An approaching cold front triggered a line of storms over the western highlands during the early afternoon hours of Saturday, August 12. As this line progresses eastward, one cell in the line evolved into a rotating supercell and produced wind damage across northern Juniata County.
Every event with a place to put it. Tap one for its entry below.
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.
An approaching cold front triggered a line of storms over the western highlands during the early afternoon hours of Saturday, August 12. As this line progresses eastward, one cell in the line evolved into a rotating supercell and produced wind damage across northern Juniata County. Elsewhere, the line of storms produced sporadic wind damage.
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 Aug 12, 11:25 AM EST, 1 hour 52 minutes earlier.
Area Forecast Discussion National Weather Service State College PA 1225 PM EDT Sat Aug 12 2017 .SYNOPSIS... A slow moving cold front will push southeast through the commonwealth late today. High pressure will build into the state from the Ohio Valley accompanied by fair, dry weather for Sunday and Monday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Radar shows convection starting to fire over the Laurel Highlands up into the Northern Mountains in an increasingly unstable airmass. The first lightning strikes have been observed in Clearfield county with the showers moving basically eastward. The HRRR shows the activity continuing to blossom into the afternoon, especially as the convection moves into the Susq Valley. Have to stay alert for flooding as portions of the lower Susq saw rainfall totals exceeding 3 inches last evening. SPC has upgraded the area to a Slight Risk given respectable shear and the expected development of CAPE in the 1500-2000J range by the height of afternoon heating. NCAR's 00Z Ensemble 6-hour total rainfall (ending at 00Z Sunday) implies that locations across the Lower Susq Valley could be under the gun again this afternoon with localized 0.75 to 1.25 inch amounts. High temps today will range from the mid 70s across the NW mtns and Laurel Highlands, to the low 80s in the SE valleys and Metro Areas. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... Latest guidance shows the main shortwave energy speeding by to our north allowing drier air to build in behind a departing cold front tonight into Sunday. There should be enough of a light WNW breeze tonight to cause some upslope stratus across the Alleghenies of Western PA, but not much in the way of fog. Will still mention patchy 1-2SM fog in the deeper valleys late tonight through the mid morning hours Sunday. Sunday should be a splendid day for outdoor activities with temps slightly below seasonal normals, sct-bkn stratocu and cu, and comfortable/low relative humidity with sfc dewpoints ranging from the 50s across the central and nw zones, to around 60F in the southeast. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Surface high pressure center slides across PA Sunday night and off the coast Monday. Most areas will remain dry under the high but on the back side of the high moisture will move north along the spine of the Appalachians with an inverted trough bringing a by late afternoon over the Laurels and slight chances/isolated north over the mpuntains. Monday night a short-wave trough to our west over the Great Lakes will bring some clouds and a slight chance of a shower. As the short-wave nears and with heating of the day Tuesday, some scattered convection will develop over the central and eastern counties of PA. Short-wave ridge moves in behind this Tuesday night with a dry high pressure pattern over PA through Wednesday. A backdoor cold front moves into northeast area Wednesday night but likely only some clouds. The next storm system approaches from the west with a slight chance of showers moving into the western zones by morning. Warm front will increase POPs on Thursday spreading east across the PA with a cold front approaching western PA by afternoon Thursday. Models showing some uncertainty with the timing of this next system through PA. The pattern aloft becomes more zonal with short-waves moving across keeping the weather unsettled into the weekend. Temperatures next week will average near to slightly cooler than normal. && .AVIATION /16Z SATURDAY THROUGH WEDNESDAY/... Lingering MVFR ceilings over our western higher elevations will become mainly VFR by early afternoon. VFR will prevail with local restrictions developing associated with scattered strong to potentially severe thunderstorms by early to mid ahead of a cold front pushing southeast from the lower Great Lakes and Ohio Valley. Surface pattern looks more favorable for low stratus over the western TAFs tonight with mainly VFR at the eastern terminals into Sunday. .OUTLOOK... Sun...No significant weather. Mon...Mainly VFR, but scattered SHRA in the afternoon/evening. Tue-Wed...No significant weather. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && SYNOPSIS...La Corte/Lambert NEAR TERM...La Corte/Lambert SHORT TERM...Fitzgerald/Lambert LONG TERM...Watson AVIATION...La Corte/Steinbugl
Hazardous Weather Outlook National Weather Service State College PA 120 PM EDT Sat Aug 12 2017 PAZ004-131730- Warren- 120 PM EDT Sat Aug 12 2017 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...This Afternoon and Tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Sunday through Friday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. PAZ005-006-010-011-017-024-025-033-034-131730- McKean-Potter-Elk-Cameron-Clearfield-Cambria-Blair-Somerset-Bedford- 120 PM EDT Sat Aug 12 2017 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...This Afternoon and Tonight. Widely scattered strong to severe thunderstorms with gusty winds and hail are possible during the afternoon and evening. .DAYS TWO THROUGH SEVEN...Sunday through Friday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. PAZ012-018-019-026>028-035>037-041-042-045-046-049>053-058-064>066- 131730- Northern Clinton-Northern Centre-Southern Centre-Huntingdon-Mifflin- Juniata-Fulton-Franklin-Tioga-Northern Lycoming-Sullivan- Southern Clinton-Southern Lycoming-Union-Snyder-Montour- Northumberland-Columbia-Schuylkill-Adams-York-Lancaster- 120 PM EDT Sat Aug 12 2017 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...This Afternoon and Tonight. Scattered severe thunderstorms with damaging winds of 60 mph or greater and large hail exceeding 1 inch in diameter are possible this afternoon and evening. .DAYS TWO THROUGH SEVEN...Sunday through Friday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. PAZ056-057-059-063-131730- Perry-Dauphin-Lebanon-Cumberland- 120 PM EDT Sat Aug 12 2017 ...FLASH FLOOD WATCH IN EFFECT UNTIL 10 PM EDT THIS EVENING... This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...This Afternoon and Tonight. Please listen to NOAA Weather Radio or go to weather.gov/StateCollege on the internet for more information about the following hazards. Flash Flood Watch. Scattered severe thunderstorms with damaging winds of 60 mph or greater and large hail exceeding 1 inch in diameter are possible this afternoon and evening. .DAYS TWO THROUGH SEVEN...Sunday through Friday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
Special Weather Statement National Weather Service State College PA 115 PM EDT SAT AUG 12 2017 PAZ019-026-027-121800- Huntingdon PA-Mifflin PA-Southern Centre PA- 115 PM EDT SAT AUG 12 2017 ...A STRONG THUNDERSTORM WILL AFFECT PARTS OF HUNTINGDON...CENTRE... AND MIFFLIN COUNTIES UNTIL 200 PM EDT... At 114 PM EDT, Doppler radar indicated a strong thunderstorm near Ramblewood, moving east at 20 mph. Dime size hail and winds in excess of 40 mph are possible. Locations impacted include... State College, Potters Mills, Ramblewood, Pine Grove Mills, Houserville, Boalsburg, Lemont, Park Forest Village, Centre Hall, Seven Mountains, Rock Springs, Stormstown, Barrville, Tussey Mountain Ski Area, Pennsylvania State University and Pennsylvania Military Museum. PRECAUTIONARY/PREPAREDNESS ACTIONS... Torrential rainfall is also occurring with this storm, and may lead to localized flooding. Do not drive your vehicle through flooded roadways. && LAT...LON 4073 7802 4083 7800 4085 7761 4063 7763 TIME...MOT...LOC 1714Z 282DEG 16KT 4077 7796 Evanego
Special Weather Statement National Weather Service State College PA 130 PM EDT SAT AUG 12 2017 PAZ026-121800- Huntingdon PA- 130 PM EDT SAT AUG 12 2017 ...A STRONG THUNDERSTORM WILL AFFECT PARTS OF HUNTINGDON COUNTY UNTIL 200 PM EDT... At 129 PM EDT, Doppler radar indicated a strong thunderstorm over Shy Beaver, moving east at 15 mph. Dime size hail and winds in excess of 40 mph are possible. Locations impacted include... Trough Creek State Park, Shy Beaver, Saltillo, Cassville and Three Springs. PRECAUTIONARY/PREPAREDNESS ACTIONS... Torrential rainfall is also occurring with this storm, and may lead to localized flooding. Do not drive your vehicle through flooded roadways. && LAT...LON 4025 7824 4033 7821 4036 7791 4014 7796 TIME...MOT...LOC 1729Z 278DEG 15KT 4027 7819 Evanego
The State College radar (KCCX), 43 km away, was scanning. The volume nearest the first event began at 18:15 UTC.
7 thunderstorm wind. Local standard time, as filed.
A severe thunderstorm producing winds estimated near 60 mph knocked down a tree across Salem Road between Blue Hollow Road and Jacks Lane in Armagh Township.
A severe thunderstorm producing winds estimated near 60 mph knocked down wires along North Main Street near Third Street in Derry Township.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees near the intersection of Route 35 and Jericho Road.
A severe thunderstorm producing winds estimated near 60 mph knocked down numerous trees across northern Juniata County.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees across roads in Thompsontown.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees near Liverpool.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees and wires in Lebanon.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2017Every state in 2017This day in weather historyWarnings in Pennsylvania, August 2017
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: 711529, 711530, 711531, 711532, 711534, 711535, 711536.