A mid-level short wave trough combined with an approaching cold front and a warm, humid environment to produce severe thunderstorms and flash flooding across MA and northern RI during the afternoon and evening hours. A Flash Flood Emergency occurred in the Norwood, MA area.
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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 mid-level short wave trough combined with an approaching cold front and a warm, humid environment to produce severe thunderstorms and flash flooding across MA and northern RI during the afternoon and evening hours. A Flash Flood Emergency occurred in the Norwood, MA area.
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 Jun 28, 9:01 AM EST, 3 hours 28 minutes earlier.
Area Forecast Discussion National Weather Service Boston/Norton MA 1001 AM EDT Sun Jun 28 2020 .SYNOPSIS... Warm and humid weather ahead of an upper-level disturbance will spark showers and thunderstorms later today. Strong to severe storms are possible. Slightly below normal temperatures along with pop-up afternoon/early evening showers during the first half of next week. Drier trend is expected for the second half of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 10 AM update... Cloud cover increasing in western MA with a few showers moving east across far N MA. Lots of sunshine across rest of SNE and expect at least partly sunny skies developing in western MA. Still plenty of MLCIN across SNE with instability axis back across central NY. As heating continues with dewpoints 65-70 the cap will erode with MLCAPES increasing to 1500-2000 J/kg this afternoon. Expect sct t-storms to increase in coverage this afternoon into this evening as mid level trough and shortwave moves into the region. Deep layer shear is marginal around 25-30 kt, but given robust instability will be enough to support some organization with potential for multicellular clusters. A few severe storms appear likely with damaging wind gusts the primary risk with any severe storms given fairly steep low level lapse rates and large theta-e diff from surface through the mid levels. Marginally severe hail is also possible with the strongest cores. Expect highs reaching mid 80s, except upper 70s along the immediate south coast. Sea breezes may also develop along east coastal MA with locally cooler temps here as well. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... A cold front will cross our region overnight, then should stall over the eastern coastal waters as a weak surface low pressure travels north along it. Looking at some more wet weather Monday, but much chance for severe weather. Onshore winds will mean lower temperatures Monday, with many areas staying below normal across eastern MA. Farther inland, temperatures should be near normal. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Highlights * Scattered to isolated diurnal shower and thunderstorm chances through midweek. Cooler than normal Tuesday, but some uncertainty on temperatures Wednesday. * Drier late in the week into next weekend. Monday night through Wednesday night... Omega block remains in place through at least the middle of the week. The ridge axis associated with the block extends roughly from the Southeastern US through the central Great Lakes and into northern Ontario. New England will have an upper low rotating over the region throughout this period. Expect daily shower and thunderstorm activity due to the upper low overhead. This will keep a -10 to -15 degree Celsius cold pool overhead at 500 hPa. The combination of the cold pool aloft with diurnal heating will result in scattered to isolated shower and thunderstorm activity. There is weak shear, generally 25 kts or less, within the 0-6 km layer during this timeframe, so storms will remain pulse like. This will result in many areas remaining dry, but there is 1 to 1.5 inches of PWATs in place. This could bring heavy rain in areas where showers/storms develop. Storms may be a bit more robust on Tuesday in comparison to Wednesday as mid level lapse rates are more supportive of stronger updrafts based on the GFS/NAM. The ECWMF/GEM guidance is not in line with the better mid level lapse rates on either day, so will need to keep an eye on things Tuesday. MUCAPE values range from a few hundred J/kg closer to the coast to 1500 J/kg in the interior. Tapered down precipitation chances during the night time hours and removed thunder chances after 06Z. The majority of the EPS members show little to no precipitation, but hard to remove precip chances completely with the upper low overhead. If there are any lingering showers leftover they will be diminishing and should be fairly light. Temperatures will be cooler than normal with onshore flow expected Monday night through Tuesday night. There is some uncertainty between the GFS and the ECMWF/GEM. The GFS keeps the onshore flow, while the ECMWF/GEM shifts flow to a southerly and westerly direction at 925 hPa. This appears to be a result of the upper low center rotating into northern New England with the ECWMF/GEM, whereas the GFS keeps it overhead. Due to the differences have stuck with the NBM guidance for temperatures. This keeps highs in the 70s across the region on Tuesday and Wednesday. There may be a few 80 degree readings across the CT River Valley. Thursday through Saturday... Upper low begins to breakdown as a jet digs from eastern Nunavut/northern Quebec and pushes the low offshore on Thursday. The upper low becomes a trough that digs offshore late on Thursday. Will still see the diurnal shower/storm chances on Thursday, but activity should be less widespread with the trough moving out. Start to see some differences amongst guidance for late in the week and into the weekend. A trough digs in from Quebec into northern New England on Friday. There are some timing and strength differences amongst guidance with the trough digging in. Will potentially see the ridge axis build into Quebec and the eastern Great Lakes, but this is dependent on the guidance. The GFS does this whereas the ECMWF/GEM keep the ridge in place over Ontario. Due to the differences this far out have kept the NBM guidance. This keeps the region drier with mild temperatures on Thursday, but a return to cooler than normal readings Friday through Saturday. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Today: High confidence in trends. Moderate confidence in timing. Fog already burning off and conditions should improve to VFR into the early afternoon. Will have scattered thunderstorms, some potentially strong to severe, will develop around mid- afternoon across the Berkshires and progress eastward towards the coast through late afternoon/early evening. Local MVFR/IFR visibility possible along with gusty winds and small hail. Have carried SHRA for now. Think the best opportunity for TSRA is after 18Z per HREF/HRRR guidance. Will save the explicit mention of TSRA until the timing is better known. Should have sea breeze develop at BOS, but otherwise winds SW 4-8 kt. Tonight: High confidence in trends. Moderate confidence in timing. Any showers and storms coming to an end generally before 04Z, but could have some lingering showers across Cape Cod. Expect fog to develop across any locations where thunderstorms slide through especially with very light winds and clearing skies. Have MVFR conditions mentioned, but think that IFR/LIFR possible across the south coast including Cape Cod and the Islands as low stratus advects in. BOS may see IFR ceilings develop toward the daybreak as winds become northeast. Monday: Moderate confidence. VFR farther inland, with MVFR/IFR towards the east coast. KBOS Terminal...High confidence in TAF trends. Moderate confidence in timing. KBDL Terminal...High confidence in TAF trends. Moderate confidence in timing. Outlook /Monday Night through Thursday/... Monday Night: Mainly MVFR, with local IFR possible. Slight chance SHRA, isolated TSRA. Tuesday: Mainly MVFR, with local VFR possible. Chance SHRA, isolated TSRA. Tuesday Night: Mainly MVFR, with local IFR possible. Chance SHRA, isolated TSRA. Wednesday: Mainly MVFR, with areas VFR possible. Chance SHRA, isolated TSRA. Wednesday Night: Mainly VFR, with areas MVFR possible. Chance SHRA, isolated TSRA. Thursday: Mainly VFR, with areas MVFR possible. Slight chance SHRA, isolated TSRA. && .MARINE... Rough seas will continue to diminish this morning. Thunderstorms are possible late this afternoon into early evening. More showers and a few thunderstorms possible Monday as a cold front stalls on the eastern coastal waters. Outlook /Monday Night through Thursday/... Monday Night through Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers, isolated thunderstorms. Tuesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers, isolated thunderstorms. Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, isolated thunderstorms. Wednesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers, isolated thunderstorms. Thursday: Winds less than 25 kt. Areas of seas approaching 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && SYNOPSIS...Belk/BL NEAR TERM...KJC SHORT TERM...Belk LONG TERM...BL AVIATION...Belk/BL MARINE...Belk/BL
Hazardous Weather Outlook National Weather Service Boston/Norton MA 444 AM EDT Sun Jun 28 2020 CTZ002>004-MAZ002>024-026-RIZ001>008-290845- Hartford CT-Tolland CT-Windham CT-Western Franklin MA- Eastern Franklin MA-Northern Worcester MA-Central Middlesex MA- Western Essex MA-Eastern Essex MA-Western Hampshire MA- Western Hampden MA-Eastern Hampshire MA-Eastern Hampden 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- 444 AM EDT Sun Jun 28 2020 This Hazardous Weather Outlook is for northern Connecticut, all of Massachusetts east of Berkshire County, and Rhode Island. .DAY ONE...Today and tonight. There is a risk for scattered strong to severe thunderstorms this afternoon and evening. The main threat will be damaging straight-line wind. Some hail is also possible. .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. ANZ230>237-250-251-254>256-290845- 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- 444 AM EDT Sun Jun 28 2020 This Hazardous Weather Outlook is for Massachusetts and Rhode Island coastal waters. .DAY ONE...Today and tonight. There is a risk for scattered strong thunderstorms this afternoon and evening. The main threat will be straight-line wind in excess of 34 kt. Some hail is also possible. .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. 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 1015 AM EDT Sun Jun 28 2020 CTZ002>004-MAZ002>021-026-RIZ001>007-282030- Hartford CT-Tolland CT-Windham CT-Western Franklin MA- Eastern Franklin MA-Northern Worcester MA-Central Middlesex MA- Western Essex MA-Eastern Essex MA-Western Hampshire MA- Western Hampden MA-Eastern Hampshire MA-Eastern Hampden 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-Northern Middlesex MA- Northwest Providence RI-Southeast Providence RI-Western Kent RI- Eastern Kent RI-Bristol RI-Washington RI-Newport RI- Including the cities of Hartford, Windsor Locks, Union, Vernon, Putnam, Willimantic, Charlemont, Greenfield, Orange, Barre, Fitchburg, Framingham, Lowell, Lawrence, Gloucester, Chesterfield, Blandford, Amherst, Northampton, Springfield, Milford, Worcester, Foxborough, Norwood, Cambridge, Boston, Quincy, Taunton, Brockton, Plymouth, Fall River, New Bedford, Mattapoisett, Ayer, Foster, Smithfield, Providence, Coventry, West Greenwich, East Greenwich, Warwick, West Warwick, Bristol, Narragansett, Westerly, and Newport 1015 AM EDT Sun Jun 28 2020 ...A FEW STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON ACROSS SOUTHERN NEW ENGLAND... Scattered thunderstorms are expected to develop and increase in coverage this afternoon into this evening, and a few of the stronger storms may become severe. The primary risk will be damaging wind gusts and dangerous lightning, but large hail is also possible with the strongest storms. The greatest risk for strong to severe thunderstorms will be away from the south coast. The time of greatest concern is between 3 and 8 pm. Keep an eye to the sky and seek a safe indoor shelter if thunderstorms approach.
Special Weather Statement National Weather Service Boston/Norton MA 1251 PM EDT Sun Jun 28 2020 MAZ005-014-281730- Central Middlesex County MA-Southeast Middlesex MA- 1251 PM EDT Sun Jun 28 2020 ...STRONG THUNDERSTORM IN MIDDLESEX COUNTY... At 1249 PM EDT, Doppler radar was tracking a strong thunderstorm over Sudbury and Maynard, moving east at 20 mph. Pea size hail and winds in excess of 30 mph will accompany this storm. Locations impacted include... Cambridge, Somerville, Framingham, Waltham, Malden, Medford, Arlington, Marlborough, Woburn, Watertown, Lexington, Belmont, Burlington, Wilmington, Stoneham, Winchester, Hudson, Concord, Sudbury and Bedford. 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 4239 7107 4233 7148 4241 7151 4253 7114 TIME...MOT...LOC 1649Z 247DEG 19KT 4240 7139 Field
Special Weather Statement
National Weather Service Boston/Norton MA
110 PM EDT Sun Jun 28 2020
MAZ008-009-281800-
Western Hampshire MA-Western Hampden MA-
110 PM EDT Sun Jun 28 2020
...STRONG THUNDERSTORMS DEVELOPING...
At 109 PM EDT, Doppler radar was tracking a strong thunderstorm over
Pittsfield, moving southeast at 15 mph.
Pea size hail and winds in excess of 30 mph will accompany this
storm.
Locations impacted include...
Williamsburg, Huntington, Russell, Westhampton, Chester, Blandford,
Chesterfield, Worthington, Goshen, Cummington, Montgomery and
Middlefield.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Get indoors when this storm approaches. Winds may be strong enough to
produce minor damage, such as a few downed branches.
Frequent lightning and heavy rain were occurring. Lightning can
strike far away from the storm. Go inside a building or vehicle.
Wait at least 30 minutes until after the storm has passed to resume
outdoor activities.
&&
LAT...LON 4238 7307 4239 7305 4238 7301 4250 7298
4240 7272 4216 7290 4222 7302 4225 7300
4231 7300 4231 7303 4233 7306
TIME...MOT...LOC 1709Z 303DEG 15KT 4247 7321
ChaiSpecial Weather Statement
National Weather Service Boston/Norton MA
119 PM EDT Sun Jun 28 2020
MAZ005-007-013>016-019-281800-
Eastern Essex MA-Eastern Plymouth MA-Suffolk MA-Western Norfolk MA-
Central Middlesex County MA-Eastern Norfolk MA-
Southeast Middlesex MA-
119 PM EDT Sun Jun 28 2020
...STRONG THUNDERSTORM...
At 118 PM EDT, Doppler radar was tracking a strong thunderstorm over
Watertown, moving east at 25 mph.
Penny size hail and winds in excess of 40 mph will accompany this
storm.
Locations impacted include...
Boston, Cambridge, Quincy, Lynn, Newton, Somerville, Waltham, Malden,
Brookline, Medford, Weymouth, Revere, Arlington, Everett, Woburn,
Braintree, Chelsea, Watertown, Lexington and Needham.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Get indoors when this storm approaches. Winds may be strong enough to
produce minor damage, such as a few downed branches.
Frequent lightning was occurring. Lightning can strike far away from
the storm. Go inside a building or vehicle. Wait at least 30 minutes
until after the storm has passed to resume outdoor activities.
&&
LAT...LON 4245 7094 4245 7096 4242 7091 4244 7097
4236 7097 4237 7104 4230 7105 4230 7093
4225 7088 4233 7093 4234 7088 4226 7087
4224 7076 4217 7077 4228 7130 4246 7126
TIME...MOT...LOC 1718Z 281DEG 20KT 4236 7119
ChaiThe Boston radar (KBOX), 44 km away, was scanning. The volume nearest the first event began at 17:27 UTC.
24 flood, 21 thunderstorm wind, 7 hail, 7 flash flood. Local standard time, as filed.
In Newton, a tree and power lines were down on Highland Avenue.
Quarter size hail was reported in Watertown Square.
Flooding reported on Howard Street with one of the manhole covers starting to float.
In Waltham, Main Street from Beal Road to Bowker Rod was flooded and impassable.
In Newton, a tree was down blocking Lewis Terrace at Washington Street. A second tree and wires were down in the same area.
In Newton, urban flooding caused two cars to have to be removed from flood waters near 100 Walnut Street. Also, Adams Street was flooded and impassable from Watertown Street (Route 16) to Cottage Court.
In Woburn, there was flooding at the corner of Olympia Avenue and Wildwood Avenue.
In Newton at 1250 PM EST (150 PM EDT), police responded to a report of a tree down at the intersection of Charlesbank Road and Nonantum Road. At the same time, a tree was reported down on Border Street in West Newton. On Pleasant Street, a tree was down against a house, with wires also down. At 1253 PM EST (153 PM EDT), a tree and power lines were down on Carver Road near Newton Highlands.
In Brookline, at 1259 PM EST (159 PM EDT), a tree was down onto a building on Perry Street. At 101 PM EST (201 PM EDT), a tree was down on the 200 block of Walnut Street.
Dime size hail was reported in Jamaica Plain.
At 1 PM EST (2 PM EDT), power lines were reported down on Calumet Street in the Roxbury section of Boston.
In Revere, a large tree branch was down on top of a vehicle on Reservoir Avenue.
In Roxbury, Cedar street was flooded for 3 to 4 blocks due to a catch basin.
In Brookline, Warwick Road at Beacon Street was closed due to flooding.
In Brighton, street flooding was reported at the 90 block of Strathmore Road.
In Boston, a tree fell onto the road near the Green Line MBTA outbound tracks near Huntington Avenue.
In Hull, a tree was downed on Atlantic Avenue near the baseball field.
In Hingham, a large tree branch was down on Rockland Street and Martins Lane.
In Cohasset, a tree was down on Jerusalem Road and another tree was down at the intersection of Joy Place and North Main Street.
In Quincy, a tree was down at Perley Place.
In Holyoke, flooding was reported at the intersection of Commercial Street and Sargeant Street.
Half dollar size hail was reported in Northampton.
Ping Pong ball size size hail lasted for two minutes. Reported by the public and forwaded by both amateur radio and broadcast media.
In Milton, a tree and wires were down on Randolph Avenue (Route 28).
Media reported quarter size hail in Norwood.
At 340 PM EST (440 PM EDT) a section of Route 1 was flooded with up to 1 foot of water. At 346 PM EST, Broadway was reported to be flooded and impassable. At 402 PM EST, four feet of water was reported in the basement of Norwood Hospital.
Quarter size hail was reported in Franklin.
In the southern part of Norwood, Landsdowne Way was flooded and impassable.
The public, supported by videos, reported hen egg size (2 inch diameter) hail, which was preceded by a 15-minute period of pea size hail.
In Wilbraham, a large tree and wires were down on Mountain Road.
In Stoughton, flooding was reported on Pearl Street.
In Canton, a large tree was down on Elm Street.
A Flash Flood emergency occurred, with considerable damage in the vicinity of Norwood Hospital. Severe flooding, more than 4 feet deep, occurred in the basement of the hospital. The entire pharmacy inventory was destroyed. One hundred patients had to be evacuated. Numerous cars were submerged in the parking lot, which, albeit, is in a 'bowl' not designed with flooding in mind. Damage to the hospital was estimated at $20,000,000. In addition, emergency management officials said that approximately 250 homes suffered flood damage.
A car was stuck in flood waters on East Street.
In Norfolk, trees and wires were reported down on Kingsbury Road.
In Westwood, a large tree was down on Oak Street.
In the Whitinsville section of Northbridge, flash flooding occurred, with 3 feet of water on Cross Street near East Street.
In Walpole, wires were down on Bullard Street.
In Avon, a tree was down on North Main Street.
In Brockton, flash flooding on West Street caused manhole covers to pop off.
In Northbridge, there was flooding on Church Street with road impassable.
In Brockton, a tree and wires were down on Ridge Street, on Spark Street, and on Circle Street.
In Hopedale, flooding was reported at the intersection of Adin Street and Mendon Street (Route 16).
In Wrentham, there was flooding of a finished basement on Martin Lane.
In Abington, two trees were down on Davis Street...one of them landing on a house and a car.
In Brockton, a Jeep was stuck in flood waters on Torrey Street at Calvin Street. A car was stuck in flood waters on Ames Street.
In Uxbridge, a tree was down on Paine Street.
In Northbridge, multiple backyards and basements were flooded on both Brook Street and on Douglas Road. Two apartments were flooded on Willow Street.
In Wrentham, there was a report of a flooded basement on Chestnut Street.
In Franklin, a portion of Brook Street was flooded and impassable.
In Franklin, a basement was flooded on Washington Street.
In Blackstone, two cars were stuck in flood waters on Rathbun Street. Roadway was impassable.
In North Attleboro, roadway flooding was reported at Landry Avenue and Kelley Blvd. (Route 152).
In Uxbridge, many sections of Quaker Highway (Route 146A) were flooded, with debris across the road. Also, Route 122 was flooded, with rocks in the road.
In Franklin, a flooded basement was reported on Jordan Road. Street flooding was reported on Sargent Lane at Dartmouth Road.
In Gardner, there were many areas of flooding. There was one foot of water on a section of Route 2A at 618 PM EST. A car was stuck in flooding on Timpany Blvd. at 643 PM EST. Chestnut Street at Union Square was flooded and impassable at 648 PM EST. A basement was flooded on Dean Street at 658 PM EST.
Flooding on Fleetwood Drive cause flooding into the basement of a home on Rockwood Road (Route 115).
A car was stuck in flooding on Princeton Road on the Princeton Road Bridge.
A car was stuck in flood waters three feet deep on West Boylston Street, in an area that typically receives flooding.
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, June 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: 897342, 897325, 897549, 897552, 897345, 897557, 897558, 897346, 897373, 897326, 897380, 897396, 897616, 897617, 897618, 897415, 897416, 897417, 897418, 897503, 897622, 897328, 897329, 897508, 897331, 897771, 897333, 897773, 897339, 897511, 897775, 897513, 897824, 897820, 897516, 897518, 897825, 897520, 897522, 897826, and more.