Alert archive / Pennsylvania / Flash Flood Warnings in 2011

Flash Flood Warning 6, NWS Philadelphia/Mount Holly

July 8, 2011Philadelphia County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 8, 2011, 3:45 PM EDT for Philadelphia 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: Jul 8, 2011, 3:45 PM EDT (19:45 UTC)
Expired: Jul 8, 2011, 6:45 PM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

County Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 62 km from the middle of the area, began a volume at 19:48 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

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 7.8 hours before the alert went out and 101 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1352 J/kg
Mixed-layer CIN: -35 J/kg
Mixed-layer LCL: 668 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 88 m²/s²
0-3 km storm-relative helicity: 134 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 2.9

Open this sounding in Storm Lab

The text

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

527 
WGUS51 KPHI 081945
FFWPHI
PAC101-082245-
/O.NEW.KPHI.FF.W.0006.110708T1945Z-110708T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
345 PM EDT FRI JUL 8 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 645 PM EDT

* AT 340 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
  FLASH FLOODING IS BECOMING MORE LIKELY WITHIN THE CITY OF 
  PHILADELPHIA AS THUNDERSTORMS WITH TORRENTIAL DOWNPOURS 
  ARE PASSING THROUGH THE CITY. 

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
  WISSINOMING...TACONY...ROXBOROUGH...NORTHEAST PHILADELPHIA...
  HOLMESBURG AND GERMANTOWN

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES
AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.

FLOODING IS OCCURRING OR IS IMMINENT. 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.

&&

LAT...LON 4003 7499 3995 7514 3989 7514 3988 7515
      3985 7524 3990 7527 3994 7525 3998 7528
      4001 7522 4003 7524 4008 7517 4005 7512
      4013 7504 4013 7499 4011 7497

$$

TFG

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 7, 8:56 PM EDT	Special Weather Statement	PHI	Carbon	94 min
Jul 7, 9:10 PM EDT	Severe Thunderstorm Warning	PHI	Carbon	67 min
Jul 7, 9:47 PM EDT	Severe Thunderstorm Warning	PHI	Carbon, Lehigh, Northampton	73 min
Jul 7, 10:55 PM EDT	Severe Thunderstorm Warning	PHI	Lehigh, Northampton	28 min
Jul 8, 2:40 AM EDT	Special Weather Statement	PHI	Berks	65 min
Jul 8, 3:58 AM EDT	Flash Flood Watch	PHI	Berks, Carbon, Delaware, Lehigh, Monroe, Northampton and 1 more	19 hr
Jul 8, 12:56 PM EDT	Special Weather Statement	PHI	Philadelphia	64 min
Jul 8, 2:12 PM EDT	Special Weather Statement	PHI	Delaware, Philadelphia	93 min
Jul 8, 2:23 PM EDT	Special Weather Statement	PHI	Monroe, Northampton	82 min
Jul 8, 2:25 PM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	7 hr
Jul 8, 2:48 PM EDT	Severe Thunderstorm Warning	PHI	Monroe	57 min
Jul 8, 2:51 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	54 min
Jul 8, 2:56 PM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Montgomery	3 hr
Jul 8, 3:35 PM EDT	Special Weather Statement	PHI	Montgomery	55 min
Jul 8, 3:40 PM EDT	Areal Flood Advisory	PHI	Berks, Lehigh, Northampton	3 hr
Jul 8, 3:44 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Carbon, Lehigh, Monroe, Montgomery and 1 more	76 min
Jul 8, 4:18 PM EDT	Flash Flood Warning	PHI	Monroe	2 hr
Jul 8, 4:29 PM EDT	Areal Flood Advisory	PHI	Chester	4 hr
Jul 8, 5:33 PM EDT	Areal Flood Advisory	PHI	Bucks	3 hr
Jul 8, 5:44 PM EDT	Flash Flood Warning	PHI	Delaware, Philadelphia	3 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2011 Every 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.