An approaching cold front and lee side trof helped trigger strong to locally severe thunderstorms across extreme southeastern Pennsylvania during the late afternoon on the 17th. The thunderstorms also produced some small hail.
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 PHI wrote it up.
An approaching cold front and lee side trof helped trigger strong to locally severe thunderstorms across extreme southeastern Pennsylvania during the late afternoon on the 17th. The thunderstorms also produced some small hail.
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 Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Jun 17, 2:48 PM EST, 52 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 348 PM EDT MON JUN 17 2013 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL CONTINUE TO MOVE NORTHEAST THROUGH THE SAINT LAWRENCE VALLEY TONIGHT. ITS ASSOCIATED COLD FRONT SHOULD ARRIVE TUESDAY OR TUESDAY NIGHT WITH A WEAK LOW PRESSURE SYSTEM FORMING ALONG IT. A HIGH PRESSURE SYSTEM WILL THEN BUILD INTO THE NORTHEAST THE LATTER HALF OF THE WORK WEEK BEFORE SHIFTING OFFSHORE ON SATURDAY. A WARM FRONT IS FORECAST TO MOVE THROUGH THE FORECAST AREA ON SUNDAY AND NORTHWARD INTO NEW ENGLAND ON MONDAY. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... A WEAK SURFACE TROUGH WELL AHEAD OF THE SLOW APPROACHING COLD FRONT, TO OUR NORTHWEST, HAS/IS TOUCHING OFF WIDELY SCATTERED SHOWERS WITH EMBEDDED CONVECTION. FOR THE MOST PART THIS PRE-FRONTAL TROUGH IS NOT PROVIDING A LOT OF LIFT TO GENERATE WIDESPREAD CONVECTION BUT SOME OF THE STORMS THAT DO FORM ARE TAPPING INTO A DECENT AMOUNT OF SURFACE BASED INSTABILITY AND FORMING STRONGER UPDRAFTS. DID NOT ADD ENHANCED WORDING TO THE GRIDS GIVEN THE SPATIAL COVERAGE IS LOW BUT SOME OF THESE STORMS ARE CAPABLE OF PRODUCING STRONG, POSSIBLY DAMAGING WINDS. HAIL LOOKS LESS LIKELY WITH THE FREEZING LEVEL AROUND 14KFT ACROSS MOST OF THE AREA AND WITH THE DRIER SUB-CLOUD LAYER. THE TROUGH WILL CONTINUE TO SHIFT EASTWARD THROUGH THE EVENING HOURS AND THESE STORMS SHOULD BE COMING TO AN END OVER THE NEXT COUPLE OF HOURS. ANOTHER FRONTAL BOUNDARY ACROSS THE GREAT LAKES WILL CONTINUE TO SLIDE TOWARDS THE EAST-SOUTHEAST THROUGH THE OVERNIGHT HOURS BUT BEGINS TO LOSE SOME STEAM AS IT BECOMES MORE PARALLEL TO THE MID-LEVEL FLOW. DECIDED TO KEEP CHANCE POPS IN FOR THIS EVENING AND A PART OF THE LATE NIGHT JUST ABOUT EVERYWHERE WITH THIS SECOND BOUNDARY. TEMPERATURES TONIGHT SHOULD BE A COUPLE DEGREES COOLER THAN THIS MORNING WITH LESS CLOUD COVER IN PLACE AND LIGHT/CALM WINDS. A BASIC BLEND OF THE MET/MAV WAS USED. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... FRONTAL BOUNDARY WILL CONTINUE TO SLOWLY SAG ACROSS THE REGION TOMORROW AND AGAIN TOUCH OFF SHOWERS AND POSSIBLY THUNDERSTORMS BY THE LATE MORNING/EARLY AFTERNOON TIMEFRAME. A WEAK SURFACE WAVE WILL MOVE ALONG THE FRONT WHICH HELPS WITH LARGER SCALE LIFT IN A MARGINALLY UNSTABLE ATMOSPHERE...MORE CLOUD COVER TOMORROW THAN TODAY. STILL NOT QUITE SURE HOW MUCH SURFACE BASED INSTABILITY CAN BE REALIZED TOMORROW. THE FLOW ALOFT, WHICH ONCE WAS STRONG, CONTINUES TO WEAKEN ON TUESDAY SO ANY STORMS THAT DO INITIATE ALONG THE FRONTAL BOUNDARY ALLOWING FOR A MUCH SLOWER STORM MOTION. PWATS WILL STILL BE FAIRLY HIGH SO ANY SHOWER/THUNDERSTORM COULD PRODUCE A HEAVY DOWNPOUR IN A SHORT TIME PERIOD. TEMPERATURES TOMORROW SHOULD BE A COUPLE OF DEGREES COOLER THAN TODAY WITH HIGHS IN THE LOW TO MID-80S. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... TIME PERIOD BEGINS WITH COLD FRONTAL BOUNDARY WORKING TO PUSH THROUGH THE AREA. COLD FRONTAL MOVEMENT STILL LOOKS SLOWER THAN IT DID SEVERAL DAYS AGO, SO RETAINED THE CHANCE POPS FOR BOTH TUE NIGHT AND WED, WITH THE HIGHER POPS ON WEDNESDAY CLOSER TO THE COAST. LOOKED AT BLEND OF MAV/MET ON TUE NIGHT/WEDNESDAY FOR TEMPERATURES. HIGH PRESSURE PUSHES INTO THE REGION FOR THE THURSDAY THROUGH SATURDAY TIMEFRAME, WITH TEMPERATURES RUNNING SLIGHTLY BELOW NORMAL AND DRY CONDITIONS. WARM FRONTAL BOUNDARY APPROACH ON SUNDAY BRINGS NEXT POTENTIAL PRECIPITATION AND BOTH TEMPS AND POPS ON SUNDAY AND MONDAY FOLLOWED WPC GUIDANCE CLOSELY. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THIS EVENING - TONIGHT...MOSTLY VFR. WILL CONTINUE WITH OUR LIGHT SOUTHWEST WINDS THROUGH THE EVENING HOURS. A WEAK SURFACE TROUGH IS CURRENTLY PUSHING IN FROM THE NORTHWEST AND IS INITIATING SHOWERS WITH EMBEDDED THUNDERSTORMS. DECIDED IT WOULD BE BEST, GIVEN THE CURRENT WIDELY SCATTERED ACTIVITY TO PLACE -TSRA TEMPO GROUPS IN FOR A COUPLE HOURS EARLY IN THE CYCLE. BEHIND THIS INITIAL LINE THE AIR LOOKS TOO DRY TO CONTINUE WITH THE SHOWER ACTIVITY SO THERE LOOKS TO BE A DECENT LULL BETWEEN PRECIPITATION EVENTS. ANOTHER AREA WE ARE WATCHING IS A COLD FRONT PRESSING IN FROM THE NORTHWEST MOVING ACROSS THE GREAT LAKES. MORE SHOWERS/THUNDERSTORMS ARE ERUPTING ALONG THIS LINE AS WE SPEAK AND IF THEY WERE TO HOLD TOGETHER THEY WOULD BEGIN TO IMPACT RDG/ABE BY LATE THIS EVENING. CONFIDENCE WAS NOT HIGH ON THESE SHOWERS/STORMS MAKING IT INTO OUR TERMINALS TONIGHT SO THEY WERE HELD OUT FOR THE MOMENT. TUESDAY...MVFR POSSIBLY EARLY IN THE MORNING WITH FOG ACROSS A MAJORITY OF OUR TERMINALS, THEN VFR. THE LIGHT VARIABLE/CALM WINDS WILL BEGIN TO PICK UP BY LATE MORNING AND BE MORE SOUTHEASTERLY AS A LOW PRESSURE SYSTEM MAKES ITS WAY ALONG THE FRONTAL BOUNDARY ACROSS OUR AREA. THIS WILL PROVIDE ANOTHER CHANCE AT SHOWERS AND THUNDERSTORMS WITH MVFR RESTRICTIONS. OUTLOOK... TUESDAY NIGHT...MVFR OR LOWER AT TIMES WITH SHOWERS AND THUNDERSTORMS. THERE COULD BE SOME MVFR/IFR LATE DUE TO SOME FOG. WEDNESDAY...POCKETS OF MVFR CONDITIONS IN THE MORNING, OTHERWISE VFR. WEDNESDAY NIGHT THROUGH SATURDAY...VFR. && .MARINE... SUB-ADVISORY CONDITIONS LOOK TO PERSIST ACROSS OUR WATERS TONIGHT AND TOMORROW. WEAK COLD FRONT WILL NEAR FROM THE NORTHWEST TONIGHT AND TOMORROW WHILE A SURFACE LOW PRESSURE RIDES ALONG THE FRONTAL BOUNDARY. THIS IS NOT EXPECTED TO RAISE WINDS OR SEAS SIGNIFICANTLY BUT WILL PRODUCE WIDESPREAD SHOWERS AND THUNDERSTORMS. WINDS WILL SLOWLY BACK TOWARDS THE EAST-SOUTHEAST TONIGHT AHEAD OF THE FRONT. OUTLOOK... RIGHT NOW WE ARE NOT LOOKING AT SCA CONDITIONS TO OCCUR THROUGH SATURDAY. HOWEVER, THE NORTHEAST FETCH LATE WEDNESDAY INTO WEDNESDAY NIGHT AND EARLY THURSDAY WILL BRING SEAS UP TO THE 4 FOOT RANGE, SO THIS WILL CONTINUE TO BE MONITORED CLOSELY. WINDS AND SEAS SUBSIDE AS WE MOVE INTO FRIDAY AND SATURDAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && SYNOPSIS...SZATKOWSKI NEAR TERM...HEAVENER SHORT TERM...HEAVENER LONG TERM...SZATKOWSKI AVIATION...SZATKOWSKI/HEAVENER MARINE...SZATKOWSKI/HEAVENER
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 355 PM EDT MON JUN 17 2013 DEZ001>003-MDZ008-012-015-019-020-NJZ001-007>010-012-013-015>023-027- PAZ054-055-060>062-070-071-101>106-182000- NEW CASTLE-KENT-INLAND SUSSEX-CECIL-KENT MD-QUEEN ANNES-TALBOT- CAROLINE-SUSSEX-WARREN-MORRIS-HUNTERDON-SOMERSET-MIDDLESEX- WESTERN MONMOUTH-MERCER-SALEM-GLOUCESTER-CAMDEN- NORTHWESTERN BURLINGTON-OCEAN-CUMBERLAND-ATLANTIC-CAPE MAY- SOUTHEASTERN BURLINGTON-CARBON-MONROE-BERKS-LEHIGH-NORTHAMPTON- DELAWARE-PHILADELPHIA-WESTERN CHESTER-EASTERN CHESTER- WESTERN MONTGOMERY-EASTERN MONTGOMERY-UPPER BUCKS-LOWER BUCKS- 355 PM EDT MON JUN 17 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL DELAWARE...NORTHERN DELAWARE...SOUTHERN DELAWARE...NORTHEAST MARYLAND...CENTRAL NEW JERSEY...NORTHERN NEW JERSEY...NORTHWEST NEW JERSEY...SOUTHERN NEW JERSEY...EAST CENTRAL PENNSYLVANIA...NORTHEAST PENNSYLVANIA AND SOUTHEAST PENNSYLVANIA. .DAY ONE...THIS AFTERNOON AND TONIGHT. A FEW STRONG THUNDERSTORMS MAY AFFECT THE REGION LATE THIS AFTERNOON INTO THE EVENING. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY. A SLOW MOVING COLD FRONT COULD TRIGGER SOME STRONG THUNDERSTORMS TUESDAY INTO TUESDAY NIGHT WITH ADDITIONALLY SOME HEAVY DOWNPOURS POSSIBLE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. DEZ004-NJZ014-024>026-182000- DELAWARE BEACHES-EASTERN MONMOUTH-ATLANTIC COASTAL CAPE MAY- COASTAL ATLANTIC-COASTAL OCEAN- 355 PM EDT MON JUN 17 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHERN DELAWARE...CENTRAL NEW JERSEY AND SOUTHERN NEW JERSEY. .DAY ONE...THIS AFTERNOON AND TONIGHT. A FEW STRONG THUNDERSTORMS MAY AFFECT THE REGION LATE THIS AFTERNOON INTO THE EVENING. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY. A SLOW MOVING COLD FRONT COULD TRIGGER SOME STRONG THUNDERSTORMS LATER TUESDAY INTO TUESDAY NIGHT WITH ADDITIONALLY SOME HEAVY DOWNPOURS POSSIBLE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. ANZ430-431-450>455-182000- DELAWARE BAY WATERS NORTH OF EAST POINT NJ TO SLAUGHTER BEACH DE- DELAWARE BAY WATERS SOUTH OF EAST POINT NJ TO SLAUGHTER BEACH DE- COASTAL WATERS FROM SANDY HOOK TO MANASQUAN INLET NJ OUT 20 NM- COASTAL WATERS FROM MANASQUAN INLET TO LITTLE EGG INLET NJ OUT 20 NM- COASTAL WATERS FROM LITTLE EGG INLET TO GREAT EGG INLET NJ OUT 20 NM- COASTAL WATERS FROM GREAT EGG INLET TO CAPE MAY NJ OUT 20 NM- COASTAL WATERS FROM CAPE MAY NJ TO CAPE HENLOPEN DE OUT 20 NM- COASTAL WATERS FROM CAPE HENLOPEN TO FENWICK ISLAND DE OUT 20 NM- 355 PM EDT MON JUN 17 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL WATERS AND DELAWARE BAY WATERS. .DAY ONE...THIS AFTERNOON AND TONIGHT. A FEW STRONG THUNDERSTORMS MAY AFFECT THE REGION LATE THIS AFTERNOON INTO THE EVENING. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY. A SLOW MOVING COLD FRONT COULD TRIGGER SOME STRONG THUNDERSTORMS LATER TUESDAY INTO TUESDAY NIGHT. NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. SZATKOWSKI
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
237 PM EDT MON JUN 17 2013
NJZ009-010-012-171930-
HUNTERDON NJ-MIDDLESEX NJ-SOMERSET NJ-
237 PM EDT MON JUN 17 2013
...A STRONG THUNDERSTORM WILL AFFECT CENTRAL HUNTERDON...NORTHWESTERN
MIDDLESEX AND SOMERSET COUNTIES...
AT 233 PM EDT...A STRONG THUNDERSTORM WAS NEAR CLINTON...MOVING EAST
AT 20 MPH.
WIND GUSTS TO 50 MPH AND PENNY SIZE HAIL ARE POSSIBLE WITH THIS
STORM. VERY HEAVY RAIN WILL FALL FROM THIS STORM...AND WILL CAUSE
WATER TO POND ON ROADS AND FILL POOR DRAINAGE AREAS. THE RAIN WILL
CAUSE RAPID RISES ON SMALL STREAMS AND CREEKS. THIS STORM WILL BE
NEAR ANNANDALE AROUND 250 PM...LEBANON AROUND 300 PM...WHITE HOUSE
STATION AROUND 310 PM...FLAGTOWN AROUND 320 PM AND RARITAN AROUND 330
PM.
LAT...LON 4037 7452 4057 7511 4067 7507 4070 7499
4072 7496 4062 7442 4060 7444 4060 7442
NIERENBERGSPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
325 PM EDT MON JUN 17 2013
NJZ009-010-012-172030-
HUNTERDON NJ-MIDDLESEX NJ-SOMERSET NJ-
325 PM EDT MON JUN 17 2013
...A STRONG THUNDERSTORM WILL AFFECT CENTRAL HUNTERDON...SOUTHERN
SOMERSET AND WESTERN MIDDLESEX COUNTIES...
AT 324 PM EDT...A STRONG THUNDERSTORM WAS NEAR MILFORD...MOVING EAST
AT 30 MPH.
WIND GUSTS TO 50 MPH AND PENNY SIZE HAIL ARE POSSIBLE WITH THIS
STORM. THIS STORM WILL BE NEAR MILFORD AROUND 330 PM...FLEMINGTON
AROUND 350 PM...CLOVERHILL AROUND 400 PM...FLAGTOWN AROUND 410 PM...
MILLSTONE AROUND 420 PM AND SOMERSET AROUND 430 PM.
LAT...LON 4034 7444 4041 7475 4042 7475 4042 7478
4051 7507 4054 7507 4057 7510 4057 7516
4063 7514 4065 7508 4061 7444 4060 7444
4061 7437
NIERENBERGPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
328 PM EDT MON JUN 17 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0245 PM TSTM WND DMG CLINTON 40.64N 74.91W
06/17/2013 HUNTERDON NJ EMERGENCY MNGR
TREES AND POWERLINES DOWN IN CLINTON... FRANKLIN... AND
UNION TOWNSHIPS
&&
EVENT NUMBER PHI1300125
BUNKERPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
402 PM EDT MON JUN 17 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0320 PM HAIL STANTON 40.58N 74.84W
06/17/2013 E0.88 INCH HUNTERDON NJ PUBLIC
WIND BREAKING OFF SMALL LIMBS.
&&
EVENT NUMBER PHI1300126
BUNKERPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
404 PM EDT MON JUN 17 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0350 PM HAIL BRANCHBURG 40.55N 74.72W
06/17/2013 E0.25 INCH SOMERSET NJ PUBLIC
&&
EVENT NUMBER PHI1300127
BUNKERPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
421 PM EDT MON JUN 17 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0300 PM TSTM WND DMG READINGTON TWP 40.57N 74.80W
06/17/2013 HUNTERDON NJ PUBLIC
HIGH WINDS BLEW DOWN TREES AND BRANCHES...SPRINGTOWN
ROAD IS BLOCKED BY 10 INCH DIAMETER TREE BRANCH.
&&
EVENT NUMBER PHI1300128
BUNKERThe Dover AFB radar (KDOX), 117 km away, was scanning. The volume nearest the first event began at 20:41 UTC.
1 thunderstorm wind. Local standard time, as filed.
A severe thunderstorm knocked down several trees in London Grove Township. The tree damage was concentrated around the Chatham area near the intersection of Pennsylvania State Route 41 and U.S. Route 1. Several hundred homes and businesses in the township lost power.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2013Every state in 2013This day in weather historyWarnings in Pennsylvania, June 2013
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: 462501.