A stalled frontal boundary was the focus for scattered severe thunderstorms across portions of western Pennsylvania. A slow moving thunderstorm produced isolated flash flooding over Garrett county Maryland.
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 PBZ wrote it up.
A stalled frontal boundary was the focus for scattered severe thunderstorms across portions of western Pennsylvania. A slow moving thunderstorm produced isolated flash flooding over Garrett county 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 Pittsburgh, PA wrote its last area forecast discussion before the first event at May 27, 12:03 PM EST, 1 hour 17 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 103 PM EDT SUN MAY 27 2012 .SYNOPSIS... HIGH PRESSURE WILL PROVIDE UNSEASONABLY WARM AND HUMID WEATHER THROUGH THE HOLIDAY WEEKEND. DAYTIME HEATING WILL BRING A SLIGHT CHANCE OF SHOWERS OR THUNDERSTORMS IN THE LATE AFTERNOON OR EVENING HOURS. A COLD FRONT WILL APPROACH THE AREA ON TUESDAY AND TRIGGER MORE WIDESPREAD SHOWERS AND STORMS. && .NEAR TERM /THROUGH TONIGHT/... CURRENT FORECAST REMAINS ON TRACK. MADE ONLY SMALL ADJUSTMENTS TO CLOUD COVER TO BETTER FIT CURRENT TRENDS. SHOULD ONCE AGAIN BE A WARM AND HUMID DAY. EXPECT SOME SHOWER AND THUNDERSTORM DEVELOPMENT THIS AFTERNOON AS THE NEARLY STATIONARY BOUNDARY LIFTS NORTH AS A WARM FRONT. IN ADDITION...WEAK SHORTWAVES RIDING ALONG THE NORTHERN PERIPHERY OF THE UPPER LEVEL RIDGE WILL PROVIDE ADDITIONAL LIFT. THERE WILL BE SUFFICIENT INSTABILITY...AS THE CURRENT MESO ANALYSIS SUGGESTS 3000 J/KG OF CAPE BUT MARGINAL SHEAR WILL MAKE IT DIFFICULT FOR WHAT THUNDERSTORMS THAT DO DEVELOP TO INTENSIFY AND MAINTAIN THEMSELVES. STILL NOT OUT OF THE QUESTION THAT A FEW STORMS COULD REACH SEVERE LEVELS AND WITH AMPLE MOISTURE...AND PWATS WELL OVER AN INCH...HEAVY DOWNPOURS COULD BE EXPECTED. && .SHORT TERM /MONDAY THROUGH TUESDAY/... AS THE WARM FRONT CONTINUES MOVING NORTH MONDAY WARM AND HUMID CONDITIONS WILL CONTINUE. SLIGHT CHANCE WORDING FOR DIURNAL THUNDERSTORMS WILL REMAIN IN THE FORECAST FOR MONDAY AS THERE WILL BE PLENTY OF LOW LEVEL MOISTURE AND INSTABILITY. QUESTION WILL BE WHETHER THERE WILL BE ENOUGH FORCING WITH THE UPPER RIDGE CENTERED OVERHEAD TO ASSIST IN THUNDERSTORM DEVELOPMENT. MODELS ARE IN GOOD AGREEMENT ON THE FRONTAL PASSAGE PROGGED FOR LATE TUESDAY. WITH PLENTY OF INSTABILITY AND HEATING...EXPECT SHOWERS AND THUNDERSTORMS TO DEVELOP OUT AHEAD OF THE FRONT ONCE AGAIN TUESDAY AFTERNOON. THUS...BROUGHT IN HIGH CHANCE WORDING BY THE AFTERNOON. CONTINUED TEMPERATURES NEAR MAV/MEX GUIDANCE OF 15 DEGREES ABOVE NORMAL MEMORIAL DAY AS 850HPA TEMPERATURES INCREASE TO ALMOST 20C OVERHEAD. WITH CLOUD COVER AND PRECIPITATION CHANCES INCREASING TUESDAY...KEPT TEMPERATURES A LITTLE COOLER BUT STILL ABOUT 10 DEGREES ABOVE NORMAL. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... COLD FRONT WILL BE CROSSING REGION TUESDAY NIGHT WITH SHOWERS AND THUNDERSTORMS ENDING WEST TO EAST AS NORTHWEST FLOW BEHIND FRONT BRINGS IN COOLER AND LESS HUMID CONDITIONS. A GENERALLY DRY FORECAST WEDNESDAY AND INTO EARLY THURSDAY UNDER A FLAT TROUGH ACROSS THE EASTERN U.S. AND WEAK SURFACE RIDGE. BY LATE THURSDAY INTO FRIDAY FRONT WILL BEGIN TO COME BACK NORTH AS LOW PRESSURE DEVELOPS ACROSS THE LOWER OHIO VALLEY BRINGING IN SHOWERS AND PERHAPS A THUNDERSTORMS. FOR LATE WEEK INTO THE WEEKEND MODELS DEPICTING A RATHER STRONG UPPER TROUGH ACROSS THE EASTERN U.S. FOR THE BEGINNING OF JUNE WITH WELL BELOW NORMAL TEMPERATURES. CHANCE POPS CONTINUED INTO SATURDAY AS SURFACE LOW MOVES TO NEW ENGLAND WITH INSTABILITY SHOWERS UNDER COLD POOL ALOFT. CLOSE TO HPC PROGS. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... STALLED SFC BOUNDARY JUST SOUTH OF KPIT AND NW FLOW ALOFT AN ISO SHOWER/STORM CANNOT BE RULED OUT FOR THE ENTIRE DAY. WOULD EXPECT ANY STORM DEVELOPMENT TO COME WITH DAYTIME HEATING. EXPECT PERIODS OF MID CLOUDS TODAY, WITH LIGHT WINDS VEERING TO THE SOUTH BY MID MORNING. .OUTLOOK...SUNDAY NIGHT THROUGH THURSDAY... GENERAL VFR CONDITIONS WILL PREVAIL THROUGH MONDAY WITH UPPER RIDGE ALOFT. ISOLATED THUNDERSTORMS POSSIBLE MONDAY IN LOW LEVEL INSTABILITY. ON TUESDAY...A COLD FRONT WILL BRING SHOWERS AND THUNDERSTORMS WITH THE POTENTIAL FOR RESTRICTIONS INTO TUESDAY NIGHT. SURFACE HIGH PRESSURE WILL BRING GENERAL VFR WEDNESDAY INTO THURSDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE PITTSBURGH PA 144 PM EDT SUN MAY 27 2012 OHZ039>041-049-050-PAZ007>009-013>016-020>023-029-073-074-WVZ001-002- 281745- TUSCARAWAS-CARROLL-COLUMBIANA-HARRISON-JEFFERSON OH-MERCER-VENANGO- FOREST-LAWRENCE-BUTLER-CLARION-JEFFERSON PA-BEAVER-ALLEGHENY- ARMSTRONG-INDIANA-WASHINGTON-WESTMORELAND-WESTMORELAND RIDGES- HANCOCK-BROOKE- 144 PM EDT SUN MAY 27 2012 ...SEVERE THUNDERSTORM WATCH 303 IN EFFECT UNTIL 8 PM EDT THIS EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST CENTRAL OHIO...NORTHWEST PENNSYLVANIA...SOUTHWEST PENNSYLVANIA...WEST CENTRAL PENNSYLVANIA AND NORTHERN PANHANDLE OF WEST VIRGINIA. .DAY ONE...THIS AFTERNOON AND TONIGHT. PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS. SEVERE THUNDERSTORM WATCH. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY. NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. MDZ001-OHZ048-057>059-068-069-PAZ031-075-076-WVZ003-004-012-021>023- 041-281745- GARRETT-COSHOCTON-MUSKINGUM-GUERNSEY-BELMONT-NOBLE-MONROE-GREENE- FAYETTE-FAYETTE RIDGES-OHIO-MARSHALL-WETZEL-MARION-MONONGALIA- PRESTON-TUCKER- 144 PM EDT SUN MAY 27 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN MARYLAND...EAST CENTRAL OHIO...SOUTHWEST PENNSYLVANIA...NORTHERN WEST VIRGINIA AND NORTHERN PANHANDLE OF WEST VIRGINIA. .DAY ONE...THIS AFTERNOON AND TONIGHT. NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY. NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE PITTSBURGH PA 200 PM EDT SUN MAY 27 2012 OHZ041-PAZ020-021-029-WVZ001-271845- ALLEGHENY PA-BEAVER PA-COLUMBIANA OH-HANCOCK WV-WASHINGTON PA- 200 PM EDT SUN MAY 27 2012 ...A STRONG THUNDERSTORM WILL AFFECT NORTHERN HANCOCK...NORTHWESTERN WASHINGTON...SOUTHEASTERN COLUMBIANA...SOUTHWESTERN BEAVER AND WEST CENTRAL ALLEGHENY COUNTIES... AT 150 PM EDT...A STRONG THUNDERSTORM WAS LOCATED 3 MILES SOUTH OF BEAVER CREEK STATE PARK...MOVING SOUTHEAST AT 25 MPH. WIND GUSTS TO 50 MPH AND HAIL UP TO DIME SIZE ARE POSSIBLE WITH THIS STORM. SOME LOCATIONS THAT WILL BE IMPACTED INCLUDE... NEWELL... CHESTER... BLACKHAWK... WELLSVILLE... EAST LIVERPOOL... TOMLINSON RUN STATE PARK... NEW MANCHESTER... SHIPPINGPORT... BEAVER... HARSHAVILLE... ALIQUIPPA... RACCOON CREEK STATE PARK... THIS WILL IMPACT THE FOLLOWING HIGHWAYS... I-279 BETWEEN MILE MARKERS 3 AND 8. I-376 BETWEEN MILE MARKERS 33 AND 66. I-79 IN PENNSYLVANIA BETWEEN MILE MARKERS 56 AND 69. PLEASE REPORT SIGNIFICANT WEATHER TO THE NATIONAL WEATHER SERVICE BY CALLING TOLL FREE...877-633-6772. LAT...LON 4047 7999 4024 8031 4063 8071 4083 8047
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PITTSBURGH PA
209 PM EDT SUN MAY 27 2012
WVZ041-271900-
TUCKER WV-
209 PM EDT SUN MAY 27 2012
...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN TUCKER COUNTY...
AT 202 PM EDT...A STRONG THUNDERSTORM WAS LOCATED 7 MILES EAST OF
CANAAN VALLEY STATE PARK...MOVING SOUTHEAST AT 5 MPH.
WIND GUSTS TO 40 MPH AND HAIL UP TO DIME SIZE ARE POSSIBLE WITH THIS
STORM. HEAVY RAIN WILL POND WATER ON ROADS AND QUICKLY FILL DITCHES
AND SMALL STREAMS.
SOME LOCATIONS THAT WILL BE IMPACTED INCLUDE...
CANAAN VALLEY STATE PARK...
PLEASE REPORT SIGNIFICANT WEATHER TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...877-633-6772.
LAT...LON 3903 7948 3917 7933 3916 7932 3911 7933
3909 7935 3908 7930 3906 7929 3897 7933
3896 7935 3896 7938SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PITTSBURGH PA
220 PM EDT SUN MAY 27 2012
MDZ001-271900-
GARRETT MD-
220 PM EDT SUN MAY 27 2012
...A STRONG THUNDERSTORM WILL AFFECT EASTERN GARRETT COUNTY...
AT 212 PM EDT...A STRONG THUNDERSTORM WAS LOCATED NEAR BIG RUN STATE
PARK...MOVING EAST AT 5 MPH.
WIND GUSTS TO 40 MPH AND HAIL UP TO DIME SIZE ARE POSSIBLE WITH THIS
STORM. HEAVY RAIN WILL POND WATER ON ROADS AND QUICKLY FILL DITCHES
AND SMALL STREAMS.
SOME LOCATIONS THAT WILL BE IMPACTED INCLUDE...
KITZMILLER... BITTINGER... BIG RUN STATE PARK...
BLOOMINGTON... NEW GERMANY... MERRILL...
FINZEL...
THIS WILL IMPACT...
I-68 IN MARYLAND BETWEEN MILE MARKERS 25 AND 30.
PLEASE REPORT SIGNIFICANT WEATHER TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...877-633-6772.
LAT...LON 3948 7906 3946 7910 3945 7910 3940 7914
3940 7916 3939 7916 3938 7922 3962 7929
3972 7894 3970 7894The Pittsburgh radar (KPBZ), 39 km away, was scanning. The volume nearest the first event began at 18:21 UTC.
16 thunderstorm wind, 13 hail. Local standard time, as filed.
Emergency management reported trees and power lines down near Wampum.
Emergency management reported a tree down on a mobile home.
Emergency management reported trees and power lines down.
Emergency management reported trees down across roadways.
Law enforcement reported a large tree down at Forest Drive and Miller Road.
Law enforcement reported a large tree down on a vehicle.
Law enforcement reported numerous trees down.
Law enforcement reported numerous trees down.
Emergency management reported several trees down.
A trained spotter reported numerous large tree limbs down.
Emergency management reported numerous trees and power lines down in and around the town of Indiana.
Emergency management reported numerous trees down.
Emergency management reported trees down.
The public reported several trees down.
Law enforcement reported several trees down near Ligonier.
A trained spotter reported a large tree down.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2012Every state in 2012This day in weather historyWarnings in Pennsylvania, May 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: 377765, 377752, 377753, 377754, 377755, 377766, 377756, 377757, 377767, 377758, 377768, 377770, 377769, 377771, 377772, 377774, 377773, 377759, 377760, 377775, 377761, 377776, 377779, 377777, 377762, 377778, 377763, 377764, 377780.