Heavy rain preceding a warm front that moved through southern Pennsylvania overnight on the 2nd caused flooding in the headwaters of the Perkiomen Creek.
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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 PHI wrote it up.
Heavy rain preceding a warm front that moved through southern Pennsylvania overnight on the 2nd caused flooding in the headwaters of the Perkiomen Creek.
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 Oct 2, 2:45 PM EST, 1 hour 45 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 345 PM EDT TUE OCT 2 2012 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OFF THE MIDDLE ATLANTIC COAST TONIGHT THROUGH WEDNESDAY. WEAK LOW PRESSURE MOVING ACROSS THE OHIO VALLEY WILL CAUSE A WARM FRONT TO MOVE SLOWLY ACROSS THE REGION TONIGHT AND WEDNESDAY. A COLD FRONT IS THEN EXPECTED TO MOVE ACROSS THE AREA...REACHING THE COAST ON THURSDAY. HIGH PRESSURE SHOULD THEN BUILD IN FROM THE SOUTHWEST THURSDAY NIGHT INTO FRIDAY BEFORE A WEAK COLD FRONT MOVES THROUGH FRIDAY NIGHT. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... THE LARGE AREA OF RAINFALL ASSOCIATED WITH A VORT MAX MOVING THROUGH THE AREA WILL CONTINUE TO LIFT THROUGH OUR NORTHERN ZONES LATE THIS AFTERNOON INTO THIS EVENING, WHILE SCATTERED SHOWERS MAY DEVELOP ACROSS THE REST OF THE AREA. AN AREA OF LOW PRESSURE WILL CONTINUE TO LIFT THROUGH THE OHIO RIVER VALLEY AND INTO THE GREAT LAKES REGION THROUGH TONIGHT. THIS SYSTEM'S WARM FRONT WILL SLOWLY DRIFT NORTHWARD THROUGH THE NIGHT. MODEL GUIDANCE IS NOT IN HIGH AGREEMENT WITH THE TIMING OF THE FRONT. THE NAM IS RATHER FAST, BRINGING THE FRONT THROUGH THE AREA OVERNIGHT, WHILE THE GFS IS SLOWER, BRINGING THE FRONT THROUGH DURING THE MORNING HOURS WEDNESDAY. WE DECIDED TO TAKE A SLOWER APPROACH WITH THE FRONT WHICH WILL KEEP THE AIR MASS MOSTLY STABLE BUT FULL OF MOISTURE. THERE IS A VORT MAX THAT WILL HELP TO CREATE SHOWERS THROUGH THE EVENING HOURS, ESPECIALLY FOR OUR SOUTHERN AND EASTERN AREAS, BUT THIS SHOULD PASS BY MIDNIGHT. ONCE THIS HAPPENS, THE ATMOSPHERE WILL LIKELY BEGIN TO SETTLE, AND DUE TO THE HIGH MOISTURE, WE MAY BEGIN TO GET FOG AND/OR DRIZZLE DEVELOP ACROSS THE AREA. FOR NOW, WE EXPECT VISIBILITIES TO REMAIN ABOVE 1/4 MILE FOR MOST AREAS, SO WE WILL NOT BE ISSUING ANY ADVISORIES, HOWEVER, IT IS NOT OUT OF THE QUESTION FOR A FEW AREAS TO SEE SOME DENSE FOG OVERNIGHT. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... THE AFOREMENTIONED WARM FRONT SHOULD BEGIN LIFTING THROUGH THE AREA DURING THE MORNING HOURS, AND SHOULD CLEAR BY LATE MORNING/EARLY AFTERNOON. ONCE THIS HAPPENS, WE MAY GET SOME BREAKS IN THE CLOUDS, WHICH COULD ALLOW FOR SOME HEATING TO TAKE PLACE. THEREFORE, THERE COULD BE SOME WEAK INSTABILITY ACROSS THE AREA, AND WITH THE HIGH MOISTURE CONTENT, WE MAY GET SOME SCATTERED SHOWERS DEVELOPING ACROSS THE AREA. NEITHER THE NAM OR GFS FORECAST ANY STRONG VORT MAX TO AFFECT THE AREA DURING THE DAY, ALTHOUGH THERE IS A WEAK DISTURBANCE THAT IS FORECAST TO CROSS DURING THE DAY. AGAIN, THIS MAY HELP WITH THE SHOWER DEVELOPMENT, AND IF THERE IS ENOUGH INSTABILITY AND LIFT, MAYBE AN ISOLATED THUNDERSTORM; BUT WIDESPREAD CONVECTION IS NOT ANTICIPATED AT THIS TIME. FOR MAX TEMPERATURES, WE TOOK A BLEND OF THE MAV/MET MOS AS THEY WERE RELATIVELY CLOSE. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... UNSETTLED CONDITIONS WEDNESDAY NIGHT AND THURSDAY AS THE WEAKENING SFC LOW AND UPPER TROUGH REMAIN ACROSS THE AREA. A FEW PASSING SHORT WAVES WILL LEAD ME TO LEAVE POPS IN THE SLGT CHC TO CHC RANGE FOR THESE PERIODS. DRY WEATHER FRI AND FRI NIGHT AS HIGH PRESSURE FROM THE SOUTHEAST BUILDS ACROSS THE AREA. ANOTHER FAST MOVING UPPER TROUGH AND SFC WAVE MOVE IN FROM THE WEST OVER THE WEEKEND WITH CHCS FOR SHOWERS SAT-SUN. THE ANOTHER HIGH PRESSURE AREA SETTLES ACROSS THE AREA FOR EARLY NEXT WEEK WITH DRY CONDITIONS EXPECTED. TEMPERATURES WILL BE NORMAL OR ABOVE NORMAL THU-FRI,NEAR NORMAL SAT, THEN A COLD FRONT WILL BRING READINGS BELOW NORMAL FOR SUN- TUE. OVERNIGHT LOW TEMPERATURES MAY BE COLD ENOUGH FOR SOME FROST ACROSS NRN NJ AND THE SRN POCONOS SUN NIGHT AND MON NIGHT. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. CIGS CONTINUE TO DROP ACROSS THE AREA LATE THIS AFTERNOON AND WILL CONTINUE INTO THIS EVENING AND OVERNIGHT. MOST SITES ARE NOW MVFR OR IFR WITH THEIR CIGS AND/OR VSBYS. A WARM FRONT IS EXPECTED TO MOVE THROUGH THE AREA OVERNIGHT INTO WEDNESDAY MORNING. HOWEVER, BEFORE THIS WARM FRONT LIFTS THROUGH THE AREA, CIGS ARE EXPECTED TO DROP TO IFR ACROSS ALL TAF SITES. THERE WILL BE SCATTERED SHOWERS LATE THIS AFTERNOON INTO THE EVENING, WHICH MAY THEN BECOME PATCHY DRIZZLE AND FOG OVERNIGHT. IN FACT, VSBYS MAY DROP TO 1/2-3/4 OF A MILE TOWARD DAYBREAK WEDNESDAY. THE FOG AND DRIZZLE SHOULD BEGIN TO DISSIPATE AND LIFT AFTER DAYBREAK FROM SOUTH TO NORTH AS THE WARM FRONT LIFTS NORTHWARD. CONDITIONS ARE EXPECTED IMPROVE TO VFR BY MID-DAY FOR ALL SITES. WITH THE PARTIAL CLEARING, IT IS POSSIBLE THAT SCATTERED SHOWERS, AND MAYBE AN ISOLATED THUNDERSTORM COULD DEVELOP. HOWEVER, DUE TO UNCERTAINTY IN TIMING AND PLACEMENT, WE HAVE ONLY INCLUDED VCSH WEDNESDAY AFTERNOON. OUTLOOK... WEDNESDAY NIGHT THRU THURSDAY NIGHT...SCATTERED SHOWERS WITH LOWER FLYING CONDITIONS POSSIBLE. FRI THRU FRI NIGHT...MOSTLY VFR. SAT THRU SUN...MOSTLY VFR, BUT SCATTERED SHOWERS WITH THE POSSIBILITY FOR LOWER CONDITIONS. && .MARINE... CONDITIONS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS THROUGH WEDNESDAY. WINDS ARE EXPECTED TO REMAIN BELOW 20 KNOTS AND SEAS SHOULD REMAIN 4 FEET OR LESS. THE MAIN PROBLEM WITH THE FORECAST IS HOW FAST THE WARM FRONT LIFTS THROUGH THE AREA TONIGHT INTO WEDNESDAY, AS THIS WOULD HAVE AN IMPACT ON WIND DIRECTION. FOR NOW, WE EXPECT THE WARM FRONT TO BEGIN CROSSING OUR AREA FROM SOUTH TO NORTH STARTING LATE THIS EVENING/OVERNIGHT INTO WEDNESDAY MORNING. WINDS WILL SWITCH FROM MORE OF A EAST/SOUTHEAST DIRECTION TO SOUTH/SOUTHWEST ONCE THE FRONT PASS. OUTLOOK... MOSTLY SUB-SCA CONDITIONS WED NIGHT THROUGH SAT NIGHT. A COLD FRONT WILL CROSS THE WATERS SAT NIGHT AND BRING A BETTER CHANCE FOR SCA CONDITIONS WITH GUSTS OVER 25 KTS AND SEAS 5 FT OR MORE. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && SYNOPSIS...O'HARA NEAR TERM...ROBERTSON SHORT TERM...ROBERTSON LONG TERM...O'HARA AVIATION...ROBERTSON MARINE...ROBERTSON
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 346 PM EDT TUE OCT 2 2012 DEZ001>004-MDZ008-012-015-019-020-NJZ001-007>010-012>027-PAZ054-055- 060>062-067>071-032000- NEW CASTLE-KENT-INLAND SUSSEX-DELAWARE BEACHES-CECIL-KENT MD- QUEEN ANNES-TALBOT-CAROLINE-SUSSEX-WARREN-MORRIS-HUNTERDON-SOMERSET- MIDDLESEX-WESTERN MONMOUTH-EASTERN MONMOUTH-MERCER-SALEM-GLOUCESTER- CAMDEN-NORTHWESTERN BURLINGTON-OCEAN-CUMBERLAND-ATLANTIC-CAPE MAY- ATLANTIC COASTAL CAPE MAY-COASTAL ATLANTIC-COASTAL OCEAN- SOUTHEASTERN BURLINGTON-CARBON-MONROE-BERKS-LEHIGH-NORTHAMPTON- CHESTER-MONTGOMERY-BUCKS-DELAWARE-PHILADELPHIA- 346 PM EDT TUE OCT 2 2012 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. NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY. THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. ANZ430-431-450>455-032000- 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- 346 PM EDT TUE OCT 2 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL WATERS AND DELAWARE BAY WATERS. .DAY ONE...THIS AFTERNOON AND TONIGHT. NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY. THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1251 PM EDT TUE OCT 2 2012
NJZ017>019-021-022-021745-
ATLANTIC NJ-CAMDEN NJ-CUMBERLAND NJ-GLOUCESTER NJ-
NORTHWESTERN BURLINGTON NJ-
1251 PM EDT TUE OCT 2 2012
...AN AREA OF SHOWERS PRODUCING HEAVY RAINFALL WILL AFFECT CAMDEN...
GLOUCESTER...BURLINGTON...ATLANTIC AND CUMBERLAND COUNTIES...
AT 1247 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED AN
AREA OF SHOWERS PRODUCING HEAVY RAINFALL 3 MILES NORTHWEST OF
VINELAND...MOVING NORTH AT 40 MPH. THE SHOWER WILL BE NEAR
FRANKLINVILLE...COLLINGS LAKES AROUND 100 PM...MONROE TOWNSHIP...
VICTORY LAKES...CLAYTON AROUND 105 PM...SICKLERVILLE...WILLIAMSTOWN
AROUND 110 PM...CHESILHURST AROUND 115 PM...BERLIN AND PINE VALLEY
AROUND 120 PM.
WIND GUSTS TO 40 MPH ARE POSSIBLE WITH THIS SHOWER.
LAT...LON 3986 7475 3986 7477 3984 7476 3982 7480
3978 7481 3977 7479 3942 7493 3946 7515
3950 7514 3946 7508 3957 7506 3960 7511
4000 7499 4000 7469
FORECASTER:POSPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
434 PM EDT TUE OCT 2 2012
DEZ001>003-MDZ012-015-019-020-NJZ016-021-022130-
CAROLINE MD-CUMBERLAND NJ-INLAND SUSSEX DE-KENT DE-KENT MD-
NEW CASTLE DE-QUEEN ANNE'S MD-SALEM NJ-TALBOT MD-
434 PM EDT TUE OCT 2 2012
...DEVELOPING THUNDERSTORMS WILL AFFECT PORTIONS OF CAROLINE...
CUMBERLAND...KENT...NEW CASTLE...QUEEN ANNE'S...SALEM...SUSSEX
AND TALBOT COUNTIES...
AT 429 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
DEVELOPING THUNDERSTORMS SCATTERED FROM ABOUT 10 MILES NORTHWEST
OF DOVER TO ABOUT 40 MILES WEST OF GEORGETOWN. OTHER POTENTIAL
THUNDERSTORMS WERE NEAR GEORGETOWN. ALL OF THE ACTIVITY WAS MOVING
NORTHEAST AT 25 MPH.
THE SCATTERED THUNDERSTORMS WILL BE NEAR TOWNSEND...MIDDLETOWN...
TANYARD...AND MARYDEL AROUND 435 PM...CHAMBERSVILLE...ODESSA...
GREENSBORO...AND SMYRNA AROUND 440 PM...WINDYHILL AROUND 445 PM AND
HOPE CREEK AROUND 455 PM. THE ACTIVITY NEAR GEORGETOWN WILL MOVE TO
DELAWARE BAY BY 500 PM.
DANGEROUS CLOUD TO GROUND LIGHTNING WAS DEVELOPING WITH THESE STORMS.
DO NOT SEEK SHELTER UNDER TREES WHEN LIGHTNING THREATENS...MOVE INDOORS
WHEN A THUNDERSTORM APPROACHES.
WIND GUSTS TO 30 MPH ARE POSSIBLE WITH THESE STORMS.
LAT...LON 3870 7628 3936 7591 3938 7577 3944 7577
3948 7559 3932 7543 3947 7556 3948 7556
3952 7543 3940 7509 3919 7516 3933 7541
3931 7543 3907 7539 3888 7525 3871 7531
3861 7569 3869 7590 3857 7603
MPDThe national radar mosaic for the moment the first event began.
1 flood. Local standard time, as filed.
The Perkiomen Creek at East Greenville briefly reached its flood stage of 4.0 feet at 530 p.m. EDT on the 2nd. Event precipitation totals included 1.12 inches in Gilbertsville and 1.03 inches in Pottstown.
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, October 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: 417933.