Although the best forcing for severe weather was to our west over New York state, scattered diurnal thunderstorms formed over southern New England. One caused some street flooding in northwest MA and one reached severe limits in northeast MA.
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.
Although the best forcing for severe weather was to our west over New York state, scattered diurnal thunderstorms formed over southern New England. One caused some street flooding in northwest MA and one reached severe limits in northeast MA.
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 24, 5:27 PM EST, 43 minutes earlier.
Area Forecast Discussion National Weather Service Boston/Norton MA 627 PM EDT Mon Jul 24 2023 .SYNOPSIS... Scattered thunderstorms today and Tuesday, but many hours of dry weather prevail along with seasonable temperatures and humidity. Beginning Wednesday, heat and humidity begin to build, becomes oppressive Thu and then peaks Friday. The oppressive heat and humidity breaks sometime Saturday or Sat night, with the passage of a cold front, followed by cooler and much less humid weather Sunday. This change in airmass may be preceded by scattered thunderstorms Thursday through Saturday, especially well inland. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 630 PM Update Forecast is on track so far this evening. KBOX radar is revealing a few isolated showers and thunderstorms across northeastern MA at 630 pm. These showers/storms are tracking northeast and should be out of the forecast area by 8 PM or so. No significant hazards with these storms other than lightning and brief heavy downpours. Updated the near-term forecast to reflect latest trends and observations, but otherwise no significant changes are needed. See previous discussion for more details on tonight's forecast. Previous Discussion A mid level shortwave rounding the broader trough is bringing scattered showers and thunderstorms to SNE this afternoon which will increase in coverage through early evening. While we do have ingredients for a strong to severe thunderstorm or two (CAPE around 1000 J/kg and 0-6 km shear near 30 kts) the better instability and forcing is removed to our northwest where a Severe Thunderstorm Watch remains in effect. Helping keep showers suppressed further east over RI/southeast MA is subtly rising mid level heights. For those further inland areas we'll see convection diminishing by sunset when loss of diurnal heating will help things quiet down, but can't rule out some convection overnight in western SNE, elevated above an inversion at 925 mb. Lows overnight will be limited by elevated dewpoints, in the mid to upper 60s. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Tuesday offers a better chance for more widespread convection as the mid level trough swings overhead. We'll have ample instability with CAPE values near 2000 J/kg and low level lapse rates >7.5 C/km. Bulk shear values aren't fantastic at around 30 kt, but enough to lead to sustained updrafts. Fortunately the low level shear and helicity are very low so the main threat will be from damaging winds/hail rather than tornadoes. The bulk of the shower and thunderstorm activity should occur between 12PM and 9 PM ahead of the mid level shortwave and surface cold front. Post frontal drier air then moves into the region overnight with PWATs dropping from 1.5 inches to <1 inch in some locations. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Highlights * Heat wave Wednesday through perhaps Saturday with 90+ degree high temperatures each day * Strong to severe thunderstorms a possibility late Thursday and again late Friday or Saturday afternoon * Trending cooler by the second half of the weekend Wednesday First significant heat wave of the summer will kickoff on Wednesday as a pronounced Bermuda High supports deep southwest flow over The Northeast. 850 hPa temps rise above 15 Celsius on Wednesday afternoon, and with clear skies and deep mixing likely, we should see our first round of 90 degrees temperatures Wednesday afternoon with highs in the low 90s forecast in the CT River Valley and over the coastal plain. High pressure and a dry column should support mostly sunny skies for much of the day Wednesday with only a few diurnal cu clouds expected by the afternoon. Thursday and Friday Local high pressure shifts east by Thursday and allows a surge of moisture into southern New England with dewpoints climbing into the low to mid 70s across southern New England. Afternoon highs expected to jump up a few degrees on Thursday with widespread low 90s and maybe a few locations getting as high as 94 degrees. With dewpoints in the low 70s, heat indices will be approaching 100 degrees. Some local relief may be possible Thursday night with a potential short- wave trough at 500 hPa traversing over The Northeast. With PWATs between 1.5 and 2 inches and CAPE values well over 1000 J/kg, this disturbance may provide enough forcing for ascent to support some late afternoon/early evening showers and thunderstorms. Deep layer shear looks modest at best with up to 25 knots of shear a possibility in the 0-6 km layer. Thus, there may be the potential for some storms to become strong to severe. CSU ML probs have up to a 15 percent chance of severe weather Thursday evening with the highest chances across the interior. There is still some uncertainty at this time range, but have elected to bump PoPs above what the latest NBM is advertising. Thursday's oppressive heat and humidity will continue Thursday night into Friday with low temps only expected to fall into the low to mid 70s in the urban areas making for extremely uncomfortable sleeping weather. This heat wave is expected to peak on Friday with widespread high temperatures in the mid 90s and dewpoints once again in the low to mid 70s. Heat indices up to 105 degrees are not out of the question for Friday afternoon. For this reason, heat headlines will likely be needed for Thursday and Friday. Friday night through Monday There is some uncertainty in the extended forecast toward the end of the week with respect to when the heat wave will end. Models are resolving a cold front pushing through the region either late Friday or sometime Saturday afternoon. As of now, the consensus among most models is a later arrival of the cold front which would allow for 4th straight day with temperatures in the 90s for select locations in southern New England. This front will be accompanied by strong wind shear which may support a round of strong to severe thunderstorms as it moves through the region. CIPS severe weather probs and CSU ML severe weather props are both hinting at this potential with a 15 to 30 percent chance of severe weather, mainly across the interior and western zones of southern New England. Still quite a bit of uncertainty at this time range, but this will be something to keep an eye on as we head into the weekend. Following the frontal passage will be relatively cooler weather on Sunday and Monday with highs temps significantly lower in the upper 70s and low 80s. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... Forecast Confidence Levels: Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 18Z update... Through Tuesday night...High confidence overall. Mainly VFR through this portion of the forecast. Isolated SHRA or TSRA possible across western MA this afternoon and evening. Greater risk for SHRA and TSRA across interior southern New England Tuesday. Brief MVFR in the heavier SHRA and TSRA. Generally light S to SW winds through Tuesday night. Local sea breezes along the E MA coastline today, from midday into the afternoon, including at BOS. KBOS TAF...Moderate confidence in TAF. There is a possibility that TSRA hold together long enough to reach the terminal, but low enough to keep out of the TAF for now. KBDL TAF...High confidence in TAF. Outlook /Wednesday through Saturday/... Tuesday Night through Wednesday Night: VFR. Thursday: VFR. Breezy. Slight chance SHRA, slight chance TSRA. Thursday Night: VFR. Breezy. Chance TSRA, slight chance SHRA. Friday: VFR. Breezy. Isolated TSRA. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Weak high pressure will linger over the coastal waters through Tuesday. Expecting rather tranquil boating conditions during this time, with sustained winds less than 15 kt, gusts less than 20 kt and seas less than 3 feet. This light flow will result in local seabreezes on the nearshore waters today. Outlook /Wednesday through Saturday/... Tuesday Night through Wednesday Night: Winds less than 25 kt. Thursday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Thursday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft. Slight chance of rain showers. Friday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && SYNOPSIS...BW/RM NEAR TERM...BW/RM SHORT TERM...BW LONG TERM...RM AVIATION...BW/RM MARINE...BW/RM
Hazardous Weather Outlook National Weather Service Boston/Norton MA 409 PM EDT Mon Jul 24 2023 CTZ004-MAZ004>007-012>024-026-RIZ001>008-252015- 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- 409 PM EDT Mon Jul 24 2023 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...Tuesday through Sunday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. ANZ230>237-250-251-254>256-252015- 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- 409 PM EDT Mon Jul 24 2023 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...Tuesday through Sunday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. CTZ002-003-MAZ002-003-008>011-252015- Hartford CT-Tolland CT-Western Franklin MA-Eastern Franklin MA- Western Hampshire MA-Western Hampden MA-Eastern Hampshire MA- Eastern Hampden MA- 409 PM EDT Mon Jul 24 2023 This Hazardous Weather Outlook is for northern Connecticut and western Massachusetts. .DAY ONE...Tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. 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/NWSBoston You can follow us on Twitter at @NWSBoston
Special Weather Statement National Weather Service Boston/Norton MA 208 PM EDT Mon Jul 24 2023 MAZ002>004-241915- Western Franklin MA-Northern Worcester MA-Eastern Franklin MA- 208 PM EDT Mon Jul 24 2023 ...A strong thunderstorm will impact portions of northwestern Worcester and northeastern Franklin Counties through 315 PM EDT... At 207 PM EDT, Doppler radar was tracking a strong thunderstorm over Montague, or near Greenfield, moving northeast at 20 mph. HAZARD...Minor flooding. Heavy rain in excess of 1 in/hr SOURCE...Radar indicated. IMPACT...Minor nuisance flooding of typically flood prone areas. Locations impacted include... Greenfield, Orange, Deerfield, Winchendon, Montague, Sunderland, Northfield, Bernardston, Conway, Shelburne, Erving, Gill, Royalston, Wendell and Warwick. PRECAUTIONARY/PREPAREDNESS ACTIONS... Get indoors when you hear thunder. Do not resume outdoor activities until at least 30 minutes after the storm has passed. Do not drive through flooded roads or underpasses. Avoid low lying areas near small streams. && LAT...LON 4272 7208 4248 7260 4255 7274 4273 7247 TIME...MOT...LOC 1807Z 234DEG 19KT 4256 7255 MAX HAIL SIZE...0.00 IN MAX WIND GUST...<30 MPH KP
Preliminary Local Storm Report
National Weather Service Boston/Norton MA
342 PM EDT Mon Jul 24 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0230 PM Tstm Wnd Dmg 1 SE Deerfield 42.53N 72.58W
07/24/2023 Franklin MA Amateur Radio
Tree down on Pine Nook Road north of River
Road.
&&Preliminary Local Storm Report
National Weather Service Boston/Norton MA
424 PM EDT Mon Jul 24 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0340 PM Flood 1 E Greenfield 42.59N 72.57W
07/24/2023 Franklin MA Law Enforcement
Montague City Road between Walnut Street and
Turnpike Road closed due to flooding Relayed
by Amateur Radio.
&&Special Weather Statement
National Weather Service Boston/Norton MA
652 PM EDT Mon Jul 24 2023
MAZ005-006-026-242315-
Northwest Middlesex County MA-Central Middlesex County MA-
Western Essex MA-
652 PM EDT Mon Jul 24 2023
...A strong thunderstorm will impact portions of west central Essex
and north central Middlesex Counties through 715 PM EDT...
At 652 PM EDT, Doppler radar was tracking a strong thunderstorm over
Tyngsborough, or near Chelmsford, moving northeast at 15 mph.
HAZARD...Winds in excess of 40 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...
Lowell, Methuen, Chelmsford, Andover, Dracut, Tewksbury, Westford,
Tyngsborough, Groton and Dunstable.
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 4274 7125 4265 7117 4259 7151 4263 7156
4270 7150 4270 7129
TIME...MOT...LOC 2252Z 235DEG 11KT 4264 7147
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH
KPThe Boston radar (KBOX), 101 km away, was scanning. The volume nearest the first event began at 23:11 UTC.
1 thunderstorm wind. Local standard time, as filed.
In Salisbury, a tree and wires were down on a car near Elm Street (Route 110).
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: 1113043.