Alert archive / Pennsylvania / Flash Flood Warnings in 1990

Flash Flood Warning 3, NWS Pittsburgh, PA

May 20, 1990Allegheny County, Pennsylvania

NWS Pittsburgh, PA issued this flash flood warning at May 20, 1990, 10:02 PM EDT for Allegheny County, Pennsylvania. It was in force for 3 hr.

The area

The counties it named.

The facts

Issued
May 20, 1990, 10:02 PM EDT (02:02 UTC)
Expired
May 21, 1990, 1:00 AM EDT
In force
3 hr
Issued by
NWS Pittsburgh, PA
Area
Whole counties

County Allegheny 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

Pittsburgh, PA (KPIT), launched 00:00Z, 2.0 hours before the alert went out and 12 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, Pittsburgh, PA at 00:00Z on 1990-05-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 343 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, Pittsburgh, PA at 00:00Z on 1990-05-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 122 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
343 J/kg
Mixed-layer CIN
-13 J/kg
Mixed-layer LCL
707 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
122 m²/s²
0-3 km storm-relative helicity
159 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.7

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

In the hours before

Special weather statement, May 20, 4:50 PM EDT, 5 hours 12 minutes before
PAZ001>006-013>015-WVZ001-202200-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PITTSBURGH, PA
445 PM EST SUN MAY 20 1990

...A LINE OF THUNDERSTORMS MOVING TOWARD NORTHWEST AND SOUTHWEST
   PENNSYLVANIA...

A 445 PM TWO LINES OF STRONG THUNDERSTORMS WAS MOVING OUT OF OHIO.
ONE WAS MOVING ALONG THE ERIE LAKESHORE AND SHOULD AFFECT THE EXTREME
NORTHWEST CORNER FOR THE NEXT HOUR WITH STRONG GUSTY WINDS AND
POSSIBLY HAIL.

ANOTHER LINE WAS MOVING INTO THE NORTHERN PANHANDLE OF WEST VIRGINIA IN
HANCOCK AND BROOKE COUNTY. IT SHOULD ENTER SOUTHWESTERN PENNSYLVANIA
NEAR BEAVER AND NORTHERN WASHINGTON COUNTY WITHIN THE HOUR. THE
PITTSBURGH AREA SHOULD SEE THUNDERSTORMS BETWEEN 5 AND  530 PM.

THESE STORMS WILL ALSO CONTAIN HEAVY DOWNPOURS AND GUSTY WINDS AS WELL
AS HAIL.

IF YOU SEE THREATENING WEATHER APPROACHING TAKE COVER IMMEDIATELY.

RWH

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.