Warm and humid air was stagnant over New York with a stationary frontal boundary positioned along the New York-Pennsylvania border. Thunderstorms developed along this boundary, and repeatedly moved over the same locations.
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The episode as NWS BGM wrote it up.
Warm and humid air was stagnant over New York with a stationary frontal boundary positioned along the New York-Pennsylvania border. Thunderstorms developed along this boundary, and repeatedly moved over the same locations. Locally heavy rainfall caused flash flooding over parts of the Southern Tier.
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, 1:02 PM EST, 38 minutes earlier.
Area Forecast Discussion National Weather Service Binghamton NY 202 PM EDT Fri Aug 27 2021 .SYNOPSIS... Isolated to scattered thunderstorms are expected this afternoon and evening with heavy rain possible. Warm and humid conditions are expected through the weekend as well as scattered showers and thunderstorms. A cold front Monday will bring additional showers and thunderstorms. && .NEAR TERM /THROUGH SATURDAY/... 1245 PM Update... With cloud cover present, temperatures are slow to warm up. Based on this, the highs were lowered a degree after an update was done to the temps based on latest obs. A couple of showers have popped up as well so have increased PoPs in those areas. 910 AM Update... Fog is finally starting to clear out, though visibility is still reduced across CNY, especially in the Southern Tier. Fog should continue to clear out over the next hour or two. No major changes with this update. Temps and winds were updated through the morning based on the latest obs. PoPs were cut back over the next few hours as it looks like the best chances will be around noon while the morning should be dry. 345 AM Update... Temperatures will be cooler today as a weak cold front drops southward across Central NY. This front will likely produce scattered thunderstorms this afternoon and into this evening generally from the Southern Tier on southward into NE PA. Wind flood is forecast to be fairly week so storms will be of the pulse variety. However, there will be plenty of instability available with CAPE values possibly over 2K J/kg for this afternoon. With PWATs edging near 2" and the weak steering flow, there is some concern for localized flash flooding this afternoon, especially if any storms travel over the same regions that were recently hit from the remnants of Fred and Henri last week. Severe storms appear unlikely, however, if a few of the pulse thunderstorms develop a robust enough updraft, then there would be a small threat for isolated intense downbursts to occur. The front will remain in our vicinity again tomorrow and there is some potential for isolated to scattered thunderstorms again. PWATs remain quite high in the forecast sounding, so potential for storms is something that will need to be watch as we head into tomorrow. Finally, there will be some potential for localized flash flooding again on Saturday && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... 350 AM Update... Late summer weather pattern continues, with warm and humid conditions through the short term period. There will be a low chance for a few showers or perhaps an isolated thunderstorm Saturday night into Sunday as a warm front lifts north, with the best chance coming Sunday afternoon. Otherwise, it will be partly cloudy and humid, with overnight lows in the 60s and daytime highs in the low to mid- 80s. Dew points rise into the lower 70s in the afternoon, giving max heat indices in the upper 80s to lower 90s in the valleys. The upper level ridge begins to break down later Sunday night, with a weak wave approaching our northwestern zones after midnight. This will again bring a chance for a few showers or thunderstorms. Outside of this activity, it should be another partly cloudy and muggy night, with patchy fog also possible. Overnight temperatures hover in the mid-60s to lower 70s. On Monday, a frontal boundary is forecast to press south and east across the CWA through the day. Out ahead of the front breaks of sunshine will allow for instability to build as daytime highs reach 80-85, with humid conditions once again. Surface dew points back up above 70 and PWATS around 1.75 inches will allow the developing showers and storms to produce locally heavy rainfall. Also, MLCAPE progged around 800-1500 J/Kg and deep layer shear up to 30 kts may allow for some stronger thunderstorms to develop. Will continue to closely monitor parameters in future updates to see if there will be any severe thunderstorm potential. With good model agreement on the general timing of the front and available moisture/instability, went slightly above the blended guidance (NBM) to stick closer to the previous forecast...which gives high end likely to low end categorical PoPs across the entire region. The front slips south, and likely through NE PA later Monday night. Behind the boundary things should dry and slowly clear out; although valley fog will be a good bet as weak high pressure and light winds nose into the area from the north. Still mild and a bit humid, with lows 60-65 forecast. && .LONG TERM /TUESDAY THROUGH THURSDAY/... 350 AM Update.. Some uncertainty, and therefore lower confidence in the forecast to start off the long term period. Although things seem to be trending drier for Tuesday now, based on the latest models. Model guidance differs in how far north and how fast any moisture arrives from the remnants of Ida and an upper level trough interaction. The operational GFS continues to be the fastest and furthest north/west solution, and would bring increasing chances for rain to much of the forecast area starting late Tuesday and continuing through the day Wednesday. Meanwhile, the latest 00z ECMWF operational guidance brings a pocket of dry, Canadian air to our CWA Tuesday and Tuesday night, with just some increasing mid level clouds from the south on Wednesday. The CMC operational is in-between these two solutions. The 00z GEFS members appear to be shifting south with the moisture and rain, especially when compared to the operational run. The overall theme is, there remains a lot of uncertainty in regards to where Ida and its remnants track after about Tuesday. For now the official forecast sticks very close to the latest NBM guidance, which in corporates the best performing operational and ensemble guidance. This gives a slight chance to low end chance for some shower late Tuesday into Wednesday; especially across the Southern Tier and NE PA. Currently, the blended guidance (NBM) and therefore our official forecast dry things out across the whole area Thursday into next Friday, with cooler, less humid and generally seasonable weather expected...under mostly sunny skies. Again, will still need to monitor the remnants of Ida into the end of the long term period, as some of the models are now moving it slowly into the Mid-Atlantic then off the Northeast coast Thursday into Friday. Overnight lows are forecast to drop back down into the 50s Wednesday and Thursday night...with daytime highs in the 70s Wednesday through Friday. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... Mainly VFR conditions are expected through this evening. The ceilings at ITH continue below MVFR but should lift later this afternoon. There is a chance for scattered showers/thunderstorms this afternoon. The best chances are near the NY/PA border and areas southward, so ELM, BGM, and AVP could observe some showers/storms and brief restrictions this afternoon. Confidence was too low to include thunder at ELM and BGM. By 00z, most of the showers/storms should dissipate. Fog will be an issue again overnight at ITH, ELM, BGM, and possibly at AVP. Confidence is low at AVP, so a TEMPO was used for now. ELM could see visibilities drop below 1SM and ceilings down to 200 ft AGL. BGM could see ceilings drop to Fuel Alt as well. While the fog should lift out by 14z Saturday, IFR to Fuel Alt ceilings will last throughout the rest of the day Saturday at all terminals except SYR and RME. Winds will be light and variable today except if showers/storms are over a terminal. Winds become slightly stronger tomorrow (less than 10 kts) and will be mainly out of the east-southeast. Outlook... Saturday through Monday...Mainly VFR with patchy fog possible and afternoon thunderstorms may cause brief restrictions at times. Tuesday through Wednesday...Mainly VFR. Slight chance for showers and thunderstorms and associated restrictions. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...None. && SYNOPSIS...BTL/MPK NEAR TERM...BTL/MPK SHORT TERM...MJM LONG TERM...MJM AVIATION...BTL
Hazardous Weather Outlook National Weather Service Binghamton NY 406 AM EDT Fri Aug 27 2021 NYZ022-024-055>057-062-PAZ038>040-043-044-047-048-072-280815- Steuben-Chemung-Tioga-Broome-Delaware-Sullivan-Bradford-Susquehanna- Northern Wayne-Wyoming-Lackawanna-Luzerne-Pike-Southern Wayne- 406 AM EDT Fri Aug 27 2021 This Hazardous Weather Outlook is for central New York and northeast Pennsylvania. .DAY ONE...Today and tonight. Hazardous weather is not expected at this time. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Scattered thunderstorms are expected Friday afternoon and evening. Localized flash flooding will be possible, especially in areas that have been impacted by recent rainfall events. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. NYZ009-015>018-023-025-036-037-044>046-280815- Northern Oneida-Yates-Seneca-Southern Cayuga-Onondaga-Schuyler- Tompkins-Madison-Southern Oneida-Cortland-Chenango-Otsego- 406 AM EDT Fri Aug 27 2021 This Hazardous Weather Outlook is for central New York. .DAY ONE...Today and tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The Binghamton radar (KBGM), 94 km away, was scanning. The volume nearest the first event began at 18:40 UTC.
3 flash flood. Local standard time, as filed.
Water was rushing over Dry Run Road.
Water was flooding County Road 22.
Water was flowing over County Road 119 near McMaster Road.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in New York in 2021Every state in 2021This day in weather historyWarnings in New York, August 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: 982324, 982325, 982328.