Alert archive / Pennsylvania / Flash Flood Warnings in 2012

Flash Flood Warning 8, NWS Philadelphia/Mount Holly

May 27, 2012Bucks County, Montgomery County, Philadelphia County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at May 27, 2012, 5:57 AM EDT for Bucks County, Montgomery County, Philadelphia County, Pennsylvania. It was in force for 2 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: May 27, 2012, 5:57 AM EDT (09:57 UTC)
Expired: May 27, 2012, 8:03 AM EDT
In force: 2 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Bucks County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 56 km from the middle of the area, began a volume at 09:57 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, 10.0 hours before the alert went out and 205 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: 1225 J/kg
Mixed-layer CIN: -92 J/kg
Mixed-layer LCL: 871 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: 94 m²/s²
0-3 km storm-relative helicity: 113 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.0

Open this sounding in Storm Lab

The text

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

937 
WGUS51 KPHI 270957
FFWPHI
PAC017-091-101-271400-
/O.NEW.KPHI.FF.W.0008.120527T0957Z-120527T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
557 AM EDT SUN MAY 27 2012

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  SOUTHEASTERN BUCKS COUNTY...
  SOUTHEASTERN MONTGOMERY COUNTY...
  NORTHERN PHILADELPHIA COUNTY...

* UNTIL 1000 AM EDT...

* AT 552 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
  VERY HEAVY RAIN FROM A CLUSTER OF THUNDERSTORMS NEAR CHESTNUT 
  HILL...OR 7 MILES NORTHWEST OF PHILADELPHIA...MOVING EAST AT 10 
  MPH. 

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
  PHILADELPHIA.

ADDITIONAL RAINFALL AMOUNTS OF 2 INCHES COULD FALL IN THE NEXT HOUR. 
THE HEAVY RAINFALL WILL RESULT IN FLASH FLOODING.
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4007 7489 4007 7494 4002 7500 4001 7504
      3999 7506 4000 7513 4001 7527 4013 7524
      4017 7520 4016 7502 4010 7485

$$

HAYES

2 follow-up statements

924 
WGUS71 KPHI 271123
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
723 AM EDT SUN MAY 27 2012

PAC017-091-101-271400-
/O.CON.KPHI.FF.W.0008.000000T0000Z-120527T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BUCKS PA-MONTGOMERY PA-PHILADELPHIA PA-
723 AM EDT SUN MAY 27 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1000 AM EDT FOR
NORTHERN PHILADELPHIA...SOUTHEASTERN MONTGOMERY AND SOUTHEASTERN
BUCKS COUNTIES...

AT 714 AM EDT...DOPPLER RADAR INDICATES THAT THE HEAVIEST OF THE 
RAINS HAVE OCCURRED. THE WISSAHICKON CREEK AT FORT WASHINGTON WAS 
RISING RAPIDLY AND SHOULD CREST JUST BELOW THE 9 FOOT FLOOD STAGE 
AROUND 8 AM. 

LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO PHILADELPHIA.
FORT WASHINGTON TO GLENSIDE AND WYNCOTE SHOULD HAVE EXPERIENCED 
FLOODING IN THE PAST HOUR OR SO.  THOSE WATERS SHOULD BEGIN RECEDING 
AROUND 8AM. 


PRECAUTIONARY/PREPAREDNESS ACTIONS...

PLEASE REPORT FLOODING...HAIL OR WIND DAMAGE BY CALLING YOUR LOCAL
LAW ENFORCEMENT OFFICIALS OR BY CALLING THE NATIONAL WEATHER SERVICE
TOLL FREE AT...1-877-633-6772.

&&

LAT...LON 4007 7489 4007 7494 4002 7500 4001 7504
      3999 7506 4000 7513 4001 7527 4013 7524
      4017 7520 4016 7502 4010 7485

$$

DRAG

804 
WGUS71 KPHI 271203
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
803 AM EDT SUN MAY 27 2012

PAC017-091-101-271210-
/O.CAN.KPHI.FF.W.0008.000000T0000Z-120527T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BUCKS PA-MONTGOMERY PA-PHILADELPHIA PA-
803 AM EDT SUN MAY 27 2012

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

THE WATERS FROM THE EARLIER HEAVY RAINS ARE RECEDING AND FLOOD WATERS
NO LONGER POSE A THREAT TO LIFE OR PROPERTY. THEREFORE...THE FLASH
FLOOD WARNING HAS BEEN CANCELLED.

THE WISSAHICKON CREEK AT FORT WASHINGTON CRESTED WITH A READING OF 
8.45 FEET AT 730 AM ... HALF A FOOT BELOW FLOOD STAGE AND HAD SINCE 
BEGUN RECEDING.    

LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO PHILADELPHIA.

WATER IS RECEDING...BUT JUST SOME MINOR FLOODING PROBLEMS MAY
CONTINUE FOR AN HOUR OR TWO.

LAT...LON 4007 7489 4007 7494 4002 7500 4001 7504
      3999 7506 4000 7513 4001 7527 4013 7524
      4017 7520 4016 7502 4010 7485

$$

DRAG

The office that day

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

Issued	Product	Office	Counties	Lasted
May 27, 2:19 AM EDT	Special Weather Statement	PHI	Berks, Carbon, Lehigh, Montgomery, Northampton	56 min
May 27, 2:54 AM EDT	Special Weather Statement	PHI	Bucks	66 min
May 27, 3:10 AM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Lehigh, Montgomery	3 hr
May 27, 3:35 AM EDT	Special Weather Statement	PHI	Berks	55 min
May 27, 3:46 AM EDT	Special Weather Statement	PHI	Bucks, Montgomery	59 min
May 27, 4:08 AM EDT	Flash Flood Warning	PHI	Bucks, Montgomery	4 hr
May 27, 4:35 AM EDT	Special Weather Statement	PHI	Berks	55 min
May 27, 4:46 AM EDT	Special Weather Statement	PHI	Philadelphia	59 min
May 27, 4:58 AM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery, Philadelphia	83 min
May 27, 5:08 AM EDT	Areal Flood Advisory	PHI	Berks	89 min
May 27, 5:18 AM EDT	Special Weather Statement	PHI	Berks	57 min
May 27, 5:47 AM EDT	Special Weather Statement	PHI	Berks	58 min
May 27, 8:48 AM EDT	Special Weather Statement	PHI	Montgomery	42 min
May 27, 9:26 AM EDT	Special Weather Statement	PHI	Bucks, Lehigh	49 min
May 27, 10:07 AM EDT	Areal Flood Warning	PHI	Berks, Bucks, Lehigh, Montgomery, Philadelphia	3 hr
May 27, 3:01 PM EDT	Excessive Heat Warning	PHI	Delaware, Philadelphia	52 hr
May 27, 4:56 PM EDT	Special Weather Statement	PHI	Berks	49 min
May 27, 5:51 PM EDT	Areal Flood Warning	PHI	Montgomery	95 min
May 27, 7:36 PM EDT	Special Weather Statement	PHI	Monroe	39 min
May 27, 7:45 PM EDT	Special Weather Statement	PHI	Berks	45 min

Nearby

Flash Flood Warnings in Pennsylvania, 2012 Every flash flood warning in 2012

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.