Alert archive / Pennsylvania / Flash Flood Warnings in 2011

Flash Flood Warning 47, NWS Philadelphia/Mount Holly

September 5, 2011Lehigh County, Northampton County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 5, 2011, 10:18 PM EDT for Lehigh County, Northampton 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
Sep 5, 2011, 10:18 PM EDT (02:18 UTC)
Expired
Sep 6, 2011, 2:15 AM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Lehigh County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 115 km from the middle of the area, began a volume at 02:19 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, 2.3 hours before the alert went out and 202 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 2011-09-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 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 2011-09-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 147 square meters per square second.19395878Sfc1 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
1126 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
147 m²/s²
0-3 km storm-relative helicity
157 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.

265 
WGUS51 KPHI 060218
FFWPHI
PAC077-095-060615-
/O.NEW.KPHI.FF.W.0047.110906T0218Z-110906T0615Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1018 PM EDT MON SEP 5 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 215 AM EDT...

* AT 1013 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR 
  INDICATED VERY HEAVY RAIN MOVING THROUGH THE LEHIGH VALLEY. 
  RAINFALL FROM EARLIER SHOWERS TOTALED BETWEEN ONE AND ONE-HALF AND 
  TWO AND ONE-HALF INCHES...AND THE ADDITIONAL RAINFALL WILL RESULT 
  IN FLASH FLOODING.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO ALLENTOWN
  AND EASTON.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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.

&&

LAT...LON 4093 7515 4085 7507 4084 7510 4079 7510
      4077 7513 4078 7516 4074 7520 4073 7519
      4068 7521 4067 7519 4065 7521 4062 7520
      4043 7551 4066 7583 4076 7565 4085 7532
      4089 7527

$$

HAYES
1 follow-up statement
616 
WGUS71 KPHI 060607
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
207 AM EDT TUE SEP 6 2011

PAC077-095-060617-
/O.EXP.KPHI.FF.W.0047.000000T0000Z-110906T0615Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
LEHIGH PA-NORTHAMPTON PA-
207 AM EDT TUE SEP 6 2011

...THE FLASH FLOOD WARNING WILL EXPIRE AT 215 AM EDT FOR NORTHAMPTON
AND LEHIGH COUNTIES...

THE WATERS FROM THE EARLIER HEAVY RAINS ARE RECEDING AND NO LONGER
POSE A THREAT TO LIFE OR PROPERTY. THEREFORE...THE FLASH FLOOD
WARNING WILL BE ALLOWED TO EXPIRE.

RAIN WILL CONTINUE DURING THE EARLY MORNING HOURS...BUT IT IS NOT 
EXPECTED TO RESULT IN FLASH FLOODING.

LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO ALLENTOWN AND
EASTON.

LAT...LON 4093 7515 4085 7507 4084 7510 4079 7510
      4077 7513 4078 7516 4074 7520 4073 7519
      4068 7521 4067 7519 4065 7521 4062 7520
      4043 7551 4066 7583 4076 7565 4085 7532
      4089 7527

$$

HAYES

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 5, 8:19 PM EDTAreal Flood AdvisoryPHIBerks, Bucks, Lehigh, Montgomery, Northampton116 min
Sep 5, 9:32 PM EDTAreal Flood WarningPHIMontgomery9 hr
Sep 5, 10:53 PM EDTAreal Flood AdvisoryPHIChester, Montgomery3 hr
Sep 5, 11:04 PM EDTAreal Flood AdvisoryPHIBucks6 hr
Sep 5, 11:25 PM EDTFlash Flood WarningPHIBerks4 hr
Sep 6, 12:22 AM EDTAreal Flood AdvisoryPHIDelaware, Philadelphia3 hr
Sep 6, 1:42 AM EDTAreal Flood AdvisoryPHIChester, Montgomery3 hr
Sep 6, 2:09 AM EDTAreal Flood AdvisoryPHILehigh, Northampton3 hr
Sep 6, 3:40 AM EDTAreal Flood WarningPHIBerks3 hr
Sep 6, 5:43 PM EDTAreal Flood AdvisoryPHIBucks, Chester, Delaware, Montgomery, Philadelphia3 hr
Sep 6, 5:49 PM EDTAreal Flood WarningPHIPhiladelphia20 hr
Sep 6, 6:10 PM EDTAreal Flood WarningPHIBucks, Monroe, Northampton71 hr
Sep 6, 6:32 PM EDTAreal Flood WarningPHIMontgomery26 hr
Sep 6, 6:38 PM EDTAreal Flood WarningPHIMontgomery, Philadelphia23 hr
Sep 6, 6:44 PM EDTAreal Flood WarningPHIChester, Delaware15 hr
Sep 6, 6:48 PM EDTAreal Flood WarningPHIBucks31 hr
Sep 6, 7:03 PM EDTRiver Flood WarningPHIChester16 hr
Sep 6, 7:41 PM EDTRiver Flood WarningPHIDelaware5 hr
Sep 6, 7:52 PM EDTRiver Flood WarningPHIBucks52 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.