MUWIC Newsletter - January 2007

(Issued: January 3, 2007)

 

Millersville University Weather Information Center (MUWIC)

Eric J. Horst, Director

 

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LEAD STORY: “2006 Ends with Unseasonable Warmth”

 

It sure wasn’t hard to stay warm this holiday season. Not only was there no measureable snowfall, but November and December both ranked as the fifth warmest on record here in Lancaster. While there were a few brief cold spells and even a few flurries early in the month, temperatures consistently rebounded to much above normal levels. New record highs were set on December 1st (73) and the 18th (67). There were no record lows.

 

This year-end warmth closely parallels what we experienced in November and December 2001. The temperature departures from normal then were +5.6 and +6.5, compared with +5.0 and +6.6 this past November and December. Therefore, it’s tempting to view the winter 2001-2002 as an analog for the rest of this winter. January and February 2002 both averaged much above normal with a total of only 8.2 inches of snow. However, this analog may not pan out completely as winter 2001-2002 featured ENSO neutral conditions, while this winter we are in the midst of a solid El Nino event. So while a warm bias may continue for much of the winter ahead, I expect this winter will be more stormy and potentially volatile than 2001-2002 (which produced few storms and below normal precipitation).

 

Check out the January Outlook below for a closer look at the long-range forecast.

 

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STAT OF THE MONTH

 

Eleven days in December featured an average temperature that was 10 degrees or more above normal, whereas only one possessed an average temperature that was 10 degrees below normal.

 

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DECEMBER CLIMATOLOGY (MU Weather Station)

 

Average High Temp: 50.2 F

Average Low Temp: 30.9 F                                                    

Average Monthly Temp: 40.5 F                                         

(Departure from Normal: +6.6 F)

                                       

Snowfall: trace

(Departure from Normal:  -4.6 inches)

Total Precipitation:  2.11 inches  

(Departure from Normal: -0.9)   

Annual Precipitation: 48.26 inches              

(Departure from Normal: +7.20)

 

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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 8 inches.

 

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JANUARY OUTLOOK

December concluded a remarkable 6.6 degrees above normal, ranking it as the 5th warmest December on record here in Lancaster (92-year database). The ongoing El Nino is somewhat responsible for this warmth because of its enhancing effects of the Pacific jet stream current. Meanwhile, Canadian air has been hard to come by in the Northeast and the brief visits of chilly air we've experienced so far have had no staying power due to a lack of high-latitude blocking. So, when will winter weather arrive?

Short-term, I see no significant changes over the next 7 to 10 days. The week ahead will continue the trend from December with temperatures averaging about 6 degrees above normal for the period January 2nd - 8th. A brief, glancing shot of Canadian air may work through the first half of next week, however, global teleconnections still do not support the cold air locking in over the Northeast. So, after a couple of seasonably cool days (Jan 9 & 10th), conditions should bounce back above normal by late next week.

Beyond that, it's a tough call to identify a trend for the second half of January. Given the moderately strong El Nino, however, it's likely that a mild bias will continue at times throughout the rest of the winter. Building arctic chill can still make a dramatic arrival if any high-latitude blocking develops (a -NAO configuration), and I continue to believe that we'll see a couple of spells of winter weather. But given this season's robust El Nino it's unlikely there will be any long-lasting chill from the Northern Plains and Midwest to the Northeast and Mid-Atlantic.

COPYRIGHT 2007 Millersville University

 

Published monthly by the Millersville University Weather Information Center.

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