Alert archive / Pennsylvania / Flash Flood Warnings in 2004

Flash Flood Warning 54, NWS Philadelphia/Mount Holly

August 1, 2004Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 1, 2004, 8:01 AM EDT for Montgomery County, Pennsylvania. It was in force for 89 min. 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, 8:01 AM EDT (12:01 UTC)
Expired
Aug 1, 2004, 9:30 AM EDT
In force
89 min
Issued by
NWS Philadelphia/Mount Holly
Area
Counties, with a storm outline in the text

County Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 96 km from the middle of the area, began a volume at 12:02 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, 0.0 hours before the alert went out and 220 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°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 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 011202
FFWPHI
PAC091-011330-

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

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 930 AM EDT

* AT 758 AM EDT...NATIONAL WEATHER SERVICE RADAR CONTINUED TO
  INDICATE THAT FLASH FLOODING WAS IMMINENT NEAR STREAMS AND CREEKS 
  IN MONTGOMERY COUNTY. MOREOVER...THE MANATAWNY CREEK NEAR POTTSTOWN
  HAD OVERFLOWED ITS BANKS. 

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.

LAT...LON 4029 7564 4011 7544 4015 7508 4041 7552

$$
MPD

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, 9:08 AM EDTFlash Flood WarningPHIChester, Delaware, Montgomery, Philadelphia2 hr
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.