Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 102, NWS State College, PA

July 24, 2009Lycoming County, Pennsylvania

NWS State College, PA issued this severe thunderstorm warning at Jul 24, 2009, 5:55 PM EDT for Lycoming County, Pennsylvania. It was in force for 50 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Jul 24, 2009, 5:55 PM EDT (21:55 UTC)
Expired
Jul 24, 2009, 6:45 PM EDT
In force
50 min
Issued by
NWS State College, PA
Area
Storm-based polygon

County Lycoming County, PA

The radar

The State College radar (KCCX), 92 km from the middle of the area, began a volume at 21:57 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.

The nearest sounding before it

Buffalo Intl Airport, NY (KBUF), launched 12:00Z, 9.9 hours before the alert went out and 222 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, Buffalo Intl Airport, NY at 12:00Z on 2009-07-24Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 59 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, Buffalo Intl Airport, NY at 12:00Z on 2009-07-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -7 square meters per square second.19395878Sfc1 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
59 J/kg
Mixed-layer CIN
-36 J/kg
Mixed-layer LCL
634 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
-7 m²/s²
0-3 km storm-relative helicity
11 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

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 State College, PA wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 24, 3:45 PM EDT, 2 hours 10 minutes earlier.

Area forecast discussion, Jul 24, 3:45 PM EDT, 2 hours 10 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
345 PM EDT FRI JUL 24 2009

.SYNOPSIS...
AN UPPER TROF WILL EXIT THE AREA THIS EVENING...TAKING SCATTERED
SHOWERS AND THUNDERSTORMS AWAY WITH IT. WEAK HIGH PRESSURE WILL
OVERSPREAD THE AREA LATE TONIGHT AND SATURDAY MORNING...FOLLOWED
BY A COLD FRONT MOVING ACROSS THE COMMONWEALTH LATE SATURDAY AND
STALLING OVER THE STATE ON SUNDAY...PROVIDING A FOCUS FOR MORE
WIDESPREAD PRECIPITATION. ANOTHER UPPER LEVEL TROF WILL RESIDE
ACROSS THE REGION FROM LATE THIS WEEKEND THROUGH THE MIDDLE OF
NEXT WEEK...BRINGING BELOW NORMAL TEMPERATURES AND AT LEAST A
CHANCE OF AFTERNOON SHOWERS OR THUNDERSTORMS TO CENTRAL
PENNSYLVANIA MONDAY THROUGH WEDNESDAY.

&&

.NEAR TERM /THROUGH SATURDAY/...
LATEST WATER VAPOR IMAGERY SHOWS UPPER LOW CIRCULATION TRACKING
EASTWARD OVER NORTH CENTRAL PA. SCATTERED MULTICELLULAR CONVECTION
IS BEING MAINTAINED CURRENTLY ACROSS MUCH OF CENTRAL AND
NORTHWEST SECTIONS... WITH CAPES ON THE ORDER OF 500-700 J/KG
PRODUCING STRONG ENOUGH UPDRAFTS FOR ISOLATED BRIEF DOWNPOURS AND
PEA SIZED HAIL IN SOME LOCATIONS. STORM MOTION TO THE ESE AT 20KTS
OR SO KEEPS THE CHANCE FOR ANY ADDITIONAL FLOODING RAINS
LOW...DESPITE THE HEAVY RAINS FROM YESTERDAY. FAIRLY STEEP LAPSE
RATES IN EXCESS OF 6C/KM SHOULD KEEP THE ACTIVITY GOING INTO THE
EVENING HOURS...FOLLOWED BY A GENERALLY QUIET OVERNIGHT AND COOLER
CONDITIONS AS THE SFC RIDGE BUILDS EASTWARD. WITH THE LIGHT WINDS
AND RESIDUAL LOW LEVEL MOISTURE... THERE MAY BE PATCHY LIGHT HIGHT
AND EARLY MORNING FOG.

THE PERSISTENT UPPER TROUGH ACROSS THE OHIO VALLEY/GREAT LAKES
REGION WILL DEEPEN YET AGAIN ON SATURDAY AS WEAK HIGH PRESSURE
RETREATS TO THE EAST ALONG WITH THE FLAT UPPER RIDGE.
THE GOOD NEWS IS THAT TEMPS WILL FINALLY RESEMBLE SOMETHING CLOSE
TO SUMMER TIME READINGS AS MY SOUTHEAST COUNTIES SEE MAXES
APPROACHING 90. CANNOT RULE OUT ISOLATED SHOWER OR THUNDERSTORM
IN THE AFTERNOON. ELSEWHERE...NEAR TO SLIGHTLY ABOVE NORMAL MAX
TEMPS (INTHE U70S TO MID 80S) WILL OCCUR ACROSS THE CENTRAL AND
WESTERN COUNTIES.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
A DECENT COLD FRONT WILL BE MOVING INTO THE COMMONWEALTH LATE
SATURDAY AND CONTINUE TO MOVE SLOWLY EAST ACROSS THE STATE ON
SUNDAY...PROVIDING A FOCUS FOR NUMEROUS TO WIDESPREAD SHOWERS AND
THUNDERSTORMS. THE MAJORITY OF THE ACTIVITY SAT NIGHT WILL REMAIN
ACROSS THE WESTERN HALF OF THE CWA...WITH THE FOCUS SHIFTING MORE
TO THE EASTERN HALF AS SUNDAY PROGRESSES. HIGHER PWATS WILL PUSH
INTO THE REGION IN ASSOCIATION WITH NOTICABLE 850 MB. THIS WILL AT
LEAST KEEP THE POTENTIAL FOR ISOLATED STORMS TO APPROACH SEVERE
LIMITS SAT EVE/NIGHT...ALONG WITH A DECENT AREAWIDE RAINFALL IN THE
RANGE OF 1-1.5 INCHES OVER 24 HOURS.

HIGHER PWATS LINGER IN THE SE POSSIBLY INTO MONDAY WITH COOLER AIR
ADVECTING IN AT MID LEVELS...SO COLD FRONT LOOKS TO BE PLANNING A
SLOW EXIT TO THE EAST. HENCE KEPT A CHC OF SHRA/TSRA IN THE
FORECAST...MAINLY IN THE SE.

MILD TEMPS FOR THE FIRST HALF OF THE WEEKEND WILL AGAIN DIP BACK
JUST BELOW NORMAL FOR MOST THROUGH MON...ALTHOUGH A BIT MILDER
WEATHER WILL CONTINUE IN THE SE.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
THE MAIN FORECAST CHALLENGE IN THE LONG TERM IS THE WESTWARD
PROPAGATION OF THE MID ATLANTIC RIDGE...AND CORRESPONDING WESTWARD
PROPAGATION OF UPPER TROUGH. 12Z GFS SUGGESTS THAT THE RIDGE
STARTS TO EDGE INTO PA AT THE START OF THE PERIOD...PUSHING THE
500MB TROUGH AXIS WEST OF THE MISSISSIPPI. IF THIS VERIFIES...THEN
THE THREAT OF RAIN WILL BE GREATLY DIMINISHED AS THE CWA WILL BE
SPARED FROM THE ENDLESS STRING OF SHORTWAVES SWINGING AROUND THE
UPPER LOW. A MORE LIKELY SOLUTION WOULD BE A LESS DRAMATIC WESTWARD
SHIFT FOR THE 500MB TROUGH...KEEPING THE CWA WELL WITHIN THE STORM
TRACK. REGARDLESS...PERSISTENT S/SE FLOW WILL MAKE FOR A WARM AND
FAIRLY HUMID WEEK...ESPECIALLY IN THE LOWER SUSQ WHERE DEWPOINTS
WILL NEAR 70 AND HIGHS WILL STAY IN THE MID 80S.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
A MID LEVEL TROUGH CROSSING NORTHERN PA THIS AFTERNOON WITH COOL
AIR ALOFT WILL FOCUS SCATTERED MVFR CIGS AND SHRA/TSRA OVER
CENTRAL PA RTES THIS EVENING. KEEPING CBS IN THE FORECAST THROUGH
THIS EVENING GIVEN MANY STORM TOPS OVER 30K FEET WITH SMALL HAIL
AND SFC WNDS POTENTIALLY GUSTING TO 30 KTS.

ACTIVITY WILL WANE LATE THIS EVENING AS THE LOW LEVELS STRATIFY/COOL.
CLEARING SKIES COULD LEAD TO SOME PATCHY FOG AFT MIDNIGHT...AS SFC
HIGH PRES BUILDS IN FROM THE S/W.

SAT WILL FEATURE VFR CONDS AFTER ANY PATCHY MORNING FOG
DISSIPATES. ISOLATED MVFR CIGS ARE POSSIBLE LATE AS A STRAY SHOWER
OR THUNDERSTORM MAY DEVELOP IN THE AFTERNOON.

ANOTHER SLOW MOVING UPPER TROF WILL DEEPEN AND PERSIST ACROSS THE
AREA FROM LATE THIS WEEKEND THROUGH MIDWEEK WITH MORNINGS
GENERALLY VFR TRANSITIONING TO MVFR CIGS IN SCT SHRA/TSRA CHCS
EACH AFTERNOON.

OUTLOOK...

SUN-WED...MRNG VFR WITH MVFR IN SCT AFTN SHRA/TSRA.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

SYNOPSIS...STEINBUGL
NEAR TERM...DEVOIR/DICKEY
SHORT TERM...RXR
LONG TERM...DICKEY/DEVOIR/RXR
AVIATION...DEVOIR
Hazardous weather outlook, Jul 24, 4:39 AM EDT, 13 hours 16 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE STATE COLLEGE PA
439 AM EDT FRI JUL 24 2009

PAZ004>006-010>012-017>019-024>028-033>037-041-042-045-046-049>053-
056>059-063>066-250845-
WARREN-MCKEAN-POTTER-ELK-CAMERON-NORTHERN CLINTON-CLEARFIELD-
NORTHERN CENTRE-SOUTHERN CENTRE-CAMBRIA-BLAIR-HUNTINGDON-MIFFLIN-
JUNIATA-SOMERSET-BEDFORD-FULTON-FRANKLIN-TIOGA-NORTHERN LYCOMING-
SULLIVAN-SOUTHERN CLINTON-SOUTHERN LYCOMING-UNION-SNYDER-MONTOUR-
NORTHUMBERLAND-COLUMBIA-PERRY-DAUPHIN-SCHUYLKILL-LEBANON-CUMBERLAND-
ADAMS-YORK-LANCASTER-
439 AM EDT FRI JUL 24 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA.

.DAY ONE...TODAY AND TONIGHT.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

In the hours before

Special weather statement, Jul 24, 5:05 PM EDT, 50 minutes before
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Special weather statement, Jul 24, 5:15 PM EDT, 40 minutes before
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Local storm report, Jul 24, 5:20 PM EDT, 35 minutes before
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Special weather statement, Jul 24, 5:21 PM EDT, 34 minutes before
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Local storm report, Jul 24, 5:47 PM EDT, 8 minutes before
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Special weather statement, Jul 24, 5:53 PM EDT, 2 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Jul 23, 8:02 PM EDTSevere Thunderstorm WarningCTPJuniata, Northumberland, Snyder43 min
Jul 23, 8:16 PM EDTSpecial Weather StatementCTPDauphin59 min
Jul 23, 8:19 PM EDTAreal Flood AdvisoryCTPColumbia, Lycoming, Montour, Northumberland, Snyder, Sullivan3 hr
Jul 23, 9:26 PM EDTAreal Flood WarningCTPClinton, Lycoming109 min
Jul 23, 9:57 PM EDTSpecial Weather StatementCTPAdams, York78 min
Jul 23, 10:46 PM EDTAreal Flood WarningCTPYork2 hr
Jul 23, 11:12 PM EDTSpecial Weather StatementCTPYork78 min
Jul 24, 2:08 AM EDTRiver Flood WarningCTPCumberland, York7 hr
Jul 24, 1:24 PM EDTSpecial Weather StatementCTPHuntingdon66 min
Jul 24, 2:29 PM EDTSpecial Weather StatementCTPCumberland, Franklin, Juniata, Perry61 min
Jul 24, 3:20 PM EDTSpecial Weather StatementCTPCumberland, Dauphin, Franklin40 min
Jul 24, 3:57 PM EDTSpecial Weather StatementCTPLebanon, York33 min
Jul 24, 3:58 PM EDTSpecial Weather StatementCTPFranklin47 min
Jul 24, 4:16 PM EDTSevere Thunderstorm WarningCTPDauphin, Lancaster, Lebanon59 min
Jul 24, 4:20 PM EDTSevere Thunderstorm WarningCTPAdams, Franklin, York55 min
Jul 24, 4:27 PM EDTSpecial Weather StatementCTPCameron33 min
Jul 24, 4:56 PM EDTAreal Flood AdvisoryCTPAdams, Cumberland, Franklin2 hr
Jul 24, 5:05 PM EDTSpecial Weather StatementCTPClinton55 min
Jul 24, 5:15 PM EDTSpecial Weather StatementCTPLancaster45 min
Jul 24, 5:21 PM EDTSpecial Weather StatementCTPSullivan54 min
Jul 24, 5:53 PM EDTSpecial Weather StatementCTPLycoming22 min
Jul 24, 6:44 PM EDTSevere Thunderstorm WarningCTPColumbia, Lycoming, Montour, Northumberland, Sullivan, Union61 min
Jul 24, 7:45 PM EDTSevere Thunderstorm WarningCTPColumbia, Montour, Northumberland, Schuylkill47 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2009Every severe thunderstorm warning in 2009

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; radar from the NEXRAD Level II archive.