Alert archive / Pennsylvania / Flash Flood Warnings in 2007

Flash Flood Warning 4, NWS Philadelphia/Mount Holly

April 27, 2007Bucks County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Apr 27, 2007, 1:14 AM EDT for Bucks County, Montgomery County, Pennsylvania. It was in force for 3 hr. 2 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Apr 27, 2007, 1:14 AM EDT (05:14 UTC)
Expired: Apr 27, 2007, 4:15 AM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Whole counties

Counties Bucks County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 79 km from the middle of the area, began a volume at 05:16 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.

What was reported inside it

Time	Report	Where	Remark
Apr 27, 2:40 AM EDT	FLASH FLOOD	Lansdale, PA	3.00 INCHES OF RAIN AND BASEMENT FLOODING. NUMEROUS SMALL STREAMS IN CENTRAL PART OF THE COUNTY OUT OF THEIR BANKS.
Apr 27, 3:00 AM EDT	FLASH FLOOD	Doylestown, PA	SMALL STREAMS OUT OF THEIR BANKS IN CENTRAL BUCKS. DOYLESTOWN 3.47 INCHES STORM TOTAL THROUGH 4 AM.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Brookhaven, NY (KOKX), launched 00:00Z, 5.2 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-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: 1074 m above ground
0-6 km bulk shear: 63 kt
0-1 km storm-relative helicity: 90 m²/s²
0-3 km storm-relative helicity: 179 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 270517
FFWPHI
PAC017-091-270815-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
114 AM EDT FRI APR 27 2007

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 415 AM EDT

* AT 110 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  AN AREA OF THUNDERSTORMS MOVING OVER THE SAME REGIONS 
  IN CENTRAL MONTGOMERY AND BUCKS COUNTIES. STORM TOTALS HAVE REACHED
  UP TO 1.5 INCHES IN THE WARNING AREA WITH AN ADDITIONAL INCH OF RAIN
  LIKELY WITHIN THE NEXT HOUR. THE HEAVIEST RAIN SO FAR IN MONTGOMERY
  COUNTY HAS BEEN NEAR THE PERKIOMEN AND SKIPPACK CREEKS AND IN
  BUCKS COUNTY AROUND THE EATS BRANCH OF THE PERKIOMEN CREEK AND 
  TOHICKON CREEK. 

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
  SOUDERTON...PERKASIE...DUBLIN AND DOYLESTOWN
 

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.

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 4005 7541 4032 7494 4051 7511 4024 7563

$$

TFG

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 27, 1:01 AM EDT	Flash Flood Warning	PHI	Chester	3 hr
Apr 27, 3:42 AM EDT	Flash Flood Warning	PHI	Bucks, Chester, Montgomery	4 hr
Apr 27, 8:07 AM EDT	Flash Flood Warning	PHI	Bucks, Chester, Montgomery	83 min

Nearby

Flash Flood Warnings in Pennsylvania, 2007 Every flash flood warning in 2007

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.