An upper level low pressure system drifted slowly from New England towards the Great Lakes for several days. This combined with a weak surface trough to trigger scattered showers and thunderstorms across the Mid Atlantic.
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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.
An upper level low pressure system drifted slowly from New England towards the Great Lakes for several days. This combined with a weak surface trough to trigger scattered showers and thunderstorms across the Mid Atlantic. One storm over Allegany County produced damaging winds.
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 Jul 27, 12:42 PM EST, 1 hour 3 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 142 PM EDT FRI JUL 27 2007 .SYNOPSIS... HIGH PRESSURE REMAINS OFF THE MID-ATLANTIC COAST...WHILE AN UPPER LEVEL STORM REMAINS OVER THE GREAT LAKES. THE UPPER LOW WILL FINALLY BE KICKED TO THE EAST AND WILL MOVE THROUGH NEW ENGLAND THIS WEEKEND. A COLD FRONT WILL MOVE IN FROM THE WEST ON SATURDAY AND PASS SLOWLY ACROSS THE AREA THROUGH MONDAY. HIGH PRESSURE WILL EXTEND OVER US FROM THE NORTH BY THE MIDDLE OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATED FORECAST ISSUED TO INCLUDE SEVERE THUNDERSTORM WATCH 556. LATE MORNING RADAR AND VISIBLE SATELLITE IMAGERY INDICATED A MESOSCALE CONVECTIVE SYSTEM MOVING ACROSS SOUTHEAST OHIO...SOUTHWEST PENNSYLVANIA AND NORTHERN WEST VIRGINIA. MEANWHILE...WATER VAPOR IMAGERY SHOWED AN UPPER LOW SPINNING NEAR THE EASTERN GREAT LAKES. 12Z NAM GUIDANCE SUGGESTS THAT THE MESOSCALE CONVECTIVE SYSTEM WILL CONTINUE TO MOVE EAST INTO EARLY AFTERNOON...BUT LIKELY LOSES SOME OF ITS INTENSITY. BASED ON RADAR IMAGERY AND 12Z GUIDANCE HAVE ADJUSTED POP/WX/QPF GRIDS FOR COVERAGE AND TIMING CHANGES OF CONVECTION WEST OF THE BLUE RIDGE. MORE INTERESTING WILL BE WHATEVER NEW CONVECTION INITIATES ALONG AND EAST OF THE BLUE RIDGE DURING THE MID TO LATE AFTERNOON. 12Z KIAD RAOB MODIFIED FOR 90/66 SHOWS MODERATE INSTABILITY THIS AFTERNOON...WITH SFC BASED CAPE 2K TO 2.5 J/KG AND LAPSE RATES ABOVE 7C/KM. IN ADDITION TO INSTABILITY...BOTH MOISTURE AND LIFT WILL BE IN PLACE TO SUPPORT CONVECTION. PRECIPITABLE WATERS ARE AROUND 1.5 INCHES...AND ENHANCED LIFT FROM SHORTWAVE ENERGY/PVA WILL SWING THROUGH LATER THIS AFTERNOON. EXPECT VARIOUS MESOSCALE BOUNDARIES TO ALSO BE IN PLACE (IE...REMNANT MCS BOUNDARY...LEE TROUGH...AND BAY BREEZE). SHEAR IS FORECAST TO BE RELATIVELY WEAK...GENERALLY LESS THAN 20 KT IN THE 0 TO 6 KM LAYER. HOWEVER...A HIGH CAPE ENVIRONMENT WILL SUPPORT AT LEAST ISOLATED SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING. WILL INSERT SEVERE WORDING IN UPDATED HWO. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... CONVECTION WILL PROPAGATE EAST THROUGH THE EVENING. EXPECT LINGERING POPS THROUGH THE ENTIRE NIGHT AS ADDITIONAL SHORTWAVE ENERGY SWINGS THROUGH. LOSS OF HEATING AND LOWER CAPES WILL REDUCE SEVERE RISK LATER AT NIGHT...BUT ELEVATED INSTABILITY WILL KEEP THE THREAT OF THUNDER GOING. && .LONG TERM /SATURDAY THROUGH THURSDAY/... SATURDAY AND SATURDAY NIGHT THE AXIS OF INSTAB AND MOISTURE WILL MOVE CLOSER TO THE AREA. BEST CHC OF SHOWERS AND THUNDERSTORMS WILL CONTINUE TO BE WEST...LESSER CHC EAST. SUNDAY THROUGH MONDAY...THE TROUGH OF LOW PRESSURE WILL REMAIN OVER THE REGION WHILE A COLD FRONT SLOWLY APPROACHES FROM THE GREAT LAKES. HOWEVER...THIS FRONT WILL BE VERY SLOW TO MOVE THROUGH OUR REGION THANKS TO THE STRONG HIGH OVER THE WESTERN ATLANTIC. MODEL GUIDANCE CONTINUES TO SHOW A WAVE OF LOW PRESSURE DEVELOPING ALONG THIS FRONT OVER OUR REGION. THIS COULD RESULT IN MORE WIDESPREAD SHOWER/T-STORM ACTIVITY. MONDAY NIGHT THROUGH THURSDAY NIGHT...THE COLD FRONT WILL FINALLY PUSH EAST BUT IT WILL LIKELY STALL ALONG THE MID ATLANTIC COAST. CURRENT THINKING IS THAT ENOUGH DRY AIR CAN PUSH IN FROM THE NORTHWEST BEHIND THE FRONT FOR DRY CONDITIONS ACROSS MOST LOCATIONS. HOWEVER...GUIDANCE DOES SUGGEST THE DEVELOPMENT OF ANOTHER CUT OFF LOW WITH VERY LITTLE CERTAINTY TO HOW STRONG IT WILL BE AND EXACTLY WHERE. FOR NOW...WE JUST WENT WITH SLIGHT POPS THROUGH THE PERIOD WITH SEASONABLY WARM TEMPERATURES EXPECTED. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AFTER A MARINE LAYER THIS MORNING...VISUAL FLIGHT RULES HAVE RETURNED TO ALL TERMINALS. BASED ON 12Z GUIDANCE...AM STARTING TO HAVE INCREASED CONFIDENCE IN SOME SHOWER/THUNDERSTORM ACTIVITY AFFECTING AREA TERMINALS. WILL BE INTRODUCED AT LEAST VCTS IN 18Z TAFS FOR MOST TERMINALS...LIKELY HITTING KMRB THE HARDEST WITH MVFR CONDITIONS INCLUDED GIVEN RADAR TRENDS. PERIODS OF LATE NIGHT/EARLY MORNING FOG WILL BE POSSIBLE THROUGH THE WEEKEND...WITH MVFR/IFR RESTRICTIONS POSSIBLE. SHOWER AND THUNDERSTORM POSSIBILITIES WILL REMAIN THROUGH EARLY NEXT WEEK...THEN HIGH PRESSURE WILL BUILD FOR THE MIDDLE OF NEXT WEEK. && .MARINE... WILL HAVE TO KEEP AN EYE ON SOUTHERLY OR SOUTHEASTERLY FLOW THROUGH THE WEEK AS IT CAN CHANNEL UP THE MID BAY/LOWER POTOMAC WITH HIGHER WIND SPEEDS THAN MODELS WOULD SUGGEST. HAVE BUMPED UP SPEEDS ACROSS THE MID BAY TO 15 KT THIS EVENING BASED ON THIS PHENOM. LATE AFTERNOON AND EVENING THUNDERSTORMS WILL POSE A RISK OF LIGHTNING...GUSTY WINDS...AND LOW VSBYS FOR MARINERS. INCREASING COVERAGE OF THUNDERSTORMS INTO THE EARLY WORK WEEK AS THE NEXT COLD FRONT ARRIVES IN THE REGION. HIGH PRESSURE EXPECTED TO BRING MORE TRANQUIL WEATHER TO THE REGION BY MIDWEEK. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && SYNOPSIS...CAS NEAR TERM...BPP SHORT TERM...BPP LONG TERM...BJL/CAS AVIATION...BPP/SJR/CAS MARINE...BPP/SJR/CAS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 151 PM EDT FRI JUL 27 2007 ANZ530>537-DCZ001-MDZ003>007-009>011-013-014-016>018-501-502- VAZ021-025>031-036>042-050>057-WVZ050>055-501>504-281000- 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- 151 PM EDT FRI JUL 27 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...THIS AFTERNOON AND TONIGHT A SEVERE THUNDERSTORM WATCH HAS BEEN ISSUED FOR MUCH OF THE OUTLOOK AREA UNTIL 8 PM THIS EVENING. SCATTERED TO NUMEROUS THUNDERSTORMS HAVE DEVELOPED OVER AND NEAR THE MOUNTAINS EARLY THIS AFTERNOON...AND WILL MOVE EAST OF THE MOUNTAINS INTO THE METROPOLITAN CORRIDOR DURING THE LATE AFTERNOON AND EVENING. A FEW OF THESE THUNDERSTORMS ARE EXPECTED TO BECOME SEVERE. LOCALLY DAMAGING WIND GUSTS WILL BE THE PRIMARY CONCERN. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED SATURDAY THROUGH MONDAY. A FEW OF THE STORMS MAY BECOME SEVERE WITH A THREAT OF LOCALLY DAMAGING WINDS...HAIL...AND LOCALLY HEAVY RAIN. .SPOTTER INFORMATION STATEMENT... SKYWARN SPOTTERS HAVE BEEN ACTIVATED THIS AFTERNOON.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 136 PM EDT FRI JUL 27 2007 MDZ501-502-VAZ021-WVZ054-501>504-271845- HIGHLAND VA-PENDLETON WV-WESTERN GRANT WV-EASTERN GRANT WV- CENTRAL AND EASTERN ALLEGANY MD-EXTREME WESTERN ALLEGANY MD- WESTERN MINERAL WV-EASTERN MINERAL WV- 136 PM EDT FRI JUL 27 2007 ...STRONG THUNDERSTORMS TO AFFECT HIGHLAND...PENDLETON...GRANT...ALLEGANY...AND MINERAL COUNTIES... AT 136 PM EDT...DOPPLER RADAR INDICATED A NORTH TO SOUTH LINE OF STRONG THUNDERSTORMS CROSSING THE APPALACHIAN MOUNTAINS...MOVING EAST AT 35 MPH. THESE STORMS HAVE A HISTORY OF PRODUCING SMALL HAIL...WIND GUSTS TO 50 MPH...AND CONTINUOUS CLOUD TO GROUND LIGHTNING. THOSE OUTDOORS SHOULD MOVE TO THE SAFETY OF SHELTER. THE COMMUNITIES OF WILSONIA...BEECHWOOD...WILSON...BAYARD...MOUNT STORM...KITZMILLER...EMORYVILLE...MIDLOTHIAN...FRANKLIN AND WESTERNPORT WILL BE AFFECTED BY THESE STORMS. RESIDENTS IN THESE AREAS SHOULD REMAIN ALERT IN CASE WARNINGS ARE ISSUED. ROGOWSKI
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 145 PM EDT FRI JUL 27 2007 THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ACTIVATED THE SKYWARN NETWORK DUE TO EXPECTED SEVERE WEATHER IN THE AREA. THE PRIMARY NET FREQUENCY IS 147.3 ZERO ZERO MEGA HERTZ. SPOTTERS ARE ENCOURAGED TO RELAY ANY SEVERE WEATHER REPORTS TO THE NATIONAL WEATHER SERVICE.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 215 PM EDT FRI JUL 27 2007 WVZ055-271930- HARDY WV- 215 PM EDT FRI JUL 27 2007 ...STRONG THUNDERSTORMS TO AFFECT HARDY COUNTY... AT 215 PM EDT...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM OVER MCCAULEY...MOVING EAST AT 30 MPH. THIS STORM WILL BE CAPABLE OF PRODUCING SMALL HAIL AND WIND GUSTS TO 50 MPH...IN ADDITION TO FREQUENT CLOUD TO GROUND LIGHTNING. THE COMMUNITY OF WARDENSVILLE WILL BE AFFECTED BY THIS STORM. RESIDENTS IN THESE AREAS SHOULD REMAIN ALERT IN CASE WARNINGS ARE ISSUED. ROGOWSKI
The Sterling radar (KLWX), 146 km away, was scanning. The volume nearest the first event began at 18:42 UTC.
1 thunderstorm wind. Local standard time, as filed.
Allegany County Emergency Management reported a tree down in Westernport, MD.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Maryland in 2007Every state in 2007This day in weather historyWarnings in Maryland, July 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: 47593.