Alert archive / Pennsylvania / Flash Flood Warnings in 2009

Flash Flood Warning 47, NWS Philadelphia/Mount Holly

August 22, 2009Montgomery County, Philadelphia County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 22, 2009, 1:51 AM EDT for Montgomery County, Philadelphia County, Pennsylvania. It was in force for 77 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
Aug 22, 2009, 1:51 AM EDT (05:51 UTC)
Expired
Aug 22, 2009, 3:08 AM EDT
In force
77 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 59 km from the middle of the area, began a volume at 05:51 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, 5.9 hours before the alert went out and 211 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 2009-08-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1483 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, Brookhaven, NY at 00:00Z on 2009-08-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 99 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
1483 J/kg
Mixed-layer CIN
-26 J/kg
Mixed-layer LCL
764 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
99 m²/s²
0-3 km storm-relative helicity
120 m²/s²
Significant tornado parameter
0.7
Supercell composite
6.3

Open this sounding in Storm Lab

The text

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

000 
WGUS51 KPHI 220551
FFWPHI
PAC091-101-220815-
/O.NEW.KPHI.FF.W.0047.090822T0551Z-090822T0815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
151 AM EDT SAT AUG 22 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  SOUTHEASTERN MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...
  PHILADELPHIA COUNTY IN SOUTHEAST PENNSYLVANIA...
  THIS INCLUDES THE CITY OF PHILADELPHIA...

* UNTIL 415 AM EDT

* AT 144 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
  ONE TO TWO INCHES OF RAIN QUICKLY FELL IN LOWER MONTGOMERY COUNTY  
  ACROSS THE FRANKFORD CREEK WATERSHED. THE WATER IS NOW MAKING ITS  
  WAY DOWN INTO PHILADELPHIA COUNTY WHERE THE CREEK GAGE IN          
  FRANKFORD IS INDICATING A RAPID RISE. FLASH FLOODING IS IMMINENT. 

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
  WISSINOMING...TACONY...NORTHEAST PHILADELPHIA...HOLMESBURG...
  ABINGTON...ROCKLEDGE...JENKINTOWN AND BRYN ATHYN

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.

&&

LAT...LON 4003 7499 4001 7504 3997 7509 3998 7511
      3995 7514 3991 7514 4000 7523 4006 7514
      4009 7519 4015 7508 4007 7498

$$

KRUZDLO
1 follow-up statement
000 
WGUS71 KPHI 220708
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
308 AM EDT SAT AUG 22 2009

PAC091-101-220716-
/O.CAN.KPHI.FF.W.0047.000000T0000Z-090822T0815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
PHILADELPHIA PA-MONTGOMERY PA-
308 AM EDT SAT AUG 22 2009

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR SOUTHEASTERN
MONTGOMERY AND PHILADELPHIA COUNTIES...

FRANKFORD CREEK HAS CRESTED AND IS NOW FALLING. THE FLASH FLOOD 
WARNING HAS BEEN CANCELLED. MORE RAIN IS EXPECTED THROUGH THE DAY. 
RENEWED RISES ARE LIKELY.

LAT...LON 4003 7499 4001 7504 3997 7509 3998 7511
      3995 7514 3991 7514 4000 7523 4006 7514
      4009 7519 4015 7508 4007 7498

$$

KRUZDLO

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 21, 10:14 PM EDTAreal Flood AdvisoryPHIChester3 hr
Aug 21, 10:49 PM EDTFlash Flood WarningPHIChester55 min
Aug 22, 1:40 AM EDTAreal Flood AdvisoryPHIBucks, Montgomery, Philadelphia3 hr
Aug 22, 6:03 AM EDTFlash Flood WarningPHIMontgomery, Philadelphia3 hr
Aug 22, 6:21 PM EDTFlash Flood WarningPHIBucks, Northampton3 hr
Aug 22, 7:00 PM EDTFlash Flood WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia4 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.