Alert archive / Pennsylvania / Flash Flood Warnings in 1996

Flash Flood Warning 15, NWS Philadelphia/Mount Holly

April 1, 1996Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Apr 1, 1996, 8:21 PM EST for Chester County, Montgomery County, 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 counties it named.

The facts

Issued: Apr 1, 1996, 8:21 PM EST (01:21 UTC)
Expired: Apr 2, 1996, 12:30 AM EST
In force: 4 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Whole counties

Counties Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 99 km from the middle of the area, began a volume at 01:23 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, 1.4 hours before the alert went out and 203 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: 461 m above ground
0-6 km bulk shear: 12 kt
0-1 km storm-relative helicity: 66 m²/s²
0-3 km storm-relative helicity: 136 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 
TTAA00 KPHL 020123 COR
FFWPHL
PAC029-091-020530-

BULLETIN - EAS ACTIVATION REQUESTED
FLOOD WARNING...COR FOR CALL TO ACTION
NATIONAL WEATHER SERVICE PHILADELPHIA/MOUNT HOLLY NJ
821 PM EST MON APR 1 1996

THE NATIONAL WEATHER SERVICE IN PHILADELPHIA/MOUNT HOLLY HAS ISSUED A
FLOOD WARNING EFFECTIVE UNTIL 1230 AM EST
FOR PEOPLE IN THE FOLLOWING LOCATIONS...

IN  PENNSYLVANIA

   ...CHESTER COUNTY...MONTGOMERY COUNTY

NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED THAT HEAVY RAINS OF
AROUND ONE INCH HAVE FALLEN DURING THE PAST HOUR IN MONTGOMERY COUNTY
AND BETWEEN ONE AND TWO INCHES OF RAIN DURING THE PAST THREE HOURS IN
CHESTER COUNTY. THIS AREA OF HEAVY RAIN IS SHOWING LITTLE MOVEMENT AND
ANOTHER HOUR OF HEAVY RAIN WILL CAUSE FLOODING OF THE SMALLER STREAMS
AND CREEKS IN THESE COUNTIES.  IN ADDITION THERE WILL BE CONSIDERABLE
PONDING OF WATER IN POOR DRAINAGE AREAS AND UNDERPASSES.

THE LARGER STREAMS AND CREEKS ARE WELL WITHIN THEIR BANKS AS OF 815 PM
...BUT IF HEAVY RAIN PERSISTS LONGER INTO THE EVENING...EVEN THEY WILL
BEGIN FLOODING OVERNIGHT.

AVOID AREAS WHICH ARE PRONE TO FLOODING.  BE ESPECIALLY CAUTIOUS
AT NIGHT WHEN IT IS MORE DIFFICULT TO RECOGNIZE FLOOD DANGERS.
CONTINUE TO MONITOR NOAA WEATHER RADIO...AND YOUR LOCAL RADIO AND
TELEVISION STATIONS FOR THE LATEST INFORMATION ON THE FLOOD WARNING.

TFG

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 1, 11:55 PM EST	Flash Flood Warning	PHI	Chester, Montgomery	7 hr
Apr 2, 12:35 AM EST	Flash Flood Warning	PHI	Lehigh	4 hr

Nearby

Flash Flood Warnings in Pennsylvania, 1996 Every flash flood warning in 1996

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.