not since the first week of December 1959 has there been such a large early-season (actually late Fall!) snowfall in the Lancaster area.

#2. On December 25^th, another eight-inch snowfall became Lancaster’s largest Christmas Day snowstorm since the late 1960s. In 1969, snowfall from Christmas afternoon into the morning of the 26^thaccumulated over 12 inches.

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STAT OF THE MONTH

The first eleven days of December 2002 averaged 12.4 degrees below normal making it the coldest such period on record in the Lancaster area. Previously, December 1989 held this distinction with the first eleven days averaging 10.1 degrees below normal.

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DECEMBER CLIMATOLOGY (MU Weather Station)

Average High Temp: 38.1 F

Average Low Temp: 22.7 F

Average Monthly Temp: 30.4 F

(Departure from Normal: -2.9 F)

Snowfall: 16.0 inches

(Departure from Normal: +13.3 inches)

Total Precipitation: 4.19 inches

(Departure from Normal: + 1.21)

Annual Precipitation: 34.01 inches

(Departure from Normal: - 7.05)

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JANUARY NORMALS, RECORDS & FACTS

Normal high/low temperatures for January are 39/22, respectively. The record high for the month is 77 degrees (January 27, 1950) and the record low is -18 (January 21, 1994). Normal liquid precipitation (rain and melted snow) is 3.01 inches. Average snowfall for the month is 10 inches.

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JANUARY OUTLOOK

Winter began with a bang in December as below normal temperatures and an active southern storm track combined to produce more snow than fell all of last winter. Two different southern storms followed a “near-perfect” track to produce heavy snow in our area. In that sense, December’s hefty snowfall was a bit of a fluke—as I always like to point out, it’s often a matter of just 50 or 100 miles that determines whether we get a big snowstorm or a big “wet storm.” Over the past month, everything panned out almost perfectly for snow in Lancaster county. Will this trend continue?

To some degree we’ve already got that answered in the form of a 3-inch snowfall on January 5^th. However, we also missed out on a potential big snowfall a few days earlier when up to 11 inches fell across parts of northern PA, while mostly rain and ice fell in Lancaster. With no major pattern changes expected in the next couple weeks, I’m left to conclude that the rest of January will continue in much the same way the month has begun; that is, lacking any lasting warmth and with frequent opportunities for snow, ice and cold rain.

Looking ahead, I see a brief warm-up on January 9th that will give way to a blast of arctic air the very next day. The period of January 10 to 20^th looks like it will average below normal as arctic air takes glancing blows from the northern plains to the mid-Atlantic region. Meanwhile, the well-advertised “El Nino driven” southern storm track may quiet down for a week or so. However, I do expect that a storm system will track across the southern states next week and, possibly, turn up the East coast. Overall, it looks like a continued duel between mild Pacific air masses and attempts of arctic air to dominate in the Northeast. Therefore, I believe that any warming trends will be quickly blunted by renewed presses of cold air from the north. Such a pattern places Pennsylvania right in the hard-to-forecast “battle ground.” Stay tuned!