An upper-level trough combined with an unstable atmosphere to trigger showers and thunderstorms. An isolated thunderstorms produced damaging wind gusts.
Every event with a place to put it. 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.
An upper-level trough combined with an unstable atmosphere to trigger showers and thunderstorms. An isolated thunderstorms produced damaging wind gusts. Winds changed speed and direction with height, causing enough rotation for a thunderstorm to develop into a tornado across lower southern Maryland.
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 15, 2:17 PM EST, 7 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 317 PM EDT SUN JUL 15 2012 .SYNOPSIS... AN UPPER TROUGH WILL CROSS THE MID-ATLANTIC REGION TONIGHT...BEFORE STALLING ACROSS THE CAROLINAS INTO THE MIDDLE PART OF THE WEEK. A COLD FRONT WILL CROSS THE REGION LATE WEDNESDAY... WITH HIGH PRESSURE RETURNING FOR LATE THIS WEEK INTO NEXT WEEKEND. && .NEAR TERM /THROUGH MONDAY/... AFTN SAT WV LOOP SHOWS A SHORTWAVE TROUGH ENTERING THE ERN GREAT LAKES. THIS FEATURE WILL TRACK EWD TNGT ALONG THE NRN PERIPHERY OF AN UPPER RIDGE INTO THE NORTHEAST AND NRN-MID ATLANTIC REGIONS. WARM FRONT BOUNDARY HARD TO DISCERN ON 18Z SFC ANALYSIS...BUT APPEARS TO BE DRAPED ACROSS CENTRAL PA. AFTN TEMPS IN THE LOW TO MID 90S AND DEWPOINTS IN THE LOWER 70S HAS RESULTED IN HEAT INDICES IN THE MID 90S TO NEAR 100F. IN WARM-MOIST SECTOR...ATMOSPHERE CONTINUES TO DESTABILIZE OVER THE MID-ATLANTIC REGION. DESPITE WEAK MID-LVL LAPSE RATES...DAYTIME DESTABILIZATION HAS YIELDED IN SBCAPE VALUES BETWEEN 2-3 KJ/KG IN THE CWA. CONVECTION HAS ALREADY INITIATED ALONG RESIDUAL DIFFERENTIAL HEATING BOUNDARIES OVER THE CENTRAL APPALACHIANS AND IN CENTRAL VA. MORE ORGANIZED CONVECTION OVER THE OH VLY AND WRN NY HAS DEVELOPED IN A REGION OF HEIGHT FALLS AHEAD OF THE UPPER SHORTWAVE TROUGH. THE HIGHEST COVERAGE OF SHOWERS AND STORMS THIS AFTN WILL BE OVER THE HIGHER TERRAIN AND CENTRAL VA. THIS ACTIVITY IS EXPECTED TO SHIFT EAST OF THE BLUE RIDGE LATE THIS AFTN AND I-95 CORRIDOR THIS EVE...BUT A FEW POP-UP STORMS ARE STILL POSSIBLE EARLIER. WITH HVY DOWNPOURS FROM STORMS AGAIN TDA...THERE IS A THREAT FOR LOCALIZED FLASH FLOODING. THE ENVIRONMENT HAS NOT CHANGED MUCH SINCE YDA WHEN CONVECTION PRODUCED RAINFALL AMTS OF 2-3 INCHES IN AN HR. HOWEVER...STORMS ARE MOVING FASTER TDA...WHICH WILL LIMIT AMT OF RAINFALL IN ONE LOCATION AND THUS THE EXTENT OF FLASH FLOODING. WILL STILL HIGHLIGHT LOCALIZED FLASH FLOOD THREAT IN HWO. IT DOES APPEAR THAT THE BEST ASCENT/SHEAR ASSOCIATED WITH THE UPPER TROUGH WILL NOT REACH THE AREA UNTIL AFTER PEAK HEATING HRS WHEN INSTABILITY WOULD BE MAXIMIZED. THEREFORE...DO NOT EXPECT AN ORGANIZED SEVERE WEATHER EVENT. STILL CANNOT RULE OUT A FEW DAMAGING WINDS GUSTS LATE THIS AFTN AND ERY EVE IF STORMS BECOME MULTI-CELLULAR. ACTIVITY WILL DIMINISH A FEW HRS AFTER DARK AS THE ATMOSPHERE STABILIZES...BUT MAY LINGER INTO THE OVNGT AS THE SHORTWAVE TROUGH APPROACHES. CLOUD COVER AND MOIST BOUNDARY LAYER WILL YIELD MUGGY CONDITIONS WITH OVNGT LOWS MAINLY IN THE 70S...EXCEPT UPPER 60S IN HIGHLANDS. UPPER SHORTWAVE TROUGH MOVES THRU THE CHSPK BAY REGION MON MRNG. SIGNIFICANT DRY AIR ADVECTION IN THE MID AND UPPER LVLS WILL BE ABSENT IN THE BOUNDARY LAYER DESPITE THE NWLY FLOW. WITH DEWPOINTS STILL AROUND 70F AND STRONG INSOLATION...MODEST SFC-BASED INSTABILITY WILL DEVELOP BY THE AFTN. SUBSIDENCE BEHIND THE UPPER TROUGH WILL NOT FAVOR A HIGH COVERAGE OF AFTN SHOWERS AND STORMS...BUT A FEW CELLS MAY INITIATE NEAR THE LINGERING SFC TROUGH IN THE NRN PIEDMONT AND SRN MD. RESERVED ISO POPS IN THE AFTN FCST FROM DC TO POINTS SOUTH AND EWD. MAIN STORY ON MON WILL BE THE HEAT AND HUMIDITY...WITH MAX TEMPS IN THE LOW TO MID 90S AND HEAT INDICES IN EXCESS OF 100F...BUT JUST BELOW HEAT ADVISORY CRITERIA...WITHIN THE I-95 CORRIDOR. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... A WELCOME QUIET WEATHER PERIOD ON TAP MONDAY NIGHT THROUGH TUESDAY NIGHT IN THE WAKE OF THE TROUGH MOVING THROUGH TONIGHT AND AHEAD OF THE MID WEEK COLD FRONT...AS A ZONAL FLOW DEVELOPS ACROSS THE NERN CONUS. THE HEAT WILL CONTINUE WITH 850 MB TEMPS OF 20 TO 22C ON TUESDAY SUGGESTING MAX TEMPS IN THE MID TO UPR 90S. WLY FLOW LOOKS TO MIX OUT DEWPOINTS TO THE UPR 60S TUESDAY...SO HEAT INDICES LOOK TO BE IN THE 100 TO 102F RANGE EAST OF THE BLUE RIDGE...BELOW THE GENERAL HEAT ADVISORY CRITERIA OF 105F. WHILE TUESDAY WILL BE APART OF A FOUR DAY STRETCH OF HEAT /TODAY SUNDAY THROUGH WEDNESDAY/...IT IS MID SUMMER SO IT DOES NOT SEEM NECESSARY TO GO WITH A LOWER CRITERION FOR THIS HEAT. WILL STILL MENTION HEAT INDICES IN EXCESS OF 100F IN THE HWO...PARTICULARLY SINCE MOISTURE POOLING JUST A LITTLE MORE WOULD ALLOW HEAT INDICES 105F OR MORE. MIN TEMPS INLAND U60S/L70S MON NGT AND L/M 70S TUE NGT...URBAN NEAR/SHORE M/U 70S MON NGT AND U70S/L80S TUE NGT. THE REGION WILL BE MAINLY CAPPED WITH A SUBSIDENCE INVERSION TUESDAY...THOUGH TERRAIN CIRCULATIONS COULD ALLOW FOR SOME CONVECTIVE ACTIVITY TO BREAK THROUGH. FOR NOW SOME SLIGHT CHANCES WERE INCLUDED FOR ZONES ALONG THE ALLEGHENY FRONT. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... COLD FRONT APPROACHES WEDNESDAY WITH A NORTH TO SOUTH PROGRESSION OF POSSIBLY SEVERE THUNDERSTORM ACTIVITY FROM THE AFTERNOON THROUGH THE EVENING. TERRAIN CIRCULATIONS WILL AID DEVELOPMENT IN THE AFTERNOON...SO NORTHWEST OF THE SHENANDOAH RIDGE NOW HAS LIKELY POPS FOR THE AFTERNOON. EXPECT PWATS TO APPROACH 2 INCHES AND CAPE IN EXCESS OF 3000 J/KG WITH LITTLE IN THE WAY OF SHEAR. DAMAGING WIND...HAIL...AND FLASH FLOODING ARE ALL THREATS WITH THIS FRONTAL PASSAGE WEDNESDAY INTO WEDNESDAY NIGHT...THE HWOLWX WILL BE UPDATED ACCORDINGLY. AHEAD OF THE FRONT EXPECT ANOTHER HOT DAY WEDNESDAY. CURRENT HEAT INDEX FORECAST IS FOR 100 TO 103F SO THE HWOLWX WILL CONTINUE TO MENTION HEAT. THE FRONTAL BOUNDARY WILL BE SLOW TO PUSH INTO THE CAROLINAS...SO SOME SHOWER/GENERAL THUNDERSTORM ACTIVITY IS EXPECTED TO PERSIST FOR FOR THURSDAY. NLY/NWLY FLOW WILL BRING A REPRIEVE TO THE HEAT WITH MAX TEMPS IN THE UPR 80S TO AROUND 90F. HIGH PRESSURE THEN THURSDAY NIGHT INTO THE WEEKEND WITH DRY CONDITIONS AND MAX TEMPS AROUND NORMAL IN THE MID TO UPR 80S. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... MAINLY VFR CONDITIONS ARE EXPECTED THROUGH THE TAF VALID PERIOD. PERIODIC LOWERED VSBYS ARE POSSIBLE THIS AFTERNOON AND EVENING IN SHOWERS AND THUNDERSTORMS. PRECIP SHOULD BEGIN TO DIMINISH AROUND 00Z WITH SKIES CLEARING OVERNIGHT. FOG FORMATION IS POSSIBLE AT CHO AND MRB TONIGHT. VSBYS COULD FALL TO MVFR LEVELS A FEW HOURS BEFORE SUNRISE AT THESE LOCATIONS. TOMORROW...CIGS SHOULD REMAIN AROUND OR ABOVE 4000FT. A SURFACE TROUGH DEVELOPING OVER THE AREA WILL CAUSE WIND TO SHIFT TO THE NW THROUGH MONDAY MORNING. VFR CONDITIONS EXPECTED MONDAY NIGHT THROUGH TUESDAY NIGHT WITH QUIET WEATHER. COLD FRONT APPROACHES WEDNESDAY...CROSSING WEDNESDAY NIGHT INTO THURSDAY. HEAVY AND POSSIBLE SEVERE THUNDERSTORMS ACROSS THE TERMINALS WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. && .MARINE... LGT WINDS 10 KT OR LESS THIS AFTN. HOWEVER...S-SWLY FLOW HAS CHANNELED WINDS A BIT IN THE MD CHSPK BAY...RESULTING IN 15 KT GUSTS. SHOWERS AND STORMS DEVELOPED OVER THE LOWER TIDAL POTOMAC RIVER AND SRN MD CHSPK BAY AROUND 2 PM. EXPECT COVERAGE OF STORMS TO INCREASE OVER THE WATERS LATE THIS AFTN AND EVE. HEAVY RAIN AND GUSTY WINDS ARE BOTH CONCERNS. SMW/S MAY BE REQUIRED. ISO SHOWERS AND STORMS POSSIBLE AGAIN MON AFTN. ENVIRONMENT NOT SUPPORTIVE OF STRONG STORMS TOMORROW...BUT AN ISO GUSTY WIND AND LIGHTNING IS POSSIBLE. QUIET WEATHER MONDAY NIGHT THROUGH TUESDAY NIGHT BEFORE A COLD FRONT CROSSES WEDNESDAY INTO THURSDAY. POTENTIAL FOR THUNDERSTORMS WITH DAMAGING WINDS AND HAIL AHEAD OF THE COLD FRONT. NO SMALL CRAFT ADVISORIES ARE ANTICIPATED THROUGH THE WEEK...WILL HAVE TO WATCH FOR EVENING CHANNELING. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && SYNOPSIS...BAJ/JRK NEAR TERM...JRK SHORT TERM...BAJ LONG TERM...BAJ AVIATION...BAJ/CLS MARINE...BAJ/JRK
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 106 PM EDT SUN JUL 15 2012 ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057- 161000- 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- 106 PM EDT SUN JUL 15 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...THIS AFTERNOON AND TONIGHT THUNDERSTORMS DEVELOPING THIS AFTERNOON AND EVENING WILL BE CAPABLE OF PRODUCING HEAVY RAINFALL. LOCALIZED FLASH FLOODING WILL BE POSSIBLE. IN ADDITION...A FEW STORMS WILL BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS...ESPECIALLY LATE THIS AFTERNOON AND EVENING. SPECIAL MARINE WARNINGS MAY BE NEEDED FOR ANY OF THESE STORMS THAT NEAR THE WATERS. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY HEAT AND HUMIDITY WILL INCREASE...WITH HEAT INDICES POSSIBLY EXCEEDING 100 DEGREES EACH AFTERNOON MONDAY THROUGH WEDNESDAY. A COLD FRONT WILL CROSS THE REGION LATE WEDNESDAY. SCATTERED SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THE FRONT. A FEW OF THESE STORMS MAY PRODUCE DAMAGING WIND GUSTS AND LARGE HAIL. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED AT THIS TIME. PLEASE RELAY REPORTS OF FLOODING OR THUNDERSTORM DAMAGE TO THE NATIONAL WEATHER SERVICE. MDZ003>005-009-010-501-502-VAZ025>031-036>040-042-050-051-501>504- WVZ050>053-055-501>506-161000- 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- 106 PM EDT SUN JUL 15 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...THIS AFTERNOON AND TONIGHT THUNDERSTORMS DEVELOPING THIS AFTERNOON AND EVENING WILL BE CAPABLE OF PRODUCING HEAVY RAINFALL. LOCALIZED FLASH FLOODING WILL BE POSSIBLE. IN ADDITION...A FEW STORMS WILL BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS...ESPECIALLY LATE THIS AFTERNOON AND EVENING. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY HEAT INDICES MAY EXCEED 100 DEGREES IN NORTHERN VIRGINIA EAST OF THE BLUE RIDGE EACH AFTERNOON MONDAY THROUGH WEDNESDAY. A COLD FRONT WILL CROSS THE REGION LATE WEDNESDAY. SCATTERED SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THE FRONT. A FEW OF THESE STORMS MAY PRODUCE DAMAGING WIND GUSTS AND LARGE HAIL. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED AT THIS TIME. PLEASE RELAY REPORTS OF FLOODING OR THUNDERSTORM DAMAGE TO THE NATIONAL WEATHER SERVICE.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 124 PM EDT SUN JUL 15 2012 VAZ025-504-151815- EASTERN HIGHLAND VA-AUGUSTA VA- 124 PM EDT SUN JUL 15 2012 ...STRONG THUNDERSTORM TO AFFECT EASTERN HIGHLAND AND AUGUSTA COUNTIES... AT 125 PM EDT...A STRONG THUNDERSTORM WAS LOCATED OVER CLOVER CREEK...MOVING EAST AT 15 MPH. LOCATIONS IMPACTED INCLUDE MCDOWELL...LIBERTY...HEAD WATERS AND WEST AUGUSTA. THIS STORM IS PRODUCING FREQUENT CLOUD TO GROUND LIGHTNING. MOVE INDOORS IMMEDIATELY FOR YOUR SAFETY. IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE STRUCK BY LIGHTNING. HEAVY RAIN WITH THIS STORM WILL REDUCE VISIBILITIES TO BELOW ONE MILE AND MAY CAUSE PONDING OF WATER ON ROADWAYS. WIND GUSTS OF 40 TO 50 MPH CAN BE EXPECTED WITH THIS STORM. && LAT...LON 3844 7917 3821 7913 3822 7962 3833 7964 TIME...MOT...LOC 1725Z 262DEG 14KT 3830 7953 KONARIK
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 154 PM EDT SUN JUL 15 2012 VAZ026-WVZ055-502-505-506-151845- EASTERN PENDLETON WV-HARDY WV-EASTERN GRANT WV-WESTERN PENDLETON WV- ROCKINGHAM VA- 154 PM EDT SUN JUL 15 2012 ...STRONG THUNDERSTORM TO AFFECT EASTERN PENDLETON...HARDY...EASTERN GRANT...WESTERN PENDLETON AND ROCKINGHAM COUNTIES... AT 155 PM EDT...A STRONG THUNDERSTORM WAS LOCATED 3 MILES WEST OF UPPER TRACT...MOVING EAST AT 25 MPH. LOCATIONS IMPACTED INCLUDE UPPER TRACT. HEAVY RAIN WITH THIS STORM WILL REDUCE VISIBILITIES TO BELOW ONE MILE AND MAY CAUSE PONDING OF WATER ON ROADWAYS. WIND GUSTS OF 40 TO 50 MPH CAN BE EXPECTED WITH THIS STORM. && LAT...LON 3892 7888 3861 7888 3873 7939 3881 7938 TIME...MOT...LOC 1755Z 275DEG 22KT 3878 7931 KONARIK
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 244 PM EDT SUN JUL 15 2012 VAZ026-027-029-151930- SHENANDOAH VA-PAGE VA-ROCKINGHAM VA- 244 PM EDT SUN JUL 15 2012 ...STRONG THUNDERSTORM TO AFFECT SHENANDOAH...PAGE AND ROCKINGHAM COUNTIES... AT 244 PM EDT...A STRONG THUNDERSTORM WAS LOCATED OVER FORESTVILLE... MOVING EAST AT 20 MPH. LOCATIONS IMPACTED INCLUDE MOUNT JACKSON AND LURAY. HEAVY RAIN WITH THIS STORM WILL REDUCE VISIBILITIES TO BELOW ONE MILE AND MAY CAUSE PONDING OF WATER ON ROADWAYS. WIND GUSTS OF 40 TO 50 MPH CAN BE EXPECTED WITH THIS STORM. && LAT...LON 3892 7837 3857 7842 3868 7887 3876 7889 TIME...MOT...LOC 1844Z 275DEG 16KT 3873 7871 KONARIK
The Sterling radar (KLWX), 105 km away, was scanning. The volume nearest the first event began at 19:25 UTC.
1 tornado, 1 thunderstorm wind. Local standard time, as filed.
A waterspout was reported to have moved onshore along Windy Lane near Coltons Point, becoming a tornado. The tornado snapped large tree limbs as well as removing siding and shingles to homes.
A large portion of a tree snapped off into a garage.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Maryland in 2012Every state in 2012This day in weather historyThe tornado archive for Maryland, 2012Warnings in Maryland, July 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: 404532, 404226.