A heavy lake effect snow band produced six to eight inches of snow across northwest Warren County.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS CTP wrote it up.
A heavy lake effect snow band produced six to eight inches of snow across northwest Warren County.
The local office's own words before the first event, 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 the first event at Dec 11, 5:20 AM EST, 1 hour 40 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 520 AM EST FRI DEC 11 2009 .SYNOPSIS... A BRISK WESTERLY FLOW WILL BRING SIGNIFICANT LAKE EFFECT SNOW TO FAR NORTHWESTERN PENNSYLVANIA TODAY AND TONIGHT. HIGH PRESSURE BUILDING NE FROM THE TENNESSEE VALLEY WILL BRING FAIR AND COLD WEATHER ELSEWHERE TODAY THROUGH SATURDAY. LOW PRESSURE ALONG THE GULF COAST LATE SATURDAY WILL MOVE TO THE NORTHEAST AND BRING A MIXED BAG OF GENERALLY LIGHT PRECIPITATION TO THE REGION SUNDAY MORNING...BEFORE CHANGING TO MAINLY RAIN THE AFTERNOON. AFTER A BRIEF PERIOD OF DRY WEATHER WITH MODERATING TEMPERATURES ON MONDAY...A SHARP COLD FRONT WILL PUSH ACROSS THE COMMONWEALTH TUESDAY USHERING IN ANOTHER BLAST OF ARCTIC AIR...WITH GUSTY WINDS AND SNOW SHOWERS FOR THE MIDDLE AND LATTER PART OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... COLD CYC BL FLOW WILL CONT ACROSS THE REGION TDY BEFORE GRADUALLY WANING INTO THE WEEKEND. SFC HIGH PRES INITIALLY CENTERED OVER THE TN VLY WILL SLIDE ENEWD INTO THE VA TIDEWATER BY 12/12Z...WHILE THE MID/UPPER LEVEL FLOW TRANSITIONS TWD A MORE ZONAL ORIENTATION. EARLY MORNING READINGS IN THE SINGLE DIGITS AND TEENS COMBINED WITH A BRISK AND GUSTY WEST WIND WILL RESULT IN WIND CHILLS OF 10 TO 15 BELOW ACROSS THE NORTHERN AND WESTERN MTNS. THE WIND CHILL ADVY REMAINS IN EFFECT UNTIL 9AM FOR THESE AREAS. REGIONAL RDR SHOWS INTENSE SINGLE LES BAND EXTENDING ENEWD FM ERI ACROSS THE WESTERN SOUTHERN TIER OF NYS. EARLY SEASON RELATIVE WARMTH OF LAKE ERIE HAS CERTAINLY BEEN CONTRIBUTING TO ENHANCED INSTABILITY WITH DELTA T VALUES IN EXCESS OF 20C. LATEST HI RES MDLS SUGGEST THIS BAND WILL EVENTUALLY TAKE ON A WEST-EAST ORIENTATION THRU THE DAY AS IT SAGS SWD TO ALONG THE PA/NY BORDER. UPSTREAM STLT IMAGERY AND SFC OBS APPEAR TO BE CONFIRMING THE SLIGHT VEERING OF THE MEAN LLVL WIND TO PURE WLY 270-280 DEGS BY THIS AFTN. A BLEND OF HI RES MDL QPF AND 15-20:1 SLR RESULTS IN LOCALIZED 24HR SNOW ACCUMS OF 6-8 ACROSS THE SNOWBELT OF NORTHERN WARREN COUNTY...WITH LESSER AMOUNTS OF 2-4 FURTHER EAST OVER NORTHERN MCKEAN COUNTY. THEREFORE...HAVE ISSUED A LAKE EFFECT WARNING AND ADVISORY FOR THESE AREAS THRU 12Z SAT. INC BL SHEAR AND LOWERING INVERSION HGTS WILL SPELL AN END TO THE LAKE EFFECT INTO EARLY SATURDAY. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... SFC HIGH PRESSURE RIDGE SLIDING ENE FROM THE CENTRAL APPALACHIANS WILL PROVIDE MORE TRANQUIL CONDITIONS FOR SATURDAY...WITH RATHER ABUNDANT SUNSHINE ACROSS THE SOUTHERN TWO THIRDS OF THE STATE. LITTLE MORE THAN A FEW ISOLATED/MAINLY MORNING SNOW SHOWERS ARE EXPECTED ACROSS THE FAR NORTH. AFTER A COLD START TO THE DAY...EVEN THE PLENTIFUL SUNSHINE WONT BE ABLE TO WARM TEMPS BACK TO NORMAL...GIVEN THE 850 MB TEMPS OF -6 TO -10C ACROSS THE REGION. MAX TEMPS SAT WILL BE ABOUT 5 DEG F BELOW NORMAL...RANGING FROM THE U20S ACROSS THE NW MTNS...TO THE U30S IN THE SE VALLEYS. AFTER A MAINLY CLEAR START DURING THE EVENING...CLOUDS WILL INCREASE/THICKEN UP FROM THE SW SAT NIGHT. A SHARP TEMP DROP WILL OCCUR IN THE EVENING (THANKS TO LIGHT AND VARIABLE WINDS AND DEWPOINTS IN THE SINGLE DIGITS/TEENS). TEMPS WILL LEVEL OFF LATE WITHIN A FEW DEG F OF NORMAL LOWS IN THE UPR TEENS TO MID 20S. && .LONG TERM /MONDAY THROUGH THURSDAY/... AFTER THE HIGH PRESSURE AREA DEPARTS EAST OF THE MID ATLANTIC COAST LATE SAT NIGHT...A COUPLED 300 MB JET CIRCULATION WILL DEVELOP/ADVECT EAST FROM THE OHIO RIVER VALLEY. THIS WILL HELP TO ENHANCE THE SOUTH TO SSW...850 MB JET TO 40-50 KTS (OR 1-2 ST DEVIATIONS ABOVE NORMAL) - WITH PRECIP WATER (VIA THE SUPER ENSEMBLE) INCREASING TO AROUND 0.75 BY 18Z SUNDAY. IN CONTRAST TO THE PREVIOUS FEW WINTRY STORMS...THIS SYSTEM APPEARS TO LACK SIGNIFICANT LLVL COLD AIR AND AN EAST TO NE COMPONENT TO THE SFC-925 MB WIND. THEREFORE...PRECIP TYPE WILL BE SKEWED MUCH MORE TWD A BRIEF MIX IN THE MORNING...THEN MAINLY LIGHT RAIN FOR THE AFTERNOON AS 925-850 MB WET BULB TEMPS RISE TO ABOVE ZERO WITH SFC TEMPS IN THE MID TO U30S IN MOST PLACES. THE NRN MTNS COULD HANG ONTO ENOUGH COLD AIR DURING THE DAY TO MAINTAIN A LIGHT WINTRY MIX THROUGHOUT THE AFTERNOON. LIGHT SNOW/SLEET (OR POSS FZRA) ACCUMS WILL BE LIMITED TO THE EARLY TO MID MORNING IN MOST LOCATIONS PER THE 03Z SREF PTYPE AMD THE SIMILAR OPERATIONAL 00/06Z NAM/GFS. A BRIEF LULL IN THE PRECIP...WITH PARTLY SUNNY SKIES AND SLIGHTLY ABOVE NORMAL TEMPS WILL ARRIVE TO START THE NEW WEEK AS ANOTHER AREA OF HIGH PRESSURE SLIDES NE TO THE MID ATLANTIC SEABOARD. FOR THE MONDAY NIGHT/WED TIMEFRAME...AN AMPLIFYING UPPER TROUGH AND ARCTIC FRONT WILL PLOW EAST FROM THE MIDWEST. RAIN SHOWERS WILL BE THE PRIMARY PRECIP TYPE AHEAD OF THIS FRONT...WITH EVEN A RUMBLE OF THUNDER ALONG THE CFROPA EARLY TUESDAY GIVEN THE STRONG DYNAMICS AND COLLOCATED ENTRANCE REGION OF A 160+ KT UPPER JET. AS THE PRIMARY LIFT FROM THE JET SLIDES ABOVE THE MAIN BAROCLINICITY CLOSER TO THE MID ATLANTIC COAST...A SECONDARY SFC LOW MAY SPIN UP CLOSE ENOUGH TO EXTEND THE PRECIP THROUGH THE LATE AFTERNOON TUESDAY ACROSS OUR ERN ZONES (AND POSSIBLY LEAD TO A PERIOD OF STEADY SNOW). ELSEWHERE...MAX TEMPS WILL BE ACHIEVED DURING THE MORNING...WITH STEADY OR FALLING TEMPS IN THE AFTERNOON...AS WESTERLY WINDS INCREASE AND GUST OVER 40 MPH LATER IN THE DAY AND TUESDAY NIGHT/WED. NUMEROUS SNOW SHOWERS AND AREAS OF LES EXPECTED ACROSS THE NRN AND WESTERN MTNS WITH MUCH BELOW NORMAL TEMPS FOR THE MID TO LATE WEEK PERIOD (DEC 16-18). && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... COLD CYC FLOW WILL GRADUALLY RELINQUISH ITS GRIP ON THE REGION OVER THE NEXT 24 TO 48 HOURS...AS SFC HIGH PRES SLIDES ENE FM THE TN VLY INTO THE VA TIDEWATER. UNTIL THEN...WLY FETCH OFF OF LAKE ERIE COMBINED WITH OROGRAPHIC/UPSLOPE LLVL FLOW WILL CONT TO PRODUCE OCNL SHSN AND MVFR/IFR RESTRICTIONS AT BFD/JST. EAST OF THE ALLEGHENIES...XPC MAINLY VFR WITH SCT-BKN CIGS 3-6KFT AGL. WLY SFC WNDS WL REMAIN GUSTY 25-35KTS TDY BEFORE RELAXING SOME THIS EVE. BY IN LARGE...ANTICIPATE IMPROVING CONDS TNT THRU SAT. OUTLOOK... SAT...BCMG VFR. SUN/MON...MVFR/IFR IN LIGHT MIXED PRECIPITATION. TUE...VFR TO MVFR WITH SHSN/RASN ARRIVING AHEAD OF ARCTIC FRONT. && .CTP WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SATURDAY FOR PAZ005. WIND CHILL ADVISORY UNTIL 9 AM EST THIS MORNING FOR PAZ004>006- 010>012-017-018-024-033-037-041-042. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SATURDAY FOR PAZ004. && SYNOPSIS...LAMBERT NEAR TERM...STEINBUGL SHORT TERM...LAMBERT LONG TERM...LAMBERT AVIATION...STEINBUGL
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE STATE COLLEGE PA 411 AM EST FRI DEC 11 2009 PAZ006-010>012-017-018-024-033-037-041-042-120915- POTTER-ELK-CAMERON-NORTHERN CLINTON-CLEARFIELD-NORTHERN CENTRE- CAMBRIA-SOMERSET-TIOGA-NORTHERN LYCOMING-SULLIVAN- 411 AM EST FRI DEC 11 2009 ...WIND CHILL ADVISORY IN EFFECT UNTIL 9 AM EST THIS MORNING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...TODAY AND TONIGHT. PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV/STATECOLLEGE ON THE INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS. WIND CHILL ADVISORY. .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. PAZ019-025>028-034>036-045-046-049>053-056>059-063>066-120915- SOUTHERN CENTRE-BLAIR-HUNTINGDON-MIFFLIN-JUNIATA-BEDFORD-FULTON- FRANKLIN-SOUTHERN CLINTON-SOUTHERN LYCOMING-UNION-SNYDER-MONTOUR- NORTHUMBERLAND-COLUMBIA-PERRY-DAUPHIN-SCHUYLKILL-LEBANON-CUMBERLAND- ADAMS-YORK-LANCASTER- 411 AM EST FRI DEC 11 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...TODAY AND TONIGHT. TEMPERATURES IN THE TEENS AND LOWER 20S COMBINED WITH BLUSTERY WEST WINDS WILL RESULT IN WIND CHILLS NEAR OR BELOW ZERO THIS MORNING. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY. THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SNOW AND ICE ACCUMULATIONS TO THE NATIONAL WEATHER SERVICE IN STATE COLLEGE. PAZ005-120915- MCKEAN- 411 AM EST FRI DEC 11 2009 ...WIND CHILL ADVISORY IN EFFECT UNTIL 9 AM EST THIS MORNING... ...LAKE EFFECT SNOW ADVISORY IN EFFECT UNTIL 7 AM EST SATURDAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...TODAY AND TONIGHT. PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV/STATECOLLEGE ON THE INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS. WIND CHILL ADVISORY. LAKE EFFECT SNOW ADVISORY. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY. PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV/STATECOLLEGE ON THE INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS. LAKE EFFECT SNOW ADVISORY. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SNOW AND ICE ACCUMULATIONS TO THE NATIONAL WEATHER SERVICE IN STATE COLLEGE. PAZ004-120915- WARREN- 411 AM EST FRI DEC 11 2009 ...WIND CHILL ADVISORY IN EFFECT UNTIL 9 AM EST THIS MORNING... ...LAKE EFFECT SNOW WARNING IN EFFECT UNTIL 7 AM EST SATURDAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...TODAY AND TONIGHT. PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV/STATECOLLEGE ON THE INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS. WIND CHILL ADVISORY. LAKE EFFECT SNOW WARNING. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY. PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV/STATECOLLEGE ON THE INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS. LAKE EFFECT SNOW WARNING. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SNOW AND ICE ACCUMULATIONS TO THE NATIONAL WEATHER SERVICE IN STATE COLLEGE. STEINBUGL
The national radar mosaic for the moment the first event began.
1 lake-effect snow. Local standard time, as filed.
Six to eight inches of lake effect snow was observed in Lottsville.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2009Every state in 2009This day in weather historyWarnings in Pennsylvania, December 2009
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 198940.