Low pressure over the Ohio Valley caused periods of precipitation during the first into the morning hours of the second. There was enough low-level cold air for a period of wintry precipitation before enough warm air eventually worked its way into the storm causing precipitation to change to rain.
Every event with a place to put it; 5 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS LWX wrote it up.
Low pressure over the Ohio Valley caused periods of precipitation during the first into the morning hours of the second. There was enough low-level cold air for a period of wintry precipitation before enough warm air eventually worked its way into the storm causing precipitation to change to rain.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Baltimore/Washington wrote its last area forecast discussion before the first event at Jan 31, 10:21 PM EST, 3 hours 39 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1021 PM EST MON JAN 31 2011
.SYNOPSIS...
HIGH PRESSURE MOVING OVER THE NORTHEAST STATES WILL NOSE DOWN THE
EASTERN SEABOARD TONIGHT. MEANWHILE...A STORM SYSTEM OVER THE PLAINS
WILL ENTER THE OHIO VALLEY TUESDAY NIGHT. A STRONG COLD FRONT WILL
MOVE INTO THE MID ATLANTIC STATES WEDNESDAY. HIGH PRESSURE
RETURNS FOR THE LATTER PART OF THE WEEK. COASTAL LOW PRESSURE
LOOKS AFFECT THE REGION OVER THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
UPDATE TO START THE WINTER WEATHER ADVISORY NOW. LATEST RADAR
IMAGERY SHOWS AREAS OF FREEZING DRIZZLE BEGINNING TO DEVELOP. ALSO
HAD A REPORT OF A GLAZE IN MINERAL COUNTY. PREVIOUS DISCUSSION
FOLLOWS.
ARCTIC HIGH PRESSURE WILL REMAIN OVER NEW ENGLAND WHILE A POTENT
STORM SYSTEM BEGINS TO TAKE SHAPE OVER THE CENTRAL CONUS. AS THE
STORM SYSTEM CONTINUES TO DEVELOP...WARM AND MOIST AIR WILL
OVERRUN THE COLD AIR AT THE SURFACE CAUSING LIGHT PRECIPITATION
TONIGHT. TEMPERATURES WILL REMAIN BELOW FREEZING ACROSS THE AREA
DURING THIS TIME.
WITH THE ONLY FORCING MECHANISM BEING FROM ISENTROPIC
LIFT...PRECIPITATION AMOUNTS ARE EXPECTED TO BE LIGHT.
HOWEVER...AS WARM AIR CONTINUES TO INCREASE ALOFT LIGHT SNOW AND
SLEET WILL TRANSITION TO LIGHT FREEZING RAIN AND FREEZING DRIZZLE.
HAVE INCLUDED THE ENTIRE CWA IN THE WINTER WEATHER ADVISORY FOR
TONIGHT.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
THE ADVSRY IS IN EFFECT THRU NOON TUE. QUSTNS EXIST CONCERNING
HIGH TEMPS TUE. IT MAY BE PSBL THAT THE "S OF DC COUNTIES" IN THE
ADVSRY MAY BE ABLE TO BE REMOVED B4 THE NOON EXPIRATION TIME AS
TEMPS MAY NUDGE ABV FRZG. YDA I TALKED ABT "THE USUAL SUSPECTS" IN
CAD EVENTS...WHICH ROUTINELY MEANS WEST-CENTRAL MD AND THE ERN
PANHANDLE OF WV. MDLS IMPLY AGN THAT THE COLD AIR WL LINGER
LONGEST THERE..BUT CHCS OF PCPN WL DIMINISH DURG THE TUE AFTN PD
AS WELL. IN THE END THAT RGN MAY EDGE ABV FRZG AS WELL...BUT FOR
THE MOMENT WL LV SLTLY BLO. FURTHER S TEMPS XPCTD TO GET INTO THE
L40S IN THE CENTRAL SHEN VLLY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
TUESDAY NIGHT INTO WEDNESDAY MORNING...THE CENTER OF THE LOW
PRESSURE SYSTEM WILL NORTHEAST THROUGH THE MIDWEST...BEFORE CROSSING
THE EASTERN GREAT LAKES WEDNESDAY. A WEDGE WILL PERSIST ACROSS THE
CENTRAL MID ATLANTIC WITH SFC ELY FLOW BELOW SLY LOW AND MID LEVEL
FLOW. ISENTROPIC LIFT IN THE WARMER AIR ALOFT WILL ALLOW AREAS OF
PRECIPITATION TO MOVE ACROSS THE CWA THROUGH THE EVENING AND EARLY
MORNING HOURS OF TUESDAY NIGHT. THE FREEZING ISOTHERM /DIVIDE
BETWEEN FREEZING RAIN AND PLAIN RAIN/ LOOKS TO BE FAIRLY STATIONARY
THROUGH TUESDAY NIGHT ROUGHLY FROM HWY 1 NORTH FROM DC AND I-66 WEST
FROM DC. TEMPERATURES ARE EXPECTED TO RANGE FROM UPPER 20S NORTH TO
MID 30S SOUTH ACROSS THE SHENANDOAH VALLEY. THEREFORE...FREEZING
RAIN IS EXPECTED FOR CENTRAL AND WESTERN MARYLAND...THE EASTERN WEST
VIRGINIA PANHANDLE...AND NORTHERN AND POSSIBLY CENTRAL SHENANDOAH
VALLEY THROUGH TUESDAY NIGHT...BEFORE SLOWLY PUSHING NORTH WEDNESDAY
MORNING.
SIGNIFICANT ICE ACCRETION /ON THE ORDER OF HALF AN INCH/ IS EXPECTED
ACROSS NORTHERN MARYLAND FROM HARFORD TO ALLEGANY COUNTY AS WELL AS
PORTIONS OF THE EASTERN WEST VIRGINIA PANHANDLE AND NORTHERN
SHENANDOAH VALLEY. SLY FLOW AHEAD OF THE SYSTEM WILL PROVIDE AMPLE
MOISTURE FROM THE GULF OF MEXICO WITH HALF TO ONE INCH OF LIQUID
EQUIVALENT PRECIPITATION...PRIMARILY TUESDAY NIGHT BEFORE MOVING OFF
WEDNESDAY MORNING. DESPITE TEMPERATURES BELOW FREEZING...LIGHT WIND
WILL NOT ALLOW ALL PRECIP TO ACCRETE INTO ICE. THE RATIO OF FREEZING
RAINFALL TO ICE ACCRETION LOOKS TO DECREASE SOUTH FROM THE
MASON-DIXON LINE. THE DEPTH OF COLD AIR UP ALONG THE PA/MD BORDER
COULD BECOME DEEP ENOUGH TO ALLOW SLEET FOR PORTIONS OF TUESDAY
NIGHT.
FREEZING RAIN IS A SELF DEFEATING PROCESS DUE TO PHASE CHANGE AND
WARMER AIR RADIATING DOWN TO THE SURFACE. THE PROCESS TO KEEP IT
FREEZING IS THE ADVECTION OF SFC COLD/DRY AIR. WITH NAM/GFS/ECMWF
GUIDANCE HAVING FLOW BECOMING ELY FOR MOST OF TUESDAY NIGHT...THE
PROGRESSION OF THE RAIN/FREEZING RAIN LINE MAY MOVE NORTH.
HOWEVER...SINCE THIS IS OVERNIGHT AND THE WEDGE/COLD AIR DAMMING IS
GENERALLY ERODED TOO EARLY FROM MODELS...FREEZING RAIN WAS HELD ON
THROUGH WEDNESDAY MORNING.
REST OF WEDNESDAY...THE COLD FRONT GOES THROUGH WITH PRECIP ENDING
THROUGH THE AFTERNOON AS RAIN SHOWERS EAST...UPSLOPE SNOW SHOWERS
BEGIN OUT WEST. THE GFS CONTINUES TO PROG NEAR ADVISORY WINDS /GUSTS
IN EXCESS OF 46 MPH/ FOR HIGHER ELEVATIONS FOR WEDNESDAY EVENING
WITH GUSTS PERHAPS 30 TO 35 MPH FOR LOWER ELEVATIONS. SHOULD ICE
STILL BE ON TREES/POWER LINES...THESE STRONG WINDS COULD CAUSE
FURTHER DAMAGE. WARM ADVECTION IS EXPECTED TO REACH THE SURFACE FOR
SOUTHERN ZONES WITH THE WEDGE PERSISTING NORTH. MAX TEMPS DEPEND ON
HOW FAR NORTH THIS FRONT GOES...UPPER 50S TO NEAR 60F SOUTH...MID
30S NORTH.
HIGH PRESSURE BUILDS IN WEDNESDAY NIGHT INTO FRIDAY WITH BELOW
NORMAL TEMPERATURES FOR THURSDAY NIGHT WHEN MIN TEMPS IN THE
TEENS/20S ARE EXPECTED.
A DEEP TROUGH CROSSES THE CENTRAL CONUS IN THE FRIDAY TIMEFRAME WITH
WARM AIR ADVECTION FOR THE MID ATLANTIC INTO THE WEEKEND. AS THAT
TROUGH REACHES THE EASTERN SEABOARD...COASTAL LOW PRESSURE IS
EXPECTED TO DEVELOP AND MOVE NORTHEAST. GUIDANCE HAS VARIED AS TO
HOW STRONG THIS LOW WILL BE...SO LOW CHANCES FOR SNOW/RAIN WERE
ADDED TO THE GRIDS FOR FRIDAY NIGHT THROUGH SATURDAY NIGHT.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
OVC SKIES TNGT AND TUE. FZRA/FZDZ IS IN THE FCST AT ALL MAJOR
AIRPORTS FM OVERNIGHT THROUGH TUESDAY MORNING. IFR CONDITIONS
ARE EXPECTED TO DEVELOP DURING THIS TIME.
A SWATH OF PRECIPITATION CROSSES THE TERMINALS TUESDAY NIGHT INTO
WEDNESDAY MORNING. THE PRECIP TYPE WILL BE RAIN OR FREEZING RAIN
WITH THE SURFACE TEMPERATURE BEING THE DECIDING FACTOR. THIS LINE IS
EXPECTED TO BE ROUGHLY FROM KBWI/KDCA/KIAD/KW45/KW99. KMRB LOOKS TO
BE SIGNIFICANTLY AFFECTED WITH TEMPERATURES AROUND 30F THROUGH THIS
TIME AND A QUARTER TO HALF AN INCH OF ICE ACCRETION. A TENTH OF AN
INCH OR LESS FROM AROUND THAT LINE.
RAIN SHOWERS MOVE EAST WEDNESDAY MORNING/AFTERNOON WITH WLY/NWLY
GUSTS OF 25 TO 30 KT POSSIBLE THROUGH EVENING.
HIGH PRESSURE THURSDAY/FRIDAY WITH SOME COASTAL LOW DEVELOPMENT
BRINGING CHANCES OF RAIN/SNOW THIS WEEKEND.
&&
.MARINE...
WINDS BLO SCA VALUES TNGT AND TUE. LGT FZRA/FZDZ IS EXPECTED
OVERNIGHT. LIGHT SNOW AND SLEET WILL MIX IN THIS EVENING.
SUB SCA CRIT ONSHORE FLOW CONTINUES TUESDAY NIGHT INTO WEDNESDAY
BEFORE A COLD FRONT MOVES THROUGH. MOSTLY RAIN EXPECTED...THOUGH THE
NORTHERN MD BAY COULD SEE SOME FREEZING RAIN AT TIMES. COLD FRONT
CROSSES THE WATERS AROUND MIDDAY WEDNESDAY WITH WINDS GUSTING 25 TO
30 KT THROUGH WEDNESDAY NIGHT. HIGH PRESSURE THEN THURSDAY AND
FRIDAY BEFORE SOME COASTAL LOW DEVELOPMENT THIS WEEKEND.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...WINTER WEATHER ADVISORY UNTIL NOON EST TUESDAY FOR DCZ001.
MD...WINTER WEATHER ADVISORY UNTIL NOON EST TUESDAY FOR MDZ003>007-
009>011-013-014-016>018-501-502.
WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY
MORNING FOR MDZ003>007-009>011-501-502.
VA...WINTER WEATHER ADVISORY UNTIL NOON EST TUESDAY FOR VAZ025>031-
036>040-042-050>057-501>504.
WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY
MORNING FOR VAZ027-028-030-031-042.
WV...WINTER WEATHER ADVISORY UNTIL NOON EST TUESDAY FOR WVZ050>053-
055-501>506.
WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY
MORNING FOR WVZ050>053-055-501>504.
MARINE...NONE.
&&
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...HAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1023 PM EST MON JAN 31 2011 ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057- 011000- CHESAPEAKE BAY NORTH OF POOLES ISLAND MD- CHESAPEAKE BAY FROM POOLES ISLAND TO SANDY POINT MD- CHESAPEAKE BAY FROM SANDY POINT TO NORTH BEACH MD- CHESAPEAKE BAY FROM NORTH BEACH TO DRUM POINT MD- CHESAPEAKE BAY FROM DRUM POINT MD TO SMITH POINT VA- TIDAL POTOMAC FROM KEY BRIDGE TO INDIAN HEAD MD- TIDAL POTOMAC FROM INDIAN HEAD TO COBB ISLAND MD- TIDAL POTOMAC FROM COBB ISLAND MD TO SMITH POINT VA- PATAPSCO RIVER INCLUDING BALTIMORE HARBOR- CHESTER RIVER TO QUEENSTOWN MD-EASTERN BAY- CHOPTANK RIVER TO CAMBRIDGE MD AND THE LITTLE CHOPTANK RIVER- PATUXENT RIVER TO BROOMES ISLAND MD- TANGIER SOUND AND THE INLAND WATERS SURROUNDING BLOODSWORTH ISLAND-DISTRICT OF COLUMBIA-NORTHERN BALTIMORE-HARFORD- SOUTHERN BALTIMORE-PRINCE GEORGES-ANNE ARUNDEL-CHARLES-ST. MARYS- CALVERT-PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX- ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA- KING GEORGE- 1023 PM EST MON JAN 31 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE MARYLAND PORTION OF THE CHESAPEAKE BAY...TIDAL POTOMAC RIVER...AND ADJACENT COUNTIES IN CENTRAL MARYLAND AND NORTHERN VIRGINIA AS WELL AS THE DISTRICT OF COLUMBIA. .DAY ONE...TONIGHT A WINTER WEATHER ADVISORY IS IN EFFECT TONIGHT FOR LIGHT ICE ACCUMULATIONS. PLEASE REFER TO THE LATEST HAZARD MESSAGE /WSWLWX/ FOR FURTHER DETAILS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THE WINTER WEATHER ADVISORY CONTINUES THROUGH TUESDAY MORNING. A WINTER STORM WATCH IS IN EFFECT FOR BALTIMORE AND HARFORD COUNTIES TUESDAY EVENING THROUGH WEDNESDAY MORNING. PLEASE REFER TO THE LATEST HAZARD MESSAGE /WSWLWX/ FOR FURTHER DETAILS. A SMALL CRAFT ADVISORY LIKELY WILL BE NEEDED ON WEDNESDAY FOR PORTIONS OF THE WATERS. A GALE WARNING MAY BE NEEDED WEDNESDAY NIGHT AND THURSDAY FOR PORTIONS OF THE WATERS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. MDZ003>005-009-010-501-502-VAZ025>031-036>040-042-050-051-501>504- WVZ050>053-055-501>506-011000- WASHINGTON-FREDERICK MD-CARROLL-MONTGOMERY-HOWARD- EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY-AUGUSTA- ROCKINGHAM-SHENANDOAH-FREDERICK VA-PAGE-WARREN-CLARKE-NELSON- ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-LOUDOUN-ORANGE-CULPEPER- NORTHERN FAUQUIER-SOUTHERN FAUQUIER-WESTERN HIGHLAND- EASTERN HIGHLAND-HAMPSHIRE-MORGAN-BERKELEY-JEFFERSON-HARDY- WESTERN GRANT-EASTERN GRANT-WESTERN MINERAL-EASTERN MINERAL- WESTERN PENDLETON-EASTERN PENDLETON- 1023 PM EST MON JAN 31 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN WEST VIRGINIA... NORTHERN AND CENTRAL VIRGINIA...AND CENTRAL AND WESTERN MARYLAND WITH THE EXCEPTION OF GARRETT COUNTY. .DAY ONE...TONIGHT A WINTER WEATHER ADVISORY IS IN EFFECT TONIGHT FOR LIGHT ICE ACCUMULATIONS. PLEASE REFER TO THE LATEST HAZARD MESSAGE /WSWLWX/ FOR FURTHER DETAILS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY A WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL NOON. A WINTER STORM WATCH IS IN EFFECT FOR PORTIONS OF NORTHERN VIRGINIA...THE NORTHERN SUBURBS OF WASHINGTON DC...NORTH-CENTRAL AND AND WESTERN MARYLAND...AND EASTERN WEST VIRGINIA TUESDAY EVENING THROUGH WEDNESDAY MORNING. PLEASE REFER TO THE LATEST HAZARD MESSAGE /WSWLWX/ FOR FURTHER DETAILS. STRONG WINDS ARE EXPECTED ACROSS THE RIDGE TOPS WEDNESDAY NIGHT AND THURSDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
The national radar mosaic for the moment the first event began.
8 winter weather. Local standard time, as filed.
A glaze of ice was reported near Stephens City and also about five miles northeast of Winchester.
A glaze of ice was estimated across Clarke County.
A glaze of ice was reported at Sterling.
A glaze of ice was reported at Broad Run.
A glaze of ice was estimated across Prince William County.
A glaze of ice was reported at Herndon.
Freezing drizzle was reported at Reagan National Airport.
A glaze of ice was reported across much of Loudoun County.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Virginia in 2011Every state in 2011This day in weather historyWarnings in Virginia, February 2011
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 282971, 282973, 282975, 282976, 282977, 282978, 282979, 282950.