Areas of dense fog developed across the Shenandoah Valley and Potomac Highlands as well as portions of northern Virginia during the early morning hours of May 11th. Visibilities were reduced to one quarter mile or less at times.
Every event with a place to put it; 11 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.
Areas of dense fog developed across the Shenandoah Valley and Potomac Highlands as well as portions of northern Virginia during the early morning hours of May 11th. Visibilities were reduced to one quarter mile or less at times.
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 May 10, 7:53 PM EST, 5 hours 7 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 853 PM EDT THU MAY 10 2007 .SYNOPSIS... A WEAK SURFACE TROUGH WILL REMAIN STATIONARY OVER THE MID ATLANTIC THROUGH FRIDAY. A COLD FRONT WILL MOVE SOUTHEAST ACROSS THE REGION EARLY SUNDAY...WITH HIGH PRESSURE BUILDING IN FOR THE FIRST PART OF THE WORK WEEK. A SECOND COLD FRONT IS EXPECTED DURING THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... LINGERING AREAS OF CONVECTION REMAIN ACRS NRN AND WRN PTNS OF THE FCST AREA...E OF SFC TROF WHICH APPEARS TO BE ALG THE ALLEGHENY FNT AT THE MOMENT. MODELS SHOW ENHANCED MOISTURE MVG OFF TO THE E OVERNIGHT ALG WITH A PIECE OF S/W ENERGY. AND STABILIZATION WILL TAKE PLACE AS SFC TEMPS COOL. A GRADUAL DECREASE IN POPS SEEMS IN ORDER. WILL TAKE A FINAL LOOK AT RADAR BEFORE PRODUCT RELEASES AND ADJUST NUMBERS ACCORDINGLY. ACRS SRN ZONES...WILL LIKELY REMOVE MENTION COMPLETELY. RDH. && .SHORT TERM /6 AM FRIDAY THROUGH 6 AM FRIDAY/... AFTERNOON SHOWERS AND THUNDERSTORMS WILL CONTINUE TO FOCUS ALONG THE SURFACE TROUGH SITUATED EAST OF THE BLUE RIDGE DURING THE AFTERNOON TOMORROW. NOT MUCH IN THE WAY OF MID LEVEL FORCING EVIDENT TOMORROW...BUT SURFACE INSTABILITY WILL ONCE AGAIN BE AN ISSUE. HAVE PLACED THE HIGHEST POPS IN THE VICINITY OF THE SURFACE TROUGH. && .LONG TERM /FRIDAY THROUGH THURSDAY/... NORTHERN HEMISPHERIC PATTERN DURING THE PAST 5 DAYS HAS SHIFTED FROM BLOCKED...TO ZONAL ACROSS SOUTHERN CANADA. SUBTROPICAL DEPRESSION ANDREA...AND UPPER LOWS OVER THE EASTERN GREAT LAKES AND TEXAS FORMED AS A RESULT. 12Z NAM/GFS/CANADIAN ALONG WITH 00Z UKMET/EUROPEAN ARE IN FAIRLY GOOD AGREEMENT ON THE SYNOPTIC SCALE IN THE LONG TERM. COLD FRONTS ARE FORECAST TO CROSS THE REGION SUNDAY AND DURING THE MID WEEK...DRIVEN BY WAVES DROPPING THROUGH THE CANADIAN MARITIMES. 00Z MAY 10 500MB GFS ENSEMBLES SHOW ANDREA GETTING PICKED UP BY A WEAK TROUGH IN THE SHORT TERM. WAVES DIVE ACROSS NEW ENGLAND SUNDAY AND THE END OF NEXT WORK WEEK (WITH GOOD AGREEMENT). 00Z MAY 10 ENSEMBLE MOS INDICATE MEAN HIGHS IN THE MID TO UPPER 70S...WITH LOWER 70S ON SUNDAY AND THURSDAY. MEAN LOWS ARE IN THE UPPER 50S SATURDAY MORNING...FALLING INTO THE MID 40S BY MONDAY...BEFORE RISING TO 50 TO 55F THROUGH THE LONG RANGE. MEAN POPS ARE IN THE SLIGHT CHANCE CATEGORY EARLY SUNDAY...AND AGAIN TUESDAY THROUGH THURSDAY. LEANED CLOSER TO 12Z NAM/GFS THAN OLDER 09Z SHORT RANGE ENSEMBLES...WITH CONVECTION RE-FIRING SATURDAY AHEAD OF STEEP COLD FRONT. EXPECT THIS FRONT TO CLEAR SKIES SUNDAY AND LEAD TO COOLER AND DRIER CONDITIONS. A MODERATING TREND IS EXPECTED DURING THE EARLY WORK WEEK...WITH AN INCREASE IN CLOUDS AND CHANCES OF PRECIPITATION DURING THE MID WEEK WITH THE ARRIVAL OF THE NEXT COLD FRONT. && .AVIATION /01Z FRIDAY THROUGH TUESDAY/... LGT SHRA PSBL AT THE BALTIMORE AIRPORTS NEXT FEW HOURS...OTRW NO PRECIP. MVFR FOG EXPECTED TO FORM OVERNIGHT WITH A WET GRND IN SPOTS...60S DEWPTS AND DECREASING WINDS. A WIND SHIFT IS EXPECTED BEHIND THE WEAK SURFACE TROUGH EXPECTED TO MOVE EAST OVER THE REGION TOMORROW. CIGS ARE CURRENTLY VFR OVER THE ENTIRE AREA. SCT TSRA WILL LURK AROUND THE TAF SITES THIS AFTERNOON AND EVENING. THE MODELS ARE FORECASTING FOG TO DEVELOP OVERNIGHT BUT NO STRATUS LAYER. HAVE KEPT LOW CIGS OUT OF THE FORECAST FOR NOW. HOWEVER...HAVE REDUCES VSBYS TO MVFR/VFR IN AREAS EXPECTED TO RECEIVE RAINFALL. HAVE NOT DECREASED THE VSBYS AS MUCH AS THE MODELS ARE FORECASTING...EXPECT WINDS TO REMAIN UP OVERNIGHT. SCATTERED SHOWERS AND THUNDERSTORMS SATURDAY...MOST CONCENTRATED SOUTH OF METRO HUBS CLOSER TO WARM SECTOR. NORTHERLY WIND GUSTS IN A 20 TO 30 KT WINDOW MAY OCCUR SUNDAY WITH THE PASSAGE OF A SECOND COLD FRONT. && .MARINE... WINDS HAVE BEEN A LTL STRONGER THAN EXPECTED OVR THE WATERS. WILL BUMP THEM UP A TAD. STILL BLO SCA CRITERIA HOWEVER. SMALL CRAFT ADVISORY CONDITIONS MAY OCCUR SUNDAY WITH THE PASSAGE OF A SECOND COLD FRONT. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && SYNOPSIS...LISTEMAA NEAR TERM...HITCHENS SHORT TERM...LISTEMAA LONG TERM...ROGOWSKI/LISTEMAA AVIATION...HITCHENS/LISTEMAA MARINE...HITCHENS/LISTEMAA/SJR
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1045 PM EDT THU MAY 10 2007 ANZ530>537-DCZ001-MDZ003>007-009>011-013-014-016>018-501-502- VAZ021-025>031-036>042-050>057-WVZ050>055-501>504-111015- 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- DISTRICT OF COLUMBIA-WASHINGTON-FREDERICK MD-CARROLL- NORTHERN BALTIMORE-HARFORD-MONTGOMERY-HOWARD-SOUTHERN BALTIMORE- PRINCE GEORGES-ANNE ARUNDEL-CHARLES-ST. MARYS-CALVERT- EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY-HIGHLAND- AUGUSTA-ROCKINGHAM-SHENANDOAH-FREDERICK VA-PAGE-WARREN-CLARKE- NELSON-ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-FAUQUIER-LOUDOUN- ORANGE-CULPEPER-PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX- ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA- KING GEORGE-HAMPSHIRE-MORGAN-BERKELEY-JEFFERSON-PENDLETON-HARDY- WESTERN GRANT-EASTERN GRANT-WESTERN MINERAL-EASTERN MINERAL- 1045 PM EDT THU MAY 10 2007 THIS HAZARDOUS WEATHER OUTLOOK IS FOR MARYLAND WEST OF THE EASTERN SHORE INCLUDING THE CHESAPEAKE BAY AND EAST OF GARRETT COUNTY...EASTERN WEST VIRGINIA...NORTHERN AND CENTRAL VIRGINIA... WASHINGTON DC AND THE TIDAL POTOMAC RIVER. .DAY ONE...TONIGHT HAZARDOUS WEATHER IS NOT EXPECTED. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH THURSDAY A SMALL CRAFT ADVISORY MAY BE NEEDED SUNDAY FOR THE TIDAL POTOMAC RIVER AND MARYLAND CHESAPEAKE BAY. .SPOTTER INFORMATION STATEMENT... SKYWARN ACTIVATION WILL NOT BE NECESSARY TONIGHT. RDH
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
820 PM EDT THU MAY 10 2007
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0620 PM TSTM WND DMG FLINTSTONE 39.70N 78.57W
05/10/2007 ALLEGANY MD COUNTY OFFICIAL
TREES AND POWERLINES BLOWN DOWN IN FLINSTONE AND OLDTOWN
&&
HITCHENSThe national radar mosaic for the moment the first event began.
14 dense fog. Local standard time, as filed.
Automated Observations from across the region reported dense fog, reducing visibilities to a quarter mile or less at times on the morning of May 11th.
Automated Observations from Winchester Regional Airport reported dense fog, reducing visibilities to a quarter mile or less at times on the morning of May 11th.
Automated Observations from Shenandoah Valley Regional Airport reported dense fog, reducing visibilities to a quarter mile or less at times on the morning of May 11th.
Automated Observations from Culpeper Regional Airport reported dense fog, reducing visibilities to a quarter mile or less at times on the morning of May 11th.
Automated Observations from across the region reported dense fog, reducing visibilities to a quarter mile or less at times on the morning of May 11th.
Automated Observations from across the region reported dense fog, reducing visibilities to a quarter mile or less at times on the morning of May 11th.
Automated Observations from Leesburg Executive Airport reported dense fog, reducing visibilities to a quarter mile or less at times on the morning of May 11th.
Automated Observations from across the region reported dense fog, reducing visibilities to a quarter mile or less at times on the morning of May 11th.
Automated Observations from across the region reported dense fog, reducing visibilities to a quarter mile or less at times on the morning of May 11th.
Automated Observations from across the region reported dense fog, reducing visibilities to a quarter mile or less at times on the morning of May 11th.
Automated Observations from across the region reported dense fog, reducing visibilities to a quarter mile or less at times on the morning of May 11th.
Automated Observations from across the region reported dense fog, reducing visibilities to a quarter mile or less at times on the morning of May 11th.
Automated Observations from Shenandoah Valley Regional Airport reported dense fog, reducing visibilities to a quarter mile or less at times on the morning of May 11th.
Automated Observations from across the region reported dense fog, reducing visibilities to a quarter mile or less at times on the morning of May 11th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Virginia in 2007Every state in 2007This day in weather historyWarnings in Virginia, May 2007
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: 27210, 27213, 27209, 27211, 27212, 27214, 27215, 27216, 27217, 27218, 27219, 27220, 27221, 27222.