From the ABC 7 Weather team

Odds of a White Christmas for D.C. increase (slightly)

December 22, 2011 - 12:42 PM
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The overall chances for snow falling in D.C. on Christmas Day has crept up 1 percent, says the National Weather Service. Woohoo!

Did you know that people in Maine call a snowless Christmas a 'Virginia Christmas'? It's true, at least according to the Maine resident who took this photo. (Laureen LaBar / Flickr)

Joyous tidings! According to a scroll delivered by the National Weather Service's messenger Snowy Owl this morning, the odds of a White Christmas for Washington, D.C., are looking much better!

Historically, that is. This weekend's Christmas Day still looks "sunny and near 50."

The last time this blog checked in with the D.C./Baltimore's statistics whizzes, the odds of snow falling on any given Christmas Day were 7 percent. There had only been nine instances of a Dec. 25 measurable snowfall (0.2 or more inches) in the region since 1888. If you're less of a literalist and consider a "White Christmas" to be any Christmas with snow falling or already on the ground from a previous snowstorm, then the odds crept up to 16 percent.

But the 2011 NWS discussion of White Christmas probabilities has upped the flake forecast. Now D.C. has a tremble-inducing 8 percent historical chance of a snow-falling White Christmas. Oddly enough, the odds of a W.C. with snow already on the ground drifted down to 15 percent. If anybody from the NWS is reading, I'd sure like to know how likely it is that we tie or exceed the warmest D.C. Christmas on record, the balmy 72-degree Xmas of 1964. That's like nature bringing the Florida to us.

You can find the full NWS report after the jump, which is seeded with all kinds of fascinating winter-weather tidbits. For how D.C. stacks up against other burgs on Christmas Day, have a look at this map from the National Climatic Data Center based on weather data from 1981 to 2010. A White Christmas in this case is defined as one that has at least 1 inch of snow on the ground:

2011_white_christmas_odds

 

PUBLIC INFORMATION STATEMENT

NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
426 PM EST TUE DEC 20 2011

...PUBLIC INFORMATION STATEMENT...

* * * * * * ** * * * *
* * WHITE CHRISTMAS STATISTICS * * *
* * * * * *

IT IS TIME AGAIN FOR THE CHRISTMAS STATISTICS FOR THE MID-ATLANTICREGION...COMPILED BY THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA.

WHAT ARE THE CHANCES FOR A WHITE CHRISTMAS? ...

WHAT IS TYPICAL CHRISTMAS WEATHER? ...

FIRST FOR WASHINGTON...THEN FOR BALTIMORE...


*** WASHINGTON DC ***

EXAMINATION OF CLIMATE RECORDS GOING BACK TO 1872 FOR CHRISTMASES IN WASHINGTON DC SHOW A TYPICAL CHRISTMAS DAY IS PARTLY CLOUDY WITH A FROSTY EARLY MORNING LOW OF 30 AND AN AFTERNOON HIGH OF 44. BUT THE YEAR-TO-YEAR WEATHER CAN VARY CONSIDERABLY.

COLDEST CHRISTMASES...

THE COLDEST WAS 1983...THE LOW TEMPERATURE WAS 3 DEGREES F ABOVE ZERO /-16C. THAT DAY ALSO PRODUCED THE COLDEST HIGH TEMPERATURE FOR THE DAY...A FRIGID 14 DEGREES F /-10C THAT AFTERNOON. THE FIVE COLDEST LOW TEMPERATURES WERE:

1983 - 3 DEGREES F
1872 - 5 DEGREES F
1989 - 11 DEGREES F
1980 - 12 DEGREES F
1906 - 13 DEGREES F

WARMEST CHRISTMASES...

THE WARMEST CHRISTMAS DAY...A TOASTY 72 DEGREES F IN 1964. THE WARMEST LOW TEMPERATURE WAS 49 DEGREES F IN 1987. THE 5 WARMEST CHRISTMASES:

1964 - 72 DEGREES F
1982 - 70 DEGREES F
1965 - 69 DEGREES F
1932 - 68 DEGREES F
1889 - 65 DEGREES F

RECENT PAST CHRISTMAS DAY WEATHER:

LAST YEAR...2010...A WEAK DISTURBANCE MOVING THROUGH THE AREA RESULTED IN CLOUDY SKIES FOR MOST OF THE DAY AND FLURRIES DURING THE MORNING. REAGAN NATIONAL AIRPORT...THE OFFICIAL MEASUREMENT LOCATION FOR WASHINGTON DC... RECORDED A TRACE OF SNOW. TEMPERATURES DID NOT FLUCTUATE MUCH LAST

CHRISTMAS...REMAINING IN THE LOW TO MID 30S DURING THE CALENDAR DAY.

2010 --> HI 36 LOW 32 CLOUDY/MORNING FLURRIES
2009 --> HI 47 LOW 29 SNOWMELT/CLOUDY/MID AFTERNOON-NIGHT RAIN
2008 --> HI 58 LOW 32 PARTLY SUNNY HIGH OCCURRED AT MIDNIGHT
2007 --> HI 52 LOW 37 PARTLY SUNNY AND MILD
2006 --> HI 50 LOW 37 CLOUDY WITH AFTERNOON AND NIGHT RAIN
2005 --> HI 44 LOW 30 CLOUDY WITH AFTERNOON RAIN
2004 --> HI 33 LOW 24 SUNNY AND COLD
2003 --> HI 42 LOW 31 MOSTLY SUNNY AND BLUSTERY
2002 --> HI 39 LOW 33 RAIN WITH SOME SNOW/SLEET
2001 --> HI 41 LOW 28 MOSTLY SUNNY AND COOL
2000 --> HI 28 LOW 19 SUNNY BREEZY AND COLD

FOR SNOW LOVERS...

A WHITE CHRISTMAS IS A RARITY IN WASHINGTON DC. IT LAST HAPPENED EIGHT YEARS AGO IN 2002 WHEN A GENERALLY RAINY CHRISTMAS MORNING CHANGED TO SNOW AROUND MIDDAY...YIELDING A MEASURABLE 0.2 TENTHS OF AN INCH. HOWEVER...OF THE PAST 127 YEARS SINCE 1884 WHEN SNOWFALL HAS BEEN MEASURED IN WASHINGTON DC...ONLY 10 TIMES HAS THERE BEEN MEASURABLE SNOW THAT ACTUALLY FELL ON CHRISTMAS DAY. THAT AVERAGES TO ABOUT ONCE EVERY 12-13 YEARS...OR ABOUT 8 PERCENT.

THE 6 HIGHEST SNOWFALLS OCCURRING IN WASHINGTON ON CHRISTMAS DAY...

1... 1962 ... 5.4 INCHES
2... 1909 ... 4.5 INCHES
3... 1969 ... 4.3 INCHES
4... 1902 ... 1.0 INCHES
5... 1935 ... 0.6 INCHES
6... 1892 ... 0.5 INCHES

IF YOU INTERPRET A WHITE CHRISTMAS AS EITHER MEASURABLE SNOWFALL THAT DAY OR HAVING SNOW ALREADY ON THE GROUND (A SNOW DEPTH OF AT LEAST ONE HALF INCH)...THE ODDS OF A WHITE CHRISTMAS ARE SLIGHTLY BETTER. SINCE 1888...NINETEEN TIMES MEASURABLE SNOW WAS ON THE GROUND ON CHRISTMAS DAY THAT EITHER FELL THAT DAY...OR WAS STILL ON THE GROUND FROM AN EARLIER SNOWFALL. THAT AVERAGES TO A WHITE CHRISTMAS ABOUT ONCE EVERY 6-7 YEARS...OR A 15 PERCENT CHANCE.

IN THE PAST 20 YEARS...THERE HAVE BEEN ONLY TWO CHRISTMASES THAT HAD SNOWFALL...1993 AND 2002. BOTH YEARS FEATURED JUST A FRACTION OF AN INCH. FURTHERMORE...THERE WAS ONLY TWO YEARS IN THE PAST 40 THAT HAD AN INCH OR MORE OF SNOW ON THE GROUND ON CHRISTMAS. THEY WERE DURING THE VERY COLD DECEMBER OF 1989...WHEN NEARLY 2 INCHES OF SNOW WAS ON THE GROUND FROM PREVIOUS SNOWFALL THAT MONTH AND IN 2009...WHEN 7 INCHES WAS STILL ON THE GROUND FROM THE DECEMBER 18-19 RECORD SNOWSTORM. ALL 7 INCHES OF THAT SNOWPACK ON CHRISTMAS 2009 MELTED BY THE NEXT MORNING.

OF NOTE...18 YEARS AGO...IN 1993 IN A SPAN LASTING LESS THAN 30 MINUTES IN THE EVENING...0.2 INCH SNOW FELL...WITH UPWARDS OF AN INCH FALLING IN THE WESTERN SUBURBS. THAT QUICK BURST OF SNOW ON CHRISTMAS NIGHT 1993 CAUSED SEVERE TRAVEL PROBLEMS. MUCH OF THE SNOW MELTED ON CONTACT WITH PAVED SURFACES AS TEMPERATURES WERE JUST ABOVE FREEZING AT THE TIME THE SNOW FELL. HOWEVER...AN ARCTIC COLD FRONT SWEPT IN JUST AFTER THE SNOW ENDED. ANY WATER REMAINING ON ROADS AND SIDEWALKS FROM MELTED SNOW QUICKLY FLASH FROZE INTO A THIN LAYER OF ICE...WHICH CAUSED TREACHEROUS TRAVEL THAT NIGHT.

PRECIPITATION OF ANY SORT (RAIN INCLUDED) IS MUCH EASIER TO COME BY OF COURSE. FIFTY-ONE CHRISTMASES HAVE HAD MEASURABLE PRECIPITATION. THAT TRANSLATES TO ABOUT A 36 PERCENT PROBABILITY OF MEASURABLE PRECIPITATION...OR ROUGHLY ONE IN EVERY THREE YEARS.

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