Thunderstorms developed ahead of and along a cold front during the afternoon and evening of June 21st. A warm, moist airmass ahead of the front allowed for the formation of severe thunderstorms across much of central Pennsylvania.
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.
Thunderstorms developed ahead of and along a cold front during the afternoon and evening of June 21st. A warm, moist airmass ahead of the front allowed for the formation of severe thunderstorms across much of central Pennsylvania.
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 21, 1:13 PM EST, 42 minutes earlier.
Area Forecast Discussion National Weather Service State College PA 213 PM EDT Mon Jun 21 2021 .SYNOPSIS... Hot and humid conditions for the first full day of summer 2021 will help to fuel a few rounds of gusty, and in some cases, severe thunderstorms this afternoon and evening. Showers will continue tonight and exit the southeast part of the area later Tuesday. Temperatures will trend cooler through midweek before moderating into the weekend. The precipitation pattern should stay rain- free through late week with an increasing chance of showers over the weekend and into early next week. && .NEAR TERM /THROUGH TONIGHT/... 145 PM/1845Z: Visible satellite imagery overlaid with several convective parameter shows the atmos still capped by +8C mid level air across much of Central PA and the Susq Valley, while a few deg C of cooling along with increasing deep-layer shear and llvl theta-e convergence was helping to consolidate 2 distinct lines of strong to severe TSRA across NE Ohio/NW PA and nrn WVA. Further intensification and merging of these lines of TSRA are expected across the Eastern half of the CWA late this afternoon and evening, with several discrete supercells expected within the region of stronger llvl shear and more broadly- looped hodographs across northern PA through 22Z highly conducive for a widespread severe weather outbreak this afternoon/early this evening. Previous disc... Broad warm sector over all of PA (to the SE of a potent, early summer 990 mb sfc low just north of Georgian Bay) with juicy dewpoints in the mid 60s to low 70s was leading to hefty sfc- based capes of 2000-3000 j/kg over all but the far NW zones late this morning. Nearly full sun and several more deg F of heating will contribute another 500+ j/kg of CAPE. SPC upgraded practically the entire CWA to an enhanced risk with their midday update is prudent considering strong, deep- layer shear of 35-40 kts of effective bulk shear and a growing area of DCAPE in excess of 1000 J/KG across the Central Mtns and Susq Valley. A 2-3 hour period of strong to severe multicell/transient supercell storms will grow rapidly upscale into a extensive linear MCS over Central PA and the Susq Valley for the late afternoon and evening hours with another bkn line of strong to locally severe TSRA moving through the NW Mtns early this evening along and just ahead of a cold front. Heat+Humidity peaks this afternoon with max temperatures in the mid 80s to low 90s and max heat index (HX) values forecast to approach 100F in the mid and lower Susquehanna Valley. Forecast max temperatures are a solid 5-10+ degrees above daily climo and within a shouting distance of near-record territory. Convection should weaken and decrease in coverage btwn 00-06Z due to the loss of heating and increasing CINH. Hires models show a relatively lull in precip around 06Z before showers ramp back up across the southeast half of the CWA through Tuesday morning. Minimum temperatures will have the most spread in recent nights thanks to the cold front bisecting the area with lows ranging from the upper 40s in the NW mtns to upper 60s in the far southeast zones. && .SHORT TERM /TUESDAY/... Showers will be across the southeast zones early Tuesday as secondary front traverses the region. Rain should exit this area by late in the day around 22-23Z based on the latest 06Z HRRR. Temps will trend much cooler on Tuesday with 24hrMaxT deltas of -20 to -25F lower vs. Monday. Abnormally dry (below normal PWAT) airmass accompanying area of high pressure will lead to relatively cool (refreshing to for some) nights Tue & Wed with lows in the 40s and 50s. Some of the usually colder spots in the northern tier may drop into the upper 30s Tue night similar to 6/17. Rain-free conditions extend trough midweek with temps going bullish trend starting a series of higher lows and higher highs Wed/Wed night. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... The high will move to the east later in the week with warmer, more humid air moving in from the south and east. A cold front will approach from the west next weekend, but there is still a great deal of uncertainty with the timing of that front and precipitation it will bring. GFS and ECMWF have been trending toward a slower solution on the movement of the front and perhaps even the front stalling over PA next weekend into early next week. This would result in an unsettled period with multiple rain chances for central PA through the middle of the week. && .AVIATION /17Z MONDAY THROUGH FRIDAY/... VFR expected for the next few hours western half of PA, and through the late afternoon across the Susq Valley and points east. Widespread coverage of showers/tstms is expected this afternoon with activity spreading from the NW across the CWA. These storms will bring potential for locally strong wind gusts and torrential rainfall as they impact the area through the afternoon hours. Peak areal extent of TSRA expected between 18z- 00z. A cold front will move through the CWA behind the convection with winds turning more nwrly after 00z. This frontal passage will likely be accompanied by a period of MVFR cigs, mainly across the west. Outlook... Monday-Tuesday...more widespread showers/storms possible areawide. Wednesday-Friday...widespread VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && SYNOPSIS...Lambert/Steinbugl NEAR TERM...Lambert/Steinbugl SHORT TERM...Steinbugl LONG TERM...Guseman/Travis AVIATION...Lambert/Colbert/Wagner
Hazardous Weather Outlook National Weather Service State College PA 229 PM EDT Mon Jun 21 2021 PAZ012-018-019-025>028-034>037-041-042-045-046-049>053-056>059- 063>066-221830- Northern Clinton-Northern Centre-Southern Centre-Blair-Huntingdon- Mifflin-Juniata-Bedford-Fulton-Franklin-Tioga-Northern Lycoming- Sullivan-Southern Clinton-Southern Lycoming-Union-Snyder-Montour- Northumberland-Columbia-Perry-Dauphin-Schuylkill-Lebanon-Cumberland- Adams-York-Lancaster- 229 PM EDT Mon Jun 21 2021 ...SEVERE THUNDERSTORM WATCH 302 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. Severe Thunderstorm Watch. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ004>006-010-011-017-024-033-221830- Warren-McKean-Potter-Elk-Cameron-Clearfield-Cambria-Somerset- 229 PM EDT Mon Jun 21 2021 ...SEVERE THUNDERSTORM WATCH 299 IN EFFECT UNTIL 8 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. Severe Thunderstorm Watch. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
124 PM EDT MON JUN 21 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0940 PM TSTM WND DMG 4 SSE KULPMONT 40.75N 76.45W
06/20/2021 SCHUYLKILL PA TRAINED SPOTTER
MULTIPLE TREES DOWN.
&&
QMSpecial Weather Statement
National Weather Service State College PA
219 PM EDT Mon Jun 21 2021
PAZ004-005-211900-
McKean PA-Warren PA-
219 PM EDT Mon Jun 21 2021
...A STRONG THUNDERSTORM WILL AFFECT PARTS OF MCKEAN AND WARREN
COUNTIES UNTIL 300 PM EDT...
At 218 PM EDT, Doppler radar indicated a strong thunderstorm 9 miles
south of Chapman State Park, moving northeast at 30 mph.
Penny size hail and wind gusts of 50 to 55 mph are possible.
Locations impacted include...
Kane, Sheffield, Wetmore, Ludlow and Westline.
LAT...LON 4191 7878 4166 7868 4162 7896 4163 7928
4164 7928
TIME...MOT...LOC 1818Z 239DEG 27KT 4164 7920
JCGSpecial Weather Statement
National Weather Service State College PA
255 PM EDT Mon Jun 21 2021
PAZ005-211930-
McKean PA-
255 PM EDT Mon Jun 21 2021
...A STRONG THUNDERSTORM WILL AFFECT PARTS OF MCKEAN COUNTY UNTIL 330
PM EDT...
At 255 PM EDT, Doppler radar indicated a strong thunderstorm near
Coryville, moving northeast at 40 mph.
Pea size hail and wind gusts of 50 to 55 mph are possible.
Locations impacted include...
Coryville, Eldred and Ceres.
LAT...LON 4195 7821 4187 7840 4197 7848 4200 7843
4200 7821
TIME...MOT...LOC 1855Z 237DEG 36KT 4196 7839
JCGThe Pittsburgh radar (KPBZ), 136 km away, was scanning. The volume nearest the first event began at 18:57 UTC.
26 thunderstorm wind. Local standard time, as filed.
A severe thunderstorm producing winds estimated near 60 mph brought down multiple trees along Tidioute Enterprise Rd.
A severe thunderstorm producing winds estimated near 60 mph brought down trees on powerlines along Youngsville Rd.
A severe thunderstorm producing winds estimated near 60 mph brought down trees along Enterprise Titusville Rd.
A severe thunderstorm producing winds estimated near 60 mph brought down trees near Russell City.
A severe thunderstorm producing winds estimated near 60 mph brought down trees on Route 66.
A severe thunderstorm producing winds estimated near 60 mph brought down trees at Halfmoon Valley Rd and Winesap Dr.
A severe thunderstorm producing winds estimated near 60 mph brought down multiple trees at 606 Old Curtain Rd.
A severe thunderstorm producing winds estimated near 60 mph brought down several trees and blew shingles off of a roof.
A severe thunderstorm producing winds estimated near 60 mph brought down multiple trees near Colver.
A severe thunderstorm producing winds estimated near 70 mph brought down several trees between Waynesboro and Greencastle.
A severe thunderstorm producing winds estimated near 70 mph brought down multiple trees.
A severe thunderstorm producing winds estimated near 60 mph brought down a tree across Arnot Rd.
A severe thunderstorm producing winds estimated near 60 mph brought down multiple trees along Glendale Lake Rd.
A severe thunderstorm producing winds estimated near 75 mph brought down multiple large trees off Moritz Rd.
A severe thunderstorm producing winds estimated near 60 mph brought down multiple trees and wires at the intersection of Thomas Hill Rd and Runville Rd.
A severe thunderstorm producing winds estimated near 60 mph brought down multiple trees on Somerset and Meade streets in Johnstown.
A severe thunderstorm producing winds estimated near 60 mph brought down trees and wires in Knoxville.
A severe thunderstorm producing winds estimated near 75 mph brought down multiple trees and wires from Cashtown to Fairfield.
A severe thunderstorm producing winds estimated near 60 mph brought down trees across Morris Run Rd.
A severe thunderstorm producing winds estimated near 60 mph brought down multiple trees and wires along Woodward Ave.
A severe thunderstorm with estimated winds near 60 mph brought down multiple trees.
A severe thunderstorm producing winds estimated near 60 mph brought down multiple trees in Windsor Borough, including on Manor Rd, Smith Rd and Winterstown Rd.
A severe thunderstorm producing winds estimated near 60 mph brought down trees along Worlds End Rd.
A severe thunderstorm producing winds estimated near 60 mph brought down multiple trees on SR-154 near Worlds End State Park.
A severe thunderstorm producing winds estimated near 60 mph brought down multiple trees near Route 154 and Shanersburg Rd.
A severe thunderstorm producing winds estimated near 60 mph brought down multiple trees in Willow Street.
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: 957479, 957482, 957483, 957484, 957486, 957489, 957492, 957498, 957491, 957499, 957501, 957511, 957495, 957502, 957510, 957508, 958082, 957500, 957512, 957514, 957612, 958080, 958077, 958076, 958078, 958081.