A surface trough was draped across the Mid Atlantic from the panhandle of WV through North-Central Maryland and Northern Virginia and then Southern Maryland. Fog persisted along the I-95 corridor through the daytime and dense fog continued overnight especially for areas along and near the Chesapeake Bay.
Every event with a place to put it; 6 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.
A surface trough was draped across the Mid Atlantic from the panhandle of WV through North-Central Maryland and Northern Virginia and then Southern Maryland. Fog persisted along the I-95 corridor through the daytime and dense fog continued overnight especially for areas along and near the Chesapeake Bay.
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 8, 8:43 PM EST, 26 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 843 PM EST SAT DEC 8 2012 .SYNOPSIS... A COLD FRONT WILL PASS THROUGH THE REGION TONIGHT BEFORE STALLING TO OUR SOUTH SUNDAY. THE BOUNDARY WILL LIFT NORTH AS A WARM FRONT SUNDAY NIGHT INTO MONDAY. A STRONGER COLD FRONT WILL PASS THROUGH THE AREA MONDAY NIGHT AND HIGH PRESSURE WILL BUILD OVERHEAD BEHIND THIS BOUNDARY FOR THE MIDDLE PORTION OF NEXT WEEK. && .NEAR TERM /THROUGH SUNDAY/... PATCHY DENSE FOG WILL CONTINUE THROUGH LATE THIS EVENING...ESPECIALLY FOR LOCATIONS NEAR THE CHESAPEAKE BAY. FOG WILL LIKELY LIFT OVERNIGHT NIGHT AS A COLD FRONT MOVES THROUGH. A COLD FRONT WILL PASS THROUGH THE REGION AFTER MIDNIGHT. THE BOUNDARY IS EXPECTED TO STALL OUT ACROSS SOUTHERN VIRGINIA BY SUNDAY MORNING. CLOUDS WILL CONTINUE TO INCREASE THIS EVENING AHEAD OF THE COLD FRONT. A BAND OF SHOWERS ACROSS NORTHERN VA INTO THE POTOMAC HIGHLANDS WILL WEAKEN AS THEY HEAD SOUTHEAST LATE THIS EVENING. HOWEVER...ISENTROPIC LIFT WILL INCREASE BEHIND THE BOUNDARY LATE TONIGHT ALLOWING FOR STEADIER PRECIPITATION TO DEVELOP TOWARD MORNING ACROSS THE POTOMAC HIGHLANDS...NORTHERN VIRGINIA...EASTERN WEST VIRGINIA AND NORTHERN MARYLAND. FURTHER SOUTH ACROSS CENTRAL VA AND LOWER SOUTHERN MD...DRY CONDITIONS WILL LIKELY PERSIST THROUGH TONIGHT. MIN TEMPS WILL BE A BIT COOLER BEHIND THE BOUNDARY....RANGING FROM NEAR 40 ACROSS PORTIONS OF NORTHERN MARYLAND TO NEAR 50 ACROSS PORTIONS OF CENTRAL VIRGINIA. THE BOUNDARY WILL REMAIN STALLED TO OUR SOUTH ACROSS SOUTHERN VIRGINIA SUNDAY. STEADIER RAIN ACROSS THE NORTHERN CWA DUE TO ISENTROPIC LIFT IS EXPECTED SUNDAY MORNING BEFORE SHIFTING OUR NORTH BY SUNDAY AFTERNOON. HOWEVER...AN ONSHORE FLOW WILL CAUSE LOW CLOUDS ALONG WITH AREAS OF FOG AND DRIZZLE ALL DAY SUNDAY. MAX TEMPS WILL BE NOTICEABLY COOLER COMPARED TO SATURDAY DUE TO THE CLOUD COVER. MAX TEMPS WILL RANGE FROM THE 40S ACROSS NORTHERN AND CENTRAL MARYLAND AS WELL AS NORTHERN VIRGINIA TO THE LOWER AND MIDDLE 50S ACROSS CENTRAL VIRGINIA INTO LOWER SOUTHERN MARYLAND. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... AN UPR TROUGH...WITH THE POSITIVELY TILTED AXIS DOWN THE LENGTH OF THE GREAT PLAINS...SUNDAY NIGHT WILL SHIFT NORTHEAST ACROSS THE MIDWEST AS A REINFORCING TROUGH DIGS IN ACROSS THE GREAT PLAINS THROUGH THE MIDDLE OF THE WEEK. SFC LOW CENTER FROM THE FIRST TROUGH WILL MOVE NORTHEAST ACROSS OHIO SUNDAY NIGHT AND ACROSS NEW ENGLAND MONDAY. LARGE PLUME OF GULF MOISTURE SOUTH OF THIS FEATURE. THE ASSOCIATED SFC TROUGH/COLD FRONT WILL BE SLOW TO PUSH SOUTHEAST THROUGH THE CENTRAL MID ATLANTIC MONDAY EVENING THROUGH TUESDAY MORNING. SUNDAY NIGHT...CWA IS IN THE WARM SECTOR OF THE LARGE SCALE PATTERN WITH SLY FLOW AND MOISTURE INFLUX. ISENTROPIC LIFT LOOKS BETTER IN THE FIRST HALF OF THE NIGHT IN BOTH THE 12Z GFS AND 00Z ECMWF...SO CHANCE POPS WERE REINTRODUCED FOR THE LATE EVENING HOURS ACROSS MOST OF THE CWA...LIKELIES ALONG/WEST OF THE ALLEGHENY FRONT. JUST SOME LIGHT RAIN SHOWERS FROM LOW CLOUDS. WENT WITH A MAV/MET BLEND FOR MIN TEMP BLEND WITH MID 40S WEST OF THE BLUE RIDGE AND MD/VA PIEDMONT... AROUND 50F COASTAL PLAINS. MONDAY...PREFRONTAL MODERATE TO LOCALLY HEAVY RAIN SHOWERS SHIFT EAST FROM THE ALLEGHENY FRONT TO THE BLUE RIDGE IN THE AFTERNOON. BUMPED UP POPS TO CATEGORICAL/100 WEST OF ALLEGHENY FRONT. WITH RAIN OVER RECENT DAYS MAINLY LIGHT...NO FLOODING IS EXPECTED OUT WEST...JUST A GOOD SOAKING RAIN. SCATTERED LIGHT SHOWERS EAST OF THE BLUE RIDGE. MAX TEMPS HAVE A GREAT POTENTIAL WITH 12C 850MB TEMPS EAST OF THE BLUE RIDGE. CLOUDS AND SHALLOWER MIXING WILL KEEP 80F AT BAY /IF 12C 850 TEMPS MIXED DOWN IN SUNNY SKIES/...BUT LOW 70S ARE POSSIBLE AROUND KEZF AND SRN MD WHERE RAIN WILL HOLD OUT LONGEST. MID TO UPR 60S ACROSS THE BALT-WASH METRO...LOW TO MID 60S FARTHER WEST /THOUGH THAT WILL DEPEND ON RAIN TIMING/. MONDAY NIGHT...CATEGORICAL POPS ACROSS THE BALT-WASH METRO EVEN AS INTENSITIES DECREASE/UPR FORCING SHIFTS NE ACROSS THE UPR MID-ATLANTIC. QPF ONE TO TWO TENTHS EAST OF THE BLUE RIDGE. MIN TEMPS && .LONG TERM /TUESDAY THROUGH SATURDAY/... UPR TROUGHING PERSISTENT OVER THE CENTRAL CONUS WILL KEEP THE SFC TROUGH FROM PUSHING TOO QUICKLY INTO THE SRN MID-ATLANTIC...AS WELL AS PREVENT A TYPICAL UPSLOPE SNOW EVENT. MAINTAINED CHANCE POPS FOR SERN HALF OF THE CWA FOR TUESDAY MORNING. COLD AIR SPILLING INTO THE APPALACHIANS SHOULD ENABLE SNOW ABOVE ABOUT 2500 FT LATER MONDAY NIGHT THROUGH TUESDAY...THOUGH MOISTURE WILL BE DECREASING THROUGH THIS TIME. STILL ABOVE NORMAL TEMPERATURES WITH COLD AIR SLOWLY COMING IN FROM THE WEST THROUGH TUESDAY. MID-CONTINENTAL HIGH PRESSURE EXPECTED TO BUILD ACROSS THE MID-ATLANTIC LATE TUESDAY THROUGH WEDNESDAY AND THEN PERSIST THROUGH THE END OF THE WORK WEEK. EXPECT JUST ABOVE NORMAL TEMPS WITH ABUNDANT SUNSHINE /PROBABLY JUST SOME PERIODS OF HIGH CLOUDS/ AND DRY CONDITIONS THROUGH THIS TIME. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... SUBIFR CIGS/VSBYS DUE TO LOW CLOUDS AND FOG CONTINUE ACROSS KMTN AND KBWI THIS EVENING. A COLD FRONT WILL PASS THROUGH THE TERMINALS OVERNIGHT. A LIGHT NORTHERLY FLOW WILL ALLOW FOR CIGS/VSBYS TO IMPROVE AFTER THE FRONTAL PASSAGE. HOWEVER...WINDS ARE EXPECTED TO VEER TOWARD THE EAST SUNDAY. THE ONSHORE FLOW WILL CAUSE IFR/SUBIFR CIGS AND VSBYS TO DEVELOP. TIMING OF THE IFR CONDITIONS REMAINS UNCERTAIN. CURRENT FORECAST IS FOR IFR CONDITIONS TO ARRIVE LATE MORNING/EARLY AFTERNOON. HOWEVER...THERE IS A POSSIBILITY THAT IFR CONDITIONS COULD ARRIVE CLOSER TO 12Z IF THE FLOW TURNS EAST QUICKER THAN EXPECTED BEHIND THE BOUNDARY. A COLD FRONT APPROACHES THE TERMINALS SUNDAY NIGHT THROUGH MONDAY...CROSSING MONDAY NIGHT INTO TUESDAY. IFR CIGS SUNDAY NIGHT IN SLY FLOW...SLY/WLY FLOW MONDAY GUSTING AROUND 20 KT...WHEN 20 KT NW GUSTS ON TUESDAY. HIGH PRESSURE/VFR THEN MID/LATE NEXT WEEK. && .MARINE... LIGHT AND VARIABLE WINDS WILL SHIFT TOWARD THE NORTHEAST BEHIND A COLD FRONT TOWARD SUNDAY MORNING. WINDS WILL GUST CLOSE TO SCA BEHIND THE COLD FRONT SUNDAY MORNING. HAVE CAPPED GUSTS AROUND 15 KNOTS FOR NOW DUE TO THE RELATIVELY COOLER WATERS. WINDS WILL VEER TOWARD THE EAST SUNDAY AFTERNOON WITH GUSTS AROUND 10 TO 15 KNOTS. A COLD FRONT APPROACHES THE WATER SUNDAY NIGHT THROUGH MONDAY... CROSSING LATE MONDAY NIGHT INTO TUESDAY. SLY/SWLY FLOW MONDAY GUSTING AROUND 20 KT...WHEN 20 KT NW GUSTS ON TUESDAY. SCA LIKELY FOR BOTH DAYS. NLY/NELY FLOW THEN THROUGH MIDWEEK AS A HIGH BUILDS IN FROM THE WEST. && .EQUIPMENT... THE PIKESVILLE NWR TRANSMITTER IS NOW BACK IN SVC. IT WILL GO DOWN AGN TUESDAY DECEMBER 12TH AND WEDNESDAY DECEMBER 13TH FOR AN ANTENNA REPLACEMENT. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && PRODUCTS...LASORSA/SDG/BAJ
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 632 PM EST SAT DEC 8 2012 ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057- 091000- 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- 632 PM EST SAT DEC 8 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 NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED MONDAY AND TUESDAY FOR 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>506-091000- 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- 632 PM EST SAT DEC 8 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 NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 409 PM EST SAT DEC 8 2012 MDZ006-007-011-082300- NORTHERN BALTIMORE-HARFORD-SOUTHERN BALTIMORE- INCLUDING THE CITY OF...BALTIMORE 409 PM EST SAT DEC 8 2012 DENSE FOG IS BEING OBSERVED IN HARFORD COUNTY...ESPECIALLY IN THE PART OF THE COUNTY ALONG I-95 BETWEEN ABINGDON AND HAVRE DE GRACE...AND JUST WEST OF I-95 ALONG CHURCHVILLE ROAD (ROUTE 22) AND LEVEL ROAD (ROUTE 155). MOTORISTS ARE URGED TO USE EXTREME CAUTION WHEN DRIVING IN NORTHEASTERN HARFORD COUNTY FOR THE REMAINDER OF THE AFTERNOON...AND BE PREPARED FOR RAPID REDUCTIONS IN VISIBILITY.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 558 PM EST SAT DEC 8 2012 MDZ006-007-011-090100- NORTHERN BALTIMORE-HARFORD-SOUTHERN BALTIMORE- INCLUDING THE CITY OF...BALTIMORE 558 PM EST SAT DEC 8 2012 DENSE FOG IS BEING OBSERVED IN HARFORD COUNTY...ESPECIALLY IN THE NORTHEASTERN PART OF THE COUNTY ALONG I-95 BETWEEN ABINGDON AND HAVRE DE GRACE...ALONG CHURCHVILLE ROAD (ROUTE 22) AND LEVEL ROAD (ROUTE 155) WEST TO ROUTE 1. MOTORISTS ARE URGED TO USE EXTREME CAUTION WHEN DRIVING IN NORTHEASTERN HARFORD COUNTY THIS EVENING ...AND BE PREPARED FOR RAPID REDUCTIONS IN VISIBILITY.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 802 PM EST SAT DEC 8 2012 MDZ006-007-011-090245- NORTHERN BALTIMORE-HARFORD-SOUTHERN BALTIMORE- INCLUDING THE CITY OF...BALTIMORE 802 PM EST SAT DEC 8 2012 PATCHY DENSE FOG IS BEING OBSERVED IN THE NORTHEASTERN PORTION OF HARFORD COUNTY ALONG I-95 BETWEEN ABINGDON AND HAVRE DE GRACE...ALONG CHURCHVILLE ROAD (ROUTE 22) AND LEVEL ROAD (ROUTE 155) WEST TO ROUTE 1. MOTORISTS ARE URGED TO USE EXTREME CAUTION WHEN DRIVING IN NORTHEASTERN HARFORD COUNTY THIS EVENING...AND BE PREPARED FOR RAPID REDUCTIONS IN VISIBILITY.
The national radar mosaic for the moment the first event began.
7 dense fog. Local standard time, as filed.
Visibility was reported to be around one quarter mile at Martins State and York airports.
Visibility was reported to be around one quarter mile at Martins State Airport.
Visibility was reported to be around one quarter mile at Martins State Airport.
Visibility was reported to be around one quarter mile at Baltimore Washington and Fort Meade Airport.
Visibility was reported to be around one quarter mile at St Mary's Airport.
Visibility was reported to be around one quarter mile at St Mary's and Fort Meade Airports.
Visibility was reported to be around one quarter mile at St Mary's Airport.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Maryland in 2012Every state in 2012This day in weather historyWarnings in Maryland, 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: 425857, 425858, 425859, 425861, 425860, 425863, 425865.