From the ABC 7 Weather team

A White Christmas for Washington, D.C.: Could it happen in 2011?

December 7, 2011 - 05:00 AM
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There is actually a formal study of how often White Christmases occur in the U.S. See where the District and you city ranks!

(NOAA / National Climatic Data Center)

It looks like folks around D.C. love to shovel on Christmas Day, judging from the results of the latest ABC7 poll that is more than 3 to 1 in favor of a White Christmas. But how likely is it to snow on the District on Dec. 25?

Enough public interest exists in this question that NOAA has made recurring estimates of White Christmas odds. (Full report.) Above, find a probability map for the U.S. showing how often it snows on people exchanging cards and fruitcakes. Some places like Maine, Minnesota, Wisconsin, Washington State and anywhere in the Rockies are all but guaranteed a Christmas as white as the fan base for Harold and Maude. Nearly all the southern U.S. has less than a 5 percent chance of running across the scary white rain during the fir holiday. Hawaii, meanwhile, is much more snowy than you might expect.

And in D.C.?

The local branch of the National Weather Service actually addressed that question for D.C. and Baltimore last December. Turns out that we have about a 7 percent chance of snow dropping in time for caroling, with the last Xmas snowfall being in 2002. Put another way, a measurable amount of snow has fallen on the city on Dec. 25 only nine times since 1888.

Below, find the full NWS report on this most magical of meteorological phenoms.

*** WASHINGTON D.C ***

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 29 AND AN AFTERNOON HIGH OF 43. 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... ONLY 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/22C IN 1964. THE WARMEST LOW TEMPERATURE WAS 49 DEGREES F/9C 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...2009...LOW PRESSURE AND ITS ASSOCIATED WARM FRONT OVER  THE SOUTHEAST STATES APPROACHED THE AREA DURING THE DAY. CLOUDY SKIES LASTED THROUGHOUT THE DAY. A PERIOD OF LIGHT TO MODERATE RAIN BEGAN IN THE MID AFTERNOON AND LASTED THROUGHOUT CHRISTMAS NIGHT. NEARLY TWO-THIRDS OF AN INCH OF RAIN FELL ON CHRISTMAS. TEMPERATURES RISING INTO THE MID 40S COMBINED WITH THE RAIN HELPED TO MELT THE REMAINING 7 INCH SNOWPACK LEFT OVER FROM THE DECEMBER 18-19 STORM.

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
1999 --> HI 32 LOW 21 MOSTLY SUNNY AND COLD
1998 --> HI 36 LOW 24 SUNNY AND CHILLY
1997 --> HI 49 LOW 40 PARTLY CLOUDY WITH RAIN SHOWERS
1996 --> HI 42 LOW 29 SUNNY AND COOL

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. THERE WAS ENOUGH SNOW TO YIELD A MEASURABLE 0.2 TENTHS OF AN INCH. HOWEVER...OF THE PAST 122 YEARS SINCE 1888 WHEN SNOWFALL HAS BEEN MEASURED IN WASHINGTON DC...ONLY 9 TIMES HAS THERE BEEN MEASURABLE SNOW THAT ACTUALLY FELL ON CHRISTMAS DAY. THAT AVERAGES TO ABOUT ONCE EVERY 13-14 YEARS...OR ABOUT 7 PERCENT.

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

1962 ... 5.4 INCHES
1909 ... 4.5 INCHES
1969 ... 4.3 INCHES
1902 ... 1.0 INCHES
1935 ... 0.6 INCHES
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 STORM. THAT AVERAGES TO A WHITE CHRISTMAS ABOUT ONCE EVERY 6-7 YEARS...OR A 16 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. THAT WAS DURING THE VERY COLD DECEMBER OF 1989...WHEN NEARLY 2 INCHES OF SNOW WAS ON THE GROUND FROM PREVIOUS SNOWFALL THAT MONTH AND LAST YEAR (2009) WHEN 7 INCHES OF SNOW WAS STILL ON THE GROUND. ALL 7 INCHES OF THE SNOWPACK ON CHRISTMAS 2009 MELTED BY THE NEXT MORNING.

OF NOTE...17 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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