Alert archive / Pennsylvania / Flash Flood Warnings in 2009

Flash Flood Warning 10, NWS Philadelphia/Mount Holly

June 13, 2009Bucks County, Montgomery County, Philadelphia County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jun 13, 2009, 4:07 PM EDT for Bucks County, Montgomery County, Philadelphia County, Pennsylvania. It was in force for 6 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
Jun 13, 2009, 4:07 PM EDT (20:07 UTC)
Expired
Jun 13, 2009, 10:00 PM EDT
In force
6 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Bucks County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 51 km from the middle of the area, began a volume at 20:09 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
Jun 13, 5:55 PM EDTFLASH FLOODAmbler, PABASEMENTS AND ROADS FLOODED IN ALBER.
Jun 13, 9:20 PM EDTHEAVY RAIN 0Willow Grove, PA3.78 INCHES STORM TOTAL.

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 12:00Z, 8.1 hours before the alert went out and 249 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 12:00Z on 2009-06-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 18 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 12:00Z on 2009-06-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -30 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
18 J/kg
Mixed-layer CIN
-76 J/kg
Mixed-layer LCL
989 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
-30 m²/s²
0-3 km storm-relative helicity
38 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

000 
WGUS51 KPHI 132007
FFWPHI
PAC017-091-101-140200-
/O.NEW.KPHI.FF.W.0010.090613T2007Z-090614T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
407 PM EDT SAT JUN 13 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  SOUTHERN BUCKS COUNTY IN SOUTHEAST PENNSYLVANIA...
  MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...
  THIS INCLUDES THE CITY OF WILLOW GROVE...
  NORTHERN PHILADELPHIA COUNTY IN SOUTHEAST PENNSYLVANIA...
  THIS INCLUDES THE CITY OF PHILADELPHIA...

* UNTIL 1000 PM EDT

* AT 401 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
  THUNDERSTORMS WITH TORRENTIAL RAINFALL CONTINUING OVER BUCKS
  AND MONTGOMERY COUNTIES. FLOODING IS OCCURRING ALONG THE 
  LITTLE NESHAMINY CREEK. DOPPLER RADAR STORM TOTAL ESTIMATES 
  REACHED 5.31 INCHES IN WARMINSTER TOWNSHIP IN BUCKS COUNTY.
  NUMEROUS ROADWAYS ARE CLOSED IN WARMINSTER, WARRINGTON AND 
  HORSHAM COUNTIES. A SPOTTER JUST REPORTED OVER AN INCH OF RAIN 
  IN 10 MINUTES IN AMBLER IN MONTGOMERY COUNTY.
 
  RUNOFF FROM THE HEAVY RAIN IN MONTGOMERY COUNTY
  MIGHT CAUSE FLOODING ALONG THE WISSAHICKON AND PENNYPACK CREEKS
  ALL THE WAY INTO PHILADELPHIA.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO 
  GARDENVILLE...FRICKS...WOODSIDE...SPRING MOUNT...SOUDERTON... 
  RICHBORO...NEWTOWN...LEVITTOWN...LANSDALE...LANGHORNE...IVYLAND...  
  FEASTERVILLE...DUBLIN...DOYLESTOWN...COLLEGEVILLE...CHALFONT AND   
  AMBLER.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...HIGHWAYS AND UNDERPASSES. ADDITIONALLY...COUNTRY
ROADS AND FARMLANDS ALONG THE BANKS OF CREEKS...STREAMS AND OTHER LOW
LYING AREAS ARE SUBJECT TO FLOODING.

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.

&&

LAT...LON 4012 7477 4012 7483 4007 7488 4006 7495
      3997 7509 3998 7511 3995 7515 4025 7563
      4042 7505 4031 7491 4030 7487 4024 7484
      4017 7473 4015 7472

$$
 
TFG

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 13, 2:27 PM EDTAreal Flood AdvisoryPHIChester4 hr
Jun 13, 2:32 PM EDTFlash Flood WarningPHIBucks2 hr
Jun 13, 2:33 PM EDTFlash Flood WarningPHICarbon, Lehigh, Monroe, Northampton112 min
Jun 13, 2:57 PM EDTFlash Flood WarningPHIMontgomery2 hr
Jun 13, 3:17 PM EDTAreal Flood AdvisoryPHIBucks3 hr
Jun 13, 4:59 PM EDTAreal Flood AdvisoryPHIChester4 hr
Jun 13, 5:16 PM EDTRiver Flood WarningPHIBucks13 hr
Jun 13, 6:06 PM EDTFlash Flood WarningPHIChester2 hr
Jun 13, 6:39 PM EDTSevere Thunderstorm WarningPHIMonroe66 min
Jun 13, 7:29 PM EDTSevere Thunderstorm WarningPHICarbon, Monroe61 min

Nearby

Flash Flood Warnings in Pennsylvania, 2009Every flash flood warning in 2009

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.