Alert archive / Pennsylvania / Flash Flood Warnings in 2011

Flash Flood Warning 18, NWS Philadelphia/Mount Holly

August 13, 2011Berks County, Lehigh County, Northampton County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 13, 2011, 9:56 PM EDT for Berks County, Lehigh County, Northampton County, Pennsylvania. It was in force for 4 hr. 2 reports 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 13, 2011, 9:56 PM EDT (01:56 UTC)
Expired
Aug 14, 2011, 1:45 AM EDT
In force
4 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), 121 km from the middle of the area, began a volume at 01:56 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 13, 10:15 PM EDTFLASH FLOODHamburg, PAROADS FLOODED... RESIDENTIAL FLOODING... AND MINOR ROCK MUD SLIDES
Aug 14, 1:14 AM EDTFLASH FLOODBethlehem, PAFLOODING ON THE MONOCACY CREEK CAUSED EVACUATION OF THE MUSIKFEST. ONE TENT ON THE FESTIVAL GROUNDS COLLAPSED... NO INJURIES WERE REPORTED

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

The nearest sounding before it

Brookhaven, NY (KOKX), launched 00:00Z, 1.9 hours before the alert went out and 216 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 2011-08-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL1000850700500300200100-30°-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 2011-08-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 60 square meters per square second.1939Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
NaN m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
60 m²/s²
0-3 km storm-relative helicity
96 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.

283 
WGUS51 KPHI 140156
FFWPHI
PAC011-077-095-140545-
/O.NEW.KPHI.FF.W.0018.110814T0156Z-110814T0545Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
956 PM EDT SAT AUG 13 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  NORTHEASTERN BERKS COUNTY...
  LEHIGH COUNTY...
  NORTHAMPTON COUNTY...

* UNTIL 145 AM EDT...

* AT 947 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR ESTIMATES   
  AND RAIN GAGE REPORTS INDICATED BETWEEN 2 AND 3 INCHES OF RAIN HAS 
  FALLEN OVER PORTIONS OF THE WARNED AREA DURING THE PAST FEW HOURS. 
  WITH ADDITIONAL RAIN ON THE WAY...FLASH FLOODING IS EXPECTED OR    
  ALREADY OCCURRING. ROADWAY FLOODING CAN BE EXPECTED...AND          
  SMALL STREAMS IN THE VICINITY OF HEAVY RAIN WILL EXCEED THEIR      
  BANKS.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT DRIVE YOUR CAR THROUGH FLOODED ROADWAYS...THE WATER MAY BE 
DEEPER THAN YOU THINK.

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

&&

LAT...LON 4086 7505 4084 7510 4079 7510 4074 7520
      4068 7521 4067 7519 4065 7521 4061 7521
      4057 7533 4037 7573 4056 7613 4060 7605
      4059 7603 4064 7600 4078 7570 4086 7531
      4092 7524 4096 7514

$$

FORECASTER:JJM

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 13, 9:39 PM EDTAreal Flood AdvisoryPHICarbon, Lehigh, Monroe, Northampton4 hr
Aug 13, 11:33 PM EDTAreal Flood AdvisoryPHIBucks4 hr
Aug 14, 12:37 AM EDTAreal Flood AdvisoryPHIChester3 hr
Aug 14, 1:12 AM EDTFlash Flood WarningPHIChester4 hr
Aug 14, 3:42 AM EDTFlash Flood WatchPHIBerks, Carbon, Delaware, Lehigh, Monroe, Northampton and 1 more25 hr
Aug 14, 3:55 AM EDTFlash Flood WarningPHIBucks, Delaware, Montgomery, Philadelphia4 hr
Aug 14, 4:45 AM EDTSpecial Weather StatementPHIPhiladelphia60 min
Aug 14, 6:24 AM EDTAreal Flood AdvisoryPHIBucks3 hr
Aug 14, 7:43 AM EDTFlash Flood WarningPHIBucks, Delaware, Montgomery, Philadelphia4 hr
Aug 14, 9:21 AM EDTAreal Flood WarningPHINorthampton3 hr
Aug 14, 12:37 PM EDTAreal Flood WarningPHIBucks, Lehigh, Northampton7 hr
Aug 14, 1:00 PM EDTAreal Flood WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia8 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.