Alert archive / Pennsylvania / Flash Flood Warnings in 1987

Flash Flood Warning 6, NWS State College, PA

September 12, 1987Cumberland County, Pennsylvania

NWS State College, PA issued this flash flood warning at Sep 12, 1987, 9:56 PM EDT for Cumberland County, Pennsylvania. It was in force for 6 hr.

The area

The counties it named.

The facts

Issued: Sep 12, 1987, 9:56 PM EDT (01:56 UTC)
Expired: Sep 13, 1987, 4:00 AM EDT
In force: 6 hr
Issued by: NWS State College, PA
Area: Whole counties

County Cumberland 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

Washington/Dulle, VA (KIAD), launched 00:00Z, 1.9 hours before the alert went out and 135 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: 575 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 518 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 95 m²/s²
0-3 km storm-relative helicity: 105 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 1.8

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KHAR 130158
FFWHAR
PAC041-131100-
 
BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE HARRISBURG PA
956 PM EDT SAT SEP 12 1987
 
THE NATIONAL WEATHER SERVICE HAS ISSUED A FLASH FLOOD WARNING
EFFECTIVE UNTIL 700 AM EDT FOR THE FOLLOWING COUNTY OF
 
SOUTH CENTRAL PENNSYLVANIA... CUMBERLAND
                                                                         
THE NATIONAL WEATHER SERVICE HAS EXTENDED THE FLASH FLOOD WARNING FOR
CUMBERLAND COUNTY UNTIL 7 AM EDT SUNDAY MORNING. AT 935 PM EDT THE
CONODOGUINET CREEK WAS AT 8.91 FEET. FLOOD STAGE IS 8.0 FEET. THE
CONODOGUINET CREEK IS EXPECTED TO CREST BETWEEN 12 AND 13 FEET BY
7 AM EDT SUNDAY MORNING.RAINFALL AMOUNTS OF 3 TO 5 INCHES HAVE BEEN
REPORTED DURING THE LAST 6 HOURS THROUGHOUT MANY AREAS OF CUMBERLAND 
COUNTY. 
 
A FLASH FLOOD WARNING MEANS FLOODING IN OCCURRING OR IS IMMINENT.
 
IF YOU GET ANY INDICATION THAT FLOOD WATERS ARE APPROACHING MOVE TO
HIGHER GROUND IMMEDIATELY.  DO NOT DRIVE THROUGH FLOOD WATERS.
DO NOT WADE THROUGH FLOOD WATERS.
 
A FLASH FLOOD WATCH CONTINUES FOR THE AREA.
 
MF

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, Sep 12, 8:13 PM EDT, 1 hour 43 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HARRISBURG PA.
815 PM EDT    SAT  SEP 12 1987

 ...HEAVY RAINS PRODUCE STREET AND BASEMENT FLOODING IN CUMBERLAND
    COUNTY...

RADAR SHOWED A HEAVY THUNDERSTORM THAT MOVED THROUGH CUMBERLAND COUNTY
DURING THE PAST HOUR.

WE HAVE RECEIVED NUMEROUS REPORTS OF STREET AND BASEMENT FLOODING AND
HIGHWAY FLOODING  IN MANY AREAS OF THE COUNTY BY THE COUNTY DISPATCHER.

RAINFALL AMOUNTS OF 1.50 INCHES TEO 2.50 INCHES HAVE BEEN REPORTED BY
MANY RAINFALL OBSERVERS.

THIS THUNDERSTORM WILL BE MOVING OUT OF CUMBERLAND COUNTY AND INTO DAUPHIN
COUNTY BY 830 PM EDT.

 REMEMBER...DO NOT DRIVE THROUGH FLOODED ROADWAYS.

WSO HAR NEFF

Special weather statement, Sep 12, 9:34 PM EDT, 22 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HARRISBURG PA.
930 PM EDT SAT SEP 12 1987

...FLASH FLOOD WARNING IN EFFECT FOR CUMBERLAND AND DAUPHIN COUNTIES...
...VERY HEAVY RAINFALL OCCURRING THROUGHOUT THE LOWER SUSQUEHANNA
VALLEY AND INTO THE MIDDLE SUSQUEHANNA VALLEY...

AT 920 PM EDT THE NATIONAL WEATHER SERVICE RADAR WAS OBSERVING
SCATTERED VERY HEAVY THUNDERSTORMS MOVING SLOWLY NORTHEAST THROUGH
LOWER SUSQUEHANNA VALLEY.  TORRENTIAL RAINS HAVE BEEN ASSOCIATED
WITH WITH THESE THUNDERSTORMS PRODUCING RAINFALL AMOUNTS FROM
1.50 INCHES TO 4 INCHES SINCE 700 PM EDT IN THE CAMP HILL AND
MECHANICSBURG AREA OF CUMBERLAND COUNTY.  MANY ROADS HAVE BECOME
IMPASSABLE.  A FLASH FLOOD WARNING REMAINS IN EFFECT FOR CUMBERLAND
COUNTY UNTIL 1220 AM EDT.

IN DAUPHIN COUNTY...COUNTY DISPATCHERS HAVE REPORTED MANY ROADS AND
BASEMENTS FLOODED AS A RESULT OF 2 TO 3 INCHES OF RAIN FALLING SINCE
700 PM EDT.  A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1240 AM
EDT.

AS THESE THUNDERSTORMS CONTINUE MOVING SLOWLY NORTHEAST INTO
THE MIDDLE SUSQUEHANNA VALLEY OVERNIGHT...FLOODING OF LOWLAND
AND POOR DRAINAGE AREAS IS POSSIBLE ESPECIALLY IN UNION COUNTY
AS RAINFALL AMOUNTS HAVE RANGED FROM 0.96 ICHES AT LOCHIEL TO
2.00 INCHES AT SAND MOUNTAIN DURING THE PAST 24 HOURS.

REMEMBER A FLASH FLOOD WATCH MEANS CONDITIONS ARE FAVORABLE FOR
FLASH FLOODING WHILE A FLASH FLOOD WARNING MEANS FLOODING IS
OCCURRING OR IS IMMINENT.

PERSONS WITHIN THE ENTIRE LOWER AND MIDDLE SUSQUEHANNA VALLEY SHOULD
STAY TUNED TO THE NOAA WEATHER RADIO OR LACAL RADIO AND TELEVISION
STATIONS FOR FURTHER STAEMENTS AND POSSIBLE WARNINGS.

WSO HAR FITZSIMMONS

The office that day

Everything else NWS State College, PA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 12, 8:20 PM EDT	Flash Flood Warning	CTP	Cumberland	4 hr
Sep 12, 8:44 PM EDT	Flash Flood Warning	CTP	Dauphin	4 hr

Nearby

Flash Flood Warnings in Pennsylvania, 1987 Every flash flood warning in 1987

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.