Alert archive / Pennsylvania / Flash Flood Warnings in 2004

Flash Flood Warning 101, NWS Philadelphia/Mount Holly

September 28, 2004Chester County, Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 28, 2004, 6:47 PM EDT for Chester County, Delaware 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
Sep 28, 2004, 6:47 PM EDT (22:47 UTC)
Expired
Sep 28, 2004, 9:45 PM EDT
In force
3 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Counties, with a storm outline in the text

Counties Chester County, PA, Delaware County, PA

The radar

The Philadelphia radar (KDIX), 109 km from the middle of the area, began a volume at 22:47 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, 10.8 hours before the alert went out and 60 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, Phillips Aaf/Abe, MD at 12:00Z on 2004-09-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 95 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Phillips Aaf/Abe, MD at 12:00Z on 2004-09-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 109 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
95 J/kg
Mixed-layer CIN
-78 J/kg
Mixed-layer LCL
631 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
109 m²/s²
0-3 km storm-relative helicity
172 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.4

Open this sounding in Storm Lab

The text

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

000 
WGUS51 KPHI 282251
FFWPHI
PAC029-045-290145-
/X.NEW.KPHI.FF.W.0020.040928T2247Z-040929T0145Z/
/0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
647 PM EDT TUE SEP 28 2004

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING CONTINUED FOR...
  CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA
  DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA

* UNTIL 945 PM EDT

* AT 642 PM EDT...HEAVY RAIN CONTINUES ACROSS THE AREA. MORE RAIN IS 
  ON THE WAY. EXPECT FLOODING ALONG SMALL STREAMS AND EVEN ALONG     
  THE BRANDYWINE EIVER. 


EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...HIGHWAYS AND UNDERPASSES. ADDITIONALLY...COUNTRY
ROADS AND FARMLANDS ALONG THE BANKS OF CREEKS...STREAMS AND OTHER LOW
LYING AREAS ARE SUBJECT TO FLOODING.

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. TURN AROUND, DONT DROWN.

LAT...LON 3995 7531 4025 7568 4008 7591 3974 7610
      3975 7593 3975 7582 3983 7574 3989 7561
      3984 7544

$$

JJM

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 28, 12:48 PM EDTFlash Flood WarningPHIMonroe, Northampton3 hr
Sep 28, 3:55 PM EDTFlash Flood WarningPHIChester, Delaware3 hr
Sep 28, 4:16 PM EDTFlash Flood WarningPHIBerks, Bucks, Lehigh, Montgomery, Northampton3 hr
Sep 28, 4:41 PM EDTSevere Thunderstorm WarningPHIChester, Delaware79 min
Sep 28, 4:55 PM EDTFlash Flood WarningPHICarbon, Monroe4 hr
Sep 28, 5:11 PM EDTFlash Flood WarningPHIPhiladelphia3 hr
Sep 28, 6:05 PM EDTSpecial Marine WarningPHI115 min
Sep 28, 7:11 PM EDTFlash Flood WarningPHIBerks, Bucks, Lehigh, Montgomery, Northampton6 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2004Every flash flood warning in 2004

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.