Mesoscale Discussion 2096
NWS Storm Prediction Center Norman OK
1103 AM CDT Sun Aug 23 2026

Areas affected...northern Mid-Atlantic into western New England

Concerning...Severe potential...Watch unlikely 

Valid 231603Z - 231830Z

Probability of Watch Issuance...20 percent

SUMMARY...A gradual increase in thunderstorm coverage is expected
this afternoon along with a corresponding risk for isolated severe
weather. A severe thunderstorm watch is not currently expected due
to the limited nature of the threat.

DISCUSSION...Ahead of a vorticity maximum pivoting from the lower
Great Lakes into Hudson Valley, visible satellite and radar imagery
indicate several areas of deepening moist convection. The 12Z
Buffalo and Pittsburgh soundings indicate little to no capping with
MLCAPE increasing to 1000-1500 J/kg by afternoon in areas that
receive stronger heating. Accordingly, expect a gradual increase in
thunderstorm coverage over the next few hours with the 12Z HREF
calibrated thunder and paintball plots indicating the highest
concentration of storms across the Hudson Valley this afternoon
along a persistent zone of low-level confluence.

Current VWPs and RAP-based forecast data indicate 30-35 kt of
southwesterly deep-layer shear across the region; however, the
vector orientation is expected to largely parallel that of the
evolving convective bands, limiting the potential for a more
organized damaging wind threat. Nonetheless, isolated occurrences of
damaging wind gusts appear possible in areas where steeper low-level
lapse rates can develop. Additionally, relatively cool mid-level
temperatures will be supportive of a marginally severe hail risk
with the strongest updrafts.

..Mead/Smith.. 08/23/2026

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...BTV...OKX...ALY...PHI...BGM...BUF...CTP...

LAT...LON   41277764 41777799 42857754 43787654 44387515 44617391
            44207298 43377290 41847321 41197459 41137594 41057682
            41277764 

MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0752 AM CDT Sun Aug 23 2026

Valid 231300Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN ROCKIES/PLAINS AND GREAT BASIN...

...SUMMARY...
Thunderstorms capable of producing large hail and severe/damaging
winds are forecast across parts of the northern Rockies/Plains this
afternoon and evening. Other thunderstorms with mainly a severe wind
threat may occur over portions of the northern Great Basin.

...Great Basin into the Northern Rockies/High Plains...
A mid-level shortwave trough evident on water vapor satellite
imagery this morning across the Pacific Northwest will move
east-northeastward today across the northern Rockies and western
Canada. 40-50 kt of west-southwesterly mid-level winds will
overspread the northern Rockies and adjacent High Plains of
central/eastern MT by this afternoon. As large-scale ascent
preceding the mid-level trough spreads eastward, thunderstorms
should initially form over the higher terrain of western MT.
Downstream destabilization of a sufficiently moist low-level airmass
will support the development of weak instability (MLCAPE generally
500-1000 J/kg) into central/eastern MT and vicinity. 30-40 kt of
effective bulk shear will support a mix of multicells and supercells
initially moving off the higher terrain, with both severe hail and
wind gusts possible. With time, upscale growth into bowing clusters
seems probable with eastward extent in MT, and an increasing risk
for severe/damaging winds. Given the very well-mixed boundary layer
and enhanced mid-level flow expected, some of these gusts could
exceed 75 mph on an isolated basis.

A somewhat separate area of convection should develop this afternoon
across parts of the northern Great Basin. While mid-level flow will
be somewhat weaker across this region compared to locations farther
north, the presence of generally 50s surface dewpoints across
northern UT and vicinity suggests that sufficient low-level moisture
exists to support robust updrafts. As daytime heating occurs and
low-level lapse rates steepen, loosely organized cells/clusters
should form and subsequently spread northeastward while posing a
threat for scattered severe gusts.

...Northern/Central Plains...
A band of elevated thunderstorms is ongoing this morning from
southern SD into NE, aided by modest low-level warm/moist advection.
This activity should gradually weaken through the morning as the
low-level jet subsides, but an isolated threat for severe hail may
continue in the short term given sufficient MUCAPE and deep-layer
shear to support supercells. A narrow corridor of moderate to
locally strong instability is forecast to develop this afternoon
across the western Dakotas/NE along/east of a lee surface trough
where greater low-level moisture will reside. At least isolated
thunderstorms should develop by peak afternoon heating across these
areas, with west-northwesterly flow strengthening with height
through mid/upper levels. Around 35-45 kt of deep-layer shear will
support supercells and associated threat for large hail with any
sustained surface-based convection.

Overall coverage remains uncertain given weak/nebulous large-scale
ascent, but some guidance shows these cells growing upscale into a
cluster or two this evening with some severe wind risk. Regardless,
severe hail should be the main concern with supercells initially,
and the Slight Risk has been nudged westward a little to account for
the probable zone of initiation. Weaker mid-level flow is expected
with southward extent into the central High Plains, but occasional
hail and gusty winds could still occur with any high-based
convection that develops and spreads eastward through the early
evening.

...Northeast Oklahoma/Southeast Kansas into the Ozarks...
A weak mid-level disturbance aiding convection this morning over
SD/NE will move southeastward today on the eastern periphery of
upper ridging centered over the southern High Plains/Southwest. This
feature, in tandem with increasing isentropic ascent associated with
a modest south-southwesterly low-level jet, may aid thunderstorm
development late tonight into early Monday morning across parts of
northeast OK/southeast KS into the Ozarks. Instability is forecast
to remain fairly weak (MUCAPE generally less than 1000 J/kg), but
some clustering may occur with a low chance for gusty/locally
damaging winds. No changes have been made to the Marginal Risk
across this area, as confidence remains limited in both overall
convective intensity and evolution.

...Northeast...
An upper trough/low centered over Ontario and the Great Lakes this
morning will translate slowly eastward across the Mid-Atlantic and
Northeast through the period. A corresponding weak/occluding surface
low will make only modest eastward progress into Quebec through the
day, with a cold front forecast to move eastward across parts of the
Mid-Atlantic/Northeast by this evening. Cloud cover is prevalent
across these regions per latest visible satellite imagery. This,
coupled with poor lapse rates aloft (reference 12Z observed
soundings from ALB/OKX), will limit the amount of destabilization
that can occur through this afternoon with filtered daytime heating.
Still, enhanced south-southwesterly mid-level flow will be present
today across parts of NY into New England, with around 30-35 kt of
deep-layer shear supporting some updraft organization. Current
expectations are for cells and clusters that develop along/ahead of
this front this afternoon to pose a threat for mainly isolated
damaging winds as they spread east-northeastward through this
evening before eventually weakening. Marginally severe hail may also
occur with the strongest cores. But, the weak instability and poor
lapse rates aloft should generally limit the overall severe threat.

...Southeast...
Isolated to scattered thunderstorms should develop later today
along/south of a weak front draped across the lower MS Valley into
the Gulf Coast states, and continuing northeastward into the
Carolinas. With the exception of the Carolinas, low/mid-level flow
will remain quite weak for much of the Southeast. Still, any cells
which can develop may pose an isolated threat for damaging winds, as
moderate to strong MLCAPE coupled with steep low-level lapse rates
through daytime heating support the potential for wet microbursts.
On the southern periphery of mid/upper troughing over the Great
Lakes/Mid-Atlantic and Northeast, stronger flow aloft will exist
across the Carolinas. This may foster some updraft organization
given sufficient deep-layer shear. But, most guidance continues to
show any convection that forms this afternoon across the eastern
Carolinas will move quickly offshore.

...Arizona...
To the west of a mid/upper-level anticyclone centered over the
southern Rockies/High Plains, weak southeasterly mid-level flow will
exist today across southern/central AZ. Instability across this
region is forecast to remain rather muted/weak owing to shallow
low-level moisture. A deeply mixed boundary layer is forecast to
develop with robust daytime heating, but confidence in thunderstorms
developing over the higher terrain of southeast AZ and subsequent
clustering into the lower deserts remains low. Even so, have
maintained the Marginal Risk for severe gusts with no changes.

..Gleason/Broyles.. 08/23/2026

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1135 AM CDT Sun Aug 23 2026

Valid 231630Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN ROCKIES/PLAINS AND GREAT BASIN...

...SUMMARY...
Thunderstorms capable of producing large hail and severe wind gusts
are forecast across parts of the northern Rockies/Plains this
afternoon and evening.  Other thunderstorms with mainly a severe
wind threat are probable over portions of the northern Great Basin.

...Great Basin into the Northern Rockies/High Plains...
Water-vapor imagery this morning shows an eastward-migrating
shortwave trough over the Pacific Northwest.  A belt of 40-50 kt of
west-southwesterly mid-level flow will overspread the northern
Rockies and adjacent High Plains of central/eastern MT by this
afternoon.  Heating along with ascent attendant to the disturbance
will favor initial storm development over the higher terrain over
southwest/western MT.  Steepening lapse rates over the High Plains
will favor the potential for scattered severe gusts as thunderstorms
move/develop over the plains during the late afternoon and evening. 
A mix of multicells and supercells may yield a risk for severe hail
early before upscale growth into linear clusters (60-80 mph gusts)
likely evolves during the evening.  

A somewhat separate area of convection should develop this afternoon
across parts of the northern Great Basin and Upper Snake Valley. 
While mid-level flow will be somewhat weaker across this region
compared to locations farther north, the presence of generally 50s
surface dewpoints across northern UT and vicinity suggests that
sufficient low-level moisture exists to support robust updrafts.
Very steep lapse rates will favor ample evaporative cooling in the
stronger downdrafts.  Scattered severe gusts (60-80 mph) are
possible with the stronger thunderstorm cores and outflow.

...Northern/Central Plains...
Morning surface analysis places a moisture plume (lower to mid 60s
deg F dewpoints) extending from the TX-OK Panhandles
north-northwestward through eastern CO/NE Panhandle and into the
Black Hills vicinity.  It is within this corridor moderate to strong
instability is forecast by mid-late afternoon along/east of a lee
surface trough.  At least isolated thunderstorms should develop by
peak afternoon heating across these areas, with west-northwesterly
flow strengthening with height through mid/upper levels. Around
35-45 kt of deep-layer shear will support supercells and associated
threat for large hail from northeast CO northward into the western
Dakotas.

Farther south, high-based convection is forecast to slowly
spread/move east of the Raton Mesa into the TX-OK Panhandles during
the early evening.  Very steep lapse rates and inverted-V profiles
will favor evaporative cooling and an isolated threat for severe
gusts with the stronger downdrafts and outflow surges.  

...Northeast...
Midday satellite imagery shows an upper trough/low over Ontario with
a series of embedded shortwave impulses rotating through its base. 
A lead disturbance over the Lower Great Lakes will continue to
rotate northeastward across the western portion of the Northeast and
influence scattered thunderstorm development this afternoon. 
Heating of an adequately moist airmass but relatively meager
mid-level lapse rate environment will result in weak buoyancy
developing through mid afternoon as convection deepens.  Around
30-35 kt of deep-layer shear will support some updraft organization
mainly in the form of bands of storms.  An isolated risk for strong
to locally severe gusts is expected across much of this region this
afternoon.  Towards early evening, an upstream impulse will approach
the Lake Erie vicinity with some uptick in storm coverage and
perhaps a lingering risk for wind damage before this activity
weakens by the mid evening.  

...Southeast...
Isolated to scattered thunderstorms will likely develop along/south
of a weak front draped across the lower MS Valley into the Gulf
Coast states, and continuing northeastward into the Carolinas.  An
isolated threat for strong to locally severe gusts may result in
pockets of wind damage with the more intense wet microbursts.

...Northeast Oklahoma/Southeast Kansas into the Ozarks...
Some modest increase in isentropic ascent associated with
a south-southwesterly low-level jet, may aid thunderstorm
development late tonight into early Monday morning across parts of
northeast OK/southeast KS into the Ozarks.  Instability is forecast
to remain fairly weak (MUCAPE generally less than 1000 J/kg), but
some clustering may occur with a low chance for localized severe
gusts.

...Arizona...
On the western periphery of a mid-level anticyclone centered over
eastern NM, weak southeasterly mid-level flow will remain across
southern/central AZ.  Model guidance only depicts weak buoyancy
across much of central and southern AZ, with the exception of
perhaps over far southern AZ.  Nonetheless, hot temperatures and a
deeply mixed boundary layer lend some potential for a localized
microburst risk.

..Smith/Chalmers.. 08/23/2026

Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
1124 AM CDT Sun Aug 23 2026

Valid 231700Z - 241200Z

...Southern Plains...
Much needed rainfall in the last 24 hours has occurred across
portions of northwest TX and the TX Panhandle with isolated
accumulations up to one inch. This residual moisture along with
winds not exceeding 15 mph will temporarily reduce fire weather
concerns across this area this afternoon. Thus, reduced southern
extent of existing Elevated Highlights over portions of northwest
TX. Isolated high-based thunderstorms still pose a threat for new
ignitions over very dry fuels across the northern TX Panhandle and
adjacent OK border areas this afternoon and early evening as a
mid-level short wave enters the region.

...Northern Intermountain West and northern Rockies...
The forecast remains on track with no changes implemented for this
update. Please see previous discussion for more details.

..Williams.. 08/23/2026

.PREV DISCUSSION... /ISSUED 0156 AM CDT Sun Aug 23 2026/

...Synopsis...
A robust midlevel trough will advance eastward across parts of the
Northwest and northern Rockies today. Farther south, an expansive
upper ridge will remain centered on the southern Rockies. Along the
northeastern periphery of the ridge, a low-amplitude shortwave
trough will track southeastward across the central/southern Plains.

...Northern Intermountain West and northern Rockies...
Diurnal heating and related boundary-layer mixing beneath a
well-established midlevel moisture plume (sampled by 23/00Z observed
soundings) will contribute to marginal destabilization across the
region. As large-scale forcing for ascent preceding the midlevel
trough overspreads this instability, isolated to widely scattered
high-based thunderstorms will move from west to east through the
day. Fast storm motions and the well-mixed boundary layer
(characterized by inverted-V profiles) will favor a mix of wet/dry
thunderstorms. Given dry fuels across the area, lightning-induced
ignitions will be a concern. Some of these storms may evolve into
organized clusters and pose a risk of severe wind gusts and hail --
especially with eastward extent into parts of central MT. See the
SPC Day 1 Convective Outlook for more information on the severe
risk. 

Additionally, breezy westerly surface winds will overspread the
region along/behind an eastward-moving cold front. These breezy
winds combined with 15-25 percent RH will lead to an elevated fire
risk. 

...Southern High Plains...
Aided by an evolving surface low in the vicinity of the OK
Panhandle, dry/breezy southerly return flow will develop across the
southern High Plains, resulting in elevated conditions (given
increasingly dry/receptive fuels). Furthermore, the passing midlevel
impulse will promote high-based, eastward-moving thunderstorms
during the afternoon and evening hours. Isolated ignitions will be
possible with this activity, given limited expected rainfall.

...Please see www.spc.noaa.gov/fire for graphic product...