An upper level low pressure system with weak winds and high levels of deep moisture pooling along a weak surface trough resulted in clusters of slow moving thunderstorms over Monroe County during the pre-dawn hours. These storms produced very heavy rain with multiple instances of flash flooding reported across the Rochester Metro.
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.
An upper level low pressure system with weak winds and high levels of deep moisture pooling along a weak surface trough resulted in clusters of slow moving thunderstorms over Monroe County during the pre-dawn hours. These storms produced very heavy rain with multiple instances of flash flooding reported across the Rochester Metro. Top rainfall reports included; 3.13 inches at the Rochester Airport, 3.00 inches near Greece and 2.84 inches on the northwest side of Rochester.
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 16, 3:42 AM EST, 18 minutes earlier.
Area Forecast Discussion National Weather Service Buffalo NY 442 AM EDT Wed Aug 16 2023 .SYNOPSIS... Rain showers will decrease today behind an upper level low, then drier air brings increasing amounts of sunshine through the afternoon hours. High pressure will bring a brief period of fair weather tonight and tomorrow before a sharp mid level trough crosses our region Thursday evening with gusty storms through the night, tapering off as scattered showers Friday. A cool, but dry start to the weekend. && .NEAR TERM /THROUGH TONIGHT/... Upper level low over our region this morning will advance towards New England by this evening. Showers and isolated thunder will continue through the morning hours. IR satellite imagery displaying cooling cloud tops near Rochester, with slow moving storms around the pivot point of the upper level low. Strong moisture convergence will continue the heavy rain through the predawn hours along the southern Lake Ontario shoreline. Northwest winds today behind the upper level low will maintain a wealth of clouds through the morning, this as rain showers begin to weaken and end from west to east. This northwest upslope flow along with saturated lower levels of the atmosphere will bring areas of fog and low stratus, especially across higher terrain of southwest NYS. As the deeper moisture departs our region to the east with the upper level low, drier air will bring a return to sunshine through the afternoon and early evening hours. Tonight weak surface high pressure will quickly cross our region, with a southerly flow developing later in the night. Fair weather tonight with temperatures in the mid 50s to around 60F. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... Deep trough and strong cold front approach on Thursday from the upper Great Lakes. Warmer day ahead of the system. Lead shortwave lifting across central and eastern NY will combine with building instability to result in isolated thunderstorms in the afternoon Finger Lakes to the North Country. Warm air advection within southerly flow will cause temperatures to reach the upper 70s to lower 80s, with the warmest areas lying in the Genesee Valley and Finger Lakes due to downsloping. The energetic shortwave trough will be diving southeast across the Great Lakes Thursday, supporting a surface low over the northern portions of the Ontario province. Attached to said low, is a surface cold front lying due south across the Upper Great Lakes Thursday morning. This front will arrive across the lower Great Lakes Thursday evening. Mainly due to decreasing instability farther east of when front moves through during peak heating (Michigan/Ohio), we are not highlighted in anything more than general thunder from SPC. At the least, instability between 500 and 1000 J/kg of MUCAPE will interact with a low level jet to 45 knots, supporting the potential for some gusty thunderstorms northeast and east of both lakes. In addition to the thunderstorm potential, any rain with this system will be moderate as precipitable water values climb up between 1.25 and 1.50 inches along the low level jet. As the well defined upper level trough crosses the region Friday, expect scattered showers and isolated thunder, especially across the eastern Lake Ontario region. Windy with wind gusts between 25 and 35 mph. Cool as well with highs not reaching upper 60s over the higher terrain and barely making low 70s over the lower elevations. Upper level low and sfc low pulls east into northern New England and southern Quebec Friday night. This is a slow trek though. Showers east and southeast of Lake Ontario will slowly diminish but will not end completely due to cooler air aloft and upslope flow. Farther west, skies will begin to clear out as high pressure ridge moves in from the west. This will result in river valley fog across the Southern Tier. && .LONG TERM /SATURDAY THROUGH TUESDAY/... On Saturday, some of the upslope showers southeast and east of Lake Ontario will only slowly end as the upper low finally pulls east across New England. Otherwise, dry weather will take hold the rest of Saturday into Sunday with mainly ridging taking hold. Guidance showing growing consensus for chances of a few showers on Monday as a cold front drops across. Better chances eastern areas and have now included slight chance pops to cover the potential. Next low-end chances for showers thereafter arrive later Tuesday as another shortwave trough crests over the eastern side of the ridge and across the Great Lakes. Regarding temperatures, after a rather cool night, temperatures will be below normal to kick the day off Saturday though warm to pleasant readings in the 70s as the airmass begins to modify as surface high pressure slowly migrates eastward. Temperatures are then generally expected to average near or slightly above climatological norms through early next week. && .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/... An upper level low will exit the region today, with an axis of moisture extending westward across the TAF region with IFR visibility and diminishing amounts of rain showers. As this moisture axis pivots eastward across our region, drier air will filter in from northwest to southeast, with a return to VFR flight conditions between 12Z and 16Z for the lake plain, and 16Z and 20Z for higher terrain and areas east of Lake Ontario. Surface high pressure will build towards the region tonight, with fair weather and VFR flight conditions. Scattered low end VFR stratus clouds may pass across far western TAF sites late tonight as winds become more southerly. Outlook... Thursday...VFR. Thursday night...Restrictions possible with showers and thunderstorms. Friday...Mainly VFR, a chance of showers and local MVFR east of Lake Ontario. Saturday and Sunday...Mainly VFR. && .MARINE... Northwest flow today behind a departing upper level low, with these winds across the Lakes generally 10 knots or less. Tonight these winds will lighten, and become southerly late. Thursday the south-southwest flow could approach 15 to 20 knots over the far western portion of Lake Ontario and near the Lower Niagara River...with this flow continuing into the evening before a strong cold front nears. This strong cold front will cross the area Thursday night, with increasing westerly winds behind the cold front likely bringing solid Small Craft Advisory conditions Friday. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && SYNOPSIS...Thomas NEAR TERM...Thomas SHORT TERM...EAJ/JLA LONG TERM...JLA/PP AVIATION...Thomas MARINE...Thomas
Hazardous Weather Outlook National Weather Service Buffalo NY 659 PM EDT Tue Aug 15 2023 NYZ001>008-010>014-019>021-085-162300- Niagara-Orleans-Monroe-Wayne-Northern Cayuga-Oswego-Jefferson-Lewis- Northern Erie-Genesee-Wyoming-Livingston-Ontario-Chautauqua- Cattaraugus-Allegany-Southern Erie- 659 PM EDT Tue Aug 15 2023 This Hazardous Weather Outlook is for western and north central New York. .DAY ONE...Tonight. Isolated thunderstorms through this evening could produce locally heavy rain and gusty winds. The greatest risk will be from western NY to the Finger Lakes. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Hazardous weather is not expected at this time. .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-SLZ022-024-162300- 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- 659 PM EDT Tue Aug 15 2023 This Hazardous Weather Outlook is for the New York waters of Lake Erie, Lake Ontario, and the Saint Lawrence River. .DAY ONE...Tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. No hazardous weather is expected at this time. .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 220 AM EDT Wed Aug 16 2023 NYZ003-160815- Monroe- 220 AM EDT Wed Aug 16 2023 ...MODERATE TO HEAVY RAIN OVER NORTHERN MONROE COUNTY... At 214 AM EDT, an area of moderate to heavy rain was located falling from Charlotte to Greece and North Gates. The area of rain is nearly stationary. Total rainfall of 2 to 3 inches has occurred in this area since Tuesday evening. Though not widespread, an additional 0.5 to 0.75 inch of rain will occur locally early this morning in some of these same areas. Locations impacted include... Rochester, Greece, Irondequoit, Hilton, Brighton, Gates-North Gates, Spencerport, Charlotte, Strong Memorial Hospital, Rochester General Hospital, Rochester International Airport, and Braddock Bay. This additional rain will cause ponding of water on roadways, especially in urban areas or low-lying areas with poor drainage. Motorists should slow down and be prepared for poor visibility due to the heavy rain. Remember, never drive across a flooded roadway since the water may be deeper than it looks. Turn around, don't drown. LAT...LON 4327 7750 4309 7764 4317 7785 4337 7776 TIME...MOT...LOC 0614Z 020DEG 2KT 4323 7767 JLA
Preliminary Local Storm Report
National Weather Service Buffalo NY
335 AM EDT Wed Aug 16 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0333 AM Rain 1 NW Rochester 43.18N 77.63W
08/16/2023 M2.84 inch Monroe NY Mesonet
Rainfall total since midnight.
&&
JLAPreliminary Local Storm Report
National Weather Service Buffalo NY
338 AM EDT Wed Aug 16 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0230 AM Rain 1 ENE Greece 43.22N 77.68W
08/16/2023 M3.00 inch Monroe NY Public
Total rainfall since 530 pm on Tuesday.
Still raining.
&&
JLAThe Buffalo radar (KBUF), 95 km away, was scanning. The volume nearest the first event began at 08:58 UTC.
3 flash flood. Local standard time, as filed.
A car was stuck in a sinkhole along St. Paul Boulevard between Paxon Road and Wimbledon Road. There were widespread reports of standing water on roads from Greece to the western portions of Rochester.
Foot of water flowing across Interstate 490.
A report on social media with a picture showed roads impassible and a submerged car with damage at the corner of Brooks Ave. and Marilou Dr. in Gates.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in New York in 2023Every state in 2023This day in weather historyWarnings in New York, August 2023
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: 1125876, 1125883, 1125884.