Alert archive / Pennsylvania / Flash Flood Warnings in 2007

Flash Flood Warning 8, NWS Philadelphia/Mount Holly

April 27, 2007Bucks County, Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Apr 27, 2007, 8:07 AM EDT for Bucks County, Chester County, Montgomery County, Pennsylvania. It was in force for 83 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Apr 27, 2007, 8:07 AM EDT (12:07 UTC)
Expired
Apr 27, 2007, 9:30 AM EDT
In force
83 min
Issued by
NWS Philadelphia/Mount Holly
Area
Whole counties

Counties Bucks County, PA, Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 88 km from the middle of the area, began a volume at 12:08 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 0.1 hours before the alert went out and 218 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 2007-04-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2007-04-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 155 square meters per square second.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
474 m above ground
0-6 km bulk shear
60 kt
0-1 km storm-relative helicity
155 m²/s²
0-3 km storm-relative helicity
176 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 271207
FFWPHI
PAC017-029-091-271330-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
807 AM EDT FRI APR 27 2007

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  NORTHWESTERN BUCKS COUNTY IN SOUTHEAST PENNSYLVANIA...
  CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...
  MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 930 AM EDT

* AT 805 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR SHOWED      
  ADDITIONAL RAINFALL MOVING ACROSS THE AREA THIS MORNING. AFFECTED  
  STREAM BASINS INCLUDE THE EAST BRANCH OF THE PERKIOMEN CREEK WHERE 
  THE WATER LEVEL AT SCHWENKSVILLE IS NEARING THE FLOOD STAGE OF 7.0 
  FEET. EARLIER FLASH FLOODING OCCURRED ALONG THE PICKERING CREEK 
  AND THE FRENCH CREEK IN CHESTER COUNTY, TRIBUTARIES OF THE         
  SKIPPACK CREEK AND TOWAMENCIN CREEK IN MONTGOMERY COUNTY AND       
  THE UPPER PARTS OF THE NESHAMINY CREEK AS WELL AS THE              
  PAUNNACUSSING CREEK IN BUCKS COUNTY. ADDITIONAL RUNOFF             
  WILL CONTINUE TO CAUSE AREA STREAMS AND CREEKS TO RUN HIGH WITH    
  ADDITIONAL FLOODING VERY POSSIBLE.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO SPRING
  MOUNT...SOUDERTON...QUAKERTOWN...POTTSTOWN...PHOENIXVILLE...
  PERKASIE...LANSDALE...DUBLIN...DOYLESTOWN...COLLEGEVILLE AND
  CHALFONT

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.

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. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE.

LAT...LON 4008 7591 3976 7596 4035 7497 4058 7523

$$

GORSE

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 27, 1:01 AM EDTFlash Flood WarningPHIChester3 hr
Apr 27, 1:14 AM EDTFlash Flood WarningPHIBucks, Montgomery3 hr
Apr 27, 3:42 AM EDTFlash Flood WarningPHIBucks, Chester, Montgomery4 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2007Every flash flood warning in 2007

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.