Alert archive / Pennsylvania / Flash Flood Warnings in 2007

Flash Flood Warning 3, NWS Philadelphia/Mount Holly

April 27, 2007Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Apr 27, 2007, 1:01 AM EDT for Chester County, Pennsylvania. It was in force for 3 hr. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued
Apr 27, 2007, 1:01 AM EDT (05:01 UTC)
Expired
Apr 27, 2007, 4:00 AM EDT
In force
3 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Whole counties

County Chester County, PA

The radar

The Philadelphia radar (KDIX), 114 km from the middle of the area, began a volume at 05:04 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
Apr 27, 2:00 AM EDTFLASH FLOODPhoenixville, PAFLOODING ALONG THE FRENCH CREEK. DOPPLER RADAR STORM TOTAL ESTIMATES 3 TO 4 INCHES IN CENTRAL CHESTER

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, 5.0 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-pSkew-T log-p diagram, Washington/Dulle, VA at 00:00Z on 2007-04-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2007-04-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 230 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
801 m above ground
0-6 km bulk shear
62 kt
0-1 km storm-relative helicity
230 m²/s²
0-3 km storm-relative helicity
343 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 270503
FFWPHI
PAC029-270800-

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

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 400 AM EDT

* AT 1258 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR
  INDICATED STORM TOTALS OF 1.5 TO 2.0 INCHES ACROSS WEST
  CENTRAL CHESTER COUNTY. MORE THUNDERSTORMS WITH HEAVY
  RAIN ARE OCCURRING IN LANCASTER COUNTY AND WILL BE MOVING
  OVER CHESTER COUNTY. THE HEAVIEST RAIN SO FAR HAS FALLEN 
  OVER THE MARSH CREEK, BEAVER CREEK AND THE WEST BRANCH
  OF THE BRANDYWINE CREEK. 

ADDITIONAL RAINFALL AMOUNTS OF AROUND ONE INCH ARE POSSIBLE IN THE 
WARNED AREA.

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.

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 3991 7602 3971 7598 4008 7547 4022 7569

$$

TFG

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 27, 1:14 AM EDTFlash Flood WarningPHIBucks, Montgomery3 hr
Apr 27, 3:42 AM EDTFlash Flood WarningPHIBucks, Chester, Montgomery4 hr
Apr 27, 8:07 AM EDTFlash Flood WarningPHIBucks, Chester, Montgomery83 min

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.