Alert archive / Pennsylvania / Flash Flood Warnings in 1990

Flash Flood Warning 1, NWS Philadelphia/Mount Holly

January 30, 1990Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jan 30, 1990, 4:25 AM EST for Montgomery County, Pennsylvania. It was in force for 4 hr.

The area

The counties it named.

The facts

Issued
Jan 30, 1990, 4:25 AM EST (09:25 UTC)
Expired
Jan 30, 1990, 8:20 AM EST
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Whole counties

County Montgomery County, PA

The radar

The WSR-88D network and its archive begin in 1991, so there is no radar volume for this alert.

The nearest sounding before it

Atlantic City In, NJ (KACY), launched 00:00Z, 9.4 hours before the alert went out and 112 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, Atlantic City In, NJ at 00:00Z on 1990-01-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 101 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, Atlantic City In, NJ at 00:00Z on 1990-01-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 527 square meters per square second.1939587897117136Sfc1 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
101 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
537 m above ground
0-6 km bulk shear
90 kt
0-1 km storm-relative helicity
527 m²/s²
0-3 km storm-relative helicity
627 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 300926
FFWPHL
PAC017-091-101-045-029-NJC021-005-007-015-033-301500-

BULLETIN-IMMEDIATE BROADCAST REQUESTED/EBS ACTIVATION REQUESTED
FLOOD WARNING FOR SMALL STREAMS
NATIONAL WEATHER SERVICE PHILADELPHIA PA
425 AM EST TUE JAN 30 1990

THE NATIONAL WEATHER SERVICE HAS ISSUED A FLOOD WARNING FOR SMALL
STREAMS VALID TILL 10 AM EST FOR PEOPLE IN THE FOLLOWING COUNTIES OF

SOUTHEASTERN PENNSYLVANIA...MONTGOMERY

AT 4.20 AM THIS MORNING THE RIVER GAGE ON THE PERKIOMEN CREEK AT
GRATERFORD READ 10.72 FT.  FLOOD STAGE IS 11 FT.

THE CREEK WILL CONTINUE TO RISE AT LEAST FOR THE NEXT SEVERAL HOURS
AS RUNOFF FROM MONDAYS RAINS CONTINUES TO FLOW INTO THE CREEK.   THE
CREEK IS EXPECTED TO CREST AT 11 TO 12 FT LATER TH	IS MORNING.

A FLOOD WARNING MEANS FLOODING IS IMMINENT.

IF YOU GET ANY INDICATION THAT FLOOD WATERS ARE APPROACHING...MOVE TO
HIGHER GROUND IMMEDIATELY.  DO NOT DRIVE THROUGH FLOODED AREAS.

SP

Nearby

Flash Flood Warnings in Pennsylvania, 1990Every flash flood warning in 1990

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.