A mid level closed low, more typical of the cold season, passed slowly through PA and into eastern NY. Abundant moisture in the presence of this anomalous forcing produced heavy rain and flash flooding.
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 BUF wrote it up.
A mid level closed low, more typical of the cold season, passed slowly through PA and into eastern NY. Abundant moisture in the presence of this anomalous forcing produced heavy rain and flash flooding. The main corridors of heavy rain developed along fairly subtle deformation zones and subtle low level convergence zones in Oswego, Wayne, and Ontario counties, reaching eastern Monroe County by mid-morning.
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 Buffalo, NY wrote its last area forecast discussion before the first event at Aug 14, 3:35 AM EST, 2 hours 24 minutes earlier.
Area Forecast Discussion National Weather Service Buffalo NY 435 AM EDT Tue Aug 14 2018 .SYNOPSIS... A mid-level low will move slowly from central Pennsylvania to southern New England through tonight. This system will bring scattered to numerous showers and embedded thunderstorms through today. Low chances for thunderstorms are forecast for Wednesday ahead of a surface low that will bring more widespread unsettled weather into the eastern Great Lakes late this week. && .NEAR TERM /THROUGH TONIGHT/... Mid-level closed low is centered over central PA early this morning with moist cyclonic flow pinwheeling around its center from the Mid- Atlantic north and west across New York State into the upper OH Valley. The moist airmass wrapping around this low is characterized by Pwats of 1.4 to 1.8 inches. A surface low is centered over Hudson Valley with a surface trough running from the North Country of NY southwest to Lake Erie. Radar near 4am is showing the most concentrated shower and embedded thunderstorm activity extending in a broken line from near Oswego south to Elmira. A few embedded storms north of Elmira where showing signs of training while another area of showers runs down the eastern end of Lake Erie to Erie, PA possibly hinged on land breeze moisture convergence. Weak flow aloft with mesoanalysis showing 500mb winds of 10kts or less combined with the deep moisture continues a concern for potential excessive rainfall and flash flooding. The Day 1 WPC Excessive Rainfall outlook has the Finger Lakes east across eastern NY in an Slight Risk while the majority of western NY is in a Marginal Risk. Mesoscale models have shown some potential for several inches of rain within just a few hours between the western Southern Tier and Oswego county. Here we have 24 hour basin average rainfall of 1-1.5 inches forecasted but slow moving or training thunderstorms may bring that much in just an hour. A Mesoscale Precipitation Discussion was issued by WPC highlighting the risk for heavy rainfall through 10z. Further west and north average rainfall is forecasted a quarter to three-quarters of an inch. Low temperatures this morning will mainly range from the lower to mid 60s. Widespread rainfall, locally heavy will remain in the forecast across much of western and north-central NY through the morning hours before guidance shows the parent mid-level low shifting from central NY into southern New England this afternoon into tonight. As this occurs rainfall will taper off from west to east. High temperatures today are expected to reach close to average in the mid 70s to low 80s. Clearing skies and drier air aloft tonight will bring clearing skies west to east. Light west to southwest winds and dewpoints holding in the 60s will keep temps mild tonight. Some patchy fog is possible in the Southern Tier and eastern Lake Ontario region where winds go calm. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... Wednesday will start out dry across the region, as the upper level low which has lingered across the region for the past several days, continues to slowly lessen its influence on the region, as it weakens and shifts further eastward. In its wake, sharp shortwave ridging will crest over the eastern Great Lakes region. By afternoon, a mid level shortwave will move east across Quebec, with a trailing cold front approaching the Saint Lawrence Valley by evening. This front may trigger a few widely scattered showers and thunderstorms during the afternoon across the North Country. Lake breeze convergence may also support a few widely scattered showers and storms, mainly from the Genesee Valley into the Finger Lakes. It will be a very warm day with a westerly warm advective flow pushing 850 mb temperatures into the upper teens C, which brings highs temperatures in the middle to perhaps upper 80s on the lake plains of western New York, and lower 80s elsewhere. With dewpoints well in the 60s it will feel humid out there as well. The cold front will wash out across the eastern Lake Ontario region Wednesday night, with any widely scattered showers and thunderstorms ending. This will leave most of the region dry overnight, with a few showers possibly reaching far Western NY before daybreak as the next system approaches. Lows will drop into the mid to upper 60s in most areas, a little cooler east of Lake Ontario. Wet weather looks to return to the region beginning late Wednesday night and continuing into Friday as shortwave energy and broad surface low pressure move northeast across the region from the Ohio Valley. Antecedent dry air should prevent any showers and thunderstorms from beginning until well after midnight Wednesday night across far western New York. As the surface low moves into the southern Great Lakes Thursday and then just north of the region by Friday, showers and scattered thunderstorms will become more widespread. Severe weather looks unlikely at this point with weak kinematics and abundant cloud cover. However, there will be the threat for locally heavy rain as PWATs surge to near 2 inches. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... The majority of the rain with the system moving through the area Friday will end from west to east Friday night as the surface low and mid level trough exit across New England. A few scattered showers may linger later Friday night and Saturday, mainly across the higher terrain of the Southern Tier and east of Lake Ontario as northerly upslope flow develops. It will turn less humid over the weekend as a slightly drier airmass moves south out of Ontario. Highs will be in the upper 70s Saturday, and then back to the lower 80s Sunday. Weak high pressure will then build into the Great Lakes Saturday night through Monday, bringing a return to mainly dry weather. The latest 12Z GFS brings the next system into the central Great Lakes by late Monday, but for now favored the slower ECMWF solution and kept Monday dry. The airmass will continue to warm under building mid level heights and weak warm advection. Expect highs back in the mid 80s by Monday, with a gradual uptick in humidity. && .AVIATION /09Z TUESDAY THROUGH SATURDAY/... An upper level low will continue to spiral moisture and rainfall across east to west across much of western and north-central NY through the morning hours of today. Some showers and embedded thunderstorms will be capable of heavy rainfall. Cigs may drop into MVFR with the rain while VIS has a better chance at dipping to IFR within a heavy shower or thunderstorms and patchy fog. This afternoon, the upper level low and its associated moisture/rain will begin to shift east. This will allow drier air from the west to bring a return to VFR conditions through the day today and persisting through tonight. Outlook... Wednesday...Mainly VFR with a chance of showers and thunderstorms. Thursday...Areas of MVFR with showers and thunderstorms likely. Friday...VFR/MVFR with showers and thunderstorms likely. Saturday...Mainly VFR with a chance of a shower. && .MARINE... An upper level low will slowly pass to the south and east of the region through today. This will continue to produce more widespread showers and scattered thunderstorms through the first half of today before tapering off this afternoon into tonight. Winds will remain light today, then increase somewhat out of the west and southwest by later Today into Wednesday creating some light chop, however conditions will remain below small craft advisory criteria through mid week. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && SYNOPSIS...Smith NEAR TERM...Smith SHORT TERM...Hitchcock/TMA LONG TERM...Hitchcock AVIATION...Smith MARINE...JM/Smith
Hazardous Weather Outlook National Weather Service Buffalo NY 511 AM EDT Tue Aug 14 2018 NYZ001-002-010>012-019-020-085-150915- Niagara-Orleans-Northern Erie-Genesee-Wyoming-Chautauqua-Cattaraugus- Southern Erie- 511 AM EDT Tue Aug 14 2018 This Hazardous Weather Outlook is for portions of western New York. .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. This product, along with other watches, warnings, advisories, and statements issued by the National Weather Service office in Buffalo can be found on the internet at http://www.weather.gov/buf NYZ003>008-013-014-021-150915- Monroe-Wayne-Northern Cayuga-Oswego-Jefferson-Lewis-Livingston- Ontario-Allegany- 511 AM EDT Tue Aug 14 2018 This Hazardous Weather Outlook is for portions of western and north central New York. .DAY ONE...Today and Tonight. Showers and scattered thunderstorms will continue today. A few storms may produce locally heavy rainfall, with isolated flooding possible. .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. This product, along with other watches, warnings, advisories, and statements issued by the National Weather Service office in Buffalo can be found on the internet at http://www.weather.gov/buf LEZ020-040-041-LOZ030-042>045-062>065-SLZ022-024-150915- Upper Niagara River and Buffalo Harbor- Lake Erie nearshore waters from Ripley to Dunkirk- Lake Erie nearshore waters from Dunkirk to Buffalo- Lower Niagara River- Lake Ontario nearshore waters from the Niagara River to Hamlin Beach- Lake Ontario nearshore waters from Hamlin Beach to Sodus Bay- Lake Ontario nearshore waters from Sodus Bay to Mexico Bay- Lake Ontario nearshore waters from Mexico Bay to the Saint Lawrence River- Lake Ontario open waters from the Niagara River to Hamlin Beach- Lake Ontario open waters from Hamlin Beach to Sodus Bay- Lake Ontario open waters from Sodus Bay to Mexico Bay- Lake Ontario open waters from Mexico Bay to the Saint Lawrence River- Saint Lawrence River from Cape Vincent to Ogdensburg- Saint Lawrence River from Ogdensburg to Saint Regis- 511 AM EDT Tue Aug 14 2018 This Hazardous Weather Outlook is for the New York waters of Lake Erie, Lake Ontario, and the Saint Lawrence River. .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. This product, along with other watches, warnings, advisories, and statements issued by the National Weather Service office in Buffalo can be found on the internet at http://www.weather.gov/buf
Special Weather Statement
National Weather Service Buffalo NY
524 AM EDT TUE AUG 14 2018
NYZ004>006-014-141015-
Ontario-Oswego-Wayne-Northern Cayuga-
524 AM EDT TUE AUG 14 2018
...AN AREA OF HEAVY RAIN AND EMBEDDED THUNDERSTORMS WILL AFFECT
EASTERN WAYNE...CAYUGA...SOUTHWESTERN OSWEGO AND EASTERN ONTARIO
COUNTIES...
At 520 AM EDT, an area of heavy rain and isolated embedded
thunderstorms was located over Montezuma, or 8 miles north of Seneca
Falls. The area of heavy rain was drifting slowly southwest.
Locations impacted include...
Oswego, Geneva, Fair Haven Beach State Park, Lyons, Clyde, Weedsport,
Cato, Chimney Bluffs State Park, Battle Island State Park and
Sterling.
This includes Interstate 90 between exits 42 and 40.
Torrential rainfall is also occurring with this shower, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.
LAT...LON 4330 7703 4345 7640 4303 7655 4301 7696
4287 7696 4287 7698 4283 7698
TIME...MOT...LOC 0920Z 070DEG 4KT 4303 7674
TMASpecial Weather Statement
National Weather Service Buffalo NY
620 AM EDT TUE AUG 14 2018
NYZ004-005-014-141115-
Ontario-Wayne-Northern Cayuga-
620 AM EDT TUE AUG 14 2018
...AN AREA OF HEAVY RAIN AND EMBEDDED THUNDERSTORMS WILL AFFECT
WAYNE...CAYUGA AND NORTHEASTERN ONTARIO COUNTIES...
At 616 AM EDT, an area of heavy rain and isolated embedded
thunderstorms was located over Lyons, or 13 miles northwest of
Waterloo. The area of heavy rain was drifting slowly southwest.
Locations impacted include...
Geneva, Fair Haven Beach State Park, Newark, Lyons, Clifton Springs,
Clyde, Phelps, Sodus, Rushville and Chimney Bluffs State Park.
This includes Interstate 90 near exit 42.
Torrential rainfall is occurring within this area, and may cause
poor drainage and field flooding, and ponding of water of roadways.
Do not drive your vehicle through flooded roadways.
LAT...LON 4329 7717 4335 7670 4303 7671 4301 7696
4287 7696 4286 7698 4276 7698 4276 7723
TIME...MOT...LOC 1016Z 058DEG 7KT 4308 7697
TMAThe Buffalo radar (KBUF), 129 km away, was scanning. The volume nearest the first event began at 10:59 UTC.
7 heavy rain, 7 flash flood, 2 thunderstorm wind. Local standard time, as filed.
Several trees were reported down between Palmyra and Newark.
Several trees were reported down.
Park and Woolston Roads were closed in Powder Mill Park due to flooding.
Route 96 was closed at Woodcliff Drive due to flooding.
Garnsey Road was flooded and impassable.
North Street was reported flooded and closed.
Rainfall fell between 1 and 5 PM. Basement flooding was also reported.
Five village roads flooded with six to eight inches of water across them. Water was reported up to the doors of many businesses.
Several road closures reported around Sandy Creek.
Route 41 reported flooded and closed near the railroad crossing southwest of Pulaski.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in New York in 2018Every state in 2018This day in weather historyWarnings in New York, August 2018
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: 782241, 782242, 781803, 781799, 781804, 781805, 781800, 781802, 781806, 781807, 782235, 781808, 781809, 782236, 782239, 782240.