Scattered thunderstorms developed over central Pennsylvania, ahead of a weak mid-level shortwave, during the afternoon of August 7, 2020. A few of these storms produced wind damage, as well as flash flooding across Lancaster and York Counties.
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.
Scattered thunderstorms developed over central Pennsylvania, ahead of a weak mid-level shortwave, during the afternoon of August 7, 2020. A few of these storms produced wind damage, as well as flash flooding across Lancaster and York Counties.
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 7, 6:30 AM EST, 50 minutes earlier.
Area Forecast Discussion National Weather Service State College PA 730 AM EDT Fri Aug 7 2020 .SYNOPSIS... Showers and thunderstorms are likely across most of central PA today. Locally heavy rainfall is possible with the greatest risk of flash flooding in the lower Susquehanna Valley. The overall coverage and probability of showers and storms will trend lower (drier) through the weekend with temperatures climbing 5 to 10 degrees above average into early next week. && .NEAR TERM /THROUGH TONIGHT/... Overall forecast remains on track. Current storm tracking along I-80 corridor has been persistent/strong and recently ramped its hail core to 1-2 inches. SPC may be adding a portion of the CWA to a MRGL risk with the 13Z update. Primary focus today will be on heavy rain/FF potential. WPC has upgraded the lower Susquehanna Valley to a SLGT risk ERO (level 2 out of 4). Several factors will contribute to heavy rain/FF threat in this area including but not limited to above normal moisture/PW, slow storm motions/cell training/mergers, and wet antecedent conditions. The dayshift should consider a short- fused FF watch if hires models remain bullish with +RA signal. Scattered to numerous afternoon/evening showers and storms should fade and shift eastward tonight into early Saturday morning. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... Increasing influence of high pressure sfc and aloft should spell a downward trend in diurnal convection to start the weekend. Pcpn probs derived from a blend of NBM and HREF are generally AOB 20% and focused across the eastern 1/2 to 1/3 of the CTP CWA. MaxT24hourChange will be about +2 to +6 degrees warmer vs. Friday. High confidence in dry conditions tomorrow night with mainly clear skies and light winds suggesting valley fog is possible into AM Sunday. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Fair weather should prevail on Sunday. The longer term will feature a return of warmer weather, with temperatures generally 5-10 degrees above average from Mon through Wed as an upper ridge builds over the Eastern US. Dewpoints climb back to the upper 60s and 70s for Tue and Wed, and perhaps even the mid 70s in the Lower Susq. Combined with temps in the upper 80s to near 90, this would mean Heat Index values take a run at the upper 90s to near 100 in the Lower Susq, so long as the low level moisture doesn't mix out in the afternoon and cause the dewpoint to drop. Continued to knock down afternoon dewpoints from NBM guidance across central and northwestern zones Mon and Wed afternoon, where it looks like drier air will mix down. Weak forcing will favor isolated, pulse thunderstorms on Monday, mainly in the northwest. A cold front sagging south on Tuesday and Wednesday, combined with increasing humidity, should trigger more numerous showers and thunderstorms both days. Guidance seems to indicate the cold front may stall as it moves through PA, resulting in at least one more day of unsettled weather on Thursday. && .AVIATION /11Z FRIDAY THROUGH TUESDAY/... MVFR ceilings covering much of central PA early this morning may drop to IFR for a short while around sunrise before gradually lifting through the mid morning hours. Bigger issue of the day is thunderstorm impacts. Ongoing isolated convection being driven by weak trough moving through will keep tstms mainly confined between FIG-UNV-IPT through sunrise. But scattered showers/tstms will then begin to develop areawide in the mid/late morning hours and become numerous for the afternoon for central and eastern portions. These storms will bring periodic short-duration cig/vis reductions to terminals with exact timing tough to pin down. Storms will be slow moving as well. Convective activity should fade and shift eastward during the evening hours into early Saturday morning. Fog restrictions along with low clouds likely Sat morning, but conditions bounce back to VFR quickly. Outlook... Sat-Mon...VFR. AM fog poss nrn valleys. Tue...Front approaching fm W. PM TSRA, mainly W. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && SYNOPSIS...Steinbugl NEAR TERM...Steinbugl SHORT TERM...DeVoir/Dangelo LONG TERM...Colbert/Banghoff AVIATION...RXR/Banghoff
Hazardous Weather Outlook National Weather Service State College PA 428 AM EDT Fri Aug 7 2020 PAZ004>006-010>012-017>019-024>028-033>035-037-041-042-045-046- 049>053-058-080830- Warren-McKean-Potter-Elk-Cameron-Northern Clinton-Clearfield- Northern Centre-Southern Centre-Cambria-Blair-Huntingdon-Mifflin- Juniata-Somerset-Bedford-Fulton-Tioga-Northern Lycoming-Sullivan- Southern Clinton-Southern Lycoming-Union-Snyder-Montour- Northumberland-Columbia-Schuylkill- 428 AM EDT Fri Aug 7 2020 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. PAZ036-056-057-059-063>066-080830- Franklin-Perry-Dauphin-Lebanon-Cumberland-Adams-York-Lancaster- 428 AM EDT Fri Aug 7 2020 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...Today and tonight. Slow moving showers and thunderstorms with heavy rainfall will pose a risk of mainly localized flash flooding. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather.
Special Weather Statement
National Weather Service State College PA
714 AM EDT Fri Aug 7 2020
PAZ012-019-041-045-046-071200-
Southern Lycoming PA-Southern Clinton PA-Northern Clinton PA-
Northern Lycoming PA-Southern Centre PA-
714 AM EDT Fri Aug 7 2020
...A STRONG THUNDERSTORM WILL AFFECT PARTS OF LYCOMING AND CLINTON
COUNTIES UNTIL 800 AM EDT...
At 713 AM EDT, Doppler radar indicated a strong thunderstorm near
Blanchard, moving east at 15 mph.
Wind gusts 30 to 40 mph and half inch hail are possible.
Locations impacted include...
Lock Haven, Jersey Shore, Carroll, Lamar, Mill Hall, Avis, Dunnstown,
Flemington, Castanea, Blanchard, McElhattan, Mackeyville, Bald Eagle
State Park, Beech Creek, Loganton and Lock Haven University.
LAT...LON 4105 7717 4099 7763 4107 7766 4109 7762
4111 7768 4116 7770 4131 7727
TIME...MOT...LOC 1113Z 252DEG 15KT 4110 7758
SteinbuglThe State College radar (KCCX), 75 km away, was scanning. The volume nearest the first event began at 12:20 UTC.
7 thunderstorm wind, 1 flash flood. Local standard time, as filed.
A severe thunderstorm producing winds estimated near 60 mph knocked down multiple trees along Interstate 80 near mile-marker 197.
A severe thunderstorm producing winds estimated near 60 mph knocked down multiple large trees onto Avenue F in Riverside.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees and wires in Montour County.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees onto the 300 block of Legion Road to the southwest of Bloomsburg.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees onto wires at Old Reading Road and Creek Road to the east of Slabtown.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees onto wires to the east of Mill Grove.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees along a recreational trail just south of Reeds Gap State Park.
Widespread flash flooding was reported across Lancaster and a small portion of York County.
A dozen water rescue calls were reported for areas including East Hempfield, East Lampeter, Manheim, Providence, Salisbury, Strasburg, Upper Leacock, West Earl and West Hempfield townships.
In addition to the water rescue calls, there were many reports of high water on roads across the Lancaster county, and some residential flooding.
Two rescue calls were for vehicles in water, according to initial dispatch reports, one on Meadow View Drive in West Earl Township just before 4 p.m., and one in the area of East Main Street in Upper Leacock Township just after 4 p.m.
A third water rescue call was reported in the 300 block of West Main Street in Upper Leacock Township just before 4:30 p.m.
Just before 5 p.m., more water rescue calls were reported: in the 1300 block of Marshall Avenue in Manheim Township; in the 500 block of Weaver Road in Strasburg Township; and at Independence Court and Greenfield Road in East Lampeter Township.
Others followed shortly, at Pennsy Road and Main Street in Providence Township; at Greenfield Road and railroad tracks in East Lampeter Township; at Strasburg Road and Old Strasburg Road in Salisbury Township; and at Lincoln Highway East and North Kinzer Road in Paradise Township. High water was also reported at Old Harrisburg Pike and Spooky Nook Road in West Hempfield Township, and at Snapper Dam Road and Northside Drive in East Hempfield Township.
Calls for high water on roadway later came from Bowman Road and Parker Drive in East Hempfield Township; Cardinal Road and North Elm Street in Lititz Borough; South 14th Street and Central Avenue in Columbia Borough; and Ruby Street and Froelich Avenue in Mountville Borough.
By 4:40 p.m. the list of calls for high water on roadway included Peace Road in West Earl Township; Church Street and Daryl Drive in East Hempfield Township; West Penn Grant Road and Marticville Road in Pequea Township; and Peach Bottom Road and Beaver Valley Pike in West Lampeter Township.
At 5pm a water rescue was reported at Arsenal Road and North George Stree 1 mile north of York in York County.
|Later reports came from Marticville Road and Goods Run in Pequea Township; Hollinger Road and Millwood Road in West Lampeter Township; Bachmantown Road and South Ronks Road in East Lampeter Township; Snakehill Road and Route 23 in Upper Leacock Township; and Running Pump Road in East Hempfield Township.
Starting at about 5:30 p.m., high water on roadway reports came for Embassy Drive and Rohrerstown Road in East Hempfield Township; New Holland Avenue and East Ross Street in Lancaster City; and Pleasure Road and Deer Ford Drive in Manheim Township.
Just before 5:30 p.m., PPL's outage center showed 805 customers without power in Lancaster County.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2020Every state in 2020This day in weather historyWarnings in Pennsylvania, August 2020
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: 914110, 914111, 914113, 914112, 914118, 914120, 914121, 918723.