High astronomical tides led to minor coastal flooding in the normal locations of the Boston area.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. 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.
High astronomical tides led to minor coastal flooding in the normal locations of the Boston 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 Jul 23, 9:01 PM EST, 49 minutes earlier.
Area Forecast Discussion National Weather Service Boston/Norton MA 1001 PM EDT Fri Jul 23 2021 .SYNOPSIS... Isolated showers should weaken tonight. Otherwise, mostly clear skies overnight. High pressure then builds overhead Saturday allowing for dry and seasonably mild weather. A warm front brings an increasing risk for showers later Saturday night, along with increasing humidity levels. Unsettled pattern returns Sunday with chances for showers and thunderstorms each afternoon into midweek. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Radar shows an area of showers over Southeast NH moving toward Northeast MA. Showers were holding together at 9 PM, but with the sun set and no shear to maintain organization, would expect this to dissipate overnight. Will show 20% pops south to Boston, dissipating as it moves to the south. Clearing and light winds the rest of the night as high pressure approaches from the west. A few patches of fog are possible. Also, in coordination with GYX, a coastal flood statement continues for the eastern MA coast for the high tide period. Impacts should be marginal/mainly spashover. For more detail see the Coastal Flood section below. Lows tonight in the 50s in the outlying sheltered valleys that radiate well, and the upper 50s to near 60 in the urban areas. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... Saturday: Trough aloft shifts eastward into the waters east of Cape Cod, with shortwave ridging and related background subsidence aloft building over SNE. Looking to be a generally dry and seasonably mild Saturday. A few convection-permitting models do show some pop-up showers or rogue thunderstorms on the Narrangsett Bay breeze during the afternoon but thinking this is overdone given the subsidence aloft. Highs upper 70s to mid 80s, with cooler mid 70s near the eastern MA and southern RI/SE MA coast where sea-breezes are expected to develop. Saturday Night: Saturday evening features increasing and lowering/thickening clouds. This is due to a warm front that will be moving in from eastern NY. Rain, perhaps with a rumble or two of thunder should be on the increase during the second half of the night and mainly across the western half of the forecast area. Sided toward the SREF-based PoP which brings fairly solid Likely PoP into our western zones. Turning more humid as well with mild lows in the mid 60s, with upper 60s near the South Coast/Cape and Islands. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Highlights... * Best shot of rain and thunderstorms comes Sunday and Sunday night. Drier conditions return later in the day Monday * Warmer and more humid air returns starting Sunday and into next week Details... Sunday and Sunday night... A mid level shortwave moves out of the Great Lakes into New England on Sunday, flattening the ridge and bringing with it a surge of moisture that will fuel showers and thunderstorms. As the warm front lifts through on Sunday surface dewpoints surge back into the upper 60s or low 70s but moisture also returns through the entire column; PWATs rebound to over 1.75 inches. Notably, though dewpoints surge Sunday, temperatures do not. Even with a much warmer airmass overhead (850 mb temps rising from ~10C on Saturday to ~15C on Sunday) high temperatures will be near or even slightly below what they were on Saturday thanks to abundant cloudcover and poor mixing of the boundary layer. The difference will be a much muggier feel to the air on Sunday. This poor mixing may also limit how much of the low level jet overhead mixes down; it will be breezy, but the strongest gusts will be over the Cape and Islands, 20 to 30 mph though can't rule out some higher gusts to 40 mph. Showers and thunderstorms move in with the warm front's arrival, overspreading most of southern New England by late morning. We have plenty of moisture available with good forcing for ascent, and instability is there as well, on the order of 1000-1500 J/kg of CAPE. Bulk shear values are marginal, near 30 kts, but lapse rates are poor which would help to limit strong updrafts and storm strengthening. Gusty winds and downpours are possible with any storms. Monday through Thursday... Shower and thunderstorms will come to an end behind the cold front which drops through sometime on Monday ushering in a marginally drier airmass, but won't see much relief from the humidity. Showers come to an end later Monday but we remain beneath an essentially stationary broad upper trough through at least Thursday; no uninterrupted stretch of high pressure in sight. Thus, off and on rain chances will continue as shortwaves periodically rotate through the trough. Fortunately it's looking like a "more dry than wet" situation through around Wednesday with high temperatures back in the 80s. Confidence is low beyond this timeframe, but there are signals that our next more formidable frontal system may approach around Wed/Thu bringing a better chance of rain. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Overnight... High confidence. Widely scattered showers move south from Southeast NH, and may move through BOS before dissipating around or shortly after midnight. Otherwise, mostly clear skies and VFR overnight. Isolated patches of IFR in fog possible late night. Saturday and Saturday Night...High confidence. VFR. Light and variable winds. Sea-breeze develops along the coastal areas around 14-15Z, and dissipates around 00Z. VFR continues Saturday night, but with increasing clouds from the west after midnight with showers possible in Wrn/Central MA and Nrn CT. Ceilings may lower to MVFR in some showers late at night. KBOS TAF...High confidence in TAF. Brief shower possible around midnight. KBDL TAF...High confidence in TAF. Outlook /Sunday through Wednesday/... Sunday through Sunday Night: Mainly MVFR, with local IFR possible. Breezy. Chance SHRA, chance TSRA. Monday: Mainly VFR, with local MVFR possible. Breezy. Slight chance SHRA, isolated TSRA. Monday Night: VFR. Tuesday: Mainly VFR, with local MVFR possible. Slight chance SHRA, isolated TSRA. Tuesday Night: Mainly VFR, with areas MVFR possible. Chance SHRA, isolated TSRA. Wednesday: Mainly VFR, with areas MVFR possible. SHRA likely, isolated TSRA. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Overnight...Isolated showers will dissipate after midnight. Winds less than 10 kt and seas 2 feet or less. Saturday, winds and seas look to remain below small craft advisory levels. Wind gusts mainly under 20 kt from the N/NW through tonight, becoming E/ESE on Sat. Seas remain 3 ft or less through Sat. Later Saturday night and particularly overnight, a warm front will bring about an increase in southerly winds with gusts on the outer eastern waters close to SCA levels. Seas also should build into the 2-4 ft range. /Outlook /Sunday through Wednesday/... Sunday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, chance of thunderstorms. Sunday Night: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain showers, chance of thunderstorms. Monday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers, isolated thunderstorms. Monday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Tuesday Night: Winds less than 25 kt. Seas locally 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. && .HYDROLOGY... No active river flood warnings are in effect for rivers and waterways in BOX's hydrologic service area. However, after having a tremendous amount of rainfall from early to mid July, many rivers and streams in Southern New England are running much higher than normal. This is resulting in swift currents that would not typically be seen in the summer. These swift currents can catch those swimming or tubing/kayaking on area waterways off guard. There have been 3 total reports of drownings in the last week on the Farmington River in CT and Squannacook River in MA given the higher than usual flows and swift currents. As we move into the weekend, those with interests swimming, tubing or kayaking on area rivers and waterways should be aware that swift currents due to high flows are occurring. This can result in dangerous conditions, and it is generally discouraged to swim, inner-tube, or kayak until flows decrease. && .TIDES/COASTAL FLOODING... 400 PM Update: Tides are reaching their monthly astronomical peak. This may bring a period of minor splashover with the evening high tide around midnight tonight. Weak wave action and light offshore winds should mitigate a larger coastal flood threat, but minor splashover on typically vulnerable shoreline roads are possible. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && SYNOPSIS...Loconto/RM NEAR TERM...WTB SHORT TERM...Loconto LONG TERM...BW/RM AVIATION...WTB/RM MARINE...WTB/Loconto/RM HYDROLOGY... TIDES/COASTAL FLOODING...
Hazardous Weather Outlook National Weather Service Boston/Norton MA 433 PM EDT Fri Jul 23 2021 CTZ002>004-MAZ002>024-026-RIZ001>008-242045- 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- 433 PM EDT Fri Jul 23 2021 This Hazardous Weather Outlook is for northern Connecticut, all of Massachusetts east of Berkshire County, and Rhode Island. .DAY ONE...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>256-242045- 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- 433 PM EDT Fri Jul 23 2021 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...Saturday through Thursday. 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
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
743 PM EDT FRI JUL 23 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0730 PM HAIL KINGSTON 42.00N 70.71W
07/23/2021 M0.75 INCH PLYMOUTH MA AMATEUR RADIO
&&
EVENT NUMBER BOX2102753
GAUCHERPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
754 PM EDT FRI JUL 23 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0749 PM TSTM WND DMG HALIFAX 41.98N 70.87W
07/23/2021 PLYMOUTH MA LAW ENFORCEMENT
LARGE TREE BRANCH DOWN IN THE ROAD AT OAK STREET AND
MARILYN WAY. RELAYED BY AMATEUR RADIO.
&&
EVENT NUMBER BOX2102754
GAUCHERPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
755 PM EDT FRI JUL 23 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0750 PM HAIL KINGSTON 42.00N 70.71W
07/23/2021 M1.00 INCH PLYMOUTH MA PUBLIC
PHOTOS POSTED TO SOCIAL MEDIA. RELAYED BY AMATEUR
RADIO.
&&
EVENT NUMBER BOX2102755
GAUCHERPRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
806 PM EDT FRI JUL 23 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0505 PM HAIL HAVERHILL 42.78N 71.09W
07/23/2021 M0.88 INCH ESSEX MA AMATEUR RADIO
0509 PM HAIL MERRIMAC 42.83N 71.00W
07/23/2021 M1.00 INCH ESSEX MA BROADCAST MEDIA
0519 PM HAIL WEST NEWBURY 42.80N 70.99W
07/23/2021 M0.50 INCH ESSEX MA AMATEUR RADIO
0520 PM HAIL HAVERHILL 42.78N 71.09W
07/23/2021 M1.00 INCH ESSEX MA AMATEUR RADIO
0536 PM HAIL GEORGETOWN 42.73N 70.98W
07/23/2021 M0.50 INCH ESSEX MA AMATEUR RADIO
AT I-95 AND RT 133
0540 PM HAIL BOXFORD 42.67N 70.99W
07/23/2021 M0.50 INCH ESSEX MA AMATEUR RADIO
0647 PM HAIL EAST BRIDGEWATER 42.03N 70.95W
07/23/2021 M0.50 INCH PLYMOUTH MA TRAINED SPOTTER
0647 PM HAIL EAST BRIDGEWATER 42.03N 70.95W
07/23/2021 M0.75 INCH PLYMOUTH MA AMATEUR RADIO
0648 PM HAIL BROCKTON 42.08N 71.03W
07/23/2021 M0.75 INCH PLYMOUTH MA TRAINED SPOTTER
0657 PM HAIL WHITMAN 42.08N 70.93W
07/23/2021 M0.88 INCH PLYMOUTH MA AMATEUR RADIO
0713 PM HAIL WHITMAN 42.08N 70.93W
07/23/2021 M0.50 INCH PLYMOUTH MA PUBLIC
0720 PM HAIL HALIFAX 41.98N 70.87W
07/23/2021 M0.50 INCH PLYMOUTH MA AMATEUR RADIO
0730 PM HAIL KINGSTON 42.00N 70.71W
07/23/2021 M0.75 INCH PLYMOUTH MA AMATEUR RADIO
0733 PM HAIL PLYMOUTH 41.96N 70.68W
07/23/2021 M0.75 INCH PLYMOUTH MA PUBLIC
VIDEO ON SOCIAL MEDIA.
0749 PM TSTM WND DMG HALIFAX 41.98N 70.87W
07/23/2021 PLYMOUTH MA LAW ENFORCEMENT
LARGE TREE BRANCH DOWN IN THE ROAD AT OAK STREET AND
MARILYN WAY. RELAYED BY AMATEUR RADIO.
0750 PM HAIL KINGSTON 42.00N 70.71W
07/23/2021 M1.00 INCH PLYMOUTH MA PUBLIC
PHOTOS POSTED TO SOCIAL MEDIA. RELAYED BY AMATEUR
RADIO.
&&
EVENT NUMBER BOX2102742 BOX2102740 BOX2102741 BOX2102747 BOX2102743
BOX2102744 BOX2102745 BOX2102751 BOX2102746 BOX2102749 BOX2102748
BOX2102752 BOX2102753 BOX2102750 BOX2102754 BOX2102755
GAUCHERPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
818 PM EDT FRI JUL 23 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0510 PM HAIL SEEKONK 41.82N 71.33W
07/23/2021 M0.75 INCH BRISTOL MA AMATEUR RADIO
&&
EVENT NUMBER BOX2102756
GAUCHERPRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
1028 PM EDT FRI JUL 23 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0505 PM HAIL HAVERHILL 42.78N 71.09W
07/23/2021 M0.88 INCH ESSEX MA AMATEUR RADIO
0509 PM HAIL MERRIMAC 42.83N 71.00W
07/23/2021 M1.00 INCH ESSEX MA BROADCAST MEDIA
0510 PM HAIL SEEKONK 41.82N 71.33W
07/23/2021 M0.75 INCH BRISTOL MA AMATEUR RADIO
0519 PM HAIL WEST NEWBURY 42.80N 70.99W
07/23/2021 M0.50 INCH ESSEX MA AMATEUR RADIO
0520 PM HAIL HAVERHILL 42.78N 71.09W
07/23/2021 M1.00 INCH ESSEX MA AMATEUR RADIO
0536 PM HAIL GEORGETOWN 42.73N 70.98W
07/23/2021 M0.50 INCH ESSEX MA AMATEUR RADIO
AT I-95 AND RT 133
0540 PM HAIL BOXFORD 42.67N 70.99W
07/23/2021 M0.50 INCH ESSEX MA AMATEUR RADIO
0647 PM HAIL EAST BRIDGEWATER 42.03N 70.95W
07/23/2021 M0.50 INCH PLYMOUTH MA TRAINED SPOTTER
0647 PM HAIL EAST BRIDGEWATER 42.03N 70.95W
07/23/2021 M0.75 INCH PLYMOUTH MA AMATEUR RADIO
0648 PM HAIL BROCKTON 42.08N 71.03W
07/23/2021 M0.75 INCH PLYMOUTH MA TRAINED SPOTTER
0657 PM HAIL WHITMAN 42.08N 70.93W
07/23/2021 M0.88 INCH PLYMOUTH MA AMATEUR RADIO
0710 PM HAIL PLYMOUTH 41.96N 70.68W
07/23/2021 M0.75 INCH PLYMOUTH MA AMATEUR RADIO
0713 PM HAIL WHITMAN 42.08N 70.93W
07/23/2021 M0.50 INCH PLYMOUTH MA PUBLIC
0720 PM HAIL HALIFAX 41.98N 70.87W
07/23/2021 M0.50 INCH PLYMOUTH MA AMATEUR RADIO
0730 PM HAIL KINGSTON 42.00N 70.71W
07/23/2021 M0.75 INCH PLYMOUTH MA AMATEUR RADIO
0733 PM HAIL PLYMOUTH 41.96N 70.68W
07/23/2021 M0.75 INCH PLYMOUTH MA PUBLIC
VIDEO ON SOCIAL MEDIA.
0749 PM TSTM WND DMG HALIFAX 41.98N 70.87W
07/23/2021 PLYMOUTH MA LAW ENFORCEMENT
LARGE TREE BRANCH DOWN IN THE ROAD AT OAK STREET AND
MARILYN WAY. RELAYED BY AMATEUR RADIO.
0750 PM HAIL KINGSTON 42.00N 70.71W
07/23/2021 M1.00 INCH PLYMOUTH MA PUBLIC
PHOTOS POSTED TO SOCIAL MEDIA. RELAYED BY AMATEUR
RADIO.
&&
EVENT NUMBER BOX2102742 BOX2102740 BOX2102756 BOX2102741 BOX2102747
BOX2102743 BOX2102744 BOX2102745 BOX2102751 BOX2102746 BOX2102749
BOX2102757 BOX2102748 BOX2102752 BOX2102753 BOX2102750 BOX2102754
BOX2102755
GAUCHERThe national radar mosaic for the moment the first event began.
1 coastal flood. Local standard time, as filed.
High astronomical tides caused minor flooding on the southbound lanes of Morrissey Blvf between UMass-Boston and Freeport Street. Report per MA Dept. of Conservation and Recreation.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Massachusetts in 2021Every state in 2021This day in weather historyWarnings in Massachusetts, July 2021
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: 974806.