Alert archive / Pennsylvania / Flash Flood Warnings in 2011

Flash Flood Warning 17, NWS Philadelphia/Mount Holly

August 7, 2011Berks County, Lehigh County, Northampton County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 7, 2011, 2:29 AM EDT for Berks County, Lehigh County, Northampton County, Pennsylvania. It was in force for 3 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 7, 2011, 2:29 AM EDT (06:29 UTC)
Expired
Aug 7, 2011, 5:22 AM EDT
In force
3 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Berks County, PA, Lehigh County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 131 km from the middle of the area, began a volume at 06:29 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

Brookhaven, NY (KOKX), launched 00:00Z, 6.5 hours before the alert went out and 236 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, Brookhaven, NY at 00:00Z on 2011-08-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 5 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, Brookhaven, NY at 00:00Z on 2011-08-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 120 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
5 J/kg
Mixed-layer CIN
-208 J/kg
Mixed-layer LCL
889 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
120 m²/s²
0-3 km storm-relative helicity
174 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.

185 
WGUS51 KPHI 070629
FFWPHI
PAC011-077-095-071030-
/O.NEW.KPHI.FF.W.0017.110807T0629Z-110807T1030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
229 AM EDT SUN AUG 7 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  NORTHEASTERN BERKS COUNTY IN EASTERN PENNSYLVANIA...
  LEHIGH COUNTY IN EASTERN PENNSYLVANIA...
  THIS INCLUDES THE CITY OF ALLENTOWN...
  WESTERN NORTHAMPTON COUNTY IN EASTERN PENNSYLVANIA...

* UNTIL 630 AM EDT

* AT 224 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
FLASH FLOODING FROM A THUNDERSTORM OVER THE WARNED AREA. AS MUCH AS 
3 AND ONE-HALF INCHES OF RAIN HAS FALLEN IN THE AREA...AND ANOTHER 
INCH OR SO IS POSSIBLE. THE ADDITIONAL RAIN COULD PUSH CREEKS AND 
STREAMS OUT OF THEIR BANKS. IN ADDITION...EXPECT STREET FLOODING AND 
FLOODING OF LOW LYING AREAS.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
  WANAMAKERS...NEW TRIPOLI...NEFFS...JORDAN VALLEY...EMERALD...
  COFFEETOWN...BEERSVILLE...WALNUTPORT...SLATINGTON...
  SCHNECKSVILLE...NORTHAMPTON...BETHLEHEM AND BATH

PRECAUTIONARY/PREPAREDNESS ACTIONS...

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. MOVE
UP TO HIGHER GROUND TO ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS
SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

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.

&&

LAT...LON 4063 7598 4080 7558 4082 7546 4066 7531
      4056 7553 4043 7573

$$

HAYES
2 follow-up statements
532 
WGUS71 KPHI 070826
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
426 AM EDT SUN AUG 7 2011

PAC011-077-095-071030-
/O.CON.KPHI.FF.W.0017.000000T0000Z-110807T1030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BERKS PA-LEHIGH PA-NORTHAMPTON PA-
426 AM EDT SUN AUG 7 2011

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 630 AM EDT FOR
WESTERN NORTHAMPTON...LEHIGH AND NORTHEASTERN BERKS COUNTIES...

AT 424 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
THAT THE HEAVIEST RAIN WAS ABOUT TO MOVE OUT OF THE WARNED AREA. 
ALMOST 7 INCHES OF RAIN HAS FALLEN IN THE WALNUTPORT AREA...AND 
CREEKS AND STREAMS ARE STILL RISING IN THE AREA. 

LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO WANAMAKERS...
NEW TRIPOLI...NEFFS...JORDAN VALLEY...EMERALD...BEERSVILLE...
WALNUTPORT...SLATINGTON...SCHNECKSVILLE...NORTHAMPTON AND BATH

LAT...LON 4063 7598 4080 7558 4082 7546 4066 7531
      4056 7553 4043 7573

$$

HAYES
578 
WGUS71 KPHI 070922
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
522 AM EDT SUN AUG 7 2011

PAC011-077-095-070932-
/O.CAN.KPHI.FF.W.0017.000000T0000Z-110807T1030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BERKS PA-LEHIGH PA-NORTHAMPTON PA-
522 AM EDT SUN AUG 7 2011

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR WESTERN
NORTHAMPTON...LEHIGH AND NORTHEASTERN BERKS COUNTIES...

THE HEAVIEST RAIN HAS MOVED OUT OF THE AREA. 

LAT...LON 4063 7598 4080 7558 4082 7546 4066 7531
      4056 7553 4043 7573

$$

HAYES

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 6, 8:49 PM EDTFlood WatchPHICarbon, Monroe9 hr
Aug 6, 10:06 PM EDTSpecial Weather StatementPHIBerks84 min
Aug 6, 10:14 PM EDTSpecial Weather StatementPHIPike61 min
Aug 6, 10:33 PM EDTAreal Flood AdvisoryPHIBerks, Carbon, Lehigh, Monroe, Northampton6 hr
Aug 7, 12:48 AM EDTSpecial Weather StatementPHIMontgomery57 min
Aug 7, 1:32 AM EDTAreal Flood AdvisoryPHIBerks, Bucks, Chester, Montgomery, Northampton3 hr
Aug 7, 6:03 AM EDTFlash Flood WatchPHIBerks, Carbon, Lehigh, Monroe, Northampton14 hr
Aug 7, 3:07 PM EDTSpecial Weather StatementPHIPhiladelphia23 min
Aug 7, 3:48 PM EDTSevere Thunderstorm WarningPHIBucks27 min
Aug 7, 7:20 PM EDTSpecial Weather StatementPHIMonroe40 min

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.