Alert archive / Pennsylvania / Flash Flood Warnings in 2006

Flash Flood Warning 68, NWS Philadelphia/Mount Holly

August 29, 2006Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 29, 2006, 3:50 PM EDT for Montgomery County, Pennsylvania. It was in force for 3 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 29, 2006, 3:50 PM EDT (19:50 UTC)
Expired
Aug 29, 2006, 6:45 PM EDT
In force
3 hr
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), 102 km from the middle of the area, began a volume at 19:51 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
Aug 29, 6:00 PM EDTHEAVY RAIN 2.04Royersford, PA2.04 INCHES OF RAIN WAS MEASURED IN ROYERSFORD. THERE WERE REPORTS OF SOME BASEMENT FLOODING IN PARTS OF WESTERN MONTGOMERY COUNTY.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 7.8 hours before the alert went out and 99 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, Phillips Aaf/Abe, MD at 12:00Z on 2006-08-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 21 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, Phillips Aaf/Abe, MD at 12:00Z on 2006-08-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 98 square meters per square second.193958Sfc1 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
21 J/kg
Mixed-layer CIN
-132 J/kg
Mixed-layer LCL
934 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
98 m²/s²
0-3 km storm-relative helicity
185 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

The text

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

000 
WGUS51 KPHI 291951
FFWPHI
PAC091-292245-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
350 PM EDT TUE AUG 29 2006

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 645 PM EDT

* AT 345 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  A THUNDERSTORM PRODUCING TORRENTIAL RAINFALL OVER THE WARNED AREA.
  THIS STORM HAS A HISTORY OF PRODUCING RAINFALL RATES OF 2 TO 3 
  INCHES PER HOUR, CAUSING STREET AND POOR DRAINAGE FLOODING.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO SPRING
  MOUNT...POTTSTOWN AND GILBERTSVILLE

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 4027 7568 4010 7545 4026 7531 4035 7561

$$

GORSE

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 29, 2:14 PM EDTSevere Thunderstorm WarningPHIBerks61 min
Aug 29, 2:42 PM EDTFlash Flood WarningPHIBerks3 hr
Aug 29, 2:53 PM EDTSevere Thunderstorm WarningPHIChester, Montgomery52 min
Aug 29, 3:37 PM EDTSevere Thunderstorm WarningPHIChester, Delaware, Montgomery, Philadelphia68 min
Aug 29, 3:39 PM EDTFlash Flood WarningPHIChester3 hr
Aug 29, 4:15 PM EDTFlash Flood WarningPHIPhiladelphia3 hr
Aug 29, 5:43 PM EDTFlash Flood WarningPHIBerks2 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2006Every flash flood warning in 2006

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.