Mesoscale Discussion 1819
NWS Storm Prediction Center Norman OK
0644 PM CDT Sat Aug 01 2026

Areas affected...Parts of eastern IN/KY...western
OH...middle/eastern TN

Concerning...Severe potential...Watch unlikely 

Valid 012344Z - 020145Z

Probability of Watch Issuance...20 percent

SUMMARY...A threat for a brief tornado or two and/or locally
damaging wind may continue through dusk.

DISCUSSION...An arc of thunderstorms is ongoing this evening from
eastern IN into southwest OH, eastern KY, and middle TN, in
association with a broad deep-layer clone over IL/IN and surface
trough that trails into the OH/TN Valleys. Multiple cells within
convective arc have developed brief/transient rotation over the last
1-2 hours, aided by low-level vorticity near the surface cyclone and
some SRH enhancement noted on the KILN VWP. Rich low-level moisture
is supporting MLCAPE of 1000-2000 J/kg, though poor lapse rates may
continue to temper updraft intensity and the longevity of the severe
threat with any particular storm. The strongest cells through dusk
will remain capable of producing a brief tornado or two and/or
locally damaging winds.

..Dean/Hart.. 08/01/2026

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

ATTN...WFO...RLX...MRX...JKL...ILN...LMK...IWX...OHX...IND...

LAT...LON   40158575 40508445 40428362 40058303 39198303 37968341
            37018369 36298411 35658475 35598531 35638557 35758612
            35988613 36678568 37878514 39618506 40158575 

MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0256 PM CDT Sat Aug 01 2026

Valid 012000Z - 021200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE OHIO AND TENNESSEE VALLEYS...

...SUMMARY...
Thunderstorms with severe wind gusts and an isolated tornado threat
are expected across parts of the Ohio and Tennessee Valleys this
afternoon into evening. Isolated severe wind gusts will also be
possible in parts of New Mexico, southeast Arizona, and far West
Texas.

...20Z Update...
The MRGL Risk/5-percent wind probabilities were expanded westward
into parts of central MS, where a very warm and moist PBL (upper 70s
dewpoints) are contributing to moderate-strong surface-based
buoyancy. Any thunderstorm clusters that evolve along/ahead of the
approaching cold front will pose a risk of locally damaging wind
gusts later this afternoon and evening. Elsewhere, the forecast
remains on track, and only minor adjustments were made.

..Weinman.. 08/01/2026

.PREV DISCUSSION... /ISSUED 1116 AM CDT Sat Aug 01 2026/

..OH and TN Valleys...
Recent satellite imagery shows a positively tilted shortwave trough
moving through the Mid MS Valley. Surface analysis shows an occluded
surface low over central IL beneath the shortwave. Expectation is
for this cyclone to drift slowly east-southeastward throughout the
day, with the surface low gradually filling. As this low fills, the
triple point low, currently near the IL/IN/KY border intersection,
will become more prominent through the afternoon before it too
occludes.

Showers and thunderstorms are currently ongoing from eastern
IN/western OH through eastern TN into AL, along the eastern
periphery of an arcing warm conveyor. These showers and
thunderstorms should continue northeastward/eastward as the entire
system drifts east-southeastward, with some modest moisture
advection anticipated throughout the warm sector. This should allow
the warm sector to at least moderately destabilize, but persistent
cloudiness will limit heating, likely tempering the overall
buoyancy. Expectation is for more modest buoyancy (i.e. MLCAPE
around 500 to 1000 J/kg) across IN and OH, with greater buoyancy
(i.e. MLCAPE around 1500 J/kg) farther south across central KY and
Middle TN. Thunderstorm development is anticipated along and ahead
of the cold front as it moves through this destabilized and buoyant
airmass.

Moderate mid-level flow throughout the base of the Mid MS Valley
shortwave trough will spread eastward across KY and TN, supporting
effective shear around 30 to 35 kt across KY. Reduced vertical shear
is expected farther north across the OH Valley (due to weaker
mid-level flow) and farther south across TN Valley (due to more
westerly low-level flow). Given these kinematic conditions, a
predominantly multicellular mode is favored, although a few
supercells appear possible from southeast IN/southwest OH through
central KY. Damaging wind gusts will be the most prominent hazard,
but a tornado or two is also possible, particularly within the
corridor from far southeast IN through far north-central KY and far
southwest OH. Here, some modestly increased low-level shear is
possible near the triple point low as it moves through.

...Eastern AZ through NM into west TX...
Moderate mid-level moisture will support afternoon thunderstorm
development across the higher terrain from western AZ through
central/northeast NM. Relatively strong northerly winds aloft will
aid storm organization/clustering as storms spread
south-southeastward into the deeply mixed boundary-layer across the
lower elevations. Outflow-dominant storm structures will result in
strong cold pools capable of isolated strong to severe wind gusts.
Resulting forward-propagating lines could reach as far
south/southeast as Far West TX by later this evening.

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0227 PM CDT Sat Aug 01 2026

Valid 031200Z - 041200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER EASTERN NORTH
 DAKOTA...NORTHWEST MINNESOTA...AND A SMALL PART OF NORTHEAST SOUTH
DAKOTA......

...SUMMARY...
Widely scattered to scattered severe storms are expected across
eastern North Dakota, northwest Minnesota, and a small part of
northeast South Dakota Monday. Severe wind gusts and large hail will
be the primary hazards. Isolated damaging winds are possible from
central and eastern South Dakota into western Nebraska, and in
portions of the Mid-Atlantic into southern New England.

...Synopsis...
A progressive wave with unseasonably strong mid-level flow will
eject across the northern Plains into the upper Midwest on
D3/Monday.  At the surface, a low will develop from western SD into
northern MN, with a cold front advancing through the northern Plains
and upper MS Valley. The southern extension of the front will push
into the central High Plains.

...Northern and central Plains into the upper Mississippi Valley...
Convection is expected to be ongoing near the front across portions
of North Dakota into western Minnesota Friday morning as height
falls overspread the region near the cold front. Early day storms
may be elevated, likely posing the best potential for a few
instances of large hail. Behind morning convection, steep low to
mid-level lapse rates and clearing should allow for a swath of
moderate instability to develop across western North Dakota into
northern Minnesota by the afternoon. Thunderstorm activity is
expected to redevelop near the front during this time. Supercell
wind profiles will be in place with potential for large hail and
damaging wind. High LCLs will likely limit the tornado potential.

The air mass further south across South Dakota into southern
central/Minnesota will likely remained capped and free of morning
convection. Stronger heating and moistening in this region may
result in moderate to strong instability. A conditional threat for
supercells will be possible, limited by remaining capping at the
base of the EML through the afternoon. Should storms develop, the
environment would support the potential for isolated occurrences of
severe wind gusts and perhaps some large hail.

...Southern New England into the Mid-Atlantic...
Storms will likely be ongoing at the start of the period across
southern  New England into the Mid-Atlantic, which leads to
uncertainty in the degree of air mass destabilization by afternoon
along and ahead of the front. Where filtered heating can occur, the
presence of a moist air mass will support pockets of moderate
instability by afternoon. Forcing within the right entrance region
of an upper-level jet streak lifting through northern New England
will combine with the front to yield an increase in storms through
the afternoon within a kinematic environment featuring 30-35 kt of
deep-layer shear. As such, a few strong to severe storms appear
possible, with the primary hazard being damaging wind gusts.

..Thornton.. 08/01/2026

Day 2 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0257 PM CDT Sat Aug 01 2026

Valid 021200Z - 031200Z

...CRITICAL FIRE WEATHER AREA FOR FAR NORTHERN
UTAH...WESTERN/CENTRAL WYOMING...CENTRAL/EASTERN IDAHO...AND
MONTANA...

...Wyoming...
Critical fire weather highlights have been expanded east across the
Bighorn and Wind River Basins and the adjacent mountains of central
Wyoming. Minimum RH values are forecast between 5 and 15%, with the
lowest values expected across central Wyoming amidst afternoon high
temperatures in the upper 80s to upper 90s. West to northwest
surface winds are forecast to increase to near 20 mph (gusts to 35
mph) by midday across southwest Wyoming and the Green River Basin
and later farther east.

...Elsewhere...
Elevated highlights have also been expanded across portions of
southwestern Utah and western Colorado. Southwest winds of 10-20 mph
(gusts near 35 mph) are expected amidst minimum RH near 8% across
southwestern Utah. Winds should be weaker across western Colorado,
but breezy winds coupled with hot and dry conditions over receptive
fuels support elevated fire weather concerns. 

While minimum RH of 5-13% is expected across northern Nevada behind
the front, northerly winds of 10-20 mph should preclude Critical
highlights. Farther east, minimum RH of 5-15% is expected across the
Nebraska Panhandle and adjacent Wyoming High Plains ahead of a lee
trough. While sustained winds should generally remain around 15-20
mph, frequent wind gusts to 35-45 mph will still support rapid fire
spread with locally critical fire weather conditions possible. 
  
Fuels remain receptive across the outlook area, with ERCs at or
above the 95th percentile in most locations and near the 98th
percentile across north-central Montana, supporting high fire
intensity and resistance to control on new ignitions. 

Please see the previous discussion below for more information on
tomorrow's fire weather forecast.

..Elliott.. 08/01/2026

.PREV DISCUSSION... /ISSUED 0223 AM CDT Sat Aug 01 2026/

...Synopsis...
The strong upper-level trough positioned across the Pacific
Northwest/northern Rockies will transition slowly east-northeastward
on D2/Sunday, with strong mid-level flow persisting across the
region and a dry cold front continuing to progress
east-southeastward across the region. A combination of dry and windy
conditions within the post-frontal air mass and hot, dry, and windy
conditions ahead of the front will promote widespread elevated to
critical fire weather concerns across portions of the Great Basin,
Pacific Northwest, northern Rockies, and northern Great/High Plains.
Potential also exists for lightning-induced holdovers to emerge from
thunderstorms earlier in the week across portions of eastern Idaho
and southwestern Montana.

...Montana into the northern Great Plains...
Latest model guidance suggests a dry cold front should extend across
eastern Montana south-southwestward into northern Wyoming and
eastern Idaho at the start of the D2 period (12 UTC Sunday). Strong
mid-level flow (35-45 kts at 700 mb) is forecast to persist along
the Montana/Canada border during this time frame. Coupled with a
tightened surface pressure gradient within the post-frontal air
mass, this will favor strong westerly downslope flow across much of
central/northern Montana (increasingly northwesterly with eastward
extent) beginning early in the period on Sunday. Sustained 20-25 mph
winds are forecast to be common Sunday morning, with these
magnitudes persisting across northern/central Montana but weakening
to 15-20 mph or less across eastern Montana, western SD/ND, and
northeastern Wyoming. Wind gusts to 30-40+ mph will also be possible
(primarily across Montana), with the strongest gusts most likely
Sunday morning. In addition, RH recoveries are forecast to be modest
at best Saturday night into Sunday morning, which should favor quick
RH reductions to 15-20% by late morning/early afternoon Sunday
(locally dropping to 10% later Sunday afternoon). 

With ERCs commonly exceeding the 90th and 95th percentiles (98th
percentile in central/north-central Montana), these conditions will
promote an extended period (6+ hours for some locations) of critical
fire weather conditions. The Critical highlights were expanded
slightly eastward in portions of east-central Montana with this
update. The forecast for sustained winds of around 15 mph precludes
farther eastward expansion into North Dakota at this time, but
elevated fire weather concerns are still expected across this
region. Additionally, some guidance suggests a secondary cold front
may pass through portions of north-central Montana later Sunday
night, which could bring a shift to northwesterly winds and a brief
surge in magnitude. This will be monitored for future outlooks.

Farther southeast, sustained southerly winds of around 15 mph and RH
reductions to 15-20% are forecast across portions of western South
Dakota and northwestern Nebraska, which will promote elevated fire
weather concerns. A shift to north-northwesterly winds is expected
with the passage of the southeastward progressing cold front through
the afternoon/evening.

...Central/eastern Idaho into western Wyoming...
Recent forecast guidance suggests the dry cold front is likely to
extend from northern Wyoming into eastern/southeastern Idaho early
in the period on Sunday. Within the post-frontal air mass, generally
westerly surface winds are forecast to funnel down the Snake River
Valley, with magnitudes up to 25 mph (perhaps higher) for at least 6
hours amid RH reductions to 15-20%. Farther east in western Wyoming,
initially southwesterly surface winds ahead of the front will shift
to westerly and accelerate to around 20 mph amid RH of 10-20%. While
portions of these areas have received recent rainfall, ERCs are
already noted to be around the 80-95th percentiles, and dry and
breezy conditions on D1/Saturday will aid in the drying of fine
fuels. Thus, this combination of winds, RH, and dry fuels will
promote critical fire weather concerns from central/eastern Idaho
into western Wyoming beginning late morning/early afternoon on
Sunday. Lighter winds around 15-20 mph should also support elevated
fire weather conditions across portions of central Wyoming.

...Eastern Washington/Oregon and northern Idaho...
Lingering, enhanced mid-level flow across the eastern portions of
the Pacific Northwest (including eastern WA/OR and northern ID) may
support sustained westerly/northwesterly winds up to around 15 mph
Sunday afternoon, with minimum RH values forecast to range from
20-25% (eastern WA, northern ID, and northern OR) to 10-20%
(southeastern OR). This may promote several hours of elevated fire
weather concerns on Sunday across areas that are forecast to
experience critical to extremely critical fire weather conditions on
D1/Saturday.

...Great Basin...
Westerly/southwesterly sustained surface winds are forecast to
increase to around 15 mph amid very low RH of around 10% Sunday
afternoon. Combined with ERCs generally ranging from the 80th to
95th percentiles across the region, this is expected to support at
least a few hours of elevated fire weather concerns across much of
eastern/northern Nevada and western/northern Utah Sunday afternoon.

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