Alert archive / Pennsylvania / Flash Flood Warnings in 2004

Flash Flood Warning 42, NWS Philadelphia/Mount Holly

July 27, 2004Cecil County, Maryland; 5 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 27, 2004, 10:44 PM EDT for Cecil County, Maryland; 5 counties in Pennsylvania. It was in force for 4 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 27, 2004, 10:44 PM EDT (02:44 UTC)
Expired
Jul 28, 2004, 2:30 AM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Counties, with a storm outline in the text

Counties Cecil County, MD, Berks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 113 km from the middle of the area, began a volume at 02:40 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

Washington/Dulle, VA (KIAD), launched 00:00Z, 2.7 hours before the alert went out and 179 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, Washington/Dulle, VA at 00:00Z on 2004-07-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 685 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 00:00Z on 2004-07-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 39 square meters per square second.19395878Sfc1 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
685 J/kg
Mixed-layer CIN
-9 J/kg
Mixed-layer LCL
1049 m above ground
0-6 km bulk shear
33 kt
0-1 km storm-relative helicity
39 m²/s²
0-3 km storm-relative helicity
91 m²/s²
Significant tornado parameter
0.1
Supercell composite
1.3

Open this sounding in Storm Lab

The text

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

000 
WGUS51 KPHI 280244
FFWPHI
MDC015-PAC011-029-045-091-101-280630-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1044 PM EDT TUE JUL 27 2004

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  SOUTHEASTERN BERKS COUNTY IN EASTERN PENNSYLVANIA   
  NORTHEASTERN CECIL COUNTY IN NORTHEAST MARYLAND
  CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA
  DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA
  MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA
  PHILADELPHIA COUNTY IN SOUTHEAST PENNSYLVANIA
  
* UNTIL 230 AM EDT

* AT 1030 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR
  INDICATED NUMEROUS HEAVY THUNDERSTORMS OCCURRING OVER NORTHEASTERN
  MARYLAND, SOUTHEASTERN PENNSYLVANIA, AND SOUTHWESTERN NEW JERSEY.
  THE THUNDERSTORMS WERE MOVING NORTH OR NORTHEAST AT 15 TO 20 MILES
  AN HOUR.

* OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
  YEADON...WEST GROVE...WEST CHESTER...SWARTHMORE...SPRING MOUNT...
  ROCKLEDGE...RADNOR TOWNSHIP...POTTSTOWN...PLYMOUTH MEETING...
  PHOENIXVILLE...PARKESBURG...PAOLI...OXFORD...NORRISTOWN...NETHER
  PROVIDENCE TOWNSHIP...LIONVILLE...LIMA...LANSDALE...KING OF
  PRUSSIA...KENNETT SQUARE...HONEY BROOK...GILBERTSVILLE...
  ELVERSON...EAST LANSDOWNE...DREXEL HILL...DOWNINGTOWN...
  COLLEGEVILLE...COATESVILLE...BRYN MAWR...BROOMALL...BIRDSBORO...
  RISING SUN...NORTH EAST AND ELKTON.

EXCESSIVE RUNOFF FROM CONTINUING HEAVY RAINFALL TONIGHT, IN 
ADDITION TO HEAVY RAIN EARLIER TODAY, WILL CAUSE FLOODING OF SMALL 
CREEKS AND STREAMS...HIGHWAYS AND UNDERPASSES. ADDITIONALLY...RURAL 
ROADS AND FARMLANDS ALONG THE BANKS OF CREEKS...STREAMS AND OTHER 
LOW LYING AREAS ARE SUBJECT TO FLOODING.

SOME CREEKS WHICH WERE OVER FLOOD STAGE AS OF 1030 PM INCLUDE:
MANATAWNY CREEK, AT SPANGVILLE IN SOUTHEASTERN BERKS COUNTY AS WELL 
AS AT POTTSTOWN IN NORTHWESTERN MONTGOMERY COUNTY IN PENNSYLVANIA.
ALSO, THE EAST BRANCH OF THE PERKIOMEN CREEK AT SCHWENKSVILLE IN 
MONTGOMERY COUNTY. ALSO, THE WISSAHICKON CREEK AS WELL AS FRANKFORD 
CREEK IN PHILADELPHIA. IN ADDITION, VALLEY CREEK AT VALLEY FORGE IN 
CHESTER COUNTY WAS APPROACHING FLOOD STAGE.

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.

FOR THE LATEST STORM INFORMATION...PLEASE TUNE TO NOAA WEATHER
RADIO...YOUR LOCAL RADIO OR TELEVISION STATION...OR YOUR CABLE
TELEVISION OUTLET.

LAT...LON 3978 7609 3959 7605 3943 7584 3983 7578
      3989 7542 3990 7522 4007 7504 4051 7569
      4028 7603 4016 7589

$$

MD/JRP

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 28, 2:28 AM EDTFlash Flood WarningPHICecil3 hr
Jul 27, 9:37 PM EDTSevere Thunderstorm WarningPHIBucks, Philadelphia38 min
Jul 27, 9:39 PM EDTSevere Thunderstorm WarningPHIBucks, Philadelphia36 min
Jul 28, 7:00 PM EDTFlash Flood WarningPHIMontgomery2 hr
Jul 28, 7:10 PM EDTSevere Thunderstorm WarningPHIBucks50 min
Jul 28, 7:21 PM EDTFlash Flood WarningPHIBucks114 min

Nearby

Flash Flood Warnings in Pennsylvania, 2004Flash Flood Warnings in Maryland, 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.