A potent warm front with some elevated convection produced isolated to scattered thunderstorms across northern NY during the early morning hours of September 15th. One such storm in Brushton briefly produced a wind gust that knocked a tree onto some power lines.
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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 BTV wrote it up.
A potent warm front with some elevated convection produced isolated to scattered thunderstorms across northern NY during the early morning hours of September 15th. One such storm in Brushton briefly produced a wind gust that knocked a tree onto some power lines.
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 Burlington, VT wrote its last area forecast discussion before the first event at Sep 15, 12:47 AM EST, 1 hour 46 minutes earlier.
Area Forecast Discussion National Weather Service Burlington VT 147 AM EDT Wed Sep 15 2021 .SYNOPSIS... A warm front is advancing northeastward through the region drawing much warmer and more humid air into the North Country. A strong cold front will then move through the region Wednesday, resulting in widespread showers and thunderstorms. Strong to severe thunderstorms are expected Wednesday afternoon over southern and eastern portions of Vermont. After a brief cool down behind the front, above normal temperatures and mainly quiet conditions will prevail for the next several days. && .NEAR TERM /THROUGH THURSDAY/... As of 109 AM EDT Wednesday...Overall forecast in good shape with only tweak being to sharpen up the precipitation gradient across the area. Best convective threat the next few hours will be across parts of northern New York while Vermont remains capped. Previous Discussion... A strong 997 millibar mid-latitude cyclone is moving eastward of Lake Superior and will be the main player for our weather through the next 24 hours. It will lift northeastward dragging a cold front across the North Country tomorrow. Tonight, a warm front associated with this system is lifting northeastward marked by a southeast-northwest corridor of mid-level clouds marching through the region. On the south side of the boundary, dew points are in the mid and upper 60s in most locations. The southerly flow will be strengthened overnight as a low-level jet develops, which will help make it an unseasonably mild night. A few showers and thunderstorms will be possible this evening, especially in southern portions of our northern New York counties where there will be some instability developing prior to sunset, but coverage of storms will be low given the convective inhibition expected. Many factors are favorable for severe thunderstorms tomorrow, including a strong surface boundary marked by a large gradient in temperature and moisture moving through Vermont during peak heating. Given the expected position of the cold front tomorrow and resulting lack of instability farther north and west, the area of interest is southeast of a line from about Newport, VT to Schroon Lake, NY. with greater heating/less cloud cover farther south and east to support better chances of stronger storms. During the midday hours, mid and upper 60 dew points will be present with substantial southwesterly speed shear of 40 knots. Several hours of surface heating will help boost instability as cooler air aloft further increases CAPE to 1000 to 2500 J/kg. Higher values will likely be in southern Rutland County and the lower Connecticut River Valley; this area is where we expect the greatest threat for damaging wind gusts. Furthermore, enough 0-1 km shear may be present for some rotating storms. Given lack of CIN, discrete storms should quickly form into a line, which again leads to emphasis on the strong thunderstorm wind potential. In addition to the severe weather threat, of note is potential for localized flash flooding. Current flash flood guidance ranges from about 2.5" to 3" over 6 hours, 1.75" to 2.5" over 3 hours, and 1.3 to 2" over 1 hour, in most of the southeastern half of Vermont. High probabilities (> 70%) of greater than inch of rainfall, but under 10% for three inches, associated with the thunderstorm activity in this area. Probability-matched mean values continue to show greatest rainfall across the southern Green Mountains where over 2 inches of rain is indicated. && .SHORT TERM /THURSDAY NIGHT/... As of 331 PM EDT Tuesday...We dry out quickly behind Wednesday's system with a 1025mb surface high wasting no time in moving overhead on Thursday. It will have just rained, but the boundary layer air is quite dry. So perhaps there's some lingering fog, but it should be mostly clear. Anticipate some fair weather cumulus to develop, but even then, atmospheric moisture content will not allow for much. Temperatures will be near normal in the low to mid 70s. This surface high doesn't seem content to stay in one place for long, as it will exit east Thursday evening, and southerly flow will resume overnight. This will result in a warm night in the mid 50s to lower 60s, with some of the cold hollows near 50. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 331 PM EDT Tuesday...Shallow moisture lingers a bit Friday, but suspect that with diurnal destabilization, drizzle should decrease. A strong warm nose around 650 hPa should keep us capped. 925 hPa temps will be around 19C, which should mean about temperatures climb close to 80 in the broader valleys. Friday night should remain warm under south to southwest flow with lows in the mid 50s to lower 60s. Saturday should be a repeat, maybe a degree or two warmer. A frontal boundary will shift south Saturday night, but looks to cross with little fanfare. A late season upper high will develop across the Ohio River Valley and slowly shift east towards the Mid-Atlantic coast. This should result in a stretch of highly pleasant weather conditions with above normal temperatures and dry conditions. Some moisture will be rounding the periphery of the ridge midweek, and we'll see if that brings us rain, and will only advertise some slight chances for rain showers along the international border at this time. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... Through 06Z Thursday...VFR across the airspace for most TAF sites overnight ahead of an approaching cold front. Main aviation concern tonight will be LLWS associated with a strong 40-45 kt LLJ. The core of this jet will be over the region through 4 AM before exiting eastward into NH. The threat for LLWS will exist through 12z after which it should subside. South winds 10-15 kt with gusts up to 25 kt possible at KBTV & KMSS overnight. As this front approaches from the west, rain with embedded thunder will be possible from through 12z for KSLK & KMSS. This area of rain will shift eastward in the morning with rain likely at KPBG and northern VT terminals after 12z. MVFR visibilities/ceilings are expected with this line of showers. Further south, at KRUT, this line will move through towards 18z with thunderstorms likely...have included mention of VCTS from 18-22z to convey this threat. Behind this front, winds turn out of the W/NW. Outlook... Thursday: VFR. NO SIG WX. Thursday Night: Mainly VFR, with local MVFR possible. NO SIG WX. Friday: Mainly VFR, with local MVFR possible. NO SIG WX. Friday Night: Mainly VFR, with local IFR possible. Slight chance SHRA. Saturday: Mainly VFR, with local MVFR possible. Chance SHRA. Saturday Night: Mainly VFR, with areas MVFR possible. Slight chance SHRA. Sunday: VFR. NO SIG WX. && .MARINE... A lake wind advisory is in effect for south winds 15 to 25 knots with gusts up to 30 knots at times for the northern waters, including Colchester Reef and Burton Island. The timing of the strongest winds will occur through 4 AM, then gradually subsiding towards 8 AM. Waves building to 2 to 4 feet are possible through early morning. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && SYNOPSIS...Kutikoff NEAR TERM...Evenson/Kutikoff SHORT TERM...Haynes LONG TERM...Haynes AVIATION...LaRocca MARINE...LaRocca
Hazardous Weather Outlook National Weather Service Burlington VT 329 PM EDT Tue Sep 14 2021 NYZ026>031-034-035-087-VTZ001>012-016>019-151930- Northern St. Lawrence-Northern Franklin-Eastern Clinton- Southeastern St. Lawrence-Southern Franklin-Western Clinton- Western Essex-Eastern Essex-Southwestern St. Lawrence-Grand Isle- Western Franklin-Orleans-Essex-Western Chittenden-Lamoille-Caledonia- Washington-Western Addison-Orange-Western Rutland-Windsor- Eastern Franklin-Eastern Chittenden-Eastern Addison-Eastern Rutland- 329 PM EDT Tue Sep 14 2021 This Hazardous Weather Outlook is for northern New York, central Vermont, northeast Vermont, northwest Vermont and southern Vermont. .DAY ONE...This afternoon and tonight. Hazardous weather is not expected at this time. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. There is a high likelihood for some thunderstorms to be strong to severe across the southern and eastern half of Vermont Wednesday afternoon and evening. These storms will produce gusty winds and heavy rain which will cause localized downed trees and flooded roadways. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The Burlington radar (KCXX), 112 km away, was scanning. The volume nearest the first event began at 07:32 UTC.
1 thunderstorm wind. Local standard time, as filed.
Tree on wires on Delancy Avenue.
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, 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: 973546.