Several areas of weakening convection moved through the area during the morning. Following this, debris clouds slowly eroded and allowed moderate instability to develop.
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.
Several areas of weakening convection moved through the area during the morning. Following this, debris clouds slowly eroded and allowed moderate instability to develop. Remnant outflow boundaries and differential heating boundaries from areas of lingering cloud cover acted as the focus for new convective development in the afternoon, mainly from the western Finger Lakes to points southeast and east of Lake Ontario. Moderate instability coupled with limited shear produced a pulse storm environment, with brief, marginal severe structures. Storms were stronger and longer lived farther east in central and eastern New York where stronger instability developed. The pulse storms produced several instances of spotty wind damage. Convection briefly trained over eastern Ontario County, with numerous reports of flooded and closed roads. A little later in the evening, a short line segment briefly developed in the western Finger Lakes, along an old remnant outflow boundary from earlier upstream convection.
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 18, 2:33 PM EST, 8 minutes earlier.
Area Forecast Discussion National Weather Service Buffalo NY 333 PM EDT Sun Aug 18 2019 .SYNOPSIS... Warm and muggy conditions will remain over the region through the middle of the week. While the sub tropical airmass will fuel some showers and thunderstorms during this period...the vast majority of the time will be rain free. A strong cold front that will pass through the region late Wednesday will then introduce a cooler and notably more comfortable airmass to our region for the second half of the week. && .NEAR TERM /THROUGH MONDAY/... As of 18z...a well defined lake shadow has developed downwind of Lake Erie. Well inland though...strong to severe convection was depicted by regional radars immediately east of our general forecast area. While this activity will continue to move northeast and remain out of our forecast area...visible sat imagery is showing some enhanced Cu developing along a secondary lake breeze boundary that is aligned from about Batavia southwest to the Chautauqua ridge. SBCAPE values of 1000- 1500 j/kg are found just to the east of this line of developing Cu... and with several more hours of heating...this area will have to be watched for strong convection. Bulk shear values in this area average 25 kts...so its not out of the question that any convection could support small line segments with potentially strong wind gusts. Any discreet cells that form over the Genesee Valley...western Finger Lakes or western southern tier through 23z could also support large hail. As we progress into the early evening hours...any remaining convection will dissipate. This will leave fair but muggy conditions for the first part of the night...but another round of showers and thunderstorms will then be possible as we move past midnight. A pair of shortwaves over the mid west will take aim on our region for the overnight period. The stronger of the two features will track to our north and should produce strong convection over Southern Ontario... possibly clipping the IAG Frontier in the process. The other shortwave (pushing across Indiana at 18z) will tend to shear out as it makes its way across the Lower Great Lakes between 04 and 09z. This will be the feature to watch in regards to convection over our region. While there will initially be some upper level lift for the system to work with... this will weaken with time. Will maintain chc pops for now...as this does not look supportive for significant convection or areal coverage. Otherwise tonight will be warm and sultry with temperatures only lowering to within a few degrees of 70. The aforementioned shortwaves will precede a weak cool front that will gradually push south across our forecast area during the day Monday. This front will help to focus yet another round of showers and thunderstorms over the region...mainly during the midday and afternoon when instability will be at its greatest. Once again though...a lack of upper level jet support or notable low level jet will leave the bulk of the forcing to convergence in the vcnty of the front or other subtle boundaries within a conditionally unstable airmass with MLCAPE values under 1000 j/kg. Bulk shear values are not forecast to exceed 20-25 knots...so am not anticipating widespread strong to severe convection. Otherwise...the largely rain free day will feature muggy conditions with dew points within a few degrees of 70. Max temps will range from 80 to 85. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... This period will feature a mainly dry and warm, but less humid day on Tuesday, followed by showers and thunderstorms on Wednesday into Wednesday evening as a strong cold front plows across the area. Monday night into Tuesday will be mainly dry as a push of somewhat drier air works in behind a weak, stalled out frontal boundary lying across northern PA. With no discernible shortwaves moving over the area, there will just a slight chance for a few showers toward the PA line closest to the boundary. Dew points will drop off some across the entire area, bringing some relief to the mugginess, especially east of Lake Ontario where dewpoints could fall into the upper 50s. Temperatures Monday night will be some ten degrees cooler than the previous night, with lows in the upper 50s to lower 60s. Highs on Tuesday will be mainly in the upper 70s to lower 80s, however will a drier 'feel' to the air. Tuesday night, the frontal boundary over PA will start to make a move back to the north as a weak warm front, while an upper level shortwave approaches the Lower Great Lakes. While the night may start out dry, deeper moisture to our south will make a push back to the north ahead of the now northward advancing warm front. This will increase the chance of some showers/isolated storms from south to north across the area, especially during the second half of the night due to added lift associated with the approaching shortwave. Humidity levels will be a bit higher, as will overnight temperatures as compared to Monday night, with lows mainly in the mid 60s. The exception will be across the northcountry, where lows will bottom out in the upper 50s to lower 60s. A cold front will be poised to plow across the region later Wednesday into early part of Wednesday night. A warm, humid airmass will be found out ahead of the approaching cold front. As the upper level trough sharpens just to the west over the central Great Lakes, enhanced lift provided by this feature within an already unstable environment will promote widespread showers and thunderstorms Wednesday afternoon/early evening with the pre-frontal trough out ahead of the main cold front. The main cold front will then plow across the region later Wednesday evening into the early overnight, with possibly another round of general showers and storms. Storms Wednesday afternoon into the early evening hours could become strong with both gusty winds and hail possible. Mid level lapse rates will increase with height falls aloft, bulk wind shear values upwards of 35 to 40 knots and CAPE deepening through the mid levels on forecast soundings will support these stronger storms. Temperatures on Wednesday will be similar to Tuesday, however dew points pushing back into the upper 60s to near 70 will make it feel more uncomfortable outside. Cooler, less humid air will pour in behind the cold front Wednesday night. Lows will generally be in the upper 50s to lower 60s, with some mid 50s across the higher terrain east of Lake Ontario. && .LONG TERM /THURSDAY THROUGH SUNDAY/... In the wake of a strong cold front...a much cooler and drier airmass will continue to overspread our region Thursday and Thursday night... with 850 mb temperatures falling to within a couple degrees either side of +7C. The combination of lingering secondary surface troughing and a digging upper level trough could lead to a few more isolated to widely scattered showers on Thursday...with the cooler airmass and loss of diurnal influences then potentially supporting a weak lake response east and southeast of Lake Ontario Thursday night into early Friday...with this limited by the rather dry nature of the airmass. Otherwise...the Thursday-Friday time frame will be dry and notably cooler as expansive surface-based ridging slowly builds southeastward across the Great Lakes. Expect highs to mostly be in the lower half of the 70s both days...though some of the higher terrain may see readings confined to the upper 60s. Meanwhile lows will be mainly in the 50s... with some upper 40s possible across interior portions of the Southern Tier and North Country. After that...the axis of the aforementioned surface ridge will crest across our region on Saturday...then will drift to the Atlantic coastline on Sunday. This will provide our region with continued fair dry weather both days...with diurnal airmass modification and eventually warm air advection allowing highs to climb back into the mid to upper 70s on Saturday...and to the upper 70s to lower 80s on Sunday. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... Mainly VFR conditions will be found across the region during the remainder of the afternoon...although more convection will develop. The bulk of this will be found across the Southern Tier and Finger Lakes region where some of the storms could become strong with local wind gusts over 40 kts. Any convection from the afternoon will dissipate during the early evening...but the next mid level disturbance will support renewed showers and thunderstorms after 03z. This will especially be the case over the far western counties where conditions may briefly deteriorate to MVFR levels. While VFR conditions are expected for the bulk of Monday...the passing of a weak cool front will support more scattered convection. Some of the shower and thunderstorm activity will have the potential to briefly lower conditions to MVFR levels. Outlook... Monday night...Mainly VFR...but IFR vsbys possible across the Southern Tier late. Tuesday...VFR...with a chance of showers and thunderstorms across the Southern Tier Wednesday...Thunderstorms likely that could impact operations. Thursday and friday...Mainly VFR. && .MARINE... A weak pressure gradient will maintain generally light to modest winds across the Lower Great Lakes through the rest of the weekend and into early next week, along with correspondingly minimal waves. This said, there is a risk for showers and thunderstorms today through Monday and these could produce locally stronger winds and higher waves. Looking further out into the middle of next week...a cold front will cross the region on Wednesday along with more showers and thunderstorms. In its wake...increasingly brisk northwesterly winds will bring an increase in wave action and could eventually require the issuance of Small Craft Advisories for Wednesday night and Thursday. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && SYNOPSIS...RSH NEAR TERM...RSH SHORT TERM...JM LONG TERM...JJR AVIATION...RSH MARINE...Apffel/RSH
Hazardous Weather Outlook National Weather Service Buffalo NY 456 AM EDT Sun Aug 18 2019 NYZ012-019>021-085-190900- Wyoming-Chautauqua-Cattaraugus-Allegany-Southern Erie- 456 AM EDT Sun Aug 18 2019 This Hazardous Weather Outlook is for portions of western New York. .DAY ONE...Today and tonight. There is a marginal risk for severe storms today, with damaging winds and hail the primary risks. There may also be heavy rains from these storms with poor drainage flooding. .DAYS TWO THROUGH SEVEN...Monday through Saturday. 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 NYZ010-011-013-014-190900- Northern Erie-Genesee-Livingston-Ontario- 456 AM EDT Sun Aug 18 2019 This Hazardous Weather Outlook is for portions of western New York. .DAY ONE...Today and tonight. There is a marginal risk for severe storms today, with damaging winds and hail the primary risks. There may also be heavy rains from these storms with poor drainage flooding. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Afternoon apparent temperatures Monday may reach the lower 90s or higher. Keep in mind that heat advisories are issued when apparent temperatures reach at least 95 for two consecutive hours. .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 NYZ001>006-190900- Niagara-Orleans-Monroe-Wayne-Northern Cayuga-Oswego- 456 AM EDT Sun Aug 18 2019 This Hazardous Weather Outlook is for portions of western and north central New York. .DAY ONE...Today and tonight. There is a marginal risk for severe storms today, with damaging winds and hail the primary risks. There may also be heavy rains from these storms with poor drainage flooding. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Afternoon apparent temperatures Monday may reach the lower 90s or higher. Keep in mind that heat advisories are issued when apparent temperatures reach at least 95 for two consecutive hours. Behind a strong cold front Wednesday night, west to northwest winds and waves will increase with possible lakeshore flooding due to high lake levels. .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 NYZ007-008-190900- Jefferson-Lewis- 456 AM EDT Sun Aug 18 2019 This Hazardous Weather Outlook is for portions of central New York. .DAY ONE...Today and tonight. There is a marginal risk for severe storms today, with damaging winds the primary risk. .DAYS TWO THROUGH SEVEN...Monday through Saturday. 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 LEZ020-040-041-LOZ030-042>045-062>065-SLZ022-024-190900- 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- 456 AM EDT Sun Aug 18 2019 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. There is a marginal risk for severe storms today, with damaging winds and hail the primary risks. .DAYS TWO THROUGH SEVEN...Monday through Saturday. 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
302 PM EDT Sun Aug 18 2019
NYZ004-005-181945-
Wayne-Northern Cayuga-
302 PM EDT Sun Aug 18 2019
...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN WAYNE AND CAYUGA
COUNTIES...
At 302 PM EDT, a strong thunderstorm was located near Lyons and
moving northeast at 20 mph.
Winds in excess of 30 mph and half inch hail are possible with this
storm.
Locations impacted include...
Lyons, Clyde, Weedsport, Cato, Ira, Conquest, Savannah, Port Byron,
Meridian and South Butler.
This includes Interstate 90 near exit 40.
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.
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.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
LAT...LON 4310 7650 4303 7650 4301 7700 4308 7705
4326 7654 4326 7649 4324 7648 4315 7647
4314 7649 4311 7647
TIME...MOT...LOC 1902Z 246DEG 17KT 4303 7694
ReynoldsSpecial Weather Statement
National Weather Service Buffalo NY
316 PM EDT Sun Aug 18 2019
NYZ003>005-011>014-085-182000-
Ontario-Livingston-Southern
Erie-Wyoming-Wayne-Genesee-Monroe-Northern Cayuga-
316 PM EDT Sun Aug 18 2019
...Strong Thunderstorms Likely This Afternoon...
Thunderstorms will continue to blossom and intensify across the
region through late this afternoon. Some of the storms will become
strong to severe with the potential for damaging wind gusts and
large hail. Some sites will also experience torrential downpours
with localized rainfall amounts of an inch in less than an hours
time.
LAT...LON 4253 7884 4333 7726 4331 7697 4339 7673
4347 7662 4343 7659 4342 7662 4325 7661
4325 7648 4303 7669 4301 7696 4276 7698
4276 7732 4267 7737 4258 7737 4258 7766
4254 7766 4252 7772
RSHThe Binghamton radar (KBGM), 118 km away, was scanning. The volume nearest the first event began at 19:40 UTC.
4 thunderstorm wind, 2 flash flood. Local standard time, as filed.
Multiple reports of trees and wires down were received.
Multiple reports of trees and wires down were received.
North Street was reported flooded and impassible between Oak and Maple Streets.
Route 20 was flooded and closed, impacting multiple parked vehicles.
Trees and power lines were reported down in the Town of Nunda.
Trees and power lines were reported down in Mount Morris.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in New York in 2019Every state in 2019This day in weather historyWarnings in New York, August 2019
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: 854059, 854060, 854056, 854058, 854061, 854063.