WW 631 SEVERE TSTM CT MA NY PA VT 271750Z - 280100Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 631
NWS Storm Prediction Center Norman OK
150 PM EDT Thu Aug 27 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Far Western Connecticut
Far Western Massachusetts
New York
Northeast Pennsylvania
Far Southern Vermont
* Effective this Thursday afternoon and evening from 150 PM until
900 PM EDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph likely
Scattered large hail events to 1.5 inches in diameter possible
A tornado or two possible
SUMMARY...Thunderstorm intensity and coverage is expected to
increase this afternoon as shortwave trough and associated cold
front approach the region from the west. Environmental conditions
support the potential for strong to severe storms, with damaging
wind gusts and isolated large hail as the primary hazards. A
low-probability risk for a brief tornado exists as well.
The severe thunderstorm watch area is approximately along and 85
statute miles east and west of a line from 45 miles northwest of
Glens Falls NY to 20 miles west of Monticello NY. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU1).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 630...
AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
27025.
...Mosier
WW 630 SEVERE TSTM CT DE NJ NY PA CW 271645Z - 280000Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 630
NWS Storm Prediction Center Norman OK
1245 PM EDT Thu Aug 27 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Southwest Connecticut
Northern Delaware
New Jersey
Southeast New York
Far Southeast Pennsylvania
Coastal Waters
* Effective this Thursday afternoon and evening from 1245 PM
until 800 PM EDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph possible
Scattered large hail events to 1.5 inches in diameter possible
A tornado or two possible
SUMMARY...Thunderstorms intensity and coverage is expected to
increase across the region this afternoon. Environmental conditions
support the potential for strong to severe storms capable of
damaging wind gusts and isolated large hail. A low-probability
tornado risk exists with any more discrete storms as well.
The severe thunderstorm watch area is approximately along and 35
statute miles east and west of a line from 25 miles north northwest
of Newark NJ to 35 miles west southwest of Atlantic City NJ. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU0).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
26020.
...Mosier
WW 0631 Status Updates
STATUS FOR WATCH 0631 HAS NOT BEEN ISSUED YET
WW 0630 Status Updates
STATUS REPORT ON WW 630
THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.
..MEAD..08/27/26
ATTN...WFO...OKX...PHI...
STATUS REPORT FOR WS 630
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
CTC001-271840-
CT
. CONNECTICUT COUNTIES INCLUDED ARE
FAIRFIELD
DEC001-003-271840-
DE
. DELAWARE COUNTIES INCLUDED ARE
KENT NEW CASTLE
NJC001-003-005-007-009-011-013-015-017-019-021-023-025-027-029-
031-033-035-037-039-041-271840-
NJ
. NEW JERSEY COUNTIES INCLUDED ARE
ATLANTIC BERGEN BURLINGTON
CAMDEN CAPE MAY CUMBERLAND
ESSEX GLOUCESTER HUDSON
HUNTERDON MERCER MIDDLESEX
MD 2147 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR SOUTH-CENTRAL AND SOUTHEAST PENNSYLVANIA INTO THE WEST VIRGINIA PANHANDLE...NORTHERN VIRGINIA...AND PORTIONS OF MARYLAND
Mesoscale Discussion 2147
NWS Storm Prediction Center Norman OK
1252 PM CDT Thu Aug 27 2026
Areas affected...south-central and southeast Pennsylvania into the
West Virginia Panhandle...northern Virginia...and portions of
Maryland
Concerning...Severe potential...Watch likely
Valid 271752Z - 271945Z
Probability of Watch Issuance...80 percent
SUMMARY...The threat for severe thunderstorms capable of damaging
wind gusts, marginally severe hail, and perhaps a brief tornado is
expected to increase between 19-21Z. A severe thunderstorm watch is
likely.
DISCUSSION...Visible satellite imagery indicates deepening cumulus
along the high terrain from the WV Panhandle and northern VA into
portions of south-central PA amidst a warming and destabilizing
boundary layer with MLCAPE of 1500-2500 J/kg, per latest objective
analysis. Continued daytime heating coupled with the glancing
influence of a subtle disturbance passing near and to the southeast
of the area is expected to support a gradual increase in
thunderstorms across the discussion area over the next 2-3 hours.
The degree of instability combined with around 30 kt of deep-layer
shear will support some storm organization, including possible
supercell and/or bowing structures, with the primary hazard being
damaging wind gusts as low-level lapse rates continue to steepen.
Marginally severe hail is also possible, especially with any
supercells that may evolve. A conditional brief tornado threat may
materialize, particularly over northeast MD into far southeast PA,
with storms developing along or favorably interacting with an
outflow boundary associated with ongoing storms over NJ, where
low-level shear may be locally enhanced.
..Mead/Mosier.. 08/27/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CTP...LWX...
LAT...LON 39077875 39737844 40637732 40627690 40387647 39907632
39407623 38477666 38207758 38277862 39077875
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
MD 2146 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR PORTIONS OF CENTRAL AND EASTERN NEW YORK...NORTHEAST PENNSYLVANIA...SOUTHWEST VERMONT...AND WESTERN MASSACHUSETTS
Mesoscale Discussion 2146
NWS Storm Prediction Center Norman OK
1151 AM CDT Thu Aug 27 2026
Areas affected...portions of central and eastern New
York...northeast Pennsylvania...southwest Vermont...and western
Massachusetts
Concerning...Severe potential...Watch likely
Valid 271651Z - 271845Z
Probability of Watch Issuance...80 percent
SUMMARY...The threat for severe weather is expected to increase by
18-20Z. The predominant hazard will be damaging wind gusts, with
marginally severe hail and a brief tornado or two also possible. A
severe thunderstorm watch is likely.
DISCUSSION...In the wake of early-day showers and thunderstorms now
shifting east of I-81 northeast of Syracuse, visible satellite
imagery indicates deepening cumulus development over the Finger
Lakes into north-central PA. There, cloud breaks have allowed for
greater air mass destabilization to occur with steepening low-level
lapse rates.
While specific details regarding thunderstorm evolution remain
uncertain, recent model guidance indicates a gradual increase in
storm coverage and intensity over the next 2-3 hours from west to
east across the region amidst a warming boundary layer with MLCAPE
increasing to 1000-1500+ J/kg. A belt of enhanced (30-35 kt)
westerly mid-level flow observed by the 12Z Buffalo and Pittsburgh
soundings and current VWPs will yield sufficient vertical shear for
some storm organization, including bowing and transient supercell
structures. The primary hazard will be damaging wind gusts, which
will be most likely in areas that see stronger heating and the
resultant steepening of low-level lapse rates. Marginally severe
hail also appears possible. The greatest potential for a tornado or
two will exist with any supercell structures in the Hudson Valley,
where backed surface winds will yield a corridor of stronger
low-level shear.
..Mead/Mosier.. 08/27/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BTV...ALY...BGM...BUF...CTP...
LAT...LON 41447693 42027708 42557692 43047635 43877500 44147411
44147369 43967336 43237307 42277308 42067366 41547492
41217577 41107635 41237675 41447693
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1124 AM CDT Thu Aug 27 2026
Valid 271630Z - 281200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MID-ATLANTIC/NORTHEAST...THE CENTRAL PLAINS...AND CENTRAL
MONTANA...
...SUMMARY...
Scattered strong to severe thunderstorms are possible across parts
of the Northeast and Mid-Atlantic today. Damaging winds, severe
hail, and a tornado or two may accompany these thunderstorms. Large
to very large hail and severe gusts are also possible across parts
of northern High Plains and central Plains.
...Mid-Atlantic/Northeast...
Recent surface analysis places a low over western Quebec, with a
cold front arcing from this low southwestward through the middle OH
Valley, western TN Valley and then westward across central AR and
central OK. Satellite imagery reveals a shortwave trough extending
from northeastern Ontario through western PA, just west of the
analyzed surface low. There also appears to be a more subtle
shortwave trough farther south moving through WV towards VA.
Expectation is for the primary shortwave trough and cold front to
continue eastward, interacting with the very moist airmass across
the Northeast to support thunderstorm development this afternoon.
12Z ILN and PIT soundings sampled the moderate westerly flow aloft,
supporting the potential for strong multicells along both the cold
front and pre-frontal troughing. A few supercells are possible if
warm sector development can mature without too much interaction with
other convection. Primary risk will be damaging gusts, although the
modestly cool temperatures aloft (i.e. -10 to -12 deg C at 500-mb)
suggest some hail is possible as well.
A somewhat displaced area of earlier thunderstorm development is
manifesting across the northern Mid-Atlantic. As mentioned in MCD
#2145, a broken band of thunderstorms is ongoing as of mid-morning
from the New York City vicinity southwest toward Baltimore, with
that activity potentially being aided by forcing for ascent
associated with the subtle shortwave trough moving into VA. Airmass
across this region is very moist, and instability is steadily
building under modest diurnal heating. Most guidance suggests this
activity gradually increases in coverage and intensity over the next
few hours. The presence of a vertically veering wind profile
with around 30 to 35 kt of effective bulk shear would support a
conditional risk for embedded supercell structures capable of
locally damaging winds, marginally severe hail, and perhaps a brief
tornado.
...Northern Rockies/High Plains...
Recent satellite imagery depicts a shortwave trough progressing
across eastern OR towards ID and western MT. Moderate mid-level
moisture and forcing for ascent associated with this wave are
forecast to initiate thunderstorms across the northern Rockies this
afternoon. This activity is then forecast to progress northeastward
off the higher terrain into central MT, where a deeply mixed airmass
is forecast to be in place. Despite this deep mixing and somewhat
limited low-level moisture, the mid-level moisture associated with
the shortwave will allow for at least modest buoyancy (i.e. MLCAPE
over 500 J/kg). This should support storm maintenance off the
terrain, with a trend towards outflow-dominant bowing segments with
time. Primary severe risk is damaging gusts, including the potential
for gusts from 65 to 75 mph.
...Central Plains...
Moist southerly flow will help maintain moderate low-level moisture
through the NE Panhandle and into southwest SD amid the strong
heating and boundary-layer mixing expected this afternoon.
Additionally, this modest, but persistent, warm-air advection is
likely to force convective initiation this afternoon over the
western NE/SD border vicinity. Low-level southerly flow veering to
moderate northwesterlies aloft will support deep-layer shear of 40
to 50 kt, more than adequate for supercell development with any
mature convective. Any sustained supercells will be capable of
producing large hail (some 2+ inches) as they track
south-southeastward through the late afternoon into the evening.
Upscale growth into one or more bowing segments appears likely this
evening, with strong to severe gusts (65 to 75 mph) possible.
An isolated threat for severe hail/gusts may also exist
farther west/south across the CO Front Range to Raton Mesa vicinity.
Weaker buoyancy and deep-layer shear should keep any more organized
updrafts confined to the higher terrain and Foothills.
-- No other changes needed to the outlook with the text for the
additional areas appended from the 13Z Outlook below --
...Great Basin...
High-based thunderstorms should also develop this afternoon across
portions of northeast NV into northwest UT and southeast ID. While
low/mid-level winds and related thunderstorm organization will
likely be somewhat weaker/limited compared to areas farther north,
steep lapse rates and large DCAPE will support potential for strong
to severe outflow gusts as this convection spreads northeastward
into the early evening.
...South-Central/Coastal Texas into Southern Louisiana...
Ongoing thunderstorms across southern LA may pose a threat for gusty
winds this morning before they move offshore. Additional
thunderstorms may develop this afternoon from parts of south-central
TX towards the upper TX Coast, with isolated severe/damaging
downburst winds possible given ample moisture/instability forecast.
Weak deep-layer shear should limit the overall severe threat.
..Mosier/Chalmers.. 08/27/2026
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1156 AM CDT Thu Aug 27 2026
Valid 281200Z - 291200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
DAKOTAS...AND FROM NORTH GEORGIA TO THE SOUTHERN MID-ATLANTIC...
...SUMMARY...
Isolated strong to severe storms are possible across northern
Georgia into the Carolinas and Virginia, and the Dakotas.
...Northern/Central Plains...
Severe potential remains uncertain on Friday given upper ridging
over the region for much of the diurnal cycle, though the upper
ridge is expected to deampify during the evening/overnight period.
Capping may largely limit convection through much of the day.
However, surface troughing along the High Plains will strengthen
with potential for weak surface low development over southwest SD
during the evening. South/southeasterly low level flow will
transport 60s dewpoint across eastern NE into much of the Dakotas
east of the surface trough. A plume of steep midlevel lapse rates
will overspread the region atop the moistening boundary layer, and
moderate destabilization is expected. Convection may eventually
develop along the surface trough during the early evening as
stronger height falls occur. Supercell wind profiles with
elongated/straight hodographs are evident in forecast soundings,
suggesting large hail will be possible. Steep low-level lapse rates
are expected and strong outflow winds also could occur prior to
stronger nocturnal low-level stabilization.
A 40 kt south/southwesterly low-level jet is forecast to spread
across NE into SD. This could support maintenance of convection
spreading east of the surface trough, with a continued risk of hail,
and possibly sporadic strong gusts if clustering/upscale growth can
occur.
...North Georgia into the southern Mid-Atlantic...
A very moist airmass will be in place along/east of a surface
trough. Stronger heating will result in moderate destabilization
within a weakly sheared environment. Multicell thunderstorms could
pose a risk for sporadic wet microbursts within a high PW
environment.
...Maine...
A few strong storms will be possible as a cold front shifts east
across New England through early evening. Strong southwesterly flow
aloft will result in around 30 kt effective shear magnitudes and
elongated hodographs. However, poor lapse rates and cooler afternoon
temperatures will limit destabilization. Additionally, flow below
700 mb will remain rather modest. While gusty winds or small hail
could occur with the strongest storms, severe potential is expected
to remain low.
...Intermountain West...
Around 30-50 kt southwesterly flow at 500 mb will overspread
portions of the region as an upper shortwave impulse migrates from
NV into WY. Instability is expected to remain weak, modulated by
modest midlevel lapse rates and stronger heating remaining confined
to areas further south. Deep boundary layer mixing will still occur,
and could promote some potential for gusty outflow winds, but
overall severe potential appears low given limited instability.
..Leitman.. 08/27/2026
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1056 AM CDT Thu Aug 27 2026
Valid 271700Z - 281200Z
...CRITICAL FIRE WEATHER AREA FOR FAR NORTHEASTERN
CALIFORNIA...NORTHWESTERN NEVADA...AND SOUTHEASTERN OREGON...
No changes were made to the existing drawn fire weather risk areas
for today. Satellite imagery and GLM data shows thunderstorm
development already underway across portions of western MT.
Precipitation already received in the last 24 hours and resultant
ERCs below the 90th percentile, especially where the latest forecast
guidance shows convection to be most widespread today, has precluded
the introduction of any additional dry thunderstorm area(s) of
concern. Meanwhile, much of the drawn wind/RH areas show transient
scattered cloud cover this morning. Even so, enough solar radiation
is still expected to mix down stronger winds from aloft, aiding the
tightening surface pressure gradient in place across highlighted
areas of the Pacific Northwest. The area of Critical concern, near
the low elevations of southeastern OR, remains on track with
sustained southwesterly winds of 15-25 mph amid RHs of 10-15%
through several hours this afternoon ahead of an advancing cold
front. The front will move across central OR and WA today and
approach the Critical wind/RH area between sunset and midnight
tonight as it slows, turning winds west-northwesterly as it passes.
..Stearns.. 08/27/2026
.PREV DISCUSSION... /ISSUED 0103 AM CDT Thu Aug 27 2026/
...Synopsis...
An upper-level trough will continue to promote fire weather concerns
across portions of the northwestern CONUS, northern Great Basin and
northern Rockies today. Enhanced southwest winds and dry conditions
will bring elevated fire weather conditions across the Columbia
Basin with a more pronounced critical fire weather threat from far
northeastern CA into southeastern OR. Farther east, sufficient
mid-level moisture, upper diffluence ahead of the aforementioned
trough and daytime instability, will aid in development in
high-based thunderstorms across portions of the northern Rockies and
adjacent MT high plains. Breezy offshore winds across Southern
California will present an elevated fire weather threat this evening
and tonight after well-above normal temperatures this afternoon.
...Pacific Northwest into Oregon High Desert and northeastern
California...
Dry, downslope flow into the Columbia Basin is expected today as
upper trough pushes farther into the Pacific Northwest. As the
onshore pressure gradient tightens, west to southwest winds of
around 15 mph (locally 20 mph in areas just east and adjacent to the
Cascades) will develop and couple with RH as low as 15% by
mid-afternoon. These atmospheric conditions along with receptive
fuels will promote an elevated fire weather threat across the
Columbia Basin. Farther south, a 50-60 knot mid-level jet will
stretch from northeastern CA into central ID. Diminishing cloud
cover from southwest to northeast will enhance boundary layer mixing
most across far northeastern CA, far northwestern NV and
southeastern OR where sustained surface winds of 15-25 mph are
expected this afternoon. Within this corridor of stronger winds, RH
should fall to below 10% at times by peak heating. Fuels remain
quite dry with forecast ERCs near the 95th percentile. This
meteorological setup along with a receptive fuelscape (as evidenced
by recent fire activity) supports critical fire weather highlights
from far northeastern CA into southeastern OR.
...Northern Rockies...
A supportive thunderstorm environment will exist over portions of
the northern Rockies as the Pacific Northwest trough translates
eastward. Forcing for ascent ahead of the trough, aligning with
mid/upper level moisture and daytime instability, will bring mainly
high-based thunderstorms to portions of central ID into much of
western MT. Increasing thunderstorm motions to the east-northeast
will be bolstered by strengthening vertical wind shear as the upper
trough pushes east, further limiting rainfall accumulation in lower
elevations. Isolated dry thunderstorm highlights remain over this
region with only minor changes.
...Southern California...
A northerly wind component will increase again this evening and
tonight across portions of southern CA as the offshore pressure
gradient tightens. Hot and dry conditions during the day with near
record high temperatures in the 90s and 100s away from the coast are
supporting increasingly dry fuels across the region. Wind speeds of
10-20 mph with higher gusts are possible in wind prone areas and
terrain gap features across LA/Ventura/Santa Barbara counties. These
winds coupled with RH around 20% will present an elevated fire
weather threat.
...Please see www.spc.noaa.gov/fire for graphic product...
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