Alert archive / Pennsylvania / Flash Flood Warnings in 2004

Flash Flood Warning 59, NWS Philadelphia/Mount Holly

August 1, 20044 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 1, 2004, 9:08 AM EDT for 4 counties in 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 outline as issued.

The facts

Issued
Aug 1, 2004, 9:08 AM EDT (13:08 UTC)
Expired
Aug 1, 2004, 11:15 AM EDT
In force
2 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Counties, with a storm outline in the text

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

The radar

The Philadelphia radar (KDIX), 95 km from the middle of the area, began a volume at 13:04 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.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 1.1 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 12:00Z on 2004-08-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1100 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 2004-08-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 131 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
1100 J/kg
Mixed-layer CIN
-8 J/kg
Mixed-layer LCL
506 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
131 m²/s²
0-3 km storm-relative helicity
127 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.0

Open this sounding in Storm Lab

The text

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

000 
WGUS51 KPHI 011312
FFWPHI
PAC029-045-091-101-011515-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
908 AM EDT SUN AUG 1 2004

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS EXTENDED THE

* FLASH FLOOD WARNING FOR...
  EASTERN CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA
  DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA
  MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA
  PHILADELPHIA COUNTY IN SOUTHEAST PENNSYLVANIA 

* UNTIL 1115 AM EDT

* AT 905 AM EDT...ONGOING FLOODING WAS OCCURRING ALONG THE 
  MANATAWNY CREEK IN MONTGOMERY COUNTY...WISSAHICKON CREEK IN
  PHILADELPHIA...VALLEY CREEK IN CHESTER COUNTY AND THE CRUM CREEK
  IN DELAWARE COUNTY. IN ADDITION OTHER SMALLER CREEKS ARE LIKELY
  OUT OF THEIR BANKS. THE HEAVIEST RAIN IS OVER AND THE RUNOFF FROM
  THE HEAVY RAIN HAS TO MOVE THROUGH THE AREA STREAMS.
  

EXCESSIVE RUNOFF FROM HEAVY RAINFALL HAS CAUSED FLOODING OF SMALL
CREEKS AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES
AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.

FLOODING IS OCCURRING. 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.

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

FOR THE LATEST STORM INFORMATION...PLEASE TUNE TO NOAA WEATHER
RADIO...YOUR LOCAL RADIO OR TELEVISION STATION...OR YOUR CABLE
TELEVISION OUTLET.

LAT...LON 4019 7573 3983 7556 4006 7498 4038 7548

$$

TFG

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 1, 7:12 AM EDTFlash Flood WarningPHIMontgomery2 hr
Aug 1, 7:30 AM EDTFlash Flood WarningPHIPhiladelphia2 hr
Aug 1, 7:43 AM EDTFlash Flood WarningPHIBucks2 hr
Aug 1, 7:50 AM EDTFlash Flood WarningPHIChester, Delaware115 min
Aug 1, 8:01 AM EDTFlash Flood WarningPHIMontgomery89 min
Aug 1, 10:59 AM EDTFlash Flood WarningPHIDelaware, Montgomery, Philadelphia2 hr
Aug 1, 12:52 PM EDTFlash Flood WarningPHIDelaware, Philadelphia4 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2004Every flash flood warning in 2004

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.