Onshore flow continued in the Mid Atlantic region as high pressure continued to move off the coast. Areas in northeast Maryland and along the Chesapeake Bay had fog throughout the day.
Every event with a place to put it; 4 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.
Onshore flow continued in the Mid Atlantic region as high pressure continued to move off the coast. Areas in northeast Maryland and along the Chesapeake Bay had fog throughout the day. Moisture continued to move inland and impacted areas in Northern Maryland and the panhandle of WV.
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 Dec 17, 5:33 PM EST, 1 hour 2 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
533 PM EST MON DEC 17 2012
.SYNOPSIS...
A STATIONARY BOUNDARY WILL REMAIN OVER THE REGION THIS EVENING.
LOW PRESSURE WILL PASS BY TO THE WEST OVERNIGHT AND THE COLD FRONT
ASSOCIATED WITH THIS SYSTEM IS EXPECTED TO MOVE THROUGH OUR AREA
DURING THIS TIME. BLUSTERY CONDITIONS ARE EXPECTED BEHIND THE
FRONT TUESDAY. HIGH PRESSURE WILL BUILD OVERHEAD WEDNESDAY BEFORE
ANOTHER COLD FRONT MOVES THROUGH THURSDAY. NOTICEABLY CHILLIER
CONDITIONS ARE EXPECTED BEHIND THE FRONT LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
UPDATED DENSE FOG ADVISORY TO EXPAND THE HEADLINE FARTHER
WEST/SOUTH INTO THE WRN SUBURBS OF BALTIMORE...DC...NOVA AND ERN
SUBURBS OF FREDERICKSBURG INTO LWR SRN MD. VSBYS DROPPED DOWN TO
1/2SM NEAR SUNSET IN THESE LOCATIONS...WITH REPORTS OF AT LEAST
PATCHY DENSE FOG ALREADY. EXPECT DENSE FOG TO BECOME MORE
WIDESPREAD IN THE ADVISORY AREA. A TEMPORARY IMPROVEMENT OF VSBYS
STILL POSSIBLE FOR A FEW HRS DURING THE SECOND HALF OF THE EVE IF
SHOWERS DVLP AS EXPECTED.
PREVIOUS DISCUSSION...
LOW PRESSURE WILL PASS THROUGH THE OHIO VALLEY THIS EVENING
BEFORE MOVING INTO THE EASTERN GREAT LAKES OVERNIGHT.
SHOWERS ASSOCIATED WITH THE LOW WILL HAVE ALREADY MOVED INTO WEST
VIRGINIA THIS AFTERNOON WHILE ANOTHER AREA OF SHOWERS ASSOCIATED
WITH AN UPPER-LEVEL JET AND DEEP MOISTURE MOVES THROUGH THE
CAROLINAS. OUR CWA WILL REMAIN SPLIT BETWEEN THESE TWO DISTINCT
AREAS OF PRECIPITATION. HOWEVER...THERE SHOULD BE ENOUGH OVERRUNNING
AND LIFT FOR SHOWERS TO FILL IN ACROSS OUR AREA LATE THIS AFTERNOON
AND EVENING. RAINFALL AMOUNTS SHOULD BE LIGHT...GENERALLY LESS THAN
A QUARTER INCH. HOWEVER...LOCALIZED AMOUNTS AROUND ONE HALF INCH ARE
POSSIBLE ESPECIALLY ACROSS THE ALLEGHENY AND POTOMAC HIGHLANDS INTO
NORTHERN MARYLAND.
THE COLD FRONT ASSOCIATED WITH THE LOW WILL PASS THROUGH THE REGION
LATE TONIGHT. A FEW LINGERING SHOWERS ARE POSSIBLE OVERNIGHT AS THE
COLD FRONT MOVES THROUGH. PRECIPITATION OVERNIGHT WILL BE LIGHT. THE
BEST CHANCE FOR PRECIPITATION WILL BE ACROSS THE ALLEGHENY AND
POTOMAC HIGHLANDS DUE TO AN UPSLOPE FLOW BEHIND THE FRONT.
A DENSE FOG ADVISORY IS IN EFFECT FOR NORTHEASTERN MARYLAND THROUGH
TONIGHT. THE INVERSION REMAINS STRONG AND VSBYS REMAIN AROUND ONE
QUARTER MILE. THE DENSE FOG ADVISORY MAY BE NEEDED EXTENDED FOR
OTHER AREAS...ESPECIALLY ACROSS THE REST OF NORTHERN MARYLAND...THE
WASHINGTON METROPOLITAN AREA...PORTIONS OF THE EASTERN WEST VIRGINIA
PANHANDLE AND THE VIRGINIA PIEDMONT. WILL CONTINUE TO MONITOR VSBYS
LATE THIS AFTERNOON/EVENING.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
TUESDAY...
THE COLD FRONT WILL PUSH OFF TO THE EAST TUESDAY. STRONG COLD
ADVECTION IS EXPECTED BEHIND THE FRONT WHICH WILL CAUSE A BKN
STRATOCU DECK TO DEVELOP. ISOLATED/SCATTERED SHOWERS CANNOT BE RULED
OUT...ESPECIALLY LATE TUESDAY MORNING/AFTERNOON. ANY PRECIPITATION
WILL BE LIGHT. MAX TEMPS WILL REMAIN ABOVE CLIMO DUE TO SOME
SUNSHINE AND A DEEP MIXING LAYER. MAX TEMPS WILL RANGE FROM THE 30S
IN THE HIGHLANDS TO THE LOWER 60S ACROSS PORTIONS OF THE VIRGINIA
PIEDMONT. FOR LOCATIONS ALONG AND WEST OF THE ALLEGHENY FRONT...AN
UPSLOPE FLOW WILL TRIGGER MORE SHOWERS. SNOW SHOWERS ARE EXPECTED TO
DEVELOP LATER TUESDAY MORNING AND AFTERNOON AS COLDER AIR WORKS ITS
WAY IN FROM THE WEST. SNOWFALL ACCUMULATIONS SHOULD BE LIGHT.
WEDNESDAY/THURSDAY...
WED AND THE BETTER PART OF THU WILL BE THE HIGH PRESSURE DAYS IN
BETWEEN SYSTEMS...SIMILAR SYSTEMS AT THAT. THE NEXT LOW PRESSURE
SYSTEM HOWEVER WILL BE MORE POTENT...WILL DEVELOP (AND
SUBSEQUENTLY MAX-OUT) FURTHER WEST AND WILL THEREFORE BE MORE
IMPACTFUL TO THE MID ATLC REGION. PRECIP WILL STILL BE ALL-RAIN
OUTSIDE OF THE MTNS...SIMILAR TO THE CURRENT INCOMING LOW PRESSURE
SYSTEM - BUT EXPECTING MORE RAIN AND A WINDIER PASSAGE BEHIND THE
FRONT.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THE FEATURE WILL TAKE SHAPE OVER THE CNTRL PLAINS...POTENTIALLY
CREATING A WINTRY SCENARIO OVER A STRIPE FROM THE ROCKIES TO THE
WRN GREAT LAKES WED AND THU. DURING THIS TIME...THE MID ATLC WILL
BE UNDER MOSTLY CLEAR SKIES AND RECEIVING ABNORMALLY WARM TEMPS.
THE LOW'S INTENSITY WILL PEAK AS IT SLIDES ACROSS THE GREAT LAKES
ON THU...WHILE THE WARM SECTOR OF THE SYSTEM DRIFTS TOWARD THE
AREA. THIS LARGE LOW PRESSURE SYSTEM WILL EXTEND FROM THE GREAT
LAKES TO THE GULF COAST W/ A STRONG COLD FRONT TRUDGING ACROSS THE
DEEP SOUTH AND TOWARD THE APLCNS THU EVE.
MORE QPF EXPECTED W/ THE PASSAGE OF THIS SYSTEM. AT THIS
POINT...NOT EXPECTING SUBSTANTIAL RAINFALL AMOUNTS...BUT IN THE
NEIGHBORHOOD OF A HALF-INCH TO AN INCH OVER A SEVERAL HR PERIOD
WED NIGHT. AS PRECIP IS ENDING OVER THE SHENANDOAH
VLY/PIEDMONT/COASTAL AREAS...COLD AIR ADVECTION WILL BE ARRIVING
FROM THE NW AND BRIEFLY TURNING RAIN INTO SNOW ACROSS THE HIGHER
TERRAIN OF THE APLCNS.
CONDITIONS ACROSS OUR REGION WILL GO FROM WARM/MOIST AIR ON THU
AFTN TO WINDY AND DRY ON FRI. THE FRONT WILL MOVE ACROSS THE AREA
LATE THU NIGHT INTO THE EARLY MRNG HRS FRI. AS SKIES CLEAR OUT FRI
MRNG...WINDS WILL INCREASE AND STAY WINDY ALL-DAY AND INTO THE
LATE NIGHT HRS. ANOTHER DRY AND BREEZY DAY ON SAT...BUT THEN THE
EXTEND VIEW SHOWS A HANDFUL OF QUIET HIGH PRESSURE DAYS OVER OUR
AREA TO START THE COMING WEEK - AS ANOTHER STORM SYSTEM DEVELOPS
ACROSS THE PLAINS.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
A STRONG INVERSION NORTH OF A STATIONARY BOUNDARY HAS CAUSED
CIGS/VSBYS TO REMAIN LOW THIS AFTERNOON. LITTLE IF ANY IMPROVEMENT
IS EXPECTED LATE THIS AFTERNOON.
LOW PRESSURE WILL PASS BY TO THE WEST TONIGHT. SHOWERS WILL
OVERSPREAD MOST LOCATIONS BETWEEN 00Z-04Z THIS EVENING. IFR/SUBIFR
CIGS/VSBYS ARE EXPECTED DURING THIS TIME...ALTHOUGH A BRIEF
IMPROVEMENT OF VSBYS POSSIBLE IN SHRA. LOW CLOUDS AND FOG WILL HANG
AROUND OVERNIGHT...BUT A PASSING COLD FRONT MAY CAUSE CONDITIONS
TO IMPROVE TOWARD DAYBREAK.
DRIER AIR BEHIND THE FRONT WILL ALLOW FOR VFR CONDITIONS TUESDAY
ONCE ANY LEFTOVER LOW CLOUDS/FOG BURN OFF EARLY.
HOWEVER...WEST-NORTHWEST WINDS WILL FREQUENTLY GUST AROUND 20-25
KNOTS LATE TUESDAY MORNING/AFTERNOON. A BKN STRATOCU DECK IS ALSO
EXPECTED TO DEVELOP...BUT CIGS SHOULD REMAIN ABOVE 3KFT.
HIGH PRESSURE WILL GIVE THE AREA A QUIET WED W/ MAINLY CLEAR SKIES
AND LIGHT WINDS. THU DAYTIME WILL BE THE BUILD-UP TO A STRONG
FRONTAL PASSAGE LATER ON THAT NIGHT. WINDS WILL INCREASE OUT OF THE
SE...SKIES WILL FILL UP W/ MID AND LOW CLOUDS OVER THE COURSE OF THE
DAY. RAIN WILL OVERSPREAD THE REGION LATE THU EVE...JUST AHEAD OF A
STRONG COLD FRONT. THE FRONT WILL SWEEP ACROSS THE AREA DURING THE
OVERNIGHT HRS...DRYING OUT THE AREA QUICKLY HEADING INTO FRI
MRNG...BUT WINDS WILL ALSO BE ON THE INCREASE - ESPECIALLY AFTER
DAYBREAK FRI. GUSTY WLY WINDS WILL AFFECT THE AREA ALL-DAY AND INTO
THE EVE. A BRIEF DROP OFF OVERNIGHT BUT ANOTHER BREEZY DAY ON SAT
AND A TIER LOWER ON SUN BUT STILL BREEZY.
&&
.MARINE...
LOW PRESSURE WILL PASS BY TO THE NORTHWEST LATE THIS AFTERNOON
THROUGH TONIGHT. AN INCREASING GRADIENT WILL CAUSE SOUTH-SOUTHEAST
WINDS TO INCREASE DURING THIS TIME. WILL HAVE TO MONITOR FOR A
POTENTIAL SMALL CRAFT ADVISORY ACROSS PORTIONS OF THE CHESAPEAKE BAY
AND LOWER TIDAL POTOMAC. HAVE WIND GUSTS CAPPED AROUND 15 KNOTS FOR
NOW DUE TO THE RELATIVELY COOLER WATERS.
WINDS WILL SHIFT TO THE WEST-NORTHWEST TUESDAY BEHIND A COLD FRONT.
A SMALL CRAFT ADVISORY IS IN EFFECT FOR ALL OF THE WATERS.
THE MAIN FEATURE OF NOTE FOR THE EXTENDED FORECAST WILL BE A STRONG
LOW PRESSURE SYSTEM TO CLOSE OUT THE WEEK. WINDS WILL PICK UP OUT OF
THE SE ON THU AFTN...INCREASING AHEAD OF A STRONG COLD FRONT. THE
FRONT WILL CROSS THE WATERS LATE THU NIGHT INTO EARLY FRI MRNG. SCA
CONDITIONS POSSIBLE ON WED...EXPECTED ON THU AND GALE CONDITIONS
WILL BE POSSIBLE ON FRIDAY BEHIND THE FRONTAL PASSAGE. STILL WINDY
THIS WEEKEND BUT NOT AS BREEZY AS ON FRI...STAYING IN THE SOLID SCA
RANGE BOTH DAYS.
&&
.TIDES/COASTAL FLOODING...
ONSHORE FLOW HAS CAUSED TIDAL ANOMALIES AROUND ONE TO ONE AND ONE
HALF FEET ABOVE NORMAL. THE ONSHORE FLOW WILL INCREASE LATE THIS
AFTERNOON INTO TONIGHT. TIDAL ANOMALIES SHOULD INCREASE...CAUSING
MINOR TIDAL FLOODING FOR SENSITIVE AREAS AROUND HIGH TIDE. A COASTAL
FLOOD ADVISORY IS IN EFFECT FOR ANNE ARUNDEL...CALVERT AND ST MARYS
COUNTIES ALONG THE WESTERN SHORE OF THE CHESAPEAKE BAY AND ALSO FOR
WASHINGTON DC AND ALEXANDRIA ALONG THE SHORE OF THE TIDAL POTOMAC
RIVER.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...DENSE FOG ADVISORY UNTIL 6 AM EST TUESDAY FOR DCZ001.
COASTAL FLOOD ADVISORY UNTIL 3 AM EST TUESDAY FOR DCZ001.
MD...DENSE FOG ADVISORY UNTIL 6 AM EST TUESDAY FOR MDZ004>007-
009>011-013-014-016>018.
COASTAL FLOOD ADVISORY UNTIL 3 AM EST TUESDAY FOR MDZ014-017-
018.
VA...DENSE FOG ADVISORY UNTIL 6 AM EST TUESDAY FOR VAZ042-052>055-
057-501-502.
COASTAL FLOOD ADVISORY UNTIL 3 AM EST TUESDAY FOR VAZ054.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM TUESDAY TO 6 AM EST WEDNESDAY
FOR ANZ532>534-537-540>543.
SMALL CRAFT ADVISORY FROM 10 AM TO 7 PM EST TUESDAY FOR ANZ530-
531-535-536-538-539.
&&
UPDATE...KLEIN
PREV DISC...BJL/GMSHAZARDOUS WEATHER OUTLOOK...CORRECTED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 547 PM EST MON DEC 17 2012 ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057- 181045- 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- 547 PM EST MON DEC 17 2012 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 DENSE FOG ADVISORY IS IN EFFECT THROUGH THE OVERNIGHT FOR THE AREA. A COASTAL FLOOD ADVISORY IS IN EFFECT UNTIL 3 AM FOR ANNE ARUNDEL...CALVERT AND ST MARYS COUNTY ALONG THE WESTERN SHORE OF THE CHESAPEAKE BAY AND ALSO FOR WASHINGTON DC AND ALEXANDRIA ALONG THE SHORE OF THE TIDAL POTOMAC RIVER. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY A SMALL CRAFT ADVISORY IS IN EFFECT TUESDAY FOR THE WATERS. A SMALL CRAFT ADVISORY IS IN EFFECT TUESDAY NIGHT FOR THE MARYLAND CHESAPEAKE BAY FROM SANDY POINT TO SMITH POINT AND FOR THE LOWER TIDAL POTOMAC RIVER FROM COBB ISLAND TO SMITH POINT. A SMALL CRAFT ADVISORY MAY BE NEEDED FOR PORTIONS OF THE WATERS WEDNESDAY AND THURSDAY. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED FRIDAY AND A GALE WARNING MAY ALSO BE NEEDED FRIDAY. .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>506-181045- 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- 547 PM EST MON DEC 17 2012 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 DENSE FOG ADVISORY IS IN EFFECT THROUGH THE OVERNIGHT FOR THE GREATER WASHINGTON DC AND BALTIMORE METROPOLITAN AREA. A DENSE FOG ADVISORY MAY BE NEEDED FOR OTHER PORTIONS OF THE AREA. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
The national radar mosaic for the moment the first event began.
4 dense fog. Local standard time, as filed.
Visibility was reported around a quarter mile at Culpeper airport.
Visibility was reported around a quarter mile at Charlottesville airport.
Visibility was estimated around a quarter mile at Charlottesville airport.
Visibility was estimated around a quarter mile at Charlottesville airport.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Virginia in 2012Every state in 2012This day in weather historyWarnings in Virginia, December 2012
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: 426932, 426933, 426934, 426935.