A warm front moved slowly northward across southern New England during the day, reaching the Mass Pike late in the day. This provided the focus for a few severe thunderstorms in western and central Massachusetts during the early evening hours.
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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 moved slowly northward across southern New England during the day, reaching the Mass Pike late in the day. This provided the focus for a few severe thunderstorms in western and central Massachusetts during the early evening hours.
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 22, 5:53 PM EST, 3 minutes earlier.
Area Forecast Discussion National Weather Service Boston/Norton MA 653 PM EDT Wed Jul 22 2020 .SYNOPSIS... Oppressive humidity returns into Thursday as a warm front moves across the area tonight. Scattered thunderstorms possible this afternoon into early evening across western portions of Massachusetts and Connecticut. More widespread thunderstorms possible Thursday ahead of a cold front. Isolated thunderstorms will be possible Friday, otherwise expect warm and humid weather for Friday and the weekend. Two more cold fronts move through on Monday and Tuesday, bringing scattered thunderstorms. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... * Severe Thunderstorm Watch in effect until 10 PM across western MA and Hartford County CT 7 PM Update... Showers/Tstms moving through western MA. Svr tstm watch in place through 10 PM. Several good cores have been observed on radar, so potential for svr tstms remains in place. Observations show dew points 70-75 across SE MA, RI, CT and Western MA. Per wind directions, would place warm front north of Springfield/south of Worcester, north of Providence, south of Norwood and Marshfield. Warm front will slowly move north during the night. Also noting area of fog/stratus along the RI coast and Srn Ma coast. Expect this to continue for at least a part of the night. Fog should also move back into Nantucket tonight. No changes to the forecast are planned at this time. Previous discussion... A warm front was trying to move north across southern New England. As of mid afternoon, this front was generally near the Mass Pike, and will take most of the evening to reach northern New England. South of this front, dew points are expected to reach into the 70s. It will feel somewhat tropical tonight, which will also prevent temperatures from falling much. Most of the region expected to have above normal low temperatures in the upper 60s to lower 70s. There is some concern for isolated severe thunderstorms across western MA into this evening. Effective bulk shear was 30-40 kt already across much of southern New England. The limiting factor thus far has been instability. The greatest instability will remain southwest of our region into this evening, well south of the warm front. However, a few storms could produce damaging winds, small hail and downpours. Those with outdoor plans this evening in and near the watch area should remain alert for thunderstorms approaching their location. Mid level lapse rate are poor, and the mid levels rather warm. While thunderstorms may continue past sunset, the threat of severe weather is expected to diminish rather quickly. The higher dewpoints will also lead to another round of marine stratus and fog towards the south coast of New England, especially after midnight. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... Southern New England should be well within the warm sector by Thursday morning. High humidity continues, which will set the stage for a more widespread round of showers and thunderstorms as a cold front arrives from the west. It will be warmer and more humid Thursday compared to today, so will also need to be concerned with the risk for a few strong to severe thunderstorms during the afternoon and evening hours. This cold front is expected to reach the south coast of New England towards daybreak Friday. Until this front passes, will maintain at least a risk for showers. Above normal temperatures continue. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Big Picture... Zonal flow across Canada which dips over Northern New England and clips Southern New England. Shortwaves in the flow move across Southern New England Friday, possibly Saturday, and next Wednesday. There are signs of other shortwaves moving through during the long term period, as is typical of zonal flow. Heights at 500-mb over Southern New England are forecast in the mid to upper 580s, which is above normal, through the weekend. Heights then trend through the lower 580s early next week and the 570s midweek. Expect warmer than normal temperatures much of the period, trending lower during next week. Confidence is moderate-high through Sunday, then trends to low-moderate by Tuesday- Wednesday. Details... Friday... Upper shortwave and accompanying jet move offshore during the morning. The position of the jet may allow some convection along the South Coast during the morning, but this moves offshore. Weak surface pressure pattern, with signs it will support a sea breeze flow along the Eastern MA coast. SB-CAPE reaches 500-1000 J/Kg on the GFS while the NAM shows 1000-2000 J/Kg, both focused over Western/Central Mass/Northern CT/RI. PW values are 1 to 1.5 inches north of the Pike, around 1.5 inches in the south. Sufficient instability to support scattered afternoon/evening convection. Mixing to at least 825 mb...temps at that level roughly 13-15C, supporting sfc max temps 85 to 90. Cooler temps in the sea breeze in Eastern MA. Saturday and Sunday... High pressure over the Midwest builds east, bringing increasing subsidence to New England Saturday. This pattern then retreats west on Sunday. Northwest flow aloft. Expect dry weather during this period with mixing reaching to 825 mb Saturday and 850 mb Sunday. Temps aloft support 85-90 Saturday and upper 80s to low 90s Sunday. Monday through Wednesday... Shortwaves move through on Monday and Tuesday, along with corresponding upper jets and surface cold fronts. Stability parameters become favorable for convection, with CAPE at 1000-1500 J/Kg each day and LI subzero. Expect scattered showers/thunder each afternoon/evening. Temps aloft Monday will be 18-20C, lowering to 15-16C Wednesday. Will forecast highs in the upper 80s to mid 90s Monday, lowering to the mid 80s Wednesday. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight...Moderate confidence. Mainly VFR inland, lowering to MVFR during the night. Areas IFR along the south coast in marine stratus. Scattered showers and thunderstorms, mainly across western MA and northwest CT during the evening hours. Thursday...Moderate confidence. MVFR to areas of IFR towards the south coast of New England in marine stratus and isolated thunderstorms in the morning. Improvement to VFR by late morning. Areas of MVFR in thunderstorms associated with a cold frontal passage from the afternoon into early evening hours. Thursday Night...Moderate confidence. Mainly VFR. Areas MVFR in thunderstorms, mainly during the evening hours. KBOS Terminal...Moderate confidence in TAF. KBDL Terminal...Moderate confidence in TAF. Outlook /Friday through Monday/... Friday: Mainly VFR, with areas MVFR possible. Slight chance SHRA, isolated TSRA. Friday Night: Mainly VFR, with areas IFR possible. Patchy BR. Saturday: VFR. Saturday Night: Mainly VFR, with local IFR possible. Sunday through Sunday Night: VFR. Breezy. Monday: Mainly VFR, with local MVFR possible. Slight chance SHRA, isolated TSRA. && .MARINE... Winds and seas remain below Small Craft Advisory criteria through Thursday night. A warm front will continue to move north during the night. Increasing humidity will lead to areas of fog on the southern coastal waters with visibility likely reduced to 1 NM or less, especially late tonight. A cold front brings the risk for thunderstorms Thursday afternoon into evening. Outlook /Friday through Monday/... Friday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers, isolated thunderstorms, patchy fog. Local visibility 1 to 3 nm. Friday Night: Winds less than 25 kt. Patchy fog, slight chance of rain showers, isolated thunderstorms. Visibility 1 to 3 nm. Saturday: Winds less than 25 kt. Patchy fog. Areas of visibility 1 to 3 nm. Saturday Night: Winds less than 25 kt. Sunday: Winds less than 25 kt. Seas locally approaching 5 ft. Sunday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Monday: Winds less than 25 kt. Seas locally approaching 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && SYNOPSIS...WTB/Belk NEAR TERM...WTB/Belk SHORT TERM...Belk LONG TERM...WTB AVIATION...WTB/Belk MARINE...WTB/Belk
Hazardous Weather Outlook National Weather Service Boston/Norton MA 446 PM EDT Wed Jul 22 2020 CTZ003-004-MAZ004>007-012>024-026-RIZ001>008-232100- Tolland CT-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- 446 PM EDT Wed Jul 22 2020 This Hazardous Weather Outlook is for northern Connecticut, central Massachusetts, eastern Massachusetts, northeastern Massachusetts, southeastern Massachusetts, and Rhode Island. .DAY ONE...Tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Scattered thunderstorms Thursday with a few strong to severe storms possible. Damaging winds, large hail and localized flooding are the main concerns. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. ANZ230>237-250-251-254>256-232100- 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- 446 PM EDT Wed Jul 22 2020 This Hazardous Weather Outlook is for Massachusetts and Rhode Island coastal waters. .DAY ONE...Tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. CTZ002-MAZ002-003-008>011-232100- Hartford CT-Western Franklin MA-Eastern Franklin MA- Western Hampshire MA-Western Hampden MA-Eastern Hampshire MA- Eastern Hampden MA- 446 PM EDT Wed Jul 22 2020 ...SEVERE THUNDERSTORM WATCH 394 IN EFFECT UNTIL 10 PM EDT THIS EVENING... This Hazardous Weather Outlook is for northern Connecticut and western Massachusetts. .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. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Scattered thunderstorms Thursday with a few strong to severe storms possible. Damaging winds, large hail and localized flooding are the main concerns. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. 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/us.nationalweatherservice.boston.gov You can follow us on Twitter at @NWSBoston
Special Weather Statement
National Weather Service Boston/Norton MA
543 PM EDT Wed Jul 22 2020
MAZ002-003-008-009-222230-
Western Franklin MA-Western Hampshire MA-Western Hampden MA-
Eastern Franklin MA-
543 PM EDT Wed Jul 22 2020
...STRONG THUNDERSTORM...
At 543 PM EDT, Doppler radar was tracking a strong thunderstorm over
Middlefield, or 14 miles east of Pittsfield, moving northeast at 25
mph.
Pea size hail and wind gusts up to 50 mph will accompany this storm.
Locations impacted include...
Deerfield, Sunderland, Williamsburg, Huntington, Buckland, Conway,
Shelburne, Ashfield, Whately, Chester, Charlemont, Chesterfield,
Worthington, Goshen, Cummington, Heath, Plainfield, Middlefield and
Hawley.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Get indoors when this storm approaches. Winds may be strong enough to
produce minor damage, such as a few downed branches.
&&
LAT...LON 4238 7307 4239 7305 4238 7301 4253 7297
4266 7279 4247 7254 4228 7300 4231 7300
4231 7303
TIME...MOT...LOC 2143Z 236DEG 22KT 4240 7300
BWSpecial Weather Statement
National Weather Service Boston/Norton MA
549 PM EDT Wed Jul 22 2020
MAZ003-004-008>011-222245-
Western Hampshire MA-Western Hampden MA-Eastern Hampden MA-
Eastern Franklin MA-Northern Worcester MA-Eastern Hampshire MA-
549 PM EDT Wed Jul 22 2020
...STRONG THUNDERSTORM MOVING INTO THE SPRINGFIELD METRO AREA...
At 547 PM EDT, Doppler radar was tracking a strong thunderstorm over
Westfield, moving northeast at 25 mph.
Hail up to dime size and winds in excess of 40 mph will accompany
this storm. Expect brief torrential downpours and cloud to ground
lightning to also accompany this storm.
Locations impacted include...
Springfield, Chicopee, Westfield, Holyoke, Amherst, Northampton,
Agawam, West Springfield, Deerfield, Ludlow, South Hadley,
Easthampton, Belchertown, Ware, Southwick, Montague, Granby,
Southampton, Hadley and Sunderland.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Get indoors when this storm approaches. Winds may be strong enough to
produce minor damage, such as a few downed branches.
These storms may intensify and become capable of producing damage.
Stay tuned for updated statements and possible warnings.
&&
A Severe Thunderstorm Watch remains in effect until 1000 PM EDT for
northern Connecticut...and western Massachusetts.
LAT...LON 4254 7252 4233 7221 4203 7268 4204 7270
4218 7293
TIME...MOT...LOC 2147Z 224DEG 23KT 4216 7271
LocontoSpecial Weather Statement National Weather Service Boston/Norton MA 645 PM EDT Wed Jul 22 2020 MAZ003-004-010-011-222330- Eastern Hampden MA-Eastern Franklin MA-Northern Worcester MA- Eastern Hampshire MA- 645 PM EDT Wed Jul 22 2020 ...STRONG THUNDERSTORM MOVING INTO FAR SOUTHWEST WORCESTER COUNTY... At 644 PM EDT, Doppler radar was tracking a strong thunderstorm over Ludlow, or near Chicopee, moving northeast at 15 mph. Penny size hail and winds in excess of 40 mph will accompany this storm. Locations impacted include... Springfield, Chicopee, Holyoke, Amherst, Ludlow, South Hadley, East Longmeadow, Belchertown, Wilbraham, Palmer, Ware, Monson, Granby, Hadley, Hampden, West Brookfield, Hardwick, Shutesbury, Pelham and Petersham. PRECAUTIONARY/PREPAREDNESS ACTIONS... Get indoors when this storm approaches. Winds may be strong enough to produce minor damage, such as a few downed branches. These storms may intensify and become capable of producing damage. Stay tuned for updated statements and possible warnings. && A Severe Thunderstorm Watch remains in effect until 1000 PM EDT for western Massachusetts. LAT...LON 4207 7247 4218 7266 4246 7243 4229 7215 TIME...MOT...LOC 2244Z 219DEG 12KT 4219 7250 Loconto
The Albany radar (KENX), 116 km away, was scanning. The volume nearest the first event began at 22:52 UTC.
6 thunderstorm wind. Local standard time, as filed.
In Northampton, trees and power lines were down on Ryan Road and on Chestnut Street.
In Hadley, trees and wires were down on North Lane and on South Maple Street.
In Amherst, a tree and wires were downed on Pulpit Hill Road.
In Ware, several large tree branches were downed.
In West Brookfield, a funnel cloud was sighted by several emergency management officials from 5 surrounding towns. No actual tornado reached the ground. However, straight line winds downed wires on Checkered Lane.
In the Gilbertville section of Hardwick, a tree was down on wires on School Street.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Massachusetts in 2020Every state in 2020This day in weather historyWarnings in Massachusetts, July 2020
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: 908319, 908321, 908322, 908323, 908325, 908326.