The area became warm sectored in the afternoon ahead of an approaching cold front and pre-frontal trough. Aloft, a shortwave trough approached.
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 OKX wrote it up.
The area became warm sectored in the afternoon ahead of an approaching cold front and pre-frontal trough. Aloft, a shortwave trough approached. This setup allowed for multiple severe thunderstorms to develop and move through southern CT, producing damaging wind gusts.
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 New York, NY wrote its last area forecast discussion before the first event at Aug 12, 6:53 PM EST, 58 minutes earlier.
Area Forecast Discussion National Weather Service New York NY 753 PM EDT Sat Aug 12 2023 .SYNOPSIS... A cold front approaches the region tonight, moving in late tonight into Sunday. The cold front moves east of the region Sunday night with weak high pressure building in thereafter. High pressure pushes offshore Monday before another frontal system impacts the area Monday night and Tuesday. High pressure returns for Wednesday and Thursday, with a warm front possibly lifting north Thursday night. A cold front approaches the region Friday. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Severe Thunderstorm Watch in effect for western 1/2 of the CWA as discrete cells beginning to merge across Mid Hudson valley and more widespread shower/tstm activity across Central PA along pre-frontal trough expected to slide E/SE into the watch area. Shortwave forcing trigger, pre-frontal trough focus, increasing deep layer shear and steeper mid-level lapse rates point towards isolated to scattered strong to severe tstm activity working into areas N&W of NYC this evening. Less confidence in how well this activity maintains it strength towards the coastal portions of the watch area late this evening towards midnight, with waning diurnal instability a limiting factor. Flash flood threat in path of an W to E training convection. This is currently favored across the mid-Hudson valley for the next couple of hours, but could slip south into Lower Hud and SW CT in vicinity of outflow boundaries later this evening. Convection should decrease in intensity after midnight as it continues east into a stabilizing airmass. Previous Discussion... The main focus will be on the potential for strong and/or severe convection, which looks to be mainly tonight when the higher bulk shear moves in. There will be another few rounds of showers and thunderstorms for tonight. CAMs vary with their respective depictions of reflectivity and cell structures across the local region so timing could vary. Challenging forecast to pinpoint specific timing and spatial windows for each round of convection. Generally expect the showers and thunderstorms to encompass much of the interior going into early this evening, getting closer to the coast and NYC by mid to late evening, and then become more likely across Southern Connecticut and Long Island overnight. There will be a pre-frontal trough moving in this evening with a cold front moving in behind that for overnight. The speed of the thunderstorms will limit the flood threat but models indicate high precipitable waters near 2 inches so flooding will still be possible. Also, still a severe thunderstorm threat with marginal to slight risk for severe thunderstorms with an enhanced risk for Western Orange County NY. With higher wind speeds aloft and increased storm motion, already have an environment with relatively large shear to allow for thunderstorms to get organized and deep vertical motion. Models indicate bulk shear 0-6 km AGL of 35-50 kt. The instability from CAPE for tonight, generally near 500 to 1000 J/kg, relatively higher across the coastal regions. Overall, severe threat highest going into early evening especially across Lower Hudson Valley, SW CT and Northeast NJ as well as into NYC. Then, severe threat shifts farther east across the coastal areas across Long Island and the rest of Southern CT for late evening into overnight. Main severe threat will be strong wind gusts but large hail and a brief tornado will be possible especially north and west of NYC where the probabilities for strong wind gusts, hail and a brief tornado are relatively higher. The potential for a brief tornado is seen from an increase in forecast low level helicity to values near 150 to a little over 200 indicated by the NAM and RAP models in the BUFKIT data. This is from the low level veering of winds from S to SW and wind speeds increasing from surface to low levels as well. With larger scale operational models with NAM, GFS, ECMWF, and Canadian, they mostly convey under a quarter of an inch in rain accumulation by 8PM tonight. All of these models show more rain between 8PM tonight and 8AM Sunday and spread across mainly the northern half of the CWA from west to east, total run accumulation around a half to 0.75 inch of rain. There will likely be some higher amounts of rain. Have these higher rain amounts closer to 1 to 1.25 inches of rain across parts of the interior. There could even be some locally higher amounts up to near 2 inches of rain. Lows tonight were from NBM 50th percentile and consensus of raw data, ranging only from the upper 60s to lower 70s for much of the forecast region. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Mid levels show a zonal pattern but there will be some slight ridging during Sunday. At the surface, the cold front Sunday morning will be within the area, prolonging showers and thunderstorms especially across Long Island and Southern Connecticut morning into early afternoon. There will still be bulk shear 0-6km AGL near 35-40 kt, and surface CAPE reaching near near 1000 J/kg from NAM and GFS forecast model data. Model BUFKIT soundings indicate warmer temperatures just above 10kft acting as some convective inhibition. Will keep thunderstorms just chance but if there are thunderstorms, they could be strong and a very low chance (less than 5 percent) of severe. POPs for showers and thunderstorms will decrease substantially mid to late Sunday afternoon with totally dry conditions expected Sunday night. The front shifts east of the region Sunday night, allowing for surface winds to become more westerly, advecting in drier air. Instability will considerably decrease and dry conditions should prevail as weak high pressure builds in. High temperatures forecast Sunday used a blend of NBM/MET/MAV with a range from the low to upper 80s. The upper 80s forecast are mostly across Northeast NJ and NYC Metro Area where there will be less clouds and less rain. Expecting more radiational cooling Sunday night, with not much cloud coverage and light winds and therefore a more vast range for low temperatures, from upper 50s to lower 70s. && .LONG TERM /MONDAY THROUGH SATURDAY/... Weak surface ridging holds on long enough during the daytime on Monday to keep any showers from moving in from the west as the next storm system approaches from the Ohio Valley and Great Lakes. Highs near normal at 80-85. Another shortwave will approach from the Great Lakes region Monday night, and move through Tuesday into Tuesday night. A wave of low pressure will track along a nearly stationary cold front south of the region Monday night. This will bring a warm front near or into the region Monday night into Tuesday. Precipitable water values will be increasing to 2 to nearly 2 1/4 inches Monday night, and with forcing, instability, and surface CAPE increasing with the front, convection is expected to develop with periods of moderate to heavy rainfall possible. The 90% percentile from SPC's sounding climatology page is 1.75 inches, so very humid air will move into there area for this time of year. WPC currently has the region under a marginal risk for excessive rainfall, so flash flooding is a possibility, especially if heavy rain moves in during preceding days. There is uncertainty as to where the warm front will be, and a track farther to the north could bring the heavier rainfall into the region. The frontal system will be progressive as the upper trough weakens and passes to the east Tuesday night. A mid-level ridge continues to build into the area Wednesday into Thursday while high pressure builds in at the surface, keeping the region dry through the period. Then another shortwave digs into the Great Lakes and upper midwest Thursday night into Friday before becoming negative during Friday. At this time there are minimal chance for precipitation Friday. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... A pre frontal trough will move through the region this evening, followed by a cold front early Sunday. Mainly VFR, except MVFR or lower possible in showers and thunderstorms. Southerly flow around 10 to 15 kt into early evening, lightening (and possibly becoming variable) overnight before becoming westerly on Sunday. Most of the shower and thunder activity remains well to the north and west, however some isolated showers and thunderstorms have developed around the region. A better chance of storms is now expected between 02z and 06z. Storms may produce heavy rainfall and gusty winds, however, coverage and timing remain low confidence. Conditions dry out and return to VFR everywhere by 12z Sunday. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Low confidence in timing and coverage of shower and thunderstorm activity tonight. Amendments likely. OUTLOOK FOR 00Z SUNDAY THROUGH THURSDAY... Sunday: VFR. Monday through Tuesday: VFR Monday, then a chance of showers and thunderstorms Monday night and Tuesday with MVFR or lower possible. Wednesday: VFR. Thursday: VFR. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90 && .MARINE... The pressure gradient will be relatively weak enough to keep conditions on the forecast waters below SCA thresholds through the rest of this weekend and into Monday. With a persistent southerly flow Monday night into Tuesday, ahead of a cold front, ocean waters likely build to around 5 feet Tuesday afternoon, then subside Tuesday night as winds shift to the west due to a cold frontal passage. Marginal seas possible once again for the central and eastern oceans zone for Wednesday and Friday morning, subsiding during the afternoons of both days. Winds should remain below 25 kt on all waters From Monday onward. && .HYDROLOGY... Marginal to slight risk of flash flooding, layer precipitable waters reach up to near 2 inches for tonight. There will be potential for training of cells from parallel flow low to upper levels, but mean storm motion judging from looking at winds between 10 and 20 kft, stay generally in a 25-40 kt range. Individual thunderstorm complexes will be rapid moving. It just a matter of how deep the convection gets and how large the structure is that moves across that will be a main factor to assess for flooding potential. CAMs late tonight indicate in terms of structure a MCS moving across with some variance in terms of locations within the forecast region of where the most intense part of the MCS occurs. Minor flooding will be likely as the MCS moves across especially with low lying, poor drainage and urban areas with a marginal to slight risk for flash flooding. From Monday night into Tuesday, brief periods of moderate to heavy rainfall may produce isolated flash flooding. The Weather Prediction Center has placed the entire area in a marginal risk for flash flooding. Currently, the more likely scenario is for minor urban and poor drainage/nuisance flooding. From Tuesday night through the end of the week no hydrologic impacts are expected. && .TIDES/COASTAL FLOODING... There is a moderate risk for rip currents on ocean beaches Sunday with wave heights around 3 ft. There is a low risk for rip currents on NYC and Nassau Co beaches on Monday with wave heights around 2 ft, and a moderate risk for Suffolk Co beaches, where wave heights will be around 3 ft. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && SYNOPSIS...JM/JP NEAR TERM...JM/NV SHORT TERM...JM LONG TERM...JP AVIATION...BC MARINE...JM/JP HYDROLOGY...JM/JP TIDES/COASTAL FLOODING...
Hazardous Weather Outlook National Weather Service New York NY 626 PM EDT Sat Aug 12 2023 CTZ005-009-NJZ002-004-006-103>108-NYZ067>075-176>179-132230- Northern Fairfield-Southern Fairfield-Western Passaic- Eastern Passaic-Hudson-Western Bergen-Eastern Bergen-Western Essex- Eastern Essex-Western Union-Eastern Union-Orange-Putnam-Rockland- Northern Westchester-Southern Westchester-New York (Manhattan)-Bronx- Richmond (Staten Island)-Kings (Brooklyn)-Northern Queens- Northern Nassau-Southern Queens-Southern Nassau- 626 PM EDT Sat Aug 12 2023 ...SEVERE THUNDERSTORM WATCH 638 IN EFFECT UNTIL MIDNIGHT EDT TONIGHT... This Hazardous Weather Outlook is for southern Connecticut, northeast New Jersey and southeast New York. .DAY ONE...Tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Severe Thunderstorm Watch. In addition, the Weather Prediction Center has placed the area in a marginal to slight risk for excessive rainfall with a low risk of flash flooding. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Hazardous weather is not expected at this time that would meet NWS warning criteria. .SPOTTER INFORMATION STATEMENT... Spotter activation according to Standard Operating Procedures is requested and appreciated. && This Hazardous Weather Outlook provides a summary of potential widespread hazardous weather events that may reach NWS warning criteria. Most long fused NWS watches, warnings, and advisories in effect are highlighted. Please refer to the latest NWS forecasts for weather not meeting NWS warning criteria. CTZ006>008-010>012-NYZ078>081-132230- Northern New Haven-Northern Middlesex-Northern New London- Southern New Haven-Southern Middlesex-Southern New London- Northwest Suffolk-Northeast Suffolk-Southwest Suffolk- Southeast Suffolk- 626 PM EDT Sat Aug 12 2023 This Hazardous Weather Outlook is for southern Connecticut and southeast New York. .DAY ONE...Tonight. A frontal system will affect the area with the potential for strong thunderstorms. The main threat is for strong wind gusts and hail. The Storm Prediction Center has placed most of the Tri-State Area under a Marginal Risk (isolated) for severe weather. In addition, the Weather Prediction Center has placed the area in a marginal to slight risk for excessive rainfall with a low risk of flash flooding. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Hazardous weather is not expected at this time that would meet NWS warning criteria. .SPOTTER INFORMATION STATEMENT... Spotter activation according to Standard Operating Procedures is requested and appreciated. && This Hazardous Weather Outlook provides a summary of potential widespread hazardous weather events that may reach NWS warning criteria. Most long fused NWS watches, warnings, and advisories in effect are highlighted. Please refer to the latest NWS forecasts for weather not meeting NWS warning criteria. ANZ331-332-340-345-350-353-132230- Long Island Sound East of New Haven CT/Port Jefferson NY to the Mouth of the Connecticut River- Long Island Sound East of the Mouth of the Connecticut River- Peconic and Gardiners Bays- South Shore Bays from Jones Inlet through Shinnecock Bay- Moriches Inlet NY to Montauk Point NY out 20 nm- Fire Island Inlet NY to Moriches Inlet NY out 20 nm- 626 PM EDT Sat Aug 12 2023 This Hazardous Weather Outlook is for Atlantic coastal waters. .DAY ONE...Tonight. A frontal system will affect the area with the potential for strong thunderstorms. The main threat is for strong wind gusts and hail. The Storm Prediction Center has placed most of the Tri-State Area under a Marginal Risk (isolated) for severe weather. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Hazardous weather is not expected at this time that would meet NWS warning criteria. .SPOTTER INFORMATION STATEMENT... Spotter activation according to Standard Operating Procedures is requested and appreciated. && This Hazardous Weather Outlook provides a summary of potential widespread hazardous weather events that may reach NWS warning criteria. Most long fused NWS watches, warnings, and advisories in effect are highlighted. Please refer to the latest NWS forecasts for weather not meeting NWS warning criteria. ANZ335-338-355-132230- Long Island Sound West of New Haven CT/Port Jefferson NY- New York Harbor-Sandy Hook NJ to Fire Island Inlet NY out 20 nm- 626 PM EDT Sat Aug 12 2023 ...SEVERE THUNDERSTORM WATCH 638 IN EFFECT UNTIL MIDNIGHT EDT TONIGHT... This Hazardous Weather Outlook is for Atlantic coastal waters. .DAY ONE...Tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Severe Thunderstorm Watch. In addition, the Weather Prediction Center has placed the area in a marginal to slight risk for excessive rainfall with a low risk of flash flooding. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Hazardous weather is not expected at this time that would meet NWS warning criteria. .SPOTTER INFORMATION STATEMENT... Spotter activation according to Standard Operating Procedures is requested and appreciated. && This Hazardous Weather Outlook provides a summary of potential widespread hazardous weather events that may reach NWS warning criteria. Most long fused NWS watches, warnings, and advisories in effect are highlighted. Please refer to the latest NWS forecasts for weather not meeting NWS warning criteria.
Preliminary Local Storm Report
National Weather Service New York NY
825 PM EDT Sat Aug 12 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0810 PM Tstm Wnd Dmg 2 N Gardnertown 41.56N 74.06W
08/12/2023 Orange NY Fire Dept/Rescue
Tree down blocking road on Route 32.
&&Preliminary Local Storm Report
National Weather Service New York NY
827 PM EDT Sat Aug 12 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0815 PM Tstm Wnd Dmg 3 N Orange Lake 41.58N 74.09W
08/12/2023 Orange NY Fire Dept/Rescue
Trees and wires down on Quaker Street and
School House Lane.
&&Preliminary Local Storm Report
National Weather Service New York NY
830 PM EDT Sat Aug 12 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0810 PM Tstm Wnd Dmg 3 ENE Walden 41.58N 74.14W
08/12/2023 Orange NY Fire Dept/Rescue
Wires down on Plains Road.
&&Preliminary Local Storm Report
National Weather Service New York NY
832 PM EDT Sat Aug 12 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0833 PM Tstm Wnd Dmg Gardnertown 41.53N 74.06W
08/12/2023 Orange NY Fire Dept/Rescue
Multiple calls for trees and wires down in
and around Gardnertown.
&&Preliminary Local Storm Report
National Weather Service New York NY
844 PM EDT Sat Aug 12 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0835 PM Tstm Wnd Dmg 2 N Lake Carmel 41.49N 73.67W
08/12/2023 Putnam NY 911 Call Center
Tree down on transformer.
&&Preliminary Local Storm Report
National Weather Service New York NY
851 PM EDT Sat Aug 12 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0852 PM Tstm Wnd Dmg 1 E Lake Carmel 41.46N 73.65W
08/12/2023 Putnam NY 911 Call Center
Tree down blocking Terry Hill Road in Lake
Carmel.
&&The Brookhaven radar (KOKX), 96 km away, was scanning. The volume nearest the first event began at 00:51 UTC.
6 thunderstorm wind. Local standard time, as filed.
Three power poles down due to trees down on the border of Sherman and New Fairfield in CT.
Tree and wires down on Candlelight Drive in Danbury CT.
Tree down on wires on Route 37 south of Durgy Lane in New Fairfield CT.
Several trees down blocking roads across town including Pocono Lane, Lindencrest Drive and Flintock Drive in Danbury CT.
Tree down on vehicle on West Purchase Road in Southbury CT.
Tree down on Saw Mill City Road in Monroe CT.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Connecticut in 2023Every state in 2023This day in weather historyWarnings in Connecticut, 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: 1131035, 1131036, 1131037, 1131038, 1131039, 1131040.