Alert archive / Pennsylvania / Flash Flood Warnings in 2011

Flash Flood Warning 63, NWS Philadelphia/Mount Holly

September 11, 2011Berks County, Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 11, 2011, 9:14 PM EDT for Berks County, Chester County, Montgomery County, Pennsylvania. It was in force for 110 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
Sep 11, 2011, 9:14 PM EDT (01:14 UTC)
Expired
Sep 11, 2011, 11:04 PM EDT
In force
110 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Berks County, PA, Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 120 km from the middle of the area, began a volume at 01:14 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 00:00Z, 1.2 hours before the alert went out and 214 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 2011-09-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 420 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 00:00Z on 2011-09-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 144 square meters per square second.1939587897117Sfc1 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
420 J/kg
Mixed-layer CIN
-58 J/kg
Mixed-layer LCL
1369 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
144 m²/s²
0-3 km storm-relative helicity
126 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.

782 
WGUS51 KPHI 120114
FFWPHI
PAC011-029-091-120515-
/O.NEW.KPHI.FF.W.0063.110912T0114Z-110912T0515Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
914 PM EDT SUN SEP 11 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  NORTH CENTRAL CHESTER COUNTY...
  NORTHWESTERN MONTGOMERY COUNTY...
  EASTERN BERKS COUNTY...

* UNTIL 115 AM EDT...

* AT 911 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  VERY HEAVY RAIN FROM A THUNDERSTORM OVER EASTERN BERKS...NORTH
  CENTRAL CHESTER AND NORTHWESTERN MONTGOMERY COUNTIES.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO BALLY...
  BECHTELSVILLE...BIRDSBORO...EAST GREENVILLE...ELVERSON...
  FLEETWOOD...GILBERTSVILLE...KUTZTOWN...LYONS...POTTSTOWN...
  TOPTON...CEDARVILLE...NEW MORGAN AND PUGHTOWN.

ADDITIONAL RAINFALL AMOUNTS OF AN INCH OR TWO ARE POSSIBLE IN THE 
WARNED AREA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

PLEASE REPORT FLOODING...HAIL OR WIND DAMAGE TO THE NATIONAL WEATHER
SERVICE BY CALLING TOLL FREE...1-877-633-6772.

&&

LAT...LON 4053 7565 4042 7550 4009 7565 4013 7590
      4052 7590

$$

IOVINO
1 follow-up statement
053 
WGUS71 KPHI 120304
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1104 PM EDT SUN SEP 11 2011

PAC011-029-091-120313-
/O.CAN.KPHI.FF.W.0063.000000T0000Z-110912T0515Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CHESTER PA-MONTGOMERY PA-BERKS PA-
1104 PM EDT SUN SEP 11 2011

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR EASTERN BERKS...
NORTHWESTERN MONTGOMERY AND NORTH CENTRAL CHESTER COUNTIES...

THE WATER FROM THIS EVENING'S HEAVY RAINFALL IS RECEDING AND IT
NO LONGER POSES A THREAT TO LIFE OR PROPERTY. THEREFORE...THE FLASH 
FLOOD WARNING HAS BEEN CANCELLED.

LAT...LON 4053 7565 4042 7550 4009 7565 4013 7590
      4052 7590

$$

IOVINO

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 11, 8:19 PM EDTFlash Flood WarningPHIBerks3 hr
Sep 11, 8:46 PM EDTAreal Flood AdvisoryPHIChester3 hr
Sep 11, 9:00 PM EDTFlash Flood WarningPHIChester3 hr
Sep 11, 9:14 PM EDTSpecial Weather StatementPHIBerks, Chester, Lehigh, Montgomery61 min
Sep 11, 9:24 PM EDTSevere Thunderstorm WarningPHIChester51 min
Sep 11, 9:34 PM EDTSpecial Weather StatementPHIPhiladelphia41 min
Sep 11, 9:54 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery51 min
Sep 11, 9:56 PM EDTFlash Flood WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia4 hr
Sep 11, 10:25 PM EDTSpecial Weather StatementPHIPhiladelphia65 min
Sep 11, 10:29 PM EDTSevere Thunderstorm WarningPHIChester, Delaware46 min
Sep 11, 10:44 PM EDTAreal Flood AdvisoryPHIChester107 min
Sep 11, 10:52 PM EDTSpecial Weather StatementPHIBucks, Delaware, Montgomery, Philadelphia83 min
Sep 11, 11:10 PM EDTSevere Thunderstorm WarningPHIChester, Delaware, Philadelphia65 min
Sep 12, 11:05 AM EDTCoastal Flood StatementPHIDelaware, Philadelphia6 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2011Every flash flood warning in 2011

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.