A warm front stalled across Connecticut and Rhode Island, producing thunderstorms with very heavy rainfall. This caused significant 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 BOX wrote it up.
A warm front stalled across Connecticut and Rhode Island, producing thunderstorms with very heavy rainfall. This caused significant flash flooding. Also, wind shear was just strong enough for a few thunderstorms to become severe, with locally damaging wind gusts. A Tornado Warning was even issued for a storm in northern Worcester County, but no tornado damage was reported.
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 Boston/Norton, MA wrote its last area forecast discussion before the first event at Jul 21, 9:26 AM EST, 3 hours 31 minutes earlier.
Area Forecast Discussion National Weather Service Boston/Norton MA 1026 AM EDT Fri Jul 21 2023 .SYNOPSIS... Showers and thunderstorms return Friday. Some thunderstorms across western portions of Massachusetts and Connecticut may have strong wind gusts and heavy rain. Drying trend begins late tonight into Saturday from west to east. Otherwise, mainly dry weather prevails. Gorgeous midsummer weather for Sunday with mostly sunny skies, low humidity and seasonably warm temperatures. Then a gradual increase in heat and humidity next week, with scattered showers/thunderstorms possible Tuesday and again late next week. && .NEAR TERM /UNTIL 7 PM THIS EVENING/... 1025 am update... made modest tweaks to the grids based on latest radar/satellite trends and the initial output from the newest hi-res CAMs. SPC has increased the threat level for severe weather to the Slight category across western portions of southern New England. Looks reasonable, and in typical New England style, nothing is clear cut for how things are going to unfold. Certainly, as previous shift indicated, good signals for instability, shear and even low level helicity. The latest CAMs are all similar in that they show a broken line of convection to develop but otherwise they are all over the place in timing and location. FV3 came in more agressive than NAM3km and the recent HRRR runs. Perhaps it's on to something given we already have convective development in western CT at this time. Also some suggestion we have one batch of convection early/mid afternoon, with a second line developing later in the afternoon and getting into western sections after 6pm. In any case, as is typical with convection, we are just going to have to roll with the punches and respond to whatever Mother Nature decides to give us. 7 AM update... Lots of low clouds and patchy fog across the region, except here in eastern MA, partial sunshine with mid/high WAA clouds approaching from the west. Warm frontal showers and thunderstorms occurring across NYC into southwest CT. This activity will weaken as low/mid level jet shears off to the northeast into upstate NY and VT. Warm front will stall this afternoon somewhere across eastern CT into central MA, with warm sector airmass westward across central-western MA/CT, with MUCAPE 1000-1500 j/kg, then lowering dramatically eastward into RI and eastern MA. Best deep layer shear (around 30 kt) and CAPE profiles overlap across eastern NY into western-central CT/MA. This is where storms are expected to be most numerous and intense based on HREF UH swaths. If stronger storms form vicinity of warm front, could be sufficient low level turning for an isolated tornado. SPC has a 2% TOR prob eastward into the CT River Valley of MA/CT. PWATs up to 1.5 inches combined with rivers and streams 7 day flows greater than 90th percentile will yield low risk of flash flooding. Storm potential for 1 inch per hourly rainfall rates and isolated storm totals of 1-3 inches across western-central MA/RI. Otherwise, typical summer day with highs in the upper 70s to lower 80s and dew pts 65-70. True warm sector airmass focused across CT into western-central MA. SSE winds becoming SSW in CT and western-central MA this afternoon with arrival of warm sector. && .SHORT TERM /7 PM THIS EVENING THROUGH 6 PM SATURDAY/... A cold front should slowly cross southern New England tonight, before moving offshore after daybreak Saturday morning. Weakening thunderstorms and scattered showers cross our region tonight, with showers lingering along the east coast Saturday morning. A marked drying trend from W to E during the late morning and afternoon hours. More sunshine should produce slightly higher max temperatures Saturday. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Key Points: * Not as warm and less humid Sat night * Pick of the weekend is Sunday with sunny and seasonably warm weather, but comfortable humidity * Chance of showers/t-storms next Tue and Fri. Otherwise mainly dry weather with a gradual increase in heat & humidity, with 90s possible late next week. Short wave trough over southeast Quebec deamplifies and lifts northeast away from the region. In its wake, NW flow aloft streaming across SNE with 850 mb ensemble temp anomalies slightly cooler than normal into MA/CT/RI. This combined with light winds, decreasing clouds and dew pts falling into the mid and upper 50s, low to mid 60s for the coastline, will result in a very comfortable Sat night for late July. Departing short wave over southeast Quebec yields rising heights across SNE, supporting dry weather & sunshine. Post frontal airmass with 850 mb temps at or slightly cooler than normal will yield very pleasant conditions, with seasonably warm temps (highs in the low to mid 80s), but accompanied by dew pts in the 50s, except low to mid 60s for the coastline as afternoon seabreezes advect higher dew pts onshore. Next week, western Atlantic subtropical ridge begins to retrograde towards the east coast. Rising heights across SNE should support another mainly dry weather Monday. A warm day with highs in the 80s but humidity tolerable, with dew pts in the upper 50s to lower 60s, except mid to upper 60s along the south coast. Mean trough over the Great Lakes/OH Valley and its attending moisture plume advects eastward into New England Tue, but with trough deamplifying, not expecting sufficient forcing for ascent to warrant widespread showers/thunderstorms. Should be more widely scattered. Hence, not a washout Tuesday with many hours of dry weather likely. Continued warm Tue but more humid, with dew pts creeping up to 65-70. Deamplifying mean trough moves offshore Wed, with rising heights into SNE Thu, supporting mainly dry weather. Ensembles have 591 heights over SNE by Thu, signaling warmer (85-90) and increasing humidity with developing SW flow. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... Forecast Confidence Levels: Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 11z update...showers and scattered thunderstorms across eastern NY/western New England at 11z weaken upon moving east this morning. New storms fire this afternoon around 18z across eastern NY into western New England, then slowly moving east this afternoon but weakening as storm enter RI and eastern MA late. Strongest storms across CT into western-central MA 18z-21z. IFR/LIFR this morning lifts and improves to MVFR/VFR this afternoon. Earlier discussion below. --------------------------------------------------------------- Today...Moderate confidence. VFR across most of southern New England with areas IFR towards the Cape and islands. Low risk for IFR at Boston between 12-15Z, but favoring the lower clouds remaining just offshore of the terminal. Visibility will increase later this morning for Cape Cod and Nantucket, but low clouds will keep it IFR for most of the day. Thunderstorms are possible mainly across the western terminals this afternoon. Light and variable winds mainly out of the SSE, with pockets of a more easterly wind along the east coast at times. Tonight and Saturday...Moderate confidence. Mainly MVFR/IFR in showers and isolated thunderstorms into Saturday morning. Drying out late Saturday morning into the afternoon as a cold front moves offshore. VFR develops from W to E behind this front. Light and variable winds tonight becoming light west during Saturday morning into the afternoon. KBOS TAF...Moderate confidence in TAF. KBDL TAF...Moderate confidence in TAF. Outlook /Saturday Night through Tuesday/... Saturday Night through Monday Night: VFR. Tuesday: VFR. Slight chance SHRA. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. High confidence overall. Lower confidence on coverage of fog across the waters. Rather tranquil boating conditions expected across the waters through Saturday. Areas of fog with visibility reduced less than 1 nm expected this morning across the eastern MA coastal waters, including those around the Cape and islands. After some improvement during the day today, should see a period this evening with reduced visibility once more. Visibility finally improves late tonight into Saturday as a cold front moves offshore, bringing drier air over the coastal waters. Outlook /Saturday Night through Tuesday/... Winds less than 25 kt. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && SYNOPSIS...Belk/Nocera NEAR TERM...Belk/Nash SHORT TERM...Belk LONG TERM...Nocera AVIATION...Belk/Nocera MARINE...Belk/Nocera
Hazardous Weather Outlook National Weather Service Boston/Norton MA 419 AM EDT Fri Jul 21 2023 CTZ004-MAZ004>007-012>024-026-RIZ001>008-220830- Windham CT-Northern Worcester MA-Central Middlesex MA- Western Essex MA-Eastern Essex MA-Southern Worcester MA- Western Norfolk MA-Southeast Middlesex MA-Suffolk MA- Eastern Norfolk MA-Northern Bristol MA-Western Plymouth MA- Eastern Plymouth MA-Southern Bristol MA-Southern Plymouth MA- Barnstable MA-Dukes MA-Nantucket MA-Northern Middlesex MA- Northwest Providence RI-Southeast Providence RI-Western Kent RI- Eastern Kent RI-Bristol RI-Washington RI-Newport RI-Block Island RI- 419 AM EDT Fri Jul 21 2023 This Hazardous Weather Outlook is for northern Connecticut, central Massachusetts, eastern Massachusetts, northeastern Massachusetts, southeastern Massachusetts, and Rhode Island. .DAY ONE...Today and tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. ANZ230>237-250-251-254>256-220830- Boston Harbor-Cape Cod Bay-Nantucket Sound-Vineyard Sound- Buzzards Bay-Rhode Island Sound-Narragansett Bay-Block Island Sound- Coastal waters east of Ipswich Bay and the Stellwagen Bank National Marine Sanctuary-Massachusetts Bay and Ipswich Bay- Coastal waters from Provincetown MA to Chatham MA to Nantucket MA out 20 nm- Coastal Waters extending out to 25 nm South of Marthas Vineyard and Nantucket- Coastal Waters from Montauk NY to Marthas Vineyard extending out to 20 nm South of Block Island- 419 AM EDT Fri Jul 21 2023 This Hazardous Weather Outlook is for Massachusetts and Rhode Island coastal waters. .DAY ONE...Today and tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. CTZ002-003-MAZ002-003-008>011-220830- Hartford CT-Tolland CT-Western Franklin MA-Eastern Franklin MA- Western Hampshire MA-Western Hampden MA-Eastern Hampshire MA- Eastern Hampden MA- 419 AM EDT Fri Jul 21 2023 This Hazardous Weather Outlook is for northern Connecticut and western Massachusetts. .DAY ONE...Today and tonight. A few strong to severe thunderstorms are possible this afternoon and early evening. The main threats are damaging winds, flash flooding and large hail. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Hazardous weather is not expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation will likely be needed. For more information on upcoming hazardous weather, please see the Area Forecast Discussion on our webpage for the latest forecast thinking. There is also our Enhanced Hazardous Weather Outlook at www.weather.gov/box/ehwo For the latest updates...please visit our webpage at www.weather.gov/boston You can follow us on Facebook at www.facebook.com/NWSBoston You can follow us on Twitter at @NWSBoston
Special Weather Statement
National Weather Service Boston/Norton MA
1256 PM EDT Fri Jul 21 2023
MAZ002-003-008-211800-
Western Franklin MA-Western Hampshire MA-Eastern Franklin MA-
1256 PM EDT Fri Jul 21 2023
...A strong thunderstorm will impact portions of northwestern
Hampshire and central Franklin Counties through 200 PM EDT...
At 1256 PM EDT, Doppler radar was tracking a strong thunderstorm over
Goshen, or 11 miles northwest of Northampton, moving northeast at 15
mph.
HAZARD...Winds in excess of 30 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Strong winds could cause minor damage such as downed
branches. Little to no impact from hail is expected.
Locations impacted include...
Greenfield, Orange, Deerfield, Montague, Sunderland, Northfield,
Williamsburg, Bernardston, Buckland, Conway, Shelburne, Leverett,
Erving, Ashfield, Colrain, Gill, Whately, Charlemont, Chesterfield
and Worthington.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Get indoors when you hear thunder. Do not resume outdoor activities
until at least 30 minutes after the storm has passed.
&&
LAT...LON 4260 7285 4273 7255 4257 7229 4237 7293
TIME...MOT...LOC 1656Z 240DEG 13KT 4245 7283
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH
BWSpecial Weather Statement
National Weather Service Boston/Norton MA
155 PM EDT Fri Jul 21 2023
CTZ002-003-MAZ009>011-211900-
Hartford CT-Tolland CT-Western Hampden MA-Eastern Hampden MA-
Eastern Hampshire MA-
155 PM EDT Fri Jul 21 2023
...A strong thunderstorm will impact portions of northwestern
Tolland, northern Hartford, southeastern Hampshire and south central
Hampden Counties through 300 PM EDT...
At 155 PM EDT, Doppler radar was tracking a strong thunderstorm over
Canton, or 12 miles west of Windsor, moving northeast at 25 mph.
HAZARD...Winds in excess of 40 mph and penny size hail.
SOURCE...Radar indicated.
IMPACT...Strong winds could cause minor damage such as downed
branches. Minor damage to outdoor objects is possible.
Locations impacted include...
Springfield, Hartford, West Hartford, Bristol, Chicopee, Enfield,
Westfield, Holyoke, Windsor, Agawam, West Springfield, South Windsor,
Farmington, Simsbury, Bloomfield, Avon, South Hadley, Longmeadow,
Suffield and East Longmeadow.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Get indoors when you hear thunder. Do not resume outdoor activities
until at least 30 minutes after the storm has passed.
A Severe Thunderstorm Watch remains in effect until 800 PM EDT for
northern Connecticut...and western Massachusetts.
&&
LAT...LON 4181 7295 4184 7294 4185 7295 4189 7294
4190 7291 4197 7289 4197 7297 4223 7256
4196 7237 4167 7299 4180 7302
TIME...MOT...LOC 1755Z 231DEG 23KT 4190 7291
MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH
BWThe Albany radar (KENX), 112 km away, was scanning. The volume nearest the first event began at 17:57 UTC.
34 flash flood, 6 thunderstorm wind, 2 lightning, 1 hail. Local standard time, as filed.
In Conway, there was a flooded basement on Maple St with 2 feet of water and rising.
In Conway, there was a flooded basement on River St.
In Greenfield, there was significant street flooding on sections of High St and Hastings Rd.
In Conway, there was significant street flooding on Main Poland rd.
In Conway, the South River was overflowing its banks and flooded Rt 116, starting to wash out the road.
In Conway, there was significant flooding of Upper Baptist Rd and runoff was flowing into a residence.
In Deerfield, a section of Stillwater Rd was washed out.
In Conway, Rt 116 was closed at the Deerfield town line.
In Orange, Dexter St had significant flooding.
In Deerfield, Lower Rd was closed and 14 feet of the road collapsed. A car fell into the washed out portion and the occupant was rescued.
In Conway, Adams Rd was washed out.
In Conway, downtown was flooded up through the first floor of buildings.
In Townsend, a tree was down on wires on Barker Hill Road near Turnpike Road. Report relayed by amateur radio.
In Hubbardston, there was urban flooding with a car stuck in floodwaters.
In Leominster, both lanes of Rt 2 were closed.
In Lowell, a Jeep was stuck in street flooding on Wellman Ave.
In Billerica, Rogers St bridge was closed due to street flooding.
In Groton, a tree was down on Chicopee Row. Trees and wires were down near Hollis Street.
In Westford, there were 4 inches of water in a basement with 6-12 inches of flooding in a driveway on Polley Rd.
In Dracut, Troll Brook Ln was flooded with a sinkhole in the yard of a residence.
In Lowell, Douglas Rd was flooded to 3 feet.
In Billerica, Mt Pleasant St at the MBTA bridge was closed due to flooding with a car stuck.
In Greenfield, Rt 2 was closed at Adams Rd.
In Greenfield, a tree and wires were down on South Shelburne Road. Report relayed by amateur radio.
In Deerfield, two trees were down on River Road, north of Hillside Road.
In Holyoke, nickel size hail was reported.
In Oxford, a lightning strike caused damage to the electrical system of a house on Hillcrest Drive.
In Holliston, there was signficant basement flooding on Wedgewood Dr.
In East Brookfield, trees and wires were down on Shore Road. Report relayed by amateur radio.
In North Brookfield, a tree was down on Ayers Street. Report relayed by amateur radio.
In Chelsea, Spruce St at Everett St was flooded and closed.
In Revere, there was significant street flooding on part of Reservoir Ave near Prospect Ave. Multiple basements were flooded.
In Ashland, two cars were stuck in flood waters on Chestnut St at Rosebay Dr.
In Watertown, a car was stuck in flooding at School St and Spruce St.
In Revere, multiple cars were stuck in street flooding on Rt 1.
In Chelsea, there was significant street flooding on Rt 1 near Carter St.
In Wellesley, Rt 9 was flooded.
In Wellesley, lightning struck a tree on Schaller Street, igniting it, per Police Twitter account.
In Chelsea, several basements were flooded on Garfield and Columbus Aves.
In Cambridge, there was major flooding on the corner of Green St and Western Ave.
In Belmont, Washington St was flooded and impassable.
In West Roxbury, Spring St was closed due to flooding.
In Everett, there was flooding at 3rd St on the Chelsea line. Multiple vehicles were stranded due to flooding with trapped occupants. Water rescues were done.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Massachusetts in 2023Every state in 2023This day in weather historyWarnings in Massachusetts, July 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: 1118120, 1118121, 1118122, 1118123, 1118124, 1118125, 1118126, 1118127, 1118128, 1118129, 1118130, 1118131, 1109144, 1118132, 1118133, 1118134, 1118135, 1109146, 1118136, 1118137, 1118138, 1118139, 1118141, 1109135, 1109138, 1109134, 1109152, 1118142, 1109156, 1109161, 1118119, 1118143, 1118144, 1118145, 1118146, 1118147, 1118148, 1109150, 1118149, 1118150, and more.