Alert archive / Pennsylvania / Flash Flood Warnings in 2009

Flash Flood Warning 2, NWS Philadelphia/Mount Holly

May 7, 2009Bucks County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at May 7, 2009, 1:43 AM EDT for Bucks County, Pennsylvania. It was in force for 5 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 7, 2009, 1:43 AM EDT (05:43 UTC)
Expired: May 7, 2009, 6:45 AM EDT
In force: 5 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

County Bucks County, PA

The radar

The Philadelphia radar (KDIX), 62 km from the middle of the area, began a volume at 05:46 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, 5.7 hours before the alert went out and 187 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 760 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 42 m²/s²
0-3 km storm-relative helicity: 94 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.

000 
WGUS51 KPHI 070543
FFWPHI
PAC017-071045-
/O.NEW.KPHI.FF.W.0002.090507T0543Z-090507T1045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
143 AM EDT THU MAY 7 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  BUCKS COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 645 AM EDT

* AT 141 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
  FLASH FLOODING FROM HEAVY RAIN AND SCATTERED THUNDERSTORMS OVER 
  THE WARNED AREA WITH MORE HEAVY RAIN AND THUNDERSTORMS MOVING IN 
  FROM THE SOUTHWEST. RAINFALL RATES OF OVER AN INCH IN LESS THAN
  AN HOUR IS POSSIBLE.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO TINICUM...
  SPRINGTOWN...REVERE...PLEASANT VALLEY...PIPERSVILLE...OTTSVILLE...
  GARDENVILLE...FRICKS...BEDMINSTER...FERNDALE...QUAKERTOWN...
  PERKASIE...NEW HOPE...DUBLIN...DOYLESTOWN AND CHALFONT

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE.

&&

LAT...LON 4012 7476 4012 7483 4009 7489 4043 7549
      4060 7522 4056 7519 4048 7507 4042 7506
      4040 7502 4040 7497 4032 7493 4030 7487
      4024 7484 4017 7473 4015 7472

$$

RNS

The office that day

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

Issued	Product	Office	Counties	Lasted
May 6, 9:01 PM EDT	Flood Watch	PHI	Delaware, Philadelphia	19 hr
May 7, 1:08 AM EDT	Flash Flood Warning	PHI	Chester, Montgomery	6 hr
May 7, 1:51 AM EDT	Flash Flood Warning	PHI	Delaware, Philadelphia	5 hr
May 7, 10:15 AM EDT	Areal Flood Warning	PHI	Montgomery	3 hr
May 7, 1:42 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery	4 hr
May 7, 2:34 PM EDT	Areal Flood Advisory	PHI	Bucks, Delaware, Montgomery, Philadelphia	3 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2009 Every 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.