A few air mass thunderstorms developed over Pennsylvania on July 7. A lack of forcing and little shear limited storm coverage despite a moist and moderately unstable air mass.
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 PHI wrote it up.
A few air mass thunderstorms developed over Pennsylvania on July 7. A lack of forcing and little shear limited storm coverage despite a moist and moderately unstable air mass. In addition, the atmosphere had likely not fully recovered from an outbreak of thunderstorms the prior day. Nonetheless, isolated damaging wind occurred with a couple of stronger storms.
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 Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Jul 7, 11:51 AM EST, 1 hour 28 minutes earlier.
Area Forecast Discussion National Weather Service Mount Holly NJ 1251 PM EDT Tue Jul 7 2020 .SYNOPSIS... A summer-like pattern will persist throughout the week with scattered showers and thunderstorms expected most days along with above average temperatures. A coastal storm will impact the region Friday through Saturday as it moves north from the Carolinas. A cold front will follow the coastal storm over the weekend. && .NEAR TERM /THROUGH TONIGHT/... A few thunderstorms are making their way north and east from the Delaware Beaches to Cape May County. Otherwise, the atmosphere is behaving much better this afternoon. Increased cloud cover through the morning that continues to linger in many places looks to have inhibited morning surface heating crucial to today's convective potential. Many locations still remain a few degrees below their respective convective temperatures (mid to upper 80s). The main problem for today will be just how much the atmosphere can rebound from being so worked over yesterday. Model soundings show increasing instability as we head towards this afternoon and some of the CAMs have scattered to widespread convection developing over our forecast area. One issue is the cloud cover and how fast it gives way to sunny skies. We also lack a source of extra lift across the region as weak ridging is present aloft and no shortwaves rotate through the flow into our area today. One plus is that we have decently high CAPE values (1500-2000 J/kg) so the instability will be there. Once again, we have very weak steering flow across the region so not much help in keeping things moving should they develop. With PWATs still around 1.5-2.0", heavy, torrential rains will be possible and the greatest concern will certainly be in those areas that saw abundant rain yesterday. So while the severe threat is less the flooding threat remains pretty high. The worded forecast may be more pessimistic than it actually appears as majority of anything that does get going will likely be later in the day and may be more isolated to scattered. With plenty of moisture across the region and highs rising into the mid to upper 80s today, it will feel humid and uncomfortable. Winds will be generally out of the south to southeast through the day today and mainly around 10 to 15 mph but unfortunately might not provide much relief from the heat and humidity. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... Convection is expected to dwindle into this evening and then dissipate overnight. A few isolated showers may continue across our northern zones after midnight but for the most part we should have dry conditions across the forecast area. Conditions will remain warm and muggy as the flow remains out of the south/southeast. With continued low level moisture, we will once again see some patchy fog develop but confidence is low as to exactly where it will be since it may be largely dependent on where the rain falls. Overnight lows will be in the upper 60s to lower 70s. && .LONG TERM /THURSDAY THROUGH MONDAY/... The extended appears to be fairly active with several events to note. Wednesday starts off quiet from a sensible weather perspective as a mid level ridge sits over the region. Max temps will again start to push back into the low 90s as modest warm air advection returns. While the Mid-Atlantic is briefly quiet, our attention turns further south to the potential development of a symmetric warm core low pressure system that is expected to develop somewhere between Georgia and the Carolinas. The 12z and 18z guidance developed a weak low pressure system that takes on tropical characteristics as it moves eastward to the Atlantic. Once the system reaches the Atlantic, the Bermuda High should start to push the system towards the north up the Altantic coastline Friday into Saturday. Based on this guidance, the National Hurricane Center has upgraded the Tropical Weather Outlook to indicate a 40% chance of tropical development within the next 5 days. The 00z guidance this morning offers a slightly different solution as the low pressure system starts off symmetric warm core, but quickly undergoes extra-tropical transition becoming a cold core asymmetric system based on analysis of cyclone phase space diagrams available at moe.met.fsu.edu/cyclonephase Time will tell on how the system develops and/or how it will impact the area. However the idea that we could see a coastal low pressure system moving up the coast Thursday night into Friday appears fairly likely. This will have the potential to cause an increase in coastal tidal heights and the possibility for moderate to heavy rain depending on where the center of the low actually tracks. As the low tracks to the north, it quickly gets pushed out of the region by a deepening mid level trough dropping out of the Great Lakes. This will bring another round of widespread rainfall with scattered thunderstorms across the region. Height falls are fairly strong with the cold front and almost all of the medium ranged guidance indicates that we'll be sitting in the right rear entrance region of a 250mb jet. So there should be substantial synoptic lift available and when considering temps will again be pushing into the upper 80's to low 90s with dew points above 70F we'll likely see fairly widespread thunderstorms as EQ's are progged to be in excess of 30kFt with temps of -35C. Of course this is all based on trends in the latest suite of medium ranged guidance and subtle changes to the location of the upper level jet/mid level trough/height falls will all have significant impacts on the potential for potent thunderstorms. Coming out of the weekend the low pressure system that should track through our area on Saturday will run into a road block in the form of a broad Atlantic high pressure system. The high will force the low north and may bring an elongated low pressure system back onshore causing another round of showers and potential thunderstorms but at this rate, I dont have a significant amount of confidence in what will happen beyond the frontal passage over the weekend based on trends in guidance. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...There is another chance for showers and thunderstorms after 18Z. However, it is difficult to determine which TAF sites will be impacted at this point so have mainly included VCTS for the afternoon hours at this time. Mostly south winds around 10 knots or less outside of storms. Moderate confidence, but low confidence on the potential for and location of afternoon thunderstorms. Tonight...VFR conditions expected with possible MVFR conditions, mainly north and west of KPHL. Light southerly winds. Moderate confidence with low confidence on lower conditions. Outlook... Wednesday through Thursday...Prevailing VFR expected, however scattered showers and thunderstorms, generally between 18Z and 06Z each day, may locally lower restrictions. Winds will be generally southerly becoming southeasterly around 10 kts. Moderate confidence. Friday...MVFR/IFR ceilings probable with southeasterly to easterly winds around 10 kts. Scattered moderate to locally heavy showers with embedded thunderstorms will lower visibility and ceiling restrictions locally. Low to Moderate confidence. Saturday...Mainly VFR expected with rapidly lowering flight conditions in showers and thunderstorms. Moderate confidence. && .MARINE... Sub-advisory conditions are expected to continue on the area waters through Tuesday. South to southeast winds around 10 to 15 knots with some gusts around 20 knots. Winds will drop down to around 5 to 10 knots overnight. Seas will be around 2 to 3 feet on the ocean waters. Outlook... Wednesday through Thursday: Expect sub-sca conditions with gusts up to 15 kts and winds initially starting southerly becoming southeasterly by Thursday afternoon. Seas will be generally 2-3 feet. Afternoon and evening showers and thunderstorms are possible Tuesday through Thursday, which may locally increase winds and seas. Friday through Saturday: SCA conditions anticipated beginning Friday as seas build to 7 feet on easterly flow with gusts up to 20 kts. This continues on Saturday with seas anticipated to be 5 to 7 feet during the day with the flow becoming west to southwest behind a coastal low. Showers and thunderstorms certainly remain possible which may locally increase winds and and seas. Rip Currents... There is a low risk for the development of dangerous and life threatening rip currents through Thursday due to the combination of shorter period swells and relatively low surf heights. However heading into Friday, we anticipate the risk for dangerous rip currents to increase substantially. As seas build over the region, and we go through a prolonged period of longer period onshore swell, the risk for dangerous, life threatening rip currents will increase to at least moderate and possibly high especially for the Jersey coastline. Those with beach interests should monitor conditions closely as the development of dangerous rip currents seems quite likely based on latest trends in the forecast. && .EQUIPMENT... There is an issue with the observation equipment at Reading, KRDG. Technicians will be taking a look at the equipment on Tuesday. The NOAA Weather Radio All Hazards broadcast from Hibernia Park, PA (WNG704) remains off the air until further notice due to damage to the antenna during the June 3 derecho. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && Synopsis...Deal Near Term...Davis/Meola Short Term...Meola Long Term...Deal Aviation...Davis/Deal/Meola Marine...Deal/Meola Equipment...WFO PHI
Hazardous Weather Outlook National Weather Service Mount Holly NJ 451 AM EDT Tue Jul 7 2020 DEZ001>003-MDZ008-012-015-019-020-NJZ001-007>010-012-013-015>023-027- PAZ054-055-060>062-070-071-101>106-080900- New Castle-Kent-Inland Sussex-Cecil-Kent MD-Queen Annes-Talbot- Caroline-Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex- Western Monmouth-Mercer-Salem-Gloucester-Camden- Northwestern Burlington-Ocean-Cumberland-Atlantic-Cape May- Southeastern Burlington-Carbon-Monroe-Berks-Lehigh-Northampton- Delaware-Philadelphia-Western Chester-Eastern Chester- Western Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks- 451 AM EDT Tue Jul 7 2020 This Hazardous Weather Outlook is for central Delaware, northern Delaware, southern Delaware, northeast Maryland, central New Jersey, northern New Jersey, northwest New Jersey, southern New Jersey, east central Pennsylvania, northeast Pennsylvania and southeast Pennsylvania. .DAY ONE...Today and tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. ANZ430-431-450>455-080900- Delaware Bay waters north of East Point NJ to Slaughter Beach DE- Delaware Bay waters south of East Point NJ to Slaughter Beach DE- Coastal waters from Sandy Hook to Manasquan Inlet NJ out 20 nm- Coastal waters from Manasquan Inlet to Little Egg Inlet NJ out 20 nm- Coastal waters from Little Egg Inlet to Great Egg Inlet NJ out 20 nm- Coastal waters from Great Egg Inlet to Cape May NJ out 20 nm- Coastal waters from Cape May NJ to Cape Henlopen DE out 20 nm- Coastal waters from Cape Henlopen to Fenwick Island DE out 20 nm- 451 AM EDT Tue Jul 7 2020 This Hazardous Weather Outlook is for Atlantic coastal waters and Delaware Bay Waters. .DAY ONE...Today and tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. DEZ004-NJZ014-024>026-080900- Delaware Beaches-Eastern Monmouth-Atlantic Coastal Cape May- Coastal Atlantic-Coastal Ocean- 451 AM EDT Tue Jul 7 2020 This Hazardous Weather Outlook is for southern Delaware, central New Jersey and southern New Jersey. .DAY ONE...Today and tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. On Friday, we anticipate the risk for dangerous rip currents to increase substantially. As seas build over the region, and we go through a prolonged period of longer period onshore swell, the risk for dangerous, life threatening rip currents will increase to at least moderate and possibly high especially for the Jersey coastline. Those with beach interests should monitor conditions closely as the development of dangerous rip currents seems quite likely based on latest trends in the forecast. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
157 PM EDT TUE JUL 7 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0336 PM HAIL MORRISTOWN 40.79N 74.48W
07/06/2020 M1.00 INCH MORRIS NJ PUBLIC
CORRECTS PREVIOUS HAIL REPORT FROM
MORRISTOWN. QUARTER-SIZED HAIL AT GINTY
FIELD IN MORRISTOWN. TIME MODIFIED BASED ON
RADAR, SOCIAL MEDIA INFORMATION, AND NEARBY
HAIL REPORTS.
&&
CMSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
201 PM EDT TUE JUL 7 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0323 PM FLOOD BROWNTOWN 40.40N 74.31W
07/06/2020 MIDDLESEX NJ COUNTY OFFICIAL
CORRECTS PREVIOUS FLASH FLOOD REPORT FROM
BROWNTOWN FOR REPORT TYPE. FLOODING ALONG US
9 NORTHBOUND. OLD MILL ROAD JUGHANDLE
BLOCKED.
&&
CMSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
207 PM EDT TUE JUL 7 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0532 PM TSTM WND DMG 2 NW GERMANSVILLE 40.73N 75.73W
07/06/2020 LEHIGH PA FIRE DEPT/RESCUE
DOWNED TREES AND WIRES NEAR THE INTERSECTION
OF MOUNTAIN ROAD AND CHESTER ROAD. TIME
ESTIMATED FROM RADAR.
&&
CMSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
210 PM EDT TUE JUL 7 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0442 PM TSTM WND DMG WARWICK TWP 40.27N 75.09W
07/06/2020 BUCKS PA PUBLIC
SEVERAL TREES AND WIRES DOWN IN WARWICK TWP.
TIME ESTIMATED FROM RADAR.
&&
CMSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
212 PM EDT TUE JUL 7 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0242 PM TSTM WND DMG WARWICK TWP 40.27N 75.09W
07/06/2020 BUCKS PA PUBLIC
CORRECTS TIME OF PREVIOUS TSTM WND DMG
REPORT FROM WARWICK TWP. SEVERAL TREES AND
WIRES DOWN IN WARWICK TWP. TIME ESTIMATED
FROM RADAR.
&&
CMSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
216 PM EDT TUE JUL 7 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0711 PM TSTM WND DMG NEW MORGAN 40.19N 75.89W
07/06/2020 BERKS PA UTILITY COMPANY
DOWNED TREES AND WIRES NEAR FURNACE ROAD IN
NEW MORGAN. TIME ESTIMATED FROM RADAR.
&&
CMSThe Binghamton radar (KBGM), 122 km away, was scanning. The volume nearest the first event began at 18:19 UTC.
2 thunderstorm wind. Local standard time, as filed.
Tree limbs and wires were downed near Route 191 in Coolbaugh Twp. Time estimated from radar.
A tree was downed on Eagleville Rd near Pinetown Rd in Oaks. Time estimated from radar.
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, July 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: 905595, 905598.