Alert archive / Pennsylvania / Flash Flood Warnings in 2013

Flash Flood Warning 54, NWS Philadelphia/Mount Holly

August 13, 2013Chester County, Delaware County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 13, 2013, 6:36 AM EDT for Chester County, Delaware County, Montgomery County, Pennsylvania. It was in force for 8 hr. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 13, 2013, 6:36 AM EDT (10:36 UTC)
Expired
Aug 13, 2013, 2:30 PM EDT
In force
8 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Chester County, PA, Delaware County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 91 km from the middle of the area, began a volume at 10:37 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.

What was reported inside it

TimeReportWhereRemark
Aug 13, 8:08 AM EDTFLASH FLOODRadnor, PAFLOODING IN STREETS
Aug 13, 10:10 AM EDTFLASH FLOODTredyffrin Twp, PAROADS FLOODED IN GLENHARDIE NEIGHBORHOOD.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 10.6 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.

Skew-T log-pSkew-T log-p diagram, Washington/Dulle, VA at 00:00Z on 2013-08-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 00:00Z on 2013-08-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 31 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
1 J/kg
Mixed-layer CIN
-66 J/kg
Mixed-layer LCL
1841 m above ground
0-6 km bulk shear
39 kt
0-1 km storm-relative helicity
31 m²/s²
0-3 km storm-relative helicity
84 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

230 
WGUS51 KPHI 131036
FFWPHI
PAC029-045-091-131430-
/O.NEW.KPHI.FF.W.0054.130813T1036Z-130813T1430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
636 AM EDT TUE AUG 13 2013

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  MONTGOMERY COUNTY...
  DELAWARE COUNTY...
  EASTERN CHESTER COUNTY...

* UNTIL 1030 AM EDT...

* AT 629 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  ADDITIONAL HEAVY RAIN MOVING INTO DELAWARE COUNTY...EASTERN
  CHESTER COUNTY AND MONTGOMERY COUNTY. SOME LOCATIONS HAVE ALREADY
  RECEIVED ONE TO THREE INCHES OF RAIN. AN ADDITIONAL ONE TO THREE
  INCHES OF RAIN IS EXPECTED.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO AMBLER...
  COLLEGEVILLE...CONSHOHOCKEN...HATFIELD...LANSDALE...NORRISTOWN...
  POTTSTOWN AND WEST CHESTER.

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!

&&

LAT...LON 4023 7572 4032 7563 4029 7527 4020 7512
      4008 7520 4009 7523 4006 7526 4003 7524
      3982 7539 3984 7551 3983 7572 4012 7558
      4013 7589

$$

IOVINO
2 follow-up statements
844 
WGUS71 KPHI 131228
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
828 AM EDT TUE AUG 13 2013

PAC029-045-091-131430-
/O.CON.KPHI.FF.W.0054.000000T0000Z-130813T1430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MONTGOMERY PA-DELAWARE PA-CHESTER PA-
828 AM EDT TUE AUG 13 2013

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1030 AM EDT FOR
EASTERN CHESTER...DELAWARE AND MONTGOMERY COUNTIES...

AT 825 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR ESTIMATED
THAT TWO TO FOUR INCHES OF RAIN FELL IN MUCH OF THE AREA THIS 
MORNING. SOME LOCATIONS FROM AROUND EXTON TO VALLEY FORGE TO BLUE 
BELL MAY HAVE RECEIVED UP TO FIVE OR SIX INCHES OF RAIN. AN 
ADDITIONAL INCH OR TWO OF RAIN IS POSSIBLE AT SOME LOCATIONS AND IT 
MAY CAUSE ADDITIONAL FLASH FLOODING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

LAT...LON 4023 7572 4032 7563 4029 7527 4020 7512
      4008 7520 4009 7523 4006 7526 4003 7524
      3982 7539 3984 7551 3983 7572 4012 7558
      4013 7589

$$

IOVINO
225 
WGUS51 KPHI 131403
FFWPHI
PAC029-045-091-131830-
/O.EXT.KPHI.FF.W.0054.000000T0000Z-130813T1830Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1003 AM EDT TUE AUG 13 2013

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS EXTENDED THE

* FLASH FLOOD WARNING FOR...
  MONTGOMERY COUNTY...
  DELAWARE COUNTY...
  EASTERN CHESTER COUNTY...

* UNTIL 230 PM EDT...

* AT 956 AM EDT...FLASH FLOODING WAS REPORTED THROUGHOUT THE AREA    
  FROM HEAVY RAIN DURING THE OVERNIGHT HOURS. WHILE THE HEAVIEST     
  RAIN HAS MOVED EAST...LIGHTER RAIN IS EXPECTED FOR THE NEXT FEW    
  HOURS. THE FLASH FLOOD WARNING FOR MONTGOMERY...DELAWARE AND      
  EASTERN CHESTER COUNTY HAS THEREFORE BEEN EXTENDED INTO THE        
  AFTERNOON HOURS. 


PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT UNDERESTIMATE THE POWER OF FLOOD WATERS. ONLY A FEW INCHES OF
RAPIDLY FLOWING WATER CAN QUICKLY CARRY AWAY YOUR VEHICLE.

&&

LAT...LON 4023 7572 4032 7563 4029 7527 4020 7512
      4008 7520 4009 7523 4006 7526 4003 7524
      3982 7539 3984 7551 3983 7572 4012 7558
      4013 7589

$$

FORECASTER:JJM

The office that day

Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 13, 2:45 AM EDTFlash Flood WatchPHIBerks, Bucks, Carbon, Chester, Delaware, Lehigh and 4 more9 hr
Aug 13, 5:15 AM EDTAreal Flood AdvisoryPHIBerks, Chester, Montgomery4 hr
Aug 13, 5:47 AM EDTFlash Flood WarningPHIChester4 hr
Aug 13, 6:07 AM EDTAreal Flood AdvisoryPHIBucks, Lehigh, Northampton7 hr
Aug 13, 6:07 AM EDTSevere Thunderstorm WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia53 min
Aug 13, 6:20 AM EDTAreal Flood AdvisoryPHIBucks, Delaware, Philadelphia4 hr
Aug 13, 6:23 AM EDTSevere Thunderstorm WarningPHIChester, Delaware67 min
Aug 13, 6:32 AM EDTTornado WarningPHIChester43 min
Aug 13, 7:05 AM EDTSevere Thunderstorm WarningPHIDelaware, Philadelphia40 min
Aug 13, 7:14 AM EDTFlash Flood WarningPHIBerks4 hr
Aug 13, 7:42 AM EDTSpecial Weather StatementPHIPhiladelphia48 min
Aug 13, 7:54 AM EDTFlash Flood WarningPHIDelaware, Montgomery, Philadelphia8 hr
Aug 13, 7:54 AM EDTSpecial Weather StatementPHIDelaware, Philadelphia66 min
Aug 13, 8:07 AM EDTRiver Flood WarningPHIChester9 hr
Aug 13, 8:20 AM EDTFlash Flood WarningPHIBucks8 hr
Aug 13, 9:50 AM EDTFlash Flood WarningPHIChester4 hr
Aug 13, 11:22 AM EDTRiver Flood WarningPHIChester, Delaware16 hr
Aug 13, 2:18 PM EDTAreal Flood WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia9 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2013Every flash flood warning in 2013

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.