Following the passage of a warm front during the morning of the 27th, an unstable airmass was in place across Northeast Pennsylvania. This frontal boundary then dropped back south and east as a cold front, sparking severe thunderstorms during the afternoon and early evening.
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 BGM wrote it up.
Following the passage of a warm front during the morning of the 27th, an unstable airmass was in place across Northeast Pennsylvania. This frontal boundary then dropped back south and east as a cold front, sparking severe thunderstorms during the afternoon and early evening.
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 Binghamton, NY wrote its last area forecast discussion before the first event at Aug 27, 3:14 PM EST, 1 minute earlier.
Area Forecast Discussion National Weather Service Binghamton NY 414 PM EDT Thu Aug 27 2020 .SYNOPSIS... Numerous strong to severe thunderstorms will continue into this evening as a cold front drops through the region. Additional rounds of showers and thunderstorms are expected Friday into Saturday which may bring heavy rain to parts of the region. Quiet weather returns for Sunday and Monday as high pressure moves in. && .NEAR TERM /THROUGH FRIDAY NIGHT/... 400 PM Update Severe thunderstorm watch also in effect until 8 PM for the Finger Lakes region, Central Southern Tier, Bradford, Wyoming, Lackawanna and Luzerne counties in NE PA. The only counties not under a watch (tornado or severe) at this time area Onondaga, Madison and Oneida. One cluster of storms is moving from Broome/Chenango counties quickly off to the southeast into the southern Catskills. Another complex of supercells is moving into the Finger Lakes at this time, and is looking quite impressive. We will be watching for a third round which is currently crossing Lake Erie which may move across the Twin Tiers and NE PA this evening. The most uncertainty for severe weather in the watch area is in NE PA; we'll have to wait and see if additional convection develops and impacts this area in the evening. The surface front continues to wiggle and wave, but is now making slow/steady progress southward...located across central Cayuga County, Southern Onondaga, Madison and Otsego counties. There is an extremely wide range of temperatures across our CWA at the 4 PM hours; anywhere from the lower 60s in the far northeast to mid-90s in the Wyoming Valley region. The weather turns quiet overnight with areas of fog overnight into Friday morning. There will be a renewed chance for showers and Thunderstorms Friday afternoon, especially across the western and southern half of the CWA. SPC does have a marginal risk for severe thunderstorms south of an Elmira to Scranton line. The main threat will be isolated gusty winds and perhaps some hail. PWATS rise through the day, reaching 1.75 inches so localized heavy rain will also be possible. Periods of rain continue Friday night across the region and again, could be heavy at times with PWATs remaining high, up to 1.9 inches. 150 PM Update... Tornado watch has been issued for the eastern half of the area until 7PM this evening. Supercells have developed south of the NY Thruway and are racing off to the southeast into the western Catskills and Twin Tiers region. We will be watching for addition storms to develop across the western Finger Lakes along the actual frontal boundary dropping south. Most favorable parameters for low level rotation and possible tornadoes is confined to the Tornado watch area...in this region we currently have 20-30 kts of 0-1 km shear, 0-1 SRH of 150-300 M2S2 and LCL heights between 500-750M...producing a sig TOR parameter of 1-2...which is rather significant for our region. If additional supercells develop across NW NY we very well may need a severe thunderstorm watch for parts of the forecast areas as well. Otherwise, temperatures are surging into the mid-80s to low 90s in the warm sector with dew points still in the upper 60s to low 70s. 1100 AM Update... The surface warm front is lagging a bit to the south/west of where model guidance had it by late morning. The surface front appears to be draped NW to SE along a line from near Syracuse to Cazenovia and Cooperstown (as opposed to earlier thoughts that it would be up north of the Mohawk Valley. Also, there is more cloud cover lingering along and northeast of this boundary....but even broken clouds back to the south/west of the front. There is a decent amount of clearing from Broome County west across the southern tier, the western Finger Lakes and all of NE PA. Where partial clearing has occurred temperatures are quickly rising, as expected, into the upper 70s to mid-80s as of 11 AM and sfc dew points are in the low 70s. Across the NE portion of the CWA temperatures are stuck in the 60s still. The front and partial clearing may still nudge off to the NE a few more miles over the next several hours; however a line of storms along the cold frontal boundary is already forming along the south shore of Lake Ontario. This line of storms will slowly press off to the south-southeast through the day, while individual storms race off to the southeast around 50 mph. There could very well be training of these storms, which may produce localized torrential downpours and isolated flash flooding...PWATs are around 1.8 inches. The main story continues to the potential for severe thunderstorms from around noon to 9 PM today. SPC continues to have much of our forecast areas under an enhanced risk for severe storms. Current meso analysis shows that in the warm sector bulk effective shear is between 50-60 kts and low level 0-1 km shear is high around 30 kts. MLCAPE is quickly rising between 500-1500 J/Kg along and SW of the front...and these values should still rise a bit into the early afternoon. All indices remain favorable for severe storms capable of producing large hail and destructive winds, along with a few tornadoes. The most favorable corridor for this severe weather looks to setup (based on current data) from the western Finger Lakes southeastward across CNY, the southern tier and right into the western Catskills....or along a corridor from near Penn Yan to Ithaca to Cortland, Binghamton, Norwich, Oneonta and Delhi. The storms may eventually drift further south into the souther Catskills and NE PA after about 4-5 PM. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... 1200 PM Update... Not much change in the forecast from last night. Updated some of the timing for the precipitation on Saturday. Previous Discussion... Not much change this period. Friday plenty of clouds ahead of a warm front bringing the start of rain during the afternoon into the evening. Highs mostly upper 70s to lower 80s Friday. Still looking at a heavy rain event Friday night into Saturday. Remnants of Laura will move northeast into the lower Ohio Valley Friday night then track east. This system will be captured by a cold front associated with a surface low dropping southeast through the Great Lakes ahead of an upper level trough. Deep tropical moisture will be over the area with precipitable water amounts of 1.5 to 2 inches. Rain amounts range from around an inch to nearly 2 inches in Oneida county. Rivers are low being the end of summer so rain amounts would have to be higher to cause any flooding that way. Flash flooding possible mostly Saturday afternoon with any heavy rain. by that time the ground will be saturated. A cold front will be moving southeast through the area possible with some embedded thunderstorms. the rain exits Saturday evening with a few lingering late night showers in the Finger Lakes and western Mohawk Valley with the upper level trough. A cold northwest flow starts Saturday night with lows in the 50s. The severe weather threat looks reduced with the saturated airmass and low instability. CAPE peaks at 500 and deep wind shear is 35 to 40 kts. Clearing won't happen between the warm front and cold front to increase surface temperatures and instability. High temperatures 75 to 80 with dewpoints around 70. SPC put the far far southeast in a marginal chance of severe thunderstorms Saturday. This is further to the southeast than their outlook from yesterday which makes sense. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... 330 am update... No major changes to the long term period were made with this forecast update. The latest data supports the current forecast ideas. Sunday drier air moves in but a few showers are still possible in CNY under the upper level trough. Highs mostly only around 70. With less moisture Sunday night lows fall to 50. On Monday the surface high is centered over the area as the upper level pattern becomes zonal. A warming trend into Thursday with highs around 80 and lows around 60. A slow moving system with showers and thunderstorms starts to move in late Tuesday and exits Wednesday but another system with more showers possible Thursday. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... Very busy TAF period. Thunderstorms have mainly moved south of KSYR and KRME at this time, but still cannot rule out a stray storm through about 20-21z...however not enough probability to put in the TAF at this time. Thunderstorms are likely to impact KITH, KELM, and KBGM through 22-23z this evening and will likely bring brief IFR conditions along with possible very strong winds and even hail at any terminal that receives a direct hit from a storm core. Thunderstorms may eventually reach KAVP later, mainly from 22-02Z this evening with similar impacts. Post-frontal restrictions from low clouds or fog are anticipated to develop tonight with abundant low level moisture in the wake of the rainfall. This will bring widespread MVFR Fuel Alternate and even a period of IFR restrictions late tonight and into early Friday morning for the NY terminals. TAF sites should all return to VFR conditions after about 15-17z Friday. Winds will be WSW to W 10-20 knots with some higher gusts during the daytime except remaining variable at KRME; however, storms impacting any terminal could cause considerably stronger winds. Winds will then become variable tonight. Outlook... Friday afternoon through Saturday night...Rain developing and occasional thunderstorms expected, especially Friday night into Saturday, with associated restrictions. Sunday through Monday...Mainly VFR, but valley fog likely Sunday night for at least KELM and possibly other terminals. Tuesday...Restrictions possible with a chance for showers and a few thunderstorms. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...None. && SYNOPSIS...MDP NEAR TERM...MJM/MDP SHORT TERM...AJG/TAC LONG TERM...TAC AVIATION...MJM/MDP
Hazardous Weather Outlook National Weather Service Binghamton NY 254 PM EDT Thu Aug 27 2020 NYZ015>017-022>024-PAZ038-043-044-047-281900- Yates-Seneca-Southern Cayuga-Steuben-Schuyler-Chemung-Bradford- Wyoming-Lackawanna-Luzerne- 254 PM EDT Thu Aug 27 2020 ...SEVERE THUNDERSTORM WATCH 456 IN EFFECT UNTIL 8 PM EDT THIS EVENING... This Hazardous Weather Outlook is for central New York and northeast Pennsylvania. .DAY ONE...This afternoon and 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. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. A system late Friday through especially Saturday, will bring another round of rain and occasional thunderstorms. Heavy rainfall will be possible, which could lead to localized flooding. Monitor the forecast for updates. .SPOTTER INFORMATION STATEMENT... Spotter activation will likely be needed. Please relay any information about severe weather to the NWS while following local, state and CDC guidelines. NYZ025-044>046-055>057-062-PAZ039-040-048-072-281900- Tompkins-Cortland-Chenango-Otsego-Tioga-Broome-Delaware-Sullivan- Susquehanna-Northern Wayne-Pike-Southern Wayne- 254 PM EDT Thu Aug 27 2020 ...TORNADO WATCH 455 IN EFFECT UNTIL 7 PM EDT THIS EVENING... This Hazardous Weather Outlook is for central New York and northeast Pennsylvania. .DAY ONE...This afternoon and tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Tornado Watch. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. A system late Friday through especially Saturday, will bring another round of rain and occasional thunderstorms. Heavy rainfall will be possible, which could lead to localized flooding. Monitor the forecast for updates. .SPOTTER INFORMATION STATEMENT... Spotter activation will likely be needed. Please relay any information about severe weather to the NWS while following local, state and CDC guidelines. NYZ009-018-036-037-281900- Northern Oneida-Onondaga-Madison-Southern Oneida- 254 PM EDT Thu Aug 27 2020 This Hazardous Weather Outlook is for central New York. .DAY ONE...This afternoon and tonight. There is a low probability for widespread hazardous weather. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. A system late Friday through especially Saturday, will bring another round of rain and occasional thunderstorms. Heavy rainfall will be possible, which could lead to localized flooding. Monitor the forecast for updates. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to Standard Operating Procedures. Please relay any information about severe weather to the NWS while following local, state and CDC guidelines.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BINGHAMTON NY
241 PM EDT THU AUG 27 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0230 PM TSTM WND DMG BRISBEN 42.37N 75.68W
08/27/2020 CHENANGO NY 911 CALL CENTER
TREES AND WIRES DOWN ON WILLIAMS ROAD.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BINGHAMTON NY
254 PM EDT THU AUG 27 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0150 PM TSTM WND DMG 4 SE TRUXTON 42.68N 75.98W
08/27/2020 CORTLAND NY 911 CALL CENTER
TREE DOWN ON HICKEY AND BROWN ROADS NEAR
CAMPGROUND.
&&Special Weather Statement
National Weather Service Binghamton NY
327 PM EDT Thu Aug 27 2020
NYZ023-025-055-272000-
Schuyler NY-Tioga NY-Tompkins NY-
327 PM EDT Thu Aug 27 2020
...A STRONG THUNDERSTORM WILL AFFECT EAST CENTRAL SCHUYLER...CENTRAL
TIOGA...AND SOUTHERN TOMPKINS COUNTIES UNTIL 400 PM EDT...
At 326 PM EDT, Doppler radar was tracking a strong thunderstorm near
Alpine, or near Odessa, moving southeast at 45 mph.
Half inch hail and winds in excess of 40 mph will be possible with
this storm.
Locations impacted include...
Newfield, Owego, Danby, Berkshire, Newark Valley, Candor, Spencer,
South Danby, Willseyville and West Danby.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
Additional statements will be issued as conditions warrant.
&&
A Severe Thunderstorm Watch remains in effect until 800 PM EDT for
central New York.
LAT...LON 4235 7677 4241 7671 4229 7610 4227 7608
4226 7610 4224 7609 4208 7619 4224 7654
4228 7654 4228 7663
TIME...MOT...LOC 1926Z 295DEG 40KT 4235 7667
ButtsPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BINGHAMTON NY
330 PM EDT THU AUG 27 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0320 PM TSTM WND DMG SENECA FALLS 42.91N 76.80W
08/27/2020 SENECA NY 911 CALL CENTER
TREES AND WIRES DOWN ON LAKE ROAD.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BINGHAMTON NY
343 PM EDT THU AUG 27 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0319 PM TSTM WND DMG SENECA FALLS 42.91N 76.80W
08/27/2020 SENECA NY 911 CALL CENTER
TREES AND WIRES DOWN ON BOSTON AVE.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BINGHAMTON NY
411 PM EDT THU AUG 27 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0227 PM TSTM WND DMG MASONVILLE 42.25N 75.37W
08/27/2020 DELAWARE NY TRAINED SPOTTER
LARGE BRANCHES DOWN ALONG WITH 0.99 INCHES
OF RAIN FROM THE STORM.
&&The Binghamton radar (KBGM), 53 km away, was scanning. The volume nearest the first event began at 20:15 UTC.
6 thunderstorm wind. Local standard time, as filed.
Strong thunderstorm winds uprooted and snapped hundreds of trees in a 100 by 500 yard area.
Strong thunderstorm winds brought down numerous trees.
Strong thunderstorm winds brought down a tree on Silver Creek Road.
Strong thunderstorm winds brought down a tree on a road.
Strong thunderstorm winds brought down a tree on wires.
Strong thunderstorm winds brought down multiple trees and wires.
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: 916710, 916714, 916721, 916726, 916718, 916723.