An unseasonably strong mid-level shortwave trough progressed across Northern New England on June 18th. This brought deep layer shear that allowed for high potential storm structure organization into line segments.
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 GYX wrote it up.
An unseasonably strong mid-level shortwave trough progressed across Northern New England on June 18th. This brought deep layer shear that allowed for high potential storm structure organization into line segments. The forcing combined with deep moisture allowed for robust convection, with bowing line segments transiting across Central and Southern New Hampshire. Convective wind gusts along with a few areas of microburst wind damage brought down 1000s of trees.
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 Gray, ME wrote its last area forecast discussion before the first event at Jun 18, 1:17 PM EST, 48 minutes earlier. Its key messages:
Area Forecast Discussion
National Weather Service Gray ME
217 PM EDT Thu Jun 18 2026
.WHAT HAS CHANGED...
A Tornado Watch has been issued for New Hampshire and far
western Maine through 7PM this evening.
&&
.KEY MESSAGES...
1. An unseasonably strong storm will cross the region today,
with increasing chances for severe thunderstorms and localized
flash flooding this afternoon and early evening.
2. Unsettled pattern continues over the weekend into early next
week.
&&
.DISCUSSION...
KEY MESSAGE 1 DESCRIPTION...
Overall expectations remain largely unchanged for the remainder of
this afternoon into early this evening as we are currently watching
a squall line quickly approaching the Connective River from the
west. The environment out ahead of this line is packing plenty
of wind shear with SPC mesoanalysis having 50-60kt of effective
shear across NH and parts of far western ME and 0-1km SRH
exceeding 300 m^2/s^2. This level of speed and directional shear
is more than sufficient for severe weather in areas where there
is enough instability with the primary hazard being damaging
wind gusts along with the threat of tornadoes. The tornado
threat exists both within any discrete cells than can develop
out ahead of the line as well as within the line.
Looping back to the instability, the highest risk for severe storms
will be in NH, especially along the CT River Valley and central
and southern NH where model consensus brings in roughly 500
J/kg of surface-based CAPE. There may also even be instances of
damaging winds within cells with little to no lightning as
motion will be fast. The threat extends east into far western
ME, but SBCAPE then drops off pretty readily with eastward
extent with onshore flow in place. That said, it won't take much
to mix down the strong winds from aloft, but it's possible
storms become more elevated in nature as they progress through
western ME (although still enough elevated instability for
thunderstorms and torrential downpours).
Last, but certainly not least, is the threat of flash flooding,
especially in and around the White Mountains extending into parts of
the western ME mountains and foothills. These areas have seen the
most rain over the past week, and torrential downpours combined with
rain from this morning will pose a risk of flash flooding. Some area
river rises are also expected with the Pemi at Woodstock and the
Swift River at Roxbury possibly reaching minor flood stage.
A few showers may stick around through this evening behind the
primary line of convection, but drier air and subsidence moving in
behind the front keep things dry the rest of tonight, with the
exception of a few upslope rain showers in the mountains. Winds
could get a bit breezy overnight with low temps in the 50s.
The upper-level low will slowly move east toward the Canadian
Maritimes during the day Friday. Broad cyclonic flow and embedded
waves stemming from this low will provide enough lift to get showers
and a few storms going, mainly in the afternoon to early evening, as
daytime instability builds. This will be mainly in and around the
mountains, and a few storms may contain small hail.
Otherwise, it will be a breezy and partly sunny day, although there
may be periods of mostly cloudy skies with steep low-level lapse
rates and enough instability aloft. The steep lapse rates and good
mixing will bring down stronger winds from aloft resulting in a
breezy day. Based on forecast soundings, wind gusts of 25-35 mph are
likely with up to 40 mph possible on the higher end. Highs will be
mainly in the 70s to low 80s south of the mountains, except a bit
cooler in the mountains.
Winds likely remain somewhat breezy into Friday evening but are
expected to continue to ease overnight. A few showers remain
possible in the mountains with upslope flow, but whatever activity
develops during the day is expected to fade around sunset. Overnight
lows will be mostly in the 50s, except some upper 40s are possible
in the mountains.
KEY MESSAGE 2 DESCRIPTION...
One upper low will be lifting northeast away from the area Saturday
into Sunday while another upper low approaches from SE Canada late
Sunday into Monday.
Saturday will be breezy with NW winds 15 to 20 mph gusting up to 30
mph. Upslope near blocked flow will lead to plenty of clouds and
showers along and north of the mountains while shower chances
decrease south of the mountains with more in the way of sunshine.
Highs will range from the low 60s north to near 80F near the coast
with the aid of downsloping winds. The gradient will slacken over
the area Sunday allowing for light winds turning onshore in the
afternoon. A surface trough over the area combined with SB CAPE
building to 1000 J/kg will allow for diurnal showers and
thunderstorms to develop across much of the area Sunday. The lack of
shear will likely keep any storms sub-severe while steep mid level
lapse rates and low freezing levels could allow for some small hail.
Short wave ridging briefly builds in Sunday night into Monday
morning ahead of the next upper low for a drying trend. As the upper
low over SE Canada approaches another short wave will be
tracking through the Ohio Valley. Models diverge on whether the
short wave and upper low can phase. A phased solution would lead
to an organized area of low pressure bringing a soaking rain
late Monday into Tuesday morning while an unphased system would
bring more in the way of showers. The latest NBM brings PoPs
into the 60-70 percent range Monday afternoon through Monday
night, which seems reasonable given the time range. While there
will likely be some dry periods through the middle of next week
the overall pattern will support active weather with persistent
troughing near the Great Lakes through the Northeast.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
Through 00Z Saturday...IFR to MVFR restrictions remain likely this
afternoon into early evening with ongoing SHRA and TEMPO TSRA that
could also produce strong winds gusts. Conditions likely improve
fairly quickly to VFR from west to east this evening and tonight
behind a cold front with the last sites to improve being RKD and
AUG. However, HIE may see a period of MVFR ceilings. Southwest
winds may also gust 20-25 kt. LLWS is also forecast through
tonight.
For Friday, primarily VFR, but scattered showers and isolated storms
could produce brief MVFR restrictions with the higher potential
will be at HIE. Otherwise westerly wind gusts 25-30 kt are
likely with some gusts possibly exceeding 35 kt.
Outlook:
Friday night: VFR expected. Winds may remain breezy early on but are
expected to ease overnight.
Saturday: Upslope clouds and showers will likely bring at least
MVFR to HIE while mainly VFR prevails elsewhere. NW winds 15 kts
will gust to around 25 kts during the morning into the afternoon
and will diminish Saturday evening.
Sunday: Mainly VFR with light winds turning onshore in the
afternoon. Late morning through afternoon showers and
thunderstorms will bring brief restrictions.
Monday-Tuesday: Low pressure may bring more widespread IFR and
rain showers.
&&
.MARINE...
Gales remain likely this afternoon and early evening over the waters
with potential for even stronger gusts in offshore-moving
thunderstorms, especially from Casco Bay southward. Conditions then
turn to SCA levels tonight and Friday as winds turn west to
southwesterly behind a cold front. Winds are expected to stay below
SCA levels Friday night, but seas may remain above 5 ft for portions
of the waters.
WNW winds will gust to 20 kts Saturday with wave heights running
3-5 feet. Winds and seas diminish Saturday night and Sunday. An
area of low pressure may develop near coastal New England Monday
bringing the potential for at least SCAs.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Flood Watch until 8 PM EDT this evening for MEZ012-013.
NH...Flood Watch until 8 PM EDT this evening for NHZ002>006.
MARINE...Gale Warning until 8 PM EDT this evening for ANZ150-152>154-
180-182-184.
Small Craft Advisory until 8 AM EDT Friday for ANZ151.
&&
DISCUSSION...Combs/SchroeterThe Burlington radar (KCXX), 139 km away, was scanning. The volume nearest the first event began at 19:04 UTC.
35 thunderstorm wind. Local standard time, as filed.
Severe thunderstorm outflow winds downed multiple trees and power lines down on Red Water Brook Road in Claremont.
Chaser measured recent wind gust of 64 mph in Claremont on a handheld anemometer.
Severe thunderstorm outflow winds downed a large tree down across Moss Flower Rd, in Bath.
Severe thunderstorm outflow winds downed trees and wires blocking West Bath Rd in the area of Pettyboro Rd. in Bath.
Severe thunderstorm outflow winds downed trees and wires down in Grantham.
Severe thunderstorm outflow winds downed trees and wires down blocking Dunham Road in Unity.
Severe thunderstorm outflow winds downed trees and wires on Westminster St. in Walpole.
Severe thunderstorm outflow winds downed wires, blocking Old North Groton Road in Rumney, NH.
Severe thunderstorm outflow winds downed trees and wires down blocking Ryder Corner road in the area of North Road in Sunapee.
Severe thunderstorm outflow winds downed trees down on Cady Lane, near Spofford Lake.
Severe thunderstorm outflow winds downed a tree and wires blocking Brook Rd. in New Hampton.
Severe thunderstorm outflow winds downed a large tree down on Cheshire Rd. in Harrisville.
Severe thunderstorm outflow winds downed several trees down on Orchard Lane in Gilsum.
Severe thunderstorm outflow winds downed trees and power lines down on Court St. in Keene.
Severe thunderstorm outflow winds downed a large tree that just missed a house in Troy.
Severe thunderstorm outflow winds downed a tree down blocking Hunkins Hill Rd. in Sanbornton.
Severe thunderstorm outflow winds downed a tree and wires blocking Bay Rd. in Sanbornton.
Severe thunderstorm outflow winds downed trees and wires down on West Main Street in Antrim.
Severe thunderstorm outflow winds downed trees and wires blocking Peverly Rd. in Northfield.
Severe thunderstorm outflow winds downed wires blocking Parade Rd. in Meredith.
Severe thunderstorm outflow winds downed a trees in East Sandwich.
The first microburst occurred over the open water of Lake Winnipesaukee shortly after 4:00 PM on June 18th. Based on damage reports this likely occurred in the vicinity of Round and Welch Islands in Gilford, New Hampshire. There were pictures of trees snapped on Round Island and reported damage on parts of Welch Island. The microburst continued unimpeded by friction towards Sandy and Cow Islands in Tuftonboro, New Hampshire. There were at least three camps damaged by tree falls on Sandy Island. On the southwest side of Cow Island there was significant tree damage. At least three additional camps were damaged by falling trees, as well as at least two docks that sustained damage. An estimated 1,500 trees, mostly softwood, were either snapped or uprooted by the winds. The open water and lack of friction likely allowed this microburst to expand beyond on the accepted definition of areal extent.
Severe thunderstorm outflow winds downed tree and wires blocking NH-11 in Gilford.
Severe thunderstorm outflow winds downed trees and wires near the center of Peterborough.
It was determined that there was a second microburst just northeast of the first, along the path of the mesocyclone. There was no visible damage to the backlands of Cow |Island, so the NWS Storm Damage Survey Team estimates the second microburst began somewhere just north of Barbers Pole channel before Tuftonboro Neck. This microburst was smaller in areal extent but more intense. Another 1,500 trees, again mostly softwood, were estimated to have been snapped or uprooted. These also caused the majority of the damage observed. There were five vehicles damaged, two of which were total losses. In addition, there were five cabins or outbuildings attached to summer camps that were destroyed and at least another twelve that were damaged by falling trees. Near the Sandy Island Dock several people escaped with minor cuts and scrapes when two trees fell through the shelter they were under. In a nearby parking lot a tree fell onto a car causing one minor hand injury in which medical attention was not necessary.
Severe thunderstorm outflow winds downed power lines that blocked NH-124.
Severe thunderstorm outflow winds downed trees and wires on Emery Road in Lyndeborough.
Severe thunderstorm outflow winds downed a tree completely blocking the northbound lane of NH-13 near Goffstown.
Severe thunderstorm outflow winds downed a tree blocking NH-28 in the area of Emerson Drive in Alton.
Severe thunderstorm outflow winds downed trees on wires in Strafford.
Severe thunderstorm outflow winds downed trees blocking Wilsons Crossing Road in Auburn, NH.
Severe thunderstorm outflow winds downed a tree down blocking Roberts Road in Strafford.
Severe thunderstorm outflow winds downed several trees and powerlines in Derry.
Severe thunderstorm outflow winds downed a tree completely blocking North Lowell Road in the area of Camelot Road in Windham.
Severe thunderstorm outflow winds downed multiple trees throughout Portsmouth, blocking roads.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in New Hampshire in 2026Every state in 2026This day in weather historyWarnings in New Hampshire, June 2026
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 2026-09-30. Each event’s entry at NCEI: 1355877, 1355881, 1355786, 1355832, 1355834, 1355835, 1355838, 1355787, 1355836, 1355839, 1355866, 1355841, 1355842, 1355843, 1355845, 1355867, 1355869, 1355846, 1355870, 1355871, 1355872, 1355860, 1355873, 1355847, 1355862, 1355848, 1355850, 1355851, 1355880, 1355878, 1355859, 1355879, 1355856, 1355857, 1355855.