Alert archive / Pennsylvania / Flash Flood Warnings in 2009

Flash Flood Warning 42, NWS Philadelphia/Mount Holly

August 12, 2009Berks County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 12, 2009, 10:42 PM EDT for Berks County, Pennsylvania. It was in force for 4 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 12, 2009, 10:42 PM EDT (02:42 UTC)
Expired
Aug 13, 2009, 2:45 AM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

County Berks County, PA

The radar

The State College radar (KCCX), 152 km from the middle of the area, began a volume at 02:42 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, 2.7 hours before the alert went out and 195 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 2009-08-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 626 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 00:00Z on 2009-08-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -34 square meters per square second.1939587897Sfc1 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
626 J/kg
Mixed-layer CIN
-13 J/kg
Mixed-layer LCL
1194 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
-34 m²/s²
0-3 km storm-relative helicity
32 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.3

Open this sounding in Storm Lab

The text

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

000 
WGUS51 KPHI 130242
FFWPHI
PAC011-130645-
/O.NEW.KPHI.FF.W.0042.090813T0242Z-090813T0645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1042 PM EDT WED AUG 12 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  WEST CENTRAL BERKS COUNTY IN EASTERN PENNSYLVANIA...

* UNTIL 245 AM EDT

* AT 1035 PM EDT...NATIONAL WEATHER SERVICE RADAR INDICATED FLASH
  FLOODING FROM CONTINUING HEAVY THUNDERSTORMS OVER THE WARNED AREA.
  RADAR INDICATED THAT BETWEEN 2 AND 3 INCHES OF RAIN HAS FALLEN
  OVER THIS AREA DURING THE PAST HOUR.

* THE STORM PRODUCING FLASH FLOODING WILL REMAIN MOSTLY OVER RURAL
  AREAS OF THE INDICATED COUNTY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...COUNTRY ROADS...AS WELL AS FARMLAND ALONG THE
BANKS OF CREEKS AND STREAMS.

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.

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.

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 4050 7643 4052 7633 4052 7623 4055 7619
      4043 7618 4040 7627 4044 7635

$$
1 follow-up statement
000 
WGUS71 KPHI 130644
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
244 AM EDT THU AUG 13 2009

PAC011-130653-
/O.EXP.KPHI.FF.W.0042.000000T0000Z-090813T0645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BERKS PA-
244 AM EDT THU AUG 13 2009

...THE FLASH FLOOD WARNING WILL EXPIRE AT 245 AM EDT FOR WEST CENTRAL
BERKS COUNTY...

LIGHT RAINS CONTINUE ACROSS THE AREA...BUT THE THREAT OF FLASH 
FLOODING HAS PASSED. 

LAT...LON 4050 7643 4052 7633 4052 7623 4055 7619
      4043 7618 4040 7627 4044 7635

$$

PO

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 12, 8:54 PM EDTFlash Flood WarningPHICarbon4 hr
Aug 12, 10:33 PM EDTFlash Flood WarningPHICarbon, Lehigh, Northampton4 hr
Aug 12, 11:23 PM EDTFlash Flood WarningPHIBerks, Lehigh, Northampton7 hr
Aug 13, 2:58 AM EDTAreal Flood AdvisoryPHIChester3 hr
Aug 13, 3:36 AM EDTFlood WatchPHIBerks, Carbon, Delaware, Lehigh, Monroe, Northampton and 1 more36 min
Aug 13, 4:12 AM EDTFlash Flood WatchPHIBerks, Carbon, Delaware, Lehigh, Monroe, Northampton and 1 more15 hr
Aug 13, 6:01 AM EDTRiver Flood WarningPHIChester5 hr
Aug 13, 9:13 AM EDTRiver Flood WarningPHIChester, Delaware5 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2009Every flash flood warning in 2009

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.