A nearly-stationary front was draped in vicinity of the major axis of Lake Erie during the early evening of September 12th through the wee hours of the 13th as one low drifted northeastward over western Kansas and another remained nearly-stationary in vicinity of Labrador. A bow echo moved east-southeastward across central and eastern Lake Erie, and moved onshore in northwest Pennsylvania and…
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The episode as NWS CLE wrote it up.
A nearly-stationary front was draped in vicinity of the major axis of Lake Erie during the early evening of September 12th through the wee hours of the 13th as one low drifted northeastward over western Kansas and another remained nearly-stationary in vicinity of Labrador. A bow echo moved east-southeastward across central and eastern Lake Erie, and moved onshore in northwest Pennsylvania and western New York during the evening of the 12th. One instance of straight-line wind damage accompanied the bow echo as it traversed Erie County, PA. The bow echo encountered weak to moderate MUCAPE and DCAPE, respectively, and moderate to strong effective bulk shear.
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 Cleveland, OH wrote its last area forecast discussion before the first event at Sep 12, 9:40 PM EST, 1 hour earlier.
Area Forecast Discussion National Weather Service Cleveland OH 1040 PM EDT Sun Sep 12 2021 .SYNOPSIS... A frontal boundary will stall this evening near the southern shores of Lake Erie. This front will lift north as a warm front Monday into Tuesday ahead of another cold front expected to move east across the area on Wednesday. High pressure will build across the area behind the front. && .NEAR TERM /THROUGH MONDAY NIGHT/... Strong to severe thunderstorms over Ontario, Canada continue to move east-southeast. Bulk of activity should move into western New York but southern flank will clip Erie County in Pennsylvania. A quick severe thunderstorm watch has been issued for Erie County to account for this activity. Expecting strong damaging winds with this line; especially over the northeast corner of the county. Otherwise, rest of the forecast across the area remains unchanged. Previous Discussion... A slow moving cold was located just north of Lake Erie and drifting southward tonight. This frontal boundary is expected to stall out near the southern lakeshore of Lake Erie by late tonight or early Monday morning. Scattered showers and thunderstorms are expected to develop near this frontal boundary but will remain north of our local area as this active weather will be moving from west to east tonight. We can't rule out an isolated pop up shower this evening but warm air aloft or the "cap" will keep most the area dry and quiet tonight. The only area that may get clipped with some showers and storms late tonight will be are extremely northeast area around Erie PA. We will remain on the warm side of the front Monday with more very warm temperatures and higher humidity. Afternoon highs will climb back into the middle and upper 80s. The stalled front over Lake Erie will lift back north as a warm front Monday into Monday night. While we can't rule out a spotty shower pop near the lakeshore, most the area will remain dry and quiet weather on Monday and Monday night. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Much of the day on Tuesday should be fairly quiet with mid-level dry air in place ahead of an eastward-advancing cold front. It will be a little gusty across the area by Tuesday afternoon, with winds in the 25 to 30 mph range in some spots. The highest wind gusts are expected across NW OH. Temperatures will be above average with highs in the mid to upper 80s. By Tuesday night into Wednesday, the cold front will reach the north and northwest portions of the area, resulting in widespread showers and thunderstorms. As the upper trough continues to eject northeast across Quebec, the trailing cold front draped across the area will begin to slow, and eventually become nearly stationary. Expecting another round of showers and thunderstorms in the afternoon and evening hours, primarily across the central and eastern half of the area. Will still have to monitor instability trends for any severe weather threat, given the moderate deep layer shear profiles in place. At this point, the best chance for any decent destabilization would be across the far southeast portion of the area. We don't have a WPC ERO at this time, given Wednesday is day 4. However, anticipate we could at least be under a marginal risk by tonight's update, given favorable heavy rain profiles and cloud layer flow that is nearly parallel to the stalling front. Forecast QPF across the area on Wednesday is around an inch, with locally higher amounts possible. Temperatures will be a little cooler on Wednesday, in the upper 70s. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Uncertainty grows in the long term period with no agreement in any discernible upper air patterns and thus a lack of forcing for any shower and/or thunderstorms chances. We should maintain the warm and moist airmass through at least Friday as the aforementioned stalled cold front, lifts north as a warm front on Thursday. Will mainly keep isolated mention in the afternoon/evening on Thurs/Fri at this time. A weak cold front may move across the area on Saturday, with some model guidance hinting at cooler and more pleasant weather by the end of the weekend. && .AVIATION /00Z Monday THROUGH Friday/... Main issue this forecast period is the two clusters of thunderstorms over southern Ontario, Canada and second one back over over Michigan. Expecting first cluster to move near Erie around 03Z this evening and may slip past the terminal. Uncertain as to whether terminal will be affected but added a tempo group for the time being. Second round has a shot at hitting Erie around 08Z and will add a mention of thunder then as well. Otherwise, looking at VFR across the rest of the area overnight into tomorrow. Winds will gradually diminish through tomorrow and become light. Outlook...Non-VFR possible with showers/thunderstorms through Tuesday. Non-VFR likely Wednesday in showers and thunderstorms associated with a cold front. && .MARINE... A mostly quiet marine period is forecast through Thursday with no marine headlines anticipated. Southwest winds today, 10 to 15 knots, will shift more northerly tonight, then become northeastly by Monday as a cold front stalls just south of the lake. Winds will become southwesterly once again on Tuesday as the front lifts northeast as a warm front, 10 to 15 knots, becoming 15 to 20 knots by Tuesday night. Another cold front will stall south of the lake on Wednesday, with northerly flow of 5 to 10 knots expected. Light flow is then expected to continue into Thursday. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && SYNOPSIS...Griffin NEAR TERM...Griffin/Lombardy SHORT TERM...Kahn LONG TERM...Kahn AVIATION...Lombardy MARINE...Kahn
Hazardous Weather Outlook National Weather Service Cleveland OH 1044 PM EDT Sun Sep 12 2021 LEZ142>148-162>168-OHZ003-006>014-017>023-027>033-036>038-047-089- 140245- Maumee Bay to Reno Beach OH-Reno Beach to The Islands OH- The Islands to Vermilion OH-Vermilion to Avon Point OH- Avon Point to Willowick OH-Willowick to Geneva-on-the Lake OH-Geneva- on-the-Lake to Conneaut OH- Detroit River Lt. to Maumee Bay OH to Reno Beach OH beyond 5NM offshoreline to US-Canadian border- Reno Beach to The Islands OH beyond 5NM off shoreline to US- Canadian border- The Islands to Vermilion OH beyond 5 nm off shoreline to US- Canadian border- Vermilion to Avon Point OH beyond 5 nm off shoreline to US- Canadian border- Avon Point to Willowick OH beyond 5 nm off shoreline to US- Canadian border-Willowick to Geneva-on-the- Lake OH beyond 5NM off shoreline to US-Canadian border-Geneva-on-the- Lake to Conneaut OH beyond 5 nm off shoreline to US-Canadian border- Lucas-Wood-Ottawa-Sandusky-Erie-Lorain-Cuyahoga-Lake-Geauga- Ashtabula Inland-Hancock-Seneca-Huron-Medina-Summit-Portage-Trumbull- Wyandot-Crawford-Richland-Ashland-Wayne-Stark-Mahoning-Marion-Morrow- Holmes-Knox-Ashtabula Lakeshore- 1044 PM EDT Sun Sep 12 2021 This Hazardous Weather Outlook is for Lake Erie, north central Ohio, northeast Ohio and northwest Ohio. .DAY ONE...Tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Monday through Saturday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. LEZ061-149-169-140245- Ripley to Buffalo NY extending from 5NM off shoreline to US- Canadian border-Conneaut OH to Ripley NY- Conneaut OH to Ripley NY beyond 5 nm off shoreline to US- Canadian border- 1044 PM EDT Sun Sep 12 2021 ...SEVERE THUNDERSTORM WATCH 495 IN EFFECT UNTIL 2 AM EDT MONDAY... This Hazardous Weather Outlook is for Lake Erie. .DAY ONE...Tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Severe Thunderstorm Watch. Strong to severe thunderstorm winds are expected with a line of thunderstorms expected to move through the area. .DAYS TWO THROUGH SEVEN...Monday through Saturday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. PAZ003-140245- Crawford- 1044 PM EDT Sun Sep 12 2021 This Hazardous Weather Outlook is for northwest Pennsylvania. .DAY ONE...Tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Hazardous weather is not expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed. Please relay any information about observed severe weather to the NWS while following all local, state, and CDC guidelines. PAZ001-002-140245- Northern Erie-Southern Erie- 1044 PM EDT Sun Sep 12 2021 ...SEVERE THUNDERSTORM WATCH 495 IN EFFECT UNTIL 2 AM EDT MONDAY... This Hazardous Weather Outlook is for northwest Pennsylvania. .DAY ONE...Tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Severe Thunderstorm Watch. Strong to severe thunderstorm winds are expected with a line of thunderstorms expected to move through the area. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Hazardous weather is not expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The Buffalo radar (KBUF), 121 km away, was scanning. The volume nearest the first event began at 03:36 UTC.
1 thunderstorm wind. Local standard time, as filed.
Several large tree limbs, six to eight inches in diameter, were downed in North East. The straight-line wind damage was caused by passing thunderstorms.
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, September 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: 984346.