Alert archive / Pennsylvania / Flash Flood Warnings in 2007

Flash Flood Warning 30, NWS Philadelphia/Mount Holly

July 29, 2007Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 29, 2007, 9:28 AM EDT for Chester County, Pennsylvania. It was in force for 2 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Jul 29, 2007, 9:28 AM EDT (13:28 UTC)
Expired: Jul 29, 2007, 11:30 AM EDT
In force: 2 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Whole counties

County Chester County, PA

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 1.5 hours before the alert went out and 182 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1003 J/kg
Mixed-layer CIN: -89 J/kg
Mixed-layer LCL: 792 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 12 m²/s²
0-3 km storm-relative helicity: 89 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

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

000 
WGUS51 KPHI 291329
FFWPHI
PAC029-291530-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
928 AM EDT SUN JUL 29 2007

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 1130 AM EDT

* AT 925 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
  VERY HEAVY RAIN FROM THUNDERSTORMS OVER THE WARNED AREA.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO CHESTER
  SPRINGS...GLENMOORE...PUGHTOWN...WEST CHESTER...PARKESBURG...
  PAOLI...MARSHALLTON...LIONVILLE...HONEY BROOK...DOWNINGTOWN AND
  COATESVILLE

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.

RAINFALL TOTALS FROM ADJACENT RADARS INDICATE OVER TWO OR MORE INCHES
PER HOUR.  

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

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 3974 7607 3974 7578 3999 7548 4006 7543
      4023 7567 4012 7590

$$

EBERWINE

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 29, 4:07 AM EDT	Severe Thunderstorm Warning	PHI	Berks	53 min
Jul 29, 9:56 AM EDT	Flash Flood Warning	PHI	Lehigh, Northampton	2 hr
Jul 29, 10:22 AM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh	53 min
Jul 29, 10:50 AM EDT	Flash Flood Warning	PHI	Berks	115 min

Nearby

Flash Flood Warnings in Pennsylvania, 2007 Every 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.