Alert archive / Pennsylvania / Flash Flood Warnings in 1999

Flash Flood Warning 49, NWS State College, PA

September 6, 1999Lycoming County, Snyder County, Union County, Pennsylvania

NWS State College, PA issued this flash flood warning at Sep 6, 1999, 11:37 PM EDT for Lycoming County, Snyder County, Union County, Pennsylvania. It was in force for 3 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: Sep 6, 1999, 11:37 PM EDT (03:37 UTC)
Expired: Sep 7, 1999, 2:30 AM EDT
In force: 3 hr
Issued by: NWS State College, PA
Area: Whole counties

Counties Lycoming County, PA, Snyder County, PA, Union County, PA

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 3.6 hours before the alert went out and 233 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: 35 J/kg
Mixed-layer CIN: -19 J/kg
Mixed-layer LCL: 617 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 140 m²/s²
0-3 km storm-relative helicity: 142 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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.

NWS State College, PA wrote its last area forecast discussion before this flash flood warning went out at Sep 6, 8:10 PM EDT, 3 hours 27 minutes earlier.

Area forecast discussion, Sep 6, 8:10 PM EDT, 3 hours 27 minutes before

CENTRAL PENNSYLVANIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
810 PM EDT MON SEP 6 1999

WELL IT TOOK FOREVER FOR DENNIS TO GET HERE..BUT IT IS HERE AND THE
RAIN IS FALLING. WE HAD A BEAUTIFUL WEST TO EAST ORIENTED BAND OF
RAIN MOVE THROUGH AROUND 5 PM WITH A BLINDING DOWNPOUR AND ABOUT .5
OF RAIN IN 5 MINUTES. LOTS OF REPORTS OF LOCALIZED DOWNPOURS...BUT
NO REAL FLOODING TO SPEAK OF...YET. SOME SMALLER CREEKS AND STREAMS
ARE CLOSE TO BANKFULL...BUT LARGER ONES ARENT EVEN CLOSE.

THE SURFACE REFLECTION OF DENNIS IS HARD TO FIND AT 21Z...BUT IS
PROBABLY SOMEWHERE BETWEEN EKN AND CHO. THE UPPER SYSTEM IS MORE
IMPRESSIVE AS EVIDENCED BY THE SPIRALING RAIN SHIELD AND THE MASS
FIELDS ON THE MODEL PROGS. ETA MODELS SHOW LOW LEVEL JET ON THE
ORDER OF 35-45KT POINTED UP FROM THE SSE...CONTINUING INTO THE WEE
HOURS AND FINALLY PULLING OFF EARLY TUES.

2 CONCERNS FOR WHERE THE HEAVIEST RAIN THREATS WILL BE. FIRST IS
ALONG THE DEEP SLY FEED WHICH IS TAKING AIM AT THE CTRL AND ERN
PARTS OF MY CWA. REGIONAL RADAR MOSAICS SHOW SHOWERS FEEDING
NORTHWARD IN THE DEEP SLY FLOW ALL THE WAY FROM THE MID ATLANTIC.
WATER VAPOR SHOWS TROPICAL PLUME CONNECTING TO ABOUT THE BAHAMAS.
MODEL PRECIP WATERS TOP 2 INCHES SO THE JUICE IS NOT LACKING.

OTHER AREA IS OVER NWRN PA WHERE RADAR LOOPS SUGGEST DEFORMATION
ZONE IS FORMING. THIS COMBINED WITH A BAND WHICH HAS BEEN INCHING
EAST THRU ERN OHIO CUD MAKE FOR PROBLEMS THERE. THIS AREA TOOK A
GOOD SLUG OF RAIN LAST WEEK WHICH CAUSED MAJOR FLASH FLOODING.

WILL CONTINUE THE FLASH FLOOD WATCH INTO TUES MORNING TO DEAL WITH
THE RAIN OVERNIGHT. THE INITIAL SURGE OF RW/TRW WAS HANDLED FAIRLY
WELL BY THE RADAR PRECIP ALGORITHM...WE ARE IN TROPICAL Z/R MODE.
NOW HOWEVER...CLOUD TOPS ARE WARM...IN THE MID -20S...WITH RADAR
TOPS ONLY IN THE LOWER 20S. THIS IS STARTING TO LOOK LIKE A CLASSIC
WARM RAIN/LOW TOPPED CONVECTION EVENT...WHICH MEANS THE RADAR WILL
START TO GROSSLY UNDERESTIMATE THE PRECIP.

.CTP...FLASH FLOOD WATCH FOR ALL OF CENTRAL PA THROUGH TUESDAY
MORNING.

LA CORTE

In the hours before

Local storm report, Sep 6, 11:24 PM EDT, 13 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1124 PM EDT MON SEP 06 1999

TIME(EDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0500 PM    MARYSVILLE                PA   WIND DAMAGE
09/06/99   PERRY                          TREE DOWN BLOCKING RTE 850

Local storm report, Sep 6, 11:24 PM EDT, 13 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1124 PM EDT MON SEP 06 1999

TIME(EDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0500 PM    MARYSVILLE                PA   WIND DAMAGE
09/06/99   PERRY                          TREE DOWN BLOCKING RTE 850

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 6, 9:07 PM EDT	Flash Flood Warning	CTP	Cumberland, Dauphin, Perry, York	3 hr
Sep 6, 11:47 PM EDT	Flash Flood Warning	CTP	Cumberland, Dauphin, York	3 hr
Sep 6, 11:47 PM EDT	Flash Flood Warning	CTP	Perry	3 hr
Sep 7, 2:06 AM EDT	Flash Flood Warning	CTP	Northumberland	3 hr
Sep 7, 2:25 AM EDT	Flash Flood Warning	CTP	Perry, Snyder, Union	4 hr
Sep 7, 2:25 AM EDT	Flash Flood Warning	CTP	Dauphin, York	4 hr
Sep 7, 2:25 AM EDT	Flash Flood Warning	CTP	Lycoming	4 hr
Sep 7, 3:45 AM EDT	Flash Flood Warning	CTP	Tioga	2 hr

Nearby

Flash Flood Warnings in Pennsylvania, 1999 Every flash flood warning in 1999

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.