Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 1999

Severe Thunderstorm Warning 113, NWS Pittsburgh, PA

July 31, 1999Mercer County, Pennsylvania

NWS Pittsburgh, PA issued this severe thunderstorm warning at Jul 31, 1999, 6:04 PM EDT for Mercer County, Pennsylvania. It was in force for 59 min. 3 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Jul 31, 1999, 6:04 PM EDT (22:04 UTC)
Expired: Jul 31, 1999, 7:03 PM EDT
In force: 59 min
Issued by: NWS Pittsburgh, PA
Area: Whole counties

County Mercer County, PA

The radar

The Pittsburgh radar (KPBZ), 86 km from the middle of the area, began a volume at 22:06 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.

What was reported inside it

Time	Report	Where	Remark
Jul 31, 6:44 PM EDT	Thunderstorm Wind	Mercer, PA	Thunderstorm winds downed several trees.
Jul 31, 6:47 PM EDT	Thunderstorm Wind 57	Sharon, PA	Thunderstorm winds estimated by a spotter at 65 MPH downed several trees, some of which fell onto homes.
Jul 31, 7:05 PM EDT	Thunderstorm Wind	Sharpsville, PA	Thunderstorm winds downed a barn and several trees.

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 31, 4:15 PM EDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Pittsburgh, PA (KPIT), launched 12:00Z, 10.1 hours before the alert went out and 100 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: 50 J/kg
Mixed-layer CIN: -427 J/kg
Mixed-layer LCL: 1796 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 68 m²/s²
0-3 km storm-relative helicity: 119 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 severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Pittsburgh, PA wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 31, 2:20 PM EDT, 3 hours 44 minutes earlier.

Area forecast discussion, Jul 31, 2:20 PM EDT, 3 hours 44 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH, PA
220 PM EDT SAT JUL 31 1999

WK WARM FRONT/ASSTD TIGHT THETA-E GRADIENT PASSING E INTO LAURELS.
BEHIND THIS WARM FRONT DWPTS HV SHOT UP WELL INTO 70S ACRS AREA WITH
HEAT INDICES ARND 105 AT SVRL LOCATIONS. WL EXTND HEAT ADVISORY INTO
EARLY EVENING AS IT WILL BE SLOW TO COOL OFF.

FEW CELLS POPPING UP OVR E CNTRL OH...BUT EXPCT BULK OF ACTION WL
TAKE PLACE FARTHER W AS FRONT/ASSTD TSTMS APCH CWA. STILL EXPCT
SOMETHING TO FIRE TO EAST ALG PRVSLY MENTIONED THETA-E GRADIENT BUT
MAY BE JUST OUT OF OUR CWA.

FOR TONIGHT...WL UP POPS FM MOS OVR NWRN HALF OF CWA TO LIKELY.  OVR
SERN HALF...WL KEEP IN HI CHANCE CATEGORY.  ALL THREE MODELS DIFFER
IN TIMING OF FRONT ACRS AREA WITH AVN THE FASTEST AND ETA THE
SLOWEST. FEEL ETA IS MORE REALISTIC AND WL PULL BACK THE REINS ON
TIMING FROM NGM/MOS VALUES.  AS A RESULT...WL KEEP SMALL CHC POPS IN
FOR SOUTHERN HALF OF CWA FOR EARLY SUNDAY.

GIVEN WIND PROFILES FEEL BIGGEST SVR THREAT FM TSTMS WL BE BOW
ECHOS/STRAIGHT-LINE WINDS. ALSO FEEL SOME LOCALIZED FLOODING IS PSBL
GIVEN THE HIGH PWATS...ETA OVR 2.0 IN FEW LOCATIONS...AND PSBL
TRAINING OF CELLS. AS SUCH WL PLAY UP HVY RAIN IN ZFP BUT WL HOLD
OFF ON ANY FFA.

FOR EXTNDD...LOOKS LIKE FINALLY A BREAK FROM HEAT/HUMIDITY THIS
WEEK. MRF CONSISTNT WITH TRYING TO BRING NEXT FRONT IN LATE
WED/EARLY THURS SO WL PUT CHC SHRA/TSRA IN FOR WED PM/THURS AM.

STRAGER

.PIT...HEAT ADVISORY THRU EARLY EVENING
       OHZ039>041-048>050-057>059-068-069-
       PAZ020-021-029>032-
       WVZ001>004-012-021-022.

In the hours before

Special weather statement, Jul 31, 12:40 PM EDT, 5 hours 24 minutes before

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Special weather statement, Jul 31, 12:40 PM EDT, 5 hours 24 minutes before

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Special weather statement, Jul 31, 4:00 PM EDT, 2 hours 4 minutes before

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Special weather statement, Jul 31, 4:00 PM EDT, 2 hours 4 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 31, 6:18 PM EDT	Severe Thunderstorm Warning	PBZ	Lawrence	57 min
Jul 31, 6:22 PM EDT	Severe Thunderstorm Warning	PBZ	Venango	58 min
Jul 31, 6:33 PM EDT	Severe Thunderstorm Warning	PBZ	Forest	62 min
Jul 31, 6:59 PM EDT	Severe Thunderstorm Warning	PBZ	Clarion	76 min
Jul 31, 7:00 PM EDT	Severe Thunderstorm Warning	PBZ	Mercer	45 min
Jul 31, 7:08 PM EDT	Severe Thunderstorm Warning	PBZ	Butler, Lawrence	62 min
Jul 31, 7:37 PM EDT	Severe Thunderstorm Warning	PBZ	Jefferson	53 min
Jul 31, 7:39 PM EDT	Severe Thunderstorm Warning	PBZ	Beaver	61 min
Jul 31, 7:41 PM EDT	Severe Thunderstorm Warning	PBZ	Armstrong	64 min
Jul 31, 1:27 AM EDT	Severe Thunderstorm Warning	PBZ	Coshocton, Guernsey, Tuscarawas	63 min
Jul 31, 6:30 PM EDT	Severe Thunderstorm Warning	PBZ	Columbiana	60 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 1999 Every severe thunderstorm 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; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.