Low pressure moved east from the Great Lakes. This drew warm humid air north across Massachusetts, then swung a cold front across the state.
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.
Low pressure moved east from the Great Lakes. This drew warm humid air north across Massachusetts, then swung a cold front across the state. This caused afternoon thunderstorms; the most damaging thunderstorms moved across the northern half of Massachusetts.
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 Aug 17, 9:30 AM EST, 4 hours earlier.
Area Forecast Discussion National Weather Service Boston/Norton MA 1030 AM EDT Fri Aug 17 2018 .SYNOPSIS... Scattered showers and thunderstorms are expected this afternoon into Saturday as a cold front approaches southern New England. A few strong to severe storms are possible along with localized heavy rainfall. This front moves through late Saturday and Saturday evening. A wave of low pressure is expected to develop along the front south of New England which may bring showers at times along with cooler temperatures Sunday into Monday, especially near the coast. High pressure returns Tuesday but another approaching front will bring the risk of showers and thunderstorms Tuesday night into Wednesday. Dry and seasonable weather follows Thursday as high pressure builds into the region. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... * Strong to severe thunderstorms are possible later today into this evening * Potential for localized damaging winds and flash flooding * Isolated short lived tornado possible late today and evening Fog has dissipated across the Connecticut River Valley due to surface heating. Lower ceilings continue to move into the region from the west, with the eastern edge over taking Boston by 18z. The stationary/warm front remains across central CT and RI this morning, and will slowly lift NE as the low pressure system progresses across southern Quebec. The main area of precipitation, currently just west of Albany, NY, will move into the region by 17z. Winds from the approaching system will converge with the warm front as pushes northeast, allowing for some thunderstorms to form along the boundary. SBCAPE values are already over 1000 J/kg in our western zones, and will likely increase as the warm front pushes NE, so any storms that enter our area have the potential for becoming strong to severe quickly. However, both the HRRR and the 3K NAM are showing the highest potential for convection being closer to 00z given that's when the best instability is over our area, with higher CAPE values and better shear. Increased afternoon temperatures a couple degrees after looking at ALYs 12z sounding where temperatures at 850 mb were nearing 18C. Likely that across the interior could see temperatures reaching into the upper 80s today. The eastern coast however will likely remain cooler due to winds turning out of the east later this morning. Previous discussion... Patchy fog will burn off quickly, otherwise sunshine will give way to increasing clouds from west to east this morning. Expect initial pulse of sct showers/t-storms to develop by early afternoon in the interior with a focus along the warm front. CAPES increase to 1000-2000 J/kg so a few strong storms likely. Initially, shear is weak but strengthens late today and especially this evening as low level jet develops. Various hi- res guidance sources indicating more robust convection late today into this evening. A few severe storms appear likely and given high dewpoints/low LCLs and increasing 0-1km shear, an isolated tornado can't be ruled out, especially near the warm front which will be lifting north across MA this evening. Storms will need to be monitored closely for rotation. In addition to the severe weather threat, heavy rainfall and localized flash flooding will be a concern as PWATs increasing to 2+ inches. Temps will top off in the 80s at most locations, a tad cooler across the higher inland terrain and along the coast. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Tonight...The warm front should be NE of the region this evening, which should take most of the instability with it. Could still see some strong or even a brief severe thunderstorm through the evening. However, with a mid level short wave will move across, there will still be the threat for showers and scattered thunderstorms through the night. Could still see some storms produce locally heavy downpours as PWATs remain high. Temps will only fall back to the upper 60s to mid 70s. Saturday...Showers and scattered thunderstorms linger across the region as a cold front slowly approaches. Mid level short wave moves steadily E during the day, so the front should push across the region. Decent instability lingers mainly S of the Mass Pike, so there may be some stronger thunderstorms that develop ahead of the cold front. PWATs also remain on the high side, so heavy downpours will still be possible. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Highlights... * Cooler Sun/Mon with showers at times, especially near the coast * Mainly dry Tue, then increasing risk of showers/thunderstorms Tue night/Wed * Mainly dry and seasonable Thu Saturday night into Monday... Cold front will be near the south coast Sat evening and pushing south of New Eng. Showers and t-storms assocd with the front may linger into Sat evening, especially south of the Pike within the low level theta-e axis. Model guidance continues to be more robust with trailing shortwave which moves from mid Atlc region into New Eng Sun into Mon. This will stall the front with a wave of low pres developing along it south of New Eng. The international model suite is rather robust with sfc low tracking close to New Eng with a good slug of rain late Sat night into Sun night. Meanwhile the US models are weaker and further south with the wave with just a few showers near the south coast. The trend has been a bit stronger and further north so we will increase PoPs Sun into Sun night but not quite to the extent of the ECWMF. Expect lots of clouds Sun/Sun night with some showers at times, especially near the south coast. But if the stronger and further northward trend from the ECMWF/UKMET is realized, a cool rainy day would be in store for Sunday. The low pres begins to pull away Mon but a few showers may linger, especially eastern New Eng. Much cooler day Sun with potential for temps to remain in the 60s where showers occur, but into the 70s if it stays dry. Tuesday into Thursday... Mainly dry weather Tue with weak ridging in place, but temps remaining a bit below normal with easterly flow persisting. Then risk of showers/t-storms and humidity will increase Tue night into Wed as tropical PWAT plume moves back into SNE ahead of approaching mid level trough and cold front. Consensus of long term guidance has front moving offshore by Thu which should bring dry and seasonable weather for Thu. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Saturday/... Today and Tonight...Moderate to high confidence. VFR CIGS through most of the day, but conditions lower in any heavier showers/t-storms this afternoon and tonight. Strong wind gusts and heavy downpours possible with the stronger storms. Areas of MVFR cigs developing tonight, with IFR stratus/fog for ACK. Saturday...Moderate to high confidence. Mainly VFR conditions, but will see local MVFR-IFR in showers/isolated thunderstorms with best chance from midday through the afternoon as cold front moves across. KBOS Terminal...High confidence in TAF. Light E-SE wind early, increasing to around 10 kt at midday then S this evening. Showers/isold t-storms approach during the evening push with local MVFR-IFR conditions possible. KBDL Terminal...High confidence in TAF. Outlook /Saturday Night through Tuesday/... Saturday Night: Mainly MVFR, with local IFR possible. Breezy. Chance SHRA. Sunday: Mainly MVFR, with local VFR possible. Breezy. Chance SHRA. Sunday Night: Mainly MVFR, with local VFR possible. Chance SHRA. Monday: Mainly VFR, with areas MVFR possible. Breezy. Slight chance SHRA. Monday Night: Mainly VFR, with local MVFR possible. Tuesday: Mainly VFR, with areas MVFR possible. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Saturday/...High confidence. Today...Stalled front across the waters, with E-SE winds on the eastern waters and S-SW winds across the southern waters. Winds should remain around 10 kt or less. Front lifts NE as winds shift to S-SW during the afternoon. Seas 3 ft or less. May see scattered showers/isolated thunderstorms reach the eastern waters late in the day with locally reduced visibility. Tonight...S-SW winds gusting up to 20 kt. Seas 3 feet or less. Scattered showers/t-storms, may see gusty winds and heavy rain. Reduced visibility and locally choppy seas in any showers or storms. Saturday...SW winds gusting up to 20 kt. Seas 4 ft or less. Scattered showers/isolated thunderstorms with reduced visibility and locally choppy seas. Outlook /Saturday Night through Tuesday/... Saturday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, chance of thunderstorms. Sunday through Monday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers. Monday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers. Tuesday: Winds less than 25 kt. Areas of seas approaching 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && SYNOPSIS...KJC/EVT NEAR TERM...WTB/KJC/Correia SHORT TERM...EVT LONG TERM...KJC AVIATION...WTB/KJC/Correia MARINE...KJC/EVT
Hazardous Weather Outlook National Weather Service Boston/Norton MA 345 AM EDT Fri Aug 17 2018 CTZ002>004-MAZ002>024-026-RIZ001>008-180745- 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- 345 AM EDT Fri Aug 17 2018 This Hazardous Weather Outlook is for northern Connecticut, all of Massachusetts east of Berkshire County, and Rhode Island. .DAY ONE...Today and tonight. A few strong to severe thunderstorms are possible this afternoon and evening, mainly west of the Boston to Providence corridor. The main threat is damaging wind but an isolated tornado is also possible. Heavy rainfall and localized flash flooding is also possible. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. A few strong thunderstorms are possible Saturday. The primary threats are locally heavy rainfall and gusty wind. .SPOTTER INFORMATION STATEMENT... Spotter activation will likely be needed. ANZ230>237-250-251-254>256-180745- 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- 345 AM EDT Fri Aug 17 2018 This Hazardous Weather Outlook is for Massachusetts and Rhode Island coastal waters. .DAY ONE...Today and tonight. A few strong thunderstorms are possible late today and this evening. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. A few strong thunderstorms are possible Saturday. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. 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 1229 PM EDT Fri Aug 17 2018 CTZ002>004-MAZ002>024-026-RIZ001>008-171830- 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- 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, Chatham, Falmouth, Provincetown, Vineyard Haven, Nantucket, Ayer, Foster, Smithfield, Providence, Coventry, West Greenwich, East Greenwich, Warwick, West Warwick, Bristol, Narragansett, Westerly, Newport, and New Shoreham 1229 PM EDT Fri Aug 17 2018 ...SEVERE THUNDERSTORMS ARE POSSIBLE ACROSS SOUTHERN NEW ENGLAND THIS AFTERNOON AND TONIGHT... A few severe thunderstorms are possible in Southern New England this afternoon and early tonight. Any damaging weather that forms would most likely come as strong wind gusts. There is a low chance of an isolated tornado. In addition, heavy rainfall may produce local flooding, especially in areas of poor drainage. The best chance for damaging thunderstorms will take place in Central and Western Massachusetts, Northern Connecticut, and Northwest Rhode Island. The most likely time will be from 4 PM to Midnight. Spotters should remain alert and report any observed damaging weather. wtb
Special Weather Statement
National Weather Service Boston/Norton MA
201 PM EDT FRI AUG 17 2018
MAZ003-004-010-011-171830-
Eastern Hampden MA-Northern Worcester MA-Eastern Franklin MA-
Eastern Hampshire MA-
201 PM EDT FRI AUG 17 2018
...LINE OF STRONG THUNDERSTORMS...
At 201 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Montague to near Chicopee. Movement was
east at 30 mph.
Winds in excess of 40 mph will accompany these storms along with
locally heavy rain and possibly minor flooding.
Locations impacted include...
Chicopee, Holyoke, Amherst, Northampton, Greenfield, Orange,
Deerfield, Ludlow, South Hadley, Easthampton, Belchertown, Palmer,
Athol, Ware, Montague, Granby, Barre, Hadley, Warren and West
Brookfield.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Get indoors when these storms approach. Winds may be strong enough to
produce minor damage, such as a few downed branches.
Do not drive through flooded roads or underpasses. Avoid low lying
areas near small streams.
&&
LAT...LON 4272 7212 4221 7218 4217 7264 4262 7262
4272 7229
TIME...MOT...LOC 1801Z 256DEG 27KT 4258 7249 4222 7255
NoceraThe Albany radar (KENX), 128 km away, was scanning. The volume nearest the first event began at 18:30 UTC.
3 lightning, 3 thunderstorm wind, 1 flood. Local standard time, as filed.
At 1:30 PM EST, a house fire due to lightning was reported on Barney Hale Road in Gill.
At 1:30 PM EST, a house fire due to lightning was reported near State Route 63 in Montague.
At 1:38 PM EST, a house fire due to lightning was reported at 16 Cooleyville Road in New Salem.
At 3:10 PM EST, a tree was reported down on wires at the intersection of Boston Road and Hazen Street in Chelmsford. Also at 3:10 PM EST, a tree was down on Bridge Street blocking half the road.
At 3:44 PM EST, street flooding reached a depth of two to three feet on Gorham Street in Lowell.
At 5:28 PM EST, a tree was reported down on Carver Street in Cambridge.
At 10:15 PM EST, a tree and wires were brought down on the lower part of Town Hill Road in Middlefield.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Massachusetts in 2018Every state in 2018This day in weather historyWarnings in Massachusetts, August 2018
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: 782856, 782857, 782860, 782871, 782867, 782873, 782862.