Alert archive / Pennsylvania / Flash Flood Warnings in 2011
Flash Flood Warning 35, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 21, 2011, 3:31 PM EDT for Philadelphia County, Pennsylvania. It was in force for 8 hr. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- Aug 21, 2011, 3:31 PM EDT (19:31 UTC)
- Expired
- Aug 22, 2011, 12:00 AM EDT
- In force
- 8 hr
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Flood severity
- None
County Philadelphia County, PA
The radar
The Philadelphia radar (KDIX), 57 km from the middle of the area, began a volume at 19:30 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Brookhaven, NY (KOKX), launched 12:00Z, 7.5 hours before the alert went out and 209 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 874 J/kg
- Mixed-layer CIN
- -29 J/kg
- Mixed-layer LCL
- 857 m above ground
- 0-6 km bulk shear
- 22 kt
- 0-1 km storm-relative helicity
- 55 m²/s²
- 0-3 km storm-relative helicity
- 116 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
873
WGUS51 KPHI 211931
FFWPHI
PAC101-212230-
/O.NEW.KPHI.FF.W.0035.110821T1931Z-110821T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
331 PM EDT SUN AUG 21 2011
THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A
* FLASH FLOOD WARNING FOR...
NORTHEASTERN PHILADELPHIA COUNTY...
* UNTIL 630 PM EDT...
* AT 326 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
VERY HEAVY RAIN FROM A THUNDERSTORM OVER NORTHEASTERN PHILADELPHIA
COUNTY.
* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
PHILADELPHIA. NATIONAL WEATHER SERVICE RADAR HAS ESTIMATED BETWEEN
2 AND 2 1/2 INCHES OF RAIN DURING THE PAST HOUR. ADDITIONAL
RAINFALL AMOUNTS OF AROUND 1 INCH ARE POSSIBLE IN THE WARNED AREA.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
PLEASE REPORT FLOODING...HAIL OR WIND DAMAGE TO THE NATIONAL WEATHER
SERVICE BY CALLING TOLL FREE...1-877-633-6772.
FLOODING IS OCCURRING OR IS IMMINENT. MOST FLOOD RELATED DEATHS OCCUR
IN AUTOMOBILES. DO NOT ATTEMPT TO CROSS WATER COVERED BRIDGES...
DIPS...OR LOW WATER CROSSINGS. TURN AROUND...DON'T DROWN! NEVER TRY
TO CROSS A FLOWING STREAM...EVEN A SMALL ONE...ON FOOT. TO ESCAPE
RISING WATER MOVE UP TO HIGHER GROUND.
&&
LAT...LON 4003 7499 4001 7504 3998 7507 3998 7511
3995 7517 4006 7518 4006 7514 4005 7512
4010 7504 4010 7498
$$6 follow-up statements
383
WGUS71 KPHI 211952
FFSPHI
FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
352 PM EDT SUN AUG 21 2011
PAC101-212230-
/O.CON.KPHI.FF.W.0035.000000T0000Z-110821T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
PHILADELPHIA PA-
352 PM EDT SUN AUG 21 2011
...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 630 PM EDT FOR
NORTHEASTERN PHILADELPHIA COUNTY...
AT 347 PM EDT...DOPPLER RADAR ESTIMATES CONTINUE TO INDICATE A
THUNDERSTORM PRODUCING FLASH FLOODING OVER NORTHEASTERN PHILADELPHIA
COUNTY.
LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO PHILADELPHIA.
FRANKFORD CREEK WAS FLOODING AND RISING VERY RAPIDLY. MODERATE
FLOODING WAS OCCURRING AND MAJOR FLOODING IS LIKELY THERE THIS
AFTERNOON.
ADDITIONAL RAINFALL AMOUNTS OF 1/4 TO 1/3 INCH IS POSSIBLE IN THE
WARNED AREA DURING THE NEXT HOUR. RUNOFF WILL CONTINUE TO OCCUR THIS
AFTERNOON.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES
AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.
FLOODING IS OCCURRING OR IS IMMINENT. MOST FLOOD RELATED DEATHS
OCCUR IN AUTOMOBILES. DO NOT ATTEMPT TO CROSS WATER COVERED
BRIDGES...DIPS...OR LOW WATER CROSSINGS. NEVER TRY TO CROSS A
FLOWING STREAM...EVEN A SMALL ONE...ON FOOT. TO ESCAPE RISING WATER
MOVE UP TO HIGHER GROUND.
PLEASE REPORT FLOODING...HAIL OR WIND DAMAGE BY CALLING YOUR LOCAL
LAW ENFORCEMENT OFFICIALS OR BY CALLING THE NATIONAL WEATHER SERVICE
TOLL FREE AT...1-877-633-6772.
&&
LAT...LON 4003 7499 4001 7504 3998 7507 3998 7511
3995 7517 4006 7518 4006 7514 4005 7512
4010 7504 4010 7498
$$204
WGUS71 KPHI 212130
FFSPHI
FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
530 PM EDT SUN AUG 21 2011
PAC101-212230-
/O.CON.KPHI.FF.W.0035.000000T0000Z-110821T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
PHILADELPHIA PA-
530 PM EDT SUN AUG 21 2011
...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 630 PM EDT FOR
NORTHEASTERN PHILADELPHIA COUNTY...
AT 523 PM EDT...THUNDERSTORMS PRODUCING FLASH FLOODING WERE
CONTINUING OVER NORTHEASTERN PHILADELPHIA COUNTY.
LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO PHILADELPHIA.
ADDITIONAL RAINFALL AMOUNTS OF 1/2 TO 3/4 INCHES OF RAIN ARE
POSSIBLE IN THE WARNED AREA THROUGH 6:00 PM AS THE LAST OF SEVERAL
THUNDERSTORMS APPEARS TO BE MOVING THROUGH THE AREA. RUNOFF WILL
CONTINUE AT LEAST THROUGH 6:30 PM...AND THE WARNING MAY NEED TO BE
EXTENDED. FRANKFORD CREEK IN NORTHEASTERN PHILADELPHIA HAD STARTED
TO RECEDE ALTHOUGH IT WAS STILL ABOVE FLOOD STAGE...BUT RENEWED
RAINFALL WAS CAUSING THE CREEK TO RISE ONCE AGAIN. PENNYPACK CREEK
HAD FALLEN BELOW FLOOD STAGE...BUT WAS ALSO RISING AGAIN.
MOTORISTS ARE URGED TO NOT DRIVE INTO FLOODED ROADWAYS. IF WATER IS
RISING IN YOUR LOCATION...ABANDON YOUR CAR AND MOVE TO HIGHER GROUND
IMMEDIATELY.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES
AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.
DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.
PLEASE REPORT FLOODING...HAIL OR WIND DAMAGE BY CALLING YOUR LOCAL
LAW ENFORCEMENT OFFICIALS OR BY CALLING THE NATIONAL WEATHER SERVICE
TOLL FREE AT...1-877-633-6772.
&&
LAT...LON 4003 7499 4001 7504 3998 7507 3998 7511
3995 7517 4006 7518 4006 7514 4005 7512
4010 7504 4010 7498
$$113
WGUS51 KPHI 212212
FFWPHI
PAC101-220030-
/O.EXT.KPHI.FF.W.0035.000000T0000Z-110822T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
612 PM EDT SUN AUG 21 2011
THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS EXTENDED THE
* FLASH FLOOD WARNING FOR...
NORTHEASTERN PHILADELPHIA COUNTY...
* UNTIL 830 PM EDT...
* AT 605 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR ESTIMATES
AND RAIN GAGE REPORTS INDICATED FLASH FLOODING FROM PERSISTENT
THUNDERSTORMS OVER NORTHEASTERN PHILADELPHIA COUNTY. 2 TO AROUND
3 INCHES OF RAIN HAVE OCCURRED IN OR NEAR THE WARNED AREA THIS
AFTERNOON...MUCH OF THAT WITH AN HOUR OR TWO.
* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
PHILADELPHIA.
ADDITIONAL SIGNIFICANT RAINFALL AMOUNTS ARE NOT EXPECTED BUT
CONTINUING RUNOFF FROM THE HEAVY RAINS WILL CONTINUE IN THE WARNED
AREA.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
PLEASE REPORT FLOODING...HAIL OR WIND DAMAGE TO THE NATIONAL WEATHER
SERVICE BY CALLING TOLL FREE...1-877-633-6772.
FLOODING IS OCCURRING OR IS IMMINENT. MOST FLOOD RELATED DEATHS
OCCUR IN AUTOMOBILES. DO NOT ATTEMPT TO CROSS WATER COVERED
BRIDGES...DIPS...OR LOW WATER CROSSINGS. TURN AROUND...DON'T DROWN!
NEVER TRY TO CROSS A FLOWING STREAM...EVEN A SMALL ONE...ON FOOT. TO
ESCAPE RISING WATER MOVE UP TO HIGHER GROUND.
&&
LAT...LON 4003 7499 4001 7504 3998 7507 3998 7511
3995 7517 4006 7518 4006 7514 4005 7512
4010 7504 4010 7498
$$215
WGUS51 KPHI 212349
FFWPHI
PAC101-220200-
/O.EXT.KPHI.FF.W.0035.000000T0000Z-110822T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
749 PM EDT SUN AUG 21 2011
THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS EXTENDED THE
* FLASH FLOOD WARNING FOR...
NORTHEASTERN PHILADELPHIA COUNTY...
* UNTIL 1000 PM EDT...
* AT 745 PM EDT...FLASH FLOODING FROM PREVIOUS THUNDERSTORMS
WAS CONTINUING OVER NORTHEASTERN PHILADELPHIA COUNTY. MINOR
FLOODING WAS STILL OCCURRING ON THE WISSAHICKON CREEK...BUT THE
WATER LEVEL THERE MAY DROP BELOW FLOOD STAGE SHORTLY. OTHER CREEKS
AND STEAMS WERE RUNNING VERY HIGH. HOWEVER...ADDTIONAL SHOWERS AND
THUNDERSTORMS WERE UPSTREAM AND ADDITIONAL RAINFALL MAY OCCUR THIS
EVENING. RUNOFF WILL CONTINUE THROUGH THIS EVENING.
* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
PHILADELPHIA.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. NEVER ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR IN AN
AUTOMOBILE. TURN AROUND DON'T DROWN!
FLOODING IS OCCURRING. MOST FLOOD RELATED DEATHS OCCUR IN
AUTOMOBILES. DO NOT ATTEMPT TO CROSS WATER COVERED BRIDGES...DIPS...
OR LOW WATER CROSSINGS. TURN AROUND...DON'T DROWN! NEVER TRY TO
CROSS A FLOWING STREAM...EVEN A SMALL ONE...ON FOOT. TO ESCAPE
RISING WATER MOVE UP TO HIGHER GROUND.
&&
LAT...LON 4003 7499 4001 7504 3998 7507 3998 7511
3995 7517 4006 7518 4006 7514 4005 7512
4010 7504 4010 7498
$$989
WGUS51 KPHI 220151
FFWPHI
PAC101-220400-
/O.EXT.KPHI.FF.W.0035.000000T0000Z-110822T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
951 PM EDT SUN AUG 21 2011
THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS EXTENDED THE
* FLASH FLOOD WARNING FOR...
NORTHEASTERN PHILADELPHIA COUNTY...
* UNTIL MIDNIGHT EDT...
* AT 945 PM EDT...SHOWERS AND THUNDERSTORMS WERE ENDING OVER
PHILADELPHIA BUT HAVE COMBINED WITH THE HIGH RAIN TOTALS OF THIS
AFTERNOON TO PRODUCE CONTINUING RUNOFF LATE THIS EVENING. THE
WISSAHICKON CREEK IN PHILADELPHIA CONTINUES TO PRODUCE MINOR
FLOODING ALONG SOME OF ITS LENGTH. THEREFORE THE FLASH FLOOD
WARNING WILL BE EXTENDED THROUGH MIDNIGHT TO ALLOW WATER TO DRAIN
AWAY OVER THE NEXT COUPLE OF HOURS. MOTORISTS ARE URGED TO WATCH
FOR FLOODED AREAS ON ROADS. NEVER DRIVE INTO OR THROUGH FLOODED
ROADWAYS.
* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
PHILADELPHIA.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. MOVE
UP TO HIGHER GROUND TO ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS
SUBJECT TO FLOODING WHEN WATER BEGINS RISING.
FLOODING IS OCCURRING. MOST FLOOD RELATED DEATHS OCCUR IN
AUTOMOBILES. DO NOT ATTEMPT TO CROSS WATER COVERED BRIDGES...DIPS...
OR LOW WATER CROSSINGS. TURN AROUND...DON'T DROWN! NEVER TRY TO
CROSS A FLOWING STREAM...EVEN A SMALL ONE...ON FOOT. TO ESCAPE
RISING WATER MOVE UP TO HIGHER GROUND.
&&
LAT...LON 4003 7499 4001 7504 3998 7507 3998 7511
3995 7517 4006 7518 4006 7514 4005 7512
4010 7504 4010 7498
$$978
WGUS71 KPHI 220357
FFSPHI
FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1157 PM EDT SUN AUG 21 2011
PAC101-220407-
/O.EXP.KPHI.FF.W.0035.000000T0000Z-110822T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
PHILADELPHIA PA-
1157 PM EDT SUN AUG 21 2011
...THE FLASH FLOOD WARNING WILL EXPIRE AT MIDNIGHT EDT FOR
NORTHEASTERN PHILADELPHIA COUNTY...
THE WATERS FROM THE EARLIER HEAVY RAINS ARE RECEDING AND NO LONGER
POSE A THREAT TO LIFE OR PROPERTY. THEREFORE...THE FLASH FLOOD
WARNING WILL BE ALLOWED TO EXPIRE.
LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO PHILADELPHIA.
LAT...LON 4003 7499 4001 7504 3998 7507 3998 7511
3995 7517 4006 7518 4006 7514 4005 7512
4010 7504 4010 7498
$$
HAYESThe office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 21, 3:28 AM EDT | Flash Flood Watch | PHI | Delaware, Philadelphia | 17 hr |
| Aug 21, 1:11 PM EDT | Special Weather Statement | PHI | Montgomery | 64 min |
| Aug 21, 1:25 PM EDT | Areal Flood Advisory | PHI | Bucks, Chester, Montgomery | 110 min |
| Aug 21, 1:47 PM EDT | Severe Thunderstorm Warning | PHI | Bucks, Chester, Delaware, Montgomery, Philadelphia | 58 min |
| Aug 21, 2:33 PM EDT | Areal Flood Advisory | PHI | Bucks, Delaware, Montgomery, Philadelphia | 117 min |
| Aug 21, 2:43 PM EDT | Severe Thunderstorm Warning | PHI | Bucks, Chester, Delaware, Montgomery, Philadelphia | 62 min |
| Aug 21, 4:11 PM EDT | Special Weather Statement | PHI | Carbon, Monroe | 64 min |
| Aug 21, 4:19 PM EDT | Areal Flood Advisory | PHI | Carbon, Monroe | 3 hr |
| Aug 21, 4:35 PM EDT | Areal Flood Advisory | PHI | Berks, Bucks, Chester, Delaware, Lehigh, Montgomery and 2 more | 3 hr |
| Aug 21, 4:53 PM EDT | Special Weather Statement | PHI | Lehigh, Northampton | 67 min |
| Aug 21, 6:05 PM EDT | Flash Flood Warning | PHI | Bucks, Delaware, Montgomery, Philadelphia | 6 hr |
| Aug 21, 6:41 PM EDT | Special Weather Statement | PHI | Berks | 64 min |
| Aug 21, 7:35 PM EDT | Areal Flood Advisory | PHI | Berks, Bucks, Chester, Delaware, Montgomery, Philadelphia | 115 min |
Nearby
Flash Flood Warnings in Pennsylvania, 2011Every flash flood warning in 2011
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.