Mesoscale Discussion 0185
NWS Storm Prediction Center Norman OK
1116 AM CDT Tue Mar 10 2026

Areas affected...northern/central IL to northwest IN

Concerning...Outlook upgrade 

Valid 101616Z - 101645Z

SUMMARY...An upgrade to a tornado-driven Moderate Risk will be
issued with the midday Day 1 Convective Outlook.

DISCUSSION...Please see the forthcoming 1630Z Day 1 Convective
Outlook for further details.

..Grams/Gleason.. 03/10/2026

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

ATTN...WFO...IWX...LOT...ILX...DVN...

LAT...LON   41408978 41578768 41378634 41178621 40888627 40538790
            40329007 40419057 40839056 41408978 

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0733 AM CDT Tue Mar 10 2026

Valid 101300Z - 111200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE MID
MISSISSIPPI VALLEY INTO THE SOUTHERN GREAT LAKES...AND FROM WEST
TEXAS INTO SOUTHWEST OKLAHOMA...

...SUMMARY...
Severe thunderstorms are forecast today from the southern Plains
into the southern Great Lakes vicinity. All severe hazards are
possible, including the risk for a few strong to intense tornadoes
and very large hail.

...Synopsis...
A split-flow upper pattern persists across the CONUS this morning.
Early-morning satellite imagery shows a well-defined upper low over
the central Baja Peninsula within the southern stream and a subtle,
low-amplitude shortwave trough moving through the Pacific Northwest
within the northern stream. Surface analysis shows a large reservoir
of low-level moisture from the southern Plains and Lower MS Valley
northeastward into the southern Great Lakes. General expectation is
for both the southern-stream upper low and northern-stream shortwave
to progress eastward today, as some modest phasing occurs between
these two features. 

This evolution will contribute to strengthening mid-level flow
across much of the Plains and MS Valley, while also resulting in
increased ascent across the broad warm sector. This will result in a
large area of strong to severe thunderstorms from the southern
Plains into the southern Great Lakes, beginning during the early
afternoon and persisting through the evening and overnight. Two
areas within this broader region, west TX into southwest OK and the
Mid MS Valley into the southern Great Lakes, have environmental
conditions that support the potential for significant severe
weather, including very large hail greater than 2" in diameter and
strong to intense tornadoes.

...Mid MS Valley into the Southern Great Lakes...  
Northern-stream shortwave trough is forecast to move out of MT/WY
this evening, accompanied by strong mid-level flow (over 100 kt at
500 mb). However, this will be well west of the moist and buoyant
airmass across the Mid MS Valley. Even so, modest height falls are
anticipated over the region beginning during the late afternoon. Of
more consequence for the severe-weather potential, a surface low
(currently over the central NE/KS border vicinity) will eject
northeastward ahead of the shortwave, moving along the stationary
boundary that currently extends into far southern WI. This boundary
is also expected to sharpen throughout the day as low-level moisture
advection persists to its south and cold, northeasterly surface
winds persist to its north. Low-level convergence near the surface
low and stationary front will be augmented by the previously
mentioned subtle height falls to support thunderstorm development.
These mesoscale details as well as which side of the stationary
boundary storms develop will be key for determining the primary
severe hazard.

The airmass south of the stationary front is expected to be
moderately to strongly unstable, as temperatures in the 80s,
dewpoints in the low/mid 60s, and steep mid-level lapse rates
combine to support 2000+ J/kg of MLCAPE. Steep mid-level lapse rates
and associated moderate elevated buoyancy will persist north of the
front as well. Given the subtle forcing and mesoscale character of
this set up, CAM guidance varies notably on the timing and location
of thunderstorm development. 

Kinematic profiles suggest that any surface-based warm sector
development should quickly become supercellular, with all severe
hazards possible, including very large hail and tornadoes. A strong
to intense tornado is possible, particularly with any storms ongoing
around 00Z when the low-level flow increases notably, resulting in
considerable elongation of the low-level hodograph. Latest guidance
suggests this tornado risk will exist into parts of far southwest
Lower MI, so probabilities were expanded accordingly. Very large
hail (i.e. 2"+ in diameter) will also be possible north of the front
where strong deep-layer vertical shear exists.  

...Southern Plains...
The southern-stream upper low is forecast to eject eastward across
northern Mexico today, with ascent preceding this low overspreading
a West TX dryline by the afternoon. Initial storm development is
anticipated over the Permian Basin/Big Bend vicinity, with moderate
buoyancy and very strong vertical shear supporting a quick evolution
into supercells capable of very large hail greater than 3" in
diameter. Increasing thunderstorm coverage is expected from
southwest TX into southwest OK as the upper low continues eastward.
Very large hail will remain the primary severe risk although a trend
towards a more linear mode is expected throughout the evening.
Strong gusts could accompany the resulting squall line. The tornado
risk is expected to remain low, owing primarily to the modest
low-level flow. This low-level flow is expected to increase across
the TX Hill Country tonight, where a relatively greater tornado risk
could materialize if cells remain discrete. 

...Northern OK/KS into the Lower OH Valley...
Most guidance has trended towards greater thunderstorm coverage
tonight near the front across northern OK and KS. Moderate buoyancy
and shear will be in place, supporting strong to severe
thunderstorms. Large to isolated very large hail is possible with
the initial development before a trend towards a linear mode shifts
the primary hazard to damaging gusts. The resulting convective line
is then expected to continue eastward across AR and MO before
reaching the Lower OH Valley early tomorrow morning. Damaging gusts
will remain possible as the line moves east overnight. A
low-probability tornado threat could also exist within this line as
it moves into the greater low-level moisture and stronger low-level
flow farther east across central/southern MO and far southern IL.

..Mosier/Dean.. 03/10/2026

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1128 AM CDT Tue Mar 10 2026

Valid 101630Z - 111200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTHERN/CENTRAL ILLINOIS INTO NORTHWEST INDIANA...

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
WEST/CENTRAL TX INTO SOUTHWEST OK...AND THE MIDWEST INTO THE
SOUTHERN GREAT LAKES...

...SUMMARY...
Scattered to numerous severe thunderstorms are expected today and
tonight from the southern Plains to the southern Great Lakes
vicinity. All severe hazards are likely, including the risk for
multiple strong to intense tornadoes, damaging winds, and very large
hail.

...Midwest/Southern Great Lakes/Ohio Valley...
A weak surface low over eastern KS late this morning will translate
northeastward along a front towards northern IL through tonight.
Low-level warm/moist advection will continue today across the
Midwest/OH Valley into the southern Great Lakes, where surface
dewpoints of at least low to mid 60s will likely be present by this
evening. Large-scale ascent across this region will remain fairly
nebulous, as an upper trough ejects eastward over the northern
Plains. Still, a strengthening low-level jet across MO into IL/IN
from late afternoon into this evening should promote scattered
supercell development along/near the front in north-central IL.

Moderate to locally strong instability, steep mid-level lapse rates,
and strong deep-layer shear will all contribute to a very favorable
environment for significant severe potential. Very large hail (2+
inches in diameter) will be possible with initial supercells.
Effective SRH and related low-level shear will markedly increase
around 11/00Z and later in tandem with the strengthening low-level
jet. The supercellular tornado threat is likewise expected to
quickly increase through the late afternoon/evening, as
enlarged/curved low-level hodographs will easily support intense
low-level rotation. A focused corridor along and just south of the
front will have the best potential for multiple strong to intense
tornadoes (EF2-3+). Accordingly, greater tornado probabilities (15%)
and a categorical Moderate Risk have been included across parts of
northern/central IL into northwest IN with this update.

Convection should eventually grow upscale along/near the front late
this evening into the early morning hours on Wednesday. But, the
threat for tornadoes and severe/damaging winds will likely continue
with eastward extent across the Midwest/OH Valley, as both
sufficient instability and strong low-level/deep-layer shear will be
present across the warm sector.

...Texas into Oklahoma...
A closed mid/upper-level low over northern Mexico will move eastward
across the Southwest and southern High Plains by this evening while
devolving into an open wave. Enhanced southwesterly flow aloft and
pronounced large-scale ascent preceding the upper trough will
encourage robust thunderstorm development by mid to late afternoon
along the length of a surface dryline extending southward across
much of west TX. Steep mid-level lapse rates and strong deep-layer
shear will support updraft organization, with an attendant threat
for supercells initially. Very large hail (2-3+ inches in diameter)
will be possible with this discrete activity, before a transition to
more linear structures occurs through the evening. An increase in
the severe/damaging wind threat will likely be realized as this mode
transition occurs across parts of central TX into southern OK. Some
threat for embedded tornadoes will also exist, especially into
central TX where greater low-level moisture and shear are forecast.

A separate area of severe potential may develop this
afternoon/evening across parts of central into northeast TX in the
low-level warm advection regime. While weakly forced, there is some
chance for at least isolated supercells to develop and pose a risk
for large hail and a few tornadoes. This scenario remains uncertain,
but 5% tornado probabilities have been expanded eastward to account
for this conditional potential.

...Oklahoma/Kansas into the mid Mississippi Valley...
A dryline will be in place across western OK today, with a cold
front forecast to move slowly southward across KS and parts of MO
through tonight. While this area will largely remain between
stronger large-scale forcing to both the north and south, it appears
probable that additional thunderstorms will eventually develop this
evening/tonight along/south of the front. Tornadoes and large hail
appear possible with any sustained supercells, while damaging winds
should occur with line segments that can develop and spread eastward
through early Wednesday morning.

..Gleason/Chalmers.. 03/10/2026

Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
1138 AM CDT Tue Mar 10 2026

Valid 101700Z - 111200Z

Northern portions of the Isolated Dry Thunder area were nudged
eastward and trimmed slightly in agreement with the latest
observations and forecast guidance showing less convective
initiation along northwest portions of the previous Day 1/Tuesday
Outlook. Expansion of the Isolated Dry Thunder area was considered
farther to the southwest into the Trans Pecos as well, but showery
precipitation appeared favored over extreme southwest Texas and very
little if any storm coverage near the Big Bend area.

Similarly, the Elevated area was also expanded slightly to the east
to account for the anticipated surge of the dryline through much of
the Texas Panhandle during peak heating this afternoon. Portions of
the central Texas Panhandle will see stronger and drier southwest
winds leading to some locally critical conditions. However,
conditions are not expected to be widespread enough to warrant a
critical area being drawn. Portions of the Front Range will see
locally Elevated fire weather conditions as well but the areal
extent remains limited. A strong cold front will push through the
central and into the southern High Plains late tonight with strong
winds but higher RHs and cooler temperatures.

..Stearns/Nauslar.. 03/10/2026

.PREV DISCUSSION... /ISSUED 0215 AM CDT Tue Mar 10 2026/

...Synopsis...
An upper low over northern Mexico will eject eastward into the
southern Plains as a second upper trough moves over the northern
Plains into the Midwest. At the surface, a lee cyclone will
intensify and move eastward across parts of KS/OK dragging a
trailing dryline with it over parts of the southern Plains. East of
the dryline, rich low-level moisture and widespread
showers/thunderstorms are expected. Dry and breezy conditions behind
the dryline and east of the upper low appear likely to support some
fire-weather potential. Isolated dry thunderstorms are also possible
where lightning may interact with dry fuels over the southern High
Plains.

...Southern High Plains...
As the upper low ejects eastward, the initial surface cyclone will
move away to the northeast along the front. A secondary lee low will
deepen over KS/OK at the apex of the dryline. This, along with
strong flow aloft, will support gusty southwest winds across much of
the southern High Plains. While humidity is unlikely to be overly
low owing to cloud cover and mid-level moisture from the cold core
upper low over NM, pockets of strong heating and downslope flow west
of the dryline will support 20-30% RH values amid westerly wind of
20-30 mph. Elevated and brief critical fire-weather conditions are
likely from the Rio Grande Valley northward across much of West TX
and far eastern NM despite the modest RH minimums. Confidence in
brief critical conditions is highest across the TX Big Bend region
and the southern TX Panhandle where locally higher winds and lower
RH may briefly overlap this afternoon.

Thunderstorm development is probable this afternoon across much of
the southern Plains along the dryline and beneath the upper low over
parts of central NM. Precipitable water values, indicative of
moisture above a dry sub-cloud layer, range from 0.5 to 0.8 of an
inch and are not expected to support efficient rainfall accumulation
given storm motions of 30-40 knots. While confidence in storms is
relatively high, the exact coverage, and dryline position remain
uncertain. The IsoDryT area was expanded slightly to the
west/southwest to account for additional convection on the periphery
of the upper low. Additional changes are likely in the day1 update
as dryline placement and thunderstorm coverage/location details
become clearer.

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