A backdoor cold front slipped southward across central Pennsylvania during the afternoon and evening hours of June 9, 2021, generating scattered showers and thunderstorms in a warm and humid airmass ahead of it. A few of these storms produced localized wind damage before dissipating after sunset.
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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 backdoor cold front slipped southward across central Pennsylvania during the afternoon and evening hours of June 9, 2021, generating scattered showers and thunderstorms in a warm and humid airmass ahead of it. A few of these storms produced localized wind damage before dissipating after sunset. One flash flood was reported in Schuylkill 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 Jun 9, 11:30 AM EST, 28 minutes earlier.
Area Forecast Discussion National Weather Service State College PA 1230 PM EDT Wed Jun 9 2021 .SYNOPSIS... Muggy conditions will continue to support isolated to scattered drenching downpours through late week. Cooler and more seasonable temperatures are expected Friday into next week with a lingering chance of showers and thunderstorms. && .NEAR TERM /THROUGH TONIGHT/... 1345Z Update... Morning analysis indicates 850 mb theta-e axis draped across south central PA, which will be the focus for diurnal convection for yet another day. Forecast in great shape for today for no significant changes this morning. Based on morning analysis, collaborated a northward nudging of the Day1 Excessive Rainfall Outlook to include the WC/SC/Central Mountains and Laurels as that zone will be the focus for slow moving locally heavy downpours later this afternoon into early this evening. Previous discussion: Near and ahead of a weak upper level trough in the Ohio Valley, abundant moisture /PWATs 1-2" and 65-70F Td/ will remain in place across the region. Low level inflow and the mean 850-300mb wind are also weak, favoring another day of localized heavy downpours. Diurnal heating/instability should allow convection to concentrate mainly in the afternoon and evening hours. The 00Z HREF shows the highest neighborhood probs for QPF>1" initially over the NW Alleghenies between 18-21Z before broadening a potential axis of showers/storms with locally heavy rain farther to the southeast across the interior central mtns into the lower Susquehanna Valley from 21-03Z. This axis is also noted in the HREF exceedance probs for 1 & 3hr FFG. The WPC MRGL risk ERO only includes the areas with lowest FFGs/most vulnerable to short duration flooding/runoff issues in the SW mtns and southeast of US-30. MaxTs will to peak today in the upper 70s/80s or +5-10F above the daily climo mean with max HX values fcst to reach the lower 90s across the middle and lower Susquehanna Valley. Convective coverage gradually fizzles and fades into tonight with lingering activity confined primarily to the southwest 1/2 of the CWA. Another mild and muggy night across most of the area with fcst minTs +10-15F above normal in the 60-70F range NW to SE. && .SHORT TERM /THURSDAY/... Lower highs fcst on Thursday with 24hrMaxTChange trending 3-6F lower across the southeast 2/3 of the CWA. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... We will see a marked cooldown by Friday, as a backdoor cold front slips just south of the area. However, the front will remain close enough to keep a chc of showers in the forecast across southern PA. Heading into the weekend and early next week, expect temperatures to turn milder again. The weather will remain unsettled, although no single day looks like a washout, as a series of shortwaves drop southeastward across the northeastern United States. Scattered showers and storms are possible with each shortwave, but models differ on the exact timing and strength of the shortwaves. Have maintained at least a slight chc of showers and aftn thunder through the period. A more significant cold front is projected to cross the area by the middle of next week, ushering in cooler and drier conditions for the second half of next week. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... At 16z, showers are already developing over the higher terrain of northern and western PA, and a few flashes of lightning are beginning to be seen. Expect this activity to continue to develop and expand in coverage as the day progresses. Localized restrictions are expected in any showers/storms and brief gusty winds are possible in the vicinity of any storms. Outlook... Thu-Sun...Predominantly VFR, although scattered showers/storms may cause brief restrictions, esp during the aftn/eve hours. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && SYNOPSIS...DeVoir/Steinbugl NEAR TERM...DeVoir/Steinbugl SHORT TERM...Steinbugl LONG TERM...Evanego AVIATION...Evanego/Colbert
Hazardous Weather Outlook National Weather Service State College PA 943 AM EDT Wed Jun 9 2021 PAZ004>006-010>012-037-041-042-045-046-049>053-058-101345- Warren-McKean-Potter-Elk-Cameron-Northern Clinton-Tioga- Northern Lycoming-Sullivan-Southern Clinton-Southern Lycoming-Union- Snyder-Montour-Northumberland-Columbia-Schuylkill- 943 AM EDT Wed Jun 9 2021 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...Thursday through Tuesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. PAZ017>019-024>028-056-057-059-063-101345- Clearfield-Northern Centre-Southern Centre-Cambria-Blair-Huntingdon- Mifflin-Juniata-Perry-Dauphin-Lebanon-Cumberland- 943 AM EDT Wed Jun 9 2021 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...Today and tonight. Locally heavy downpours may result in isolated flash flooding this afternoon and evening. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. PAZ033>036-064>066-101345- Somerset-Bedford-Fulton-Franklin-Adams-York-Lancaster- 943 AM EDT Wed Jun 9 2021 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...Today and tonight. Locally heavy downpours may result in isolated flash flooding this afternoon and evening. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Locally heavy downpours may result in isolated flash flooding on Thursday and Friday. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The Sterling radar (KLWX), 126 km away, was scanning. The volume nearest the first event began at 16:56 UTC.
5 thunderstorm wind, 1 flash flood. Local standard time, as filed.
A severe thunderstorm producing winds estimated near 60 mph knocked down multiple trees in the city of York.
A severe thunderstorm producing winds estimated near 60 mph knocked down a few trees in Osceola, including one on a home.
A severe thunderstorm producing winds estimated near 60 mph knocked down multiple trees and wires in the city of Bradford.
A severe thunderstorm producing winds estimated near 60 mph knocked down multiple trees in the vicinity of Orwigsburg.
A severe thunderstorm producing winds estimated near 60 mph knocked down multiple trees in the vicinity of Summit Station.
Heavy rainfall brought flash flooding to the area. A heavily flooded road was reported on Pine Creek Drive near Orwigsburg. On Green Tree Drive a bridge and the road was reported flooded. Other roads were reported flooded in the Orwigsburg area. Route 901 was washed out in North Manheim Township. North 23rd Street in Pottsville was washed out and closed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2021Every state in 2021This day in weather historyWarnings in Pennsylvania, June 2021
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: 957448, 957451, 957453, 957457, 957460, 958952.