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December 23, 2009

Dreaming of a wet Christmas

Looks like Friday's bout of freezing rain and rain will not get rolling until just a few hours before dawn in Central Maryland. Forecasters out at Sterling are putting the chance of freezing rain Thursday night at just 20 percent after a sunny day leading to Christmas Eve. So travelers who head out Thursday should be okay.

But by Friday morning the precipitation chances rise to 80 percent. And with temperatures at the surface on Friday morning well below freezing, the rain that falls from the warmer air aloft will freeze on the way down, or on contact with sidewalks, streets, cars and railings. So be careful if you're stepping out on Christmas morning.

What's less clear is how long it will take the falling rain to "erode" the cold air dammed up at the surface, and turn the precipitation over to all rain. Forecasters say it will begin to mix at BWI-Marshall Airport between 10 a.m. and 1 p.m., and become all rain after that. But depending on Christmas traffic in rainwhere you are and how the event unfolds, the actual script may be different for you.

West of the Blue Ridge, freezing rain may be a factor all day. So if you're driving west on I-70 and I-68, be advised.

Sterling is expecting a pretty sizable volume of water, with up to a quarter inch of rain during the day Friday, followed by another quarter- to a half-inch Friday night. There's an 80 percent chance for more rain on Saturday, although the NWS has not attached an accumulation amount to that one yet.

Rest assured, coming on top of still-melting snow and ice, there will be lots of water on the ground, looking for a low spot to fill up. Watch for street and stream flooding, and be sure the storm drains around your place are clear.

Sunshine returns on Sunday, but temperatures will be colder, with highs in the 30s early next week, and lows near 20 degrees. Normal highs are in the low 40s at this time of year at BWI. The average lows are in the mid-20s. 

The good news, of course, for many, is that we will not be on the snowy side of this storm, which is going to pile up deep numbers across the northern Plains, from Kansas to northern Michigan.

But that doesn't mean we're done with big snow this winter. Mr. Foot's Forecast includes this warning today:

"If you are an HSA [the state High School Assessment] planner in Maryland, we hypothesize conditions in mid-January will turn around and warm up - just in time to get state testing completed. After that? Let's just say the Empire Strikes Back - as in the empire of Old Man Winter. The January 20 to February 15 period might be a time that tries men's souls (and ladies too of course!)" 

Europeans are enjoying a wintry patch, too. Snow in Madrid? Read more here.

For more on the weather history of Christmas in Baltimore, from the National Weather Service's Baltimore-Washington Forecast Office in Sterling, Va., read on.

(SUN PHOTO/Kenneth K. Lam/Christmas Eve 2003)

                         *** BALTIMORE ***

EXAMINATION OF WEATHER RECORDS GOING BACK TO 1872...SHOWS A TYPICAL
CHRISTMAS DAY IS PARTLY CLOUDY WITH A FROSTY EARLY MORNING LOW OF 28
AND AN AFTERNOON HIGH OF 43. BUT THE YEAR-TO-YEAR WEATHER CAN BE
ANYTHING BUT TYPICAL.

FOR THOSE WHO LIKE IT COLD...

THE COLDEST...1983 WHEN THE TEMPERATURE HIT ZERO DEGREES F/-18C.
THAT ALSO PRODUCED THE COLDEST HIGH TEMPERATURE FOR THE DAY...A
FRIGID 12 DEGREES F/-11C THAT AFTERNOON. THE FIVE COLDEST LOWS WERE:

          1983 - 0  DEGREES F          1980 - 7  DEGREES F
          1989 - 7  DEGREES F          1960 - 12 DEGREES F
                        1998 - 13 DEGREES F

HOW ABOUT A WARM CHRISTMAS?

THE WARMEST...A TOASTY 72 DEGREES F/22C IN 1964. THAT DAY ALSO PRODUCED
THE WARMEST LOW TEMPERATURE...48 DEGREES F/9C.  THE 5 WARMEST CHRISTMASES:

          1964 - 72 DEGREES F          1932 - 67 DEGREES F
          1982 - 70 DEGREES F          1893 - 67 DEGREES F
                         1965 65 DEGREES F

RECENT PAST CHRISTMAS DAY WEATHER:

LAST YEAR...2008...A COLD FRONT SWEPT ACROSS THE REGION SHORTLY
AFTER MIDNIGHT. A TRACE OF RAIN WAS RECORDED IN BALTIMORE WITH THE
FRONTAL PASSAGE. THE DAILY HIGH OCCURRED JUST PRIOR TO THE FRONTAL
PASSAGE. THE DAYTIME FEATURED PARTLY SUNNY SKIES WITH DAYTIME HIGHS
IN THE MID TO UPPER 40S.

      2008 -->  HI 59  LOW 32   PARTLY SUNNY HIGH OCCURRED AT MIDNIGHT
      2007 -->  HI 50  LOW 30   PARTLY SUNNY AND MILD
      2006 -->  HI 50  LOW 30   CLOUDY WITH AFTERNOON AND NIGHT RAIN
      2005 -->  HI 42  LOW 24   CLOUDY WITH AFTERNOON RAIN
      2004 -->  HI 31  LOW 17   SUNNY AND COLD
      2003 -->  HI 41  LOW 28   MOSTLY SUNNY AND BLUSTERY
      2002 -->  HI 38  LOW 32   RAIN WITH SOME SNOW/SLEET
      2001 -->  HI 40  LOW 23   PARTLY SUNNY AND COOL
      2000 -->  HI 27  LOW 17   SUNNY BREEZY AND COLD
      1999 -->  HI 32  LOW 14   MOSTLY SUNNY AND COLD
      1998 -->  HI 33  LOW 13   SUNNY AND COLD
      1997 -->  HI 56  LOW 41   PARTLY CLOUDY WITH RAIN SHOWERS.
      1996 -->  HI 38  LOW 24   SUNNY AND COOL.


FOR SNOW LOVERS...

A WHITE CHRISTMAS IS SOMEWHAT OF A RARITY IN BALTIMORE. SEVEN YEARS
AGO IN 2002 A GENERALLY RAINY CHRISTMAS MORNING CHANGED TO SNOW AT
DURING THE LATE MORNING. THERE WAS ENOUGH SNOW TO YIELD AN INCH OF
SNOW. HOWEVER...OF THE PAST 116 YEARS SINCE 1893 WHEN SNOWFALL HAS
BEEN MEASURED IN BALTIMORE MD...ONLY TWELVE TIMES HAS THERE BEEN
MEASURABLE SNOW THAT FELL ON CHRISTMAS DAY. THAT AVERAGES OUT TO
ABOUT 1 EVERY 10 YEARS...OR 10 PERCENT.

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

     1909 ... 9.3"
     1969 ... 6.1"
     1902 ... 3.0"
     1962 ... 2.9
     1935 ... 1.2"
     2002 ... 1.0"

IF YOU INTERPRET A WHITE CHRISTMAS TO MEAN MEASURABLE SNOWFALL OR
SNOW ON THE GROUND...AT LEAST ONE HALF INCH...THAT IMPROVES THE ODDS
SOME. TWENTY NINE TIMES SNOW WAS ON THE GROUND CHRISTMAS DAY
THAT EITHER FELL THAT DAY...OR WAS ON THE GROUND FROM A PREVIOUS
STORM. THAT GIVES ABOUT A 23 PERCENT CHANCE...OR ABOUT ONCE EVERY
FOUR YEARS.

HOWEVER...IN THE PAST 20 YEARS THERE HAVE BEEN ONLY TWO CHRISTMASES
THAT HAD SNOW FALL THAT DAY...1993 AND 2002. BOTH YEARS FEATURED AN
INCH OR LESS. FURTHERMORE...THERE WAS ONLY TWO YEARS IN THE PAST 20
THAT HAD MORE THAN AN INCH OF SNOW ON THE GROUND ON CHRISTMAS. THE
MOST RECENT OF WHICH WAS DURING THE VERY COLD DECEMBER OF 1989...
WHEN NEARLY 2 INCHES OF SNOW WAS ON THE GROUND FROM PREVIOUS
SNOWFALL THAT MONTH.

PRECIPITATION OF ANY SORT (RAIN INCLUDED) IS MUCH EASIER TO COME BY
OF COURSE. THIRTY EIGHT CHRISTMASES HAVE HAD PRECIPITATION. THAT
TRANSLATES TO ABOUT 30 PERCENT PROBABILITY OF MEASURABLE
PRECIPITATION...OR ROUGHLY ONE THIRD.

HAPPY HOLIDAYS!!
Posted by Frank Roylance at 11:40 AM | | Comments (3)
Categories: Forecasts
        

Comments

I, for one, have already had it with the snow. Let it rain, let it rain, let it rain! And please, let everything melt!!

Merry Christmas, Frank!

Frank, More rain for Xmas here in Seattle (er, Baltimore)....Imagine that!! All I want for Christmas is a snorkle and a new pair of galoshes and this never ending cycle of rain to GO AWAY!!!! Bring on the drought!!! Thanks & Merry Christmas.

take heart folks.......just think of all those happy farmers and rain lovers - who NEVER think we can get enough "much needed rainfall" - dancing in the streets at the promise of some lovely Christmas rain and flooding to top off a year that for most of us normal folks resulted in us being waterlogged and wishing for just 10 days wiithout anything wet falling from the sky :(

Cheers everyone.....Merry Christmas

FR: Sorry to miss all the rain. We're just back from Christmas with the off-line in-laws. Should be back on top of the weather shortly. Hope everyone had a great holiday in spite of the soggy skies. Cheers!

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About Frank Roylance
This site is the Maryland Weather archive. The current Maryland Weather blog can be found here.
Frank Roylance is a reporter for The Baltimore Sun. He came to Baltimore from New Bedford, Mass. in 1980 to join the old Evening Sun. He moved to the morning Sun when the papers merged in 1992, and has spent most of his time since covering science, including astronomy and the weather. One of The Baltimore Sun's first online Web logs, the Weather Blog debuted in October 2004. In June 2006 Frank also began writing comments on local weather and stargazing for The Baltimore Sun's print Weather Page. Frank also answers readers’ weather queries for the newspaper and the blog. Frank Roylance retired in October 2011. Maryland Weather is now being updated by members of The Baltimore Sun staff
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