A surface cold front was stationed near the Mason-Dixon line, with an area of surface low pressure developing and tracking across southern portions of central Pennsylvania. This brought increasing moisture across the area, with ample low-level and effective bulk shear allowing for multiple thunderstorms to develop during the morning and afternoon hours on July 31, 2025.
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.
A surface cold front was stationed near the Mason-Dixon line, with an area of surface low pressure developing and tracking across southern portions of central Pennsylvania. This brought increasing moisture across the area, with ample low-level and effective bulk shear allowing for multiple thunderstorms to develop during the morning and afternoon hours on July 31, 2025. Isolated thunderstorm development in Lancaster County began to intensity, with one thunderstorm producing multiple instances of trees and wires down in Lancaster County. Heavy rainfall continued into the afternoon hours, with flash flooding beginning to occur in Lancaster County and Little Conestoga Creek running out of its banks and closing numerous roadways. Multiple water rescues were also observed due to flash flooding throughout Lancaster 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 Jul 31, 6:24 AM EST, 4 hours 6 minutes earlier.
Area Forecast Discussion National Weather Service State College PA 724 AM EDT Thu Jul 31 2025 .SYNOPSIS... * Widespread showers and thunderstorm downpours expected for the last day of July * Potentially significant flash flooding and a few severe t-storms are most likely across parts of southeast PA this afternoon and evening * Late July heat wave breaks down with a refreshing pattern change to deliver comfortably cooler and less humid conditions to begin the month of August && .NEAR TERM /THROUGH TONIGHT/... * Significant (higher-end) flash flooding and a few severe t-storms capable of locally damaging winds are possible this afternoon into tonight with focus in southeast PA including the Lower Susquehanna Valley One of the better-looking enhanced/excessive rainfall setups we have seen so far this summer expected to evolve/impact portions of central PA in the next 24 hours. Strong synoptic/kinematic forcing has been largely absent for the most part which is common this time year as the primary jet streams retreats poleward during the warm season. However, this time we have a potent vortmax and an exceptionally strong upper level jet streak over southeast Canada in the mix, coupled with highly anomalous moisture/PW and wave of low pressure moving along a slow moving boundary. So all of the ingredients are certainly in place for a higher-end significant flooding threat; residents should ensure they have reliable means of receiving warnings throughout the day and into tonight. There are two areas of concern regarding heavy rainfall: 1) North-central into Northeast PA/Poconos Band of heavy/efficient rainfall appears to be taking shape ahead of the main cold front early this morning based on latest radar trends. PWATs will rise to the 1.8-2.0" range and low- level WAA ahead of the front will give rise to potential training. There is uncertainty regarding the amount of available instability, which could reach as high as 500 J/kg. Still, the modeled soundings depict warm cloud layers up to 13,000ft deep, so while rates may not be as high as farther to the south, warm rain processes could still provide 1-1.5"/hr rates in these areas during the afternoon and into tonight. HREF 6hr PMM shows point amounts of 2+ inches with a potential stripe of up to 4" possible. A risk level 2 out of 4 remains is in place for these regions with locally significant flash flooding possible. 2) Southern/Southeastern PA/Lower Susquehanna Valley Farther south, this area is more removed from the jet-streak dynamics to the north. However, this region is closer to the deepening surface low with strong surface-925mb southerly theta-e advection directed into the southeastward advancing surface front. A tropical air-mass (depicted by 2-2.25" PWATs and low-mid 70s dew points) will coincide within a warm sector that becomes increasingly unstable (MUCAPE between 1,000-2,000 J/kg). It is worth noting that SST anomalies along the Mid- Atlantic and Southeast coasts are well above normal too, acting as an abnormally rich moisture source for southerly low-level flow to draw from. By this afternoon, low-level WAA into the front will support storms enveloping the region with additional storms from the Laurel Highlands/south central Alleghenies tracking east. Modest vertical wind shear aloft will also support organized clusters of storms, some of which will have the potential to backbuild and train between the I-81 and I-95 corridors into tonight. Latest 12Z HREF guidance shows 24-hr probabilities for >3" of rainfall are high (>70%) across southeast PA. Just as concerning is this same region sports 30-60% chances for >5" of rainfall with 24hr PMM/LPMM values close to the ensemble maxima approaching 8 inches. We added Tioga County to the flood watch in coordination with WFO BGM. SPC has upgraded the southern portion of the Lower Susquehanna Valley (near and south of I-81/PA Turnpike/I-78) from risk level 1 to 2 (out of 5) for a damaging wind threat. Strong instability and 30-40kts of effective bulk shear will encourage the development of strong multicells and perhaps a transient supercell capable of localized damaging wind gusts. Major changes in the temperature department today with highs 10 to 20 degrees lower vs. Wednesday across the northern 3/4 of the fcst area. Max temps range from the 65-70F range in the northern tier to mid 80s along the MD line. Low temps also fall about 10F night/night with readings in the low 50s NW to mid 60s SE. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... Departing sfc low pressure moving away from the Delmarva/NJ coast will allow strong Canadian high pressure to flex eastward from the Upper Midwest/Great Lakes. Latest hires model data suggests some clouds and maybe a lingering rain shower or two in spots to start the first day of August. However, the trend will be turning decidedly drier/brighter Friday due to increasing large scale subsidence and arrival of a much drier/less humid airmass via northerly llvl flow. We blended in some higher percentile NBM for winds/gusts given the fcst pressure gradient between the exiting low offshore and sprawling high expected to migrate into PA this weekend. Max temps drop 5-10 degrees below climo into the 70s which will feel quite comfortable after several days of hot and humid weather. Clear and cool tomorrow night with low temps also below the historical average for early August into the 50-60F range in most locations; usual cold spots in the NW Alleghenies could print a minT 40-45F range using fcst dewpoints as a floor. While the air will be rather dry, there could be some radiational fog in the river and stream valleys across the northern and western portions of the forecast area. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Slightly below average daytime highs 70-80F and lows 50-60F are forecast along with no rainfall through the first weekend of August. The dry spell and pleasant conditions/low humidity should last through early next week with temperatures trending warmer/back to seasonal averages for early August. Medium range models and ensemble data show broad upper level troughing carving out and shifting eastward across the Appalachians which should translate into increasing rain chances by next Wed-Thu. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... Building clouds can be observed across the region via latest satellite imagery. VFR conditions should be prevailing for most of the remaining overnight hours, but there remains a 30% chance for some fog development before sunrise. Confidence remains low in sites experiencing visibility restrictions prior to 12Z. Increasing cloud cover will be the precursor for a frontal system stalling out over southern PA today. Numerous rain showers are expected to move over the airspace beginning as early as 14Z across the northwest near BFD. Once rain begins expect visibility restrictions and low clouds over most of central PA throughout the day. Given that latest CAM guidance is showing wide spread showers, there are long periods of rain mentioned with this TAF package with PROB30 groups extending the possibility of showers well past 00Z Friday. Expect conditions to improve from north to southeast Friday morning, as high pressure starts to build in with drier air. Ceiling and visibility restrictions will likely persist until after sunrise on Friday. Outlook... Fri...AM SHRA linger over SE PA, with restrictions possible; trending drier with VFR conditions for the afternoon. Sat-Mon...Dry with VFR conditions. && .CLIMATE... BFD tied the record high temperature of 88 yesterday 7/30. #Top10 warmest June+July #Top10 warmest July From June 1st through July 30th: Harrisburg: 76.8F average temperature ranks 7th warmest Williamsport: 74.1F average temperatures ranks 7th warmest Altoona: 73.1F average temperature ranks 3rd warmest Bradford: 67.8F average temperature ranks 2nd warmest State College: 73.1F average temperature ranks tied 4th warmest From July 1st through July 30th: Harrisburg: 79.9F average temperature ranks tied 7th warmest Williamsport: 77.0F average temperature ranks tied 8th warmest Altoona: 74.8F average temperature ranks 7th warmest Bradford: 69.8F average temperature ranks 3rd warmest State College: 75.8F average temperature ranks tied 6th warmest && .CTP WATCHES/WARNINGS/ADVISORIES... Flood Watch from 2 PM EDT this afternoon through late tonight for PAZ028-036-037-041-042-046-049>053-056>059-063>066. && SYNOPSIS...Steinbugl NEAR TERM...Steinbugl SHORT TERM...Steinbugl LONG TERM...Steinbugl/Bauco AVIATION...Bowen CLIMATE...Steinbugl/NPB
Hazardous Weather Outlook National Weather Service State College PA 517 AM EDT Thu Jul 31 2025 PAZ037-041-042-046-049>053-058-010930- Tioga-Northern Lycoming-Sullivan-Southern Lycoming-Union-Snyder- Montour-Northumberland-Columbia-Schuylkill- 517 AM EDT Thu Jul 31 2025 ...FLOOD WATCH IN EFFECT FROM 2 PM EDT THIS AFTERNOON THROUGH LATE TONIGHT... 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. Flood Watch. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ004>006-010>012-017>019-045-010930- Warren-McKean-Potter-Elk-Cameron-Northern Clinton-Clearfield- Northern Centre-Southern Centre-Southern Clinton- 517 AM EDT Thu Jul 31 2025 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...Today and tonight. Thunderstorms with very heavy rain are possible this afternoon and evening. The heavy rain may lead to isolated instances of flash flooding. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ024>027-033>035-010930- Cambria-Blair-Huntingdon-Mifflin-Somerset-Bedford-Fulton- 517 AM EDT Thu Jul 31 2025 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...Today and tonight. Thunderstorms with very heavy rain are possible this afternoon and evening. The heavy rain may lead to scattered instances of flash flooding. A few strong thunderstorms capable of wind gusts in excess of 50 mph are possible this afternoon and evening. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ028-010930- Juniata- 517 AM EDT Thu Jul 31 2025 ...FLOOD WATCH IN EFFECT FROM 2 PM EDT THIS AFTERNOON THROUGH LATE TONIGHT... 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. Flood Watch. A few strong thunderstorms capable of wind gusts in excess of 50 mph are possible this afternoon and evening. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ036-056-057-059-063>066-010930- Franklin-Perry-Dauphin-Lebanon-Cumberland-Adams-York-Lancaster- 517 AM EDT Thu Jul 31 2025 ...FLOOD WATCH IN EFFECT FROM 2 PM EDT THIS AFTERNOON THROUGH LATE TONIGHT... 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. Flood Watch. A few strong thunderstorms capable of locally damaging wind gusts in excess of 60 mph are possible this afternoon and evening. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. MRS
The Sterling radar (KLWX), 150 km away, was scanning. The volume nearest the first event began at 15:29 UTC.
5 flash flood, 1 thunderstorm wind. Local standard time, as filed.
Muddy water was observed running down Siegrist Road and through yards towards Chiques Creek in West Hempfield Township.
A severe thunderstorm, producing wind gusts estimated near 60 mph, knocked down multiple trees and wires onto roadways in the vicinity of Franklin and Marshall College in Lancaster.
High water flowing near Keller and Marshall avenues in Lancaster resulted in a water rescue.
Flash flooding pushed the Little Conestoga Creek out of its banks, with numerous road closures. 3.1 inches of rain was reported.
Flash flooding led to a water rescue near Wakefield.
PA Route 741 was closed between Noll Drive and Embassy Drive near Rohrerstown due to flash flooding.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2025Every state in 2025This day in weather historyWarnings in Pennsylvania, July 2025
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: 1278791, 1276591, 1278796, 1278799, 1278800, 1279189.