RSS Mesoscale Discussions from Storm Prediction Center
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1108 PM CST Tue Feb 17 2026
Valid 181200Z - 191200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated to widely scattered thunderstorms are possible along parts
of the West Coast, southern Great Basin, central Rockies, and the
lower Great Lakes regions. Severe weather is not anticipated.
...Discussion...
A series of mid-level troughs will traverse the CONUS Wednesday
morning through late Thursday. Across the western US, a trough will
gradually shift across the Great Basin with enhanced mid-level flow
overspreading the Desert Southwest into the central/southern High
Plains. Forcing for ascent and cooling temperatures aloft will bring
scattered thunderstorm activity across the central California coast
to the Oregon/Washington Coast. Additional thunderstorm development
will be possible across the southern Great Basin into the central
Rockies. Generally weak thermal profiles will limit severe potential
with this activity.
A secondary trough will continue to shift northeast across the Great
Lakes Region. Scattered thunderstorm development will be possible
along an eastward moving front within a narrow region of warm air
advection. Given the generally narrow/weak region of marginal
instability, activity is this region is expected to remain
sub-severe.
..Thornton/Squitieri.. 02/18/2026
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SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1200 AM CST Wed Feb 18 2026
Valid 191200Z - 201200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS MUCH OF CENTRAL
AND SOUTHERN ILLINOIS AND INDIANA...PARTS OF WESTERN AND NORTHERN
KENTUCKY AND SOUTHWESTERN OHIO...
...SUMMARY...
Severe thunderstorms, with potential to produce a few tornadoes and
damaging wind gusts, are possible across parts of the middle
Mississippi into lower Ohio Valleys Thursday afternoon into early
evening.
...Discussion...
There remains notable spread evident in the latest model output
concerning a number of synoptic and sub-synoptic developments within
the evolving pattern across North America through this period. In
general, though, guidance continues to indicate that larger-scale
mid-level troughing will slowly begin to shift inland of the Pacific
coast Thursday through Thursday night, while being maintained
downstream across the Rockies, Great Plains and Mississippi Valley,
and slowly developing toward the lower Great Lakes and Appalachians
vicinity. As this occurs, the center of a mid-level subtropical
ridge is likely to shift from the southern Gulf Basin into the
Bahamas/Caribbean, with its northern periphery maintaining an
influence across parts of the Southeast.
A couple of initially lower amplitude short wave perturbations,
within a seasonably strong belt of flow emerging from the Southwest,
may be in the process of progressing into and across the central
Great Plains toward the middle Mississippi and lower Ohio Valleys at
the outset of the period. The lead perturbation, probably
accompanied by a 500 mb speed maximum of 90-100+ kts, is forecast to
continue into and across the lower Ohio Valley during the day, as
the trailing one pivots northeastward and perhaps intensifies across
the middle Mississippi Valley toward southern Great Lakes region
later Thursday through Thursday night.
Associated with these developments, a sub-1000 mb surface cyclone is
forecast to migrate across and northeast of the lower Missouri
Valley during the day, perhaps slowly deepening, before continuing
toward the upper Great Lakes accompanied by more substantive
deepening Thursday night.
...Middle Mississippi/Lower Ohio Valley...
It appears that warming aloft, associated with subsidence to the
south of the trailing mid/upper jet, will tend to eventually
overspread the better (but still relatively modest) low-level
moisture return to the evolving warm sector across the lower Ohio
Valley. However, to still differing degrees, the latest runs of the
various model output indicate a window of opportunity for strong to
severe thunderstorm development, perhaps beginning by early
afternoon, aided by daytime heating and subtle mid-level
cooling/forcing for ascent accompanying the lead jet streak.
The consensus of latest guidance, supported by the High Resolution
Ensemble and related machine learning output, suggests that this may
initiate across portions of Illinois, near or to the north and east
of the Greater St. Louis area, with strongest activity tending to
develop eastward and perhaps peak while spreading across east
central and portions of southeastern Illinois through portions of
central and southern Indiana by early Thursday evening.
Forecast soundings across this corridor remain generally
characterized by at least modest convective instability, and CAPE on
the order of 500-750+ J/kg, in the presence of strong deep-layer
shear. Sizable clockwise-curved low-level hodographs, beneath
40-50+ kt south to southwest flow in the 850-700 mb layer, may
promote supercells capable of producing severe hail and a few
tornadoes, and activity may eventually grow upscale enough to
support increasing potential for damaging wind gusts before
convection wanes late Thursday evening.
..Kerr.. 02/18/2026
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SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0229 AM CST Wed Feb 18 2026
Valid 201200Z - 211200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Probabilities for severe storms Friday through Friday night appear
less than 5 percent across the U.S.
...Discussion...
Models indicate that mid/upper flow may undergo renewed
amplification across the central into eastern mid-latitude Pacific,
including a significant short wave trough digging south-southeast of
the Gulf of Alaska (roughly along 140W longitude), to the east of
building ridging across and north-northwest of the Aleutians.
Farther east, mid-level ridging is forecast to build inland of the
Pacific coast, with remnant larger-scale downstream troughing
developing eastward across the Rockies through Mississippi Valley.
An initially vigorous short wave perturbation, which earlier emerged
from this troughing, may maintain considerable strength into the day
Friday while progressing east-northeastward toward the lower Great
Lakes region. However, it is still generally forecast to become
sheared and weaken to the south of a mid-level high centered near
southern Hudson/James Bays. As it does, the associated occluding
cyclone is forecast to substantively weaken. It continues to appear
that secondary surface cyclogenesis across and east-northeast of the
Mid Atlantic region will remain subdued, and the primary trailing
surface frontal zone probably will tend to stall near the southern
periphery of the stronger westerlies, across parts of the Carolinas
into the Gulf Coast states by 12Z Saturday.
Further low-level moistening associated with return flow off the
Gulf is probable along and south of this front. However, warm
layers aloft, near the northwestern periphery of mid/upper
subtropical ridging centered across the Bahamas/Caribbean, may tend
inhibit destabilization and thunderstorm development. As mid/upper
forcing for ascent, associated with short waves within the strong
flow emerging from the Southwest, remains mostly to the cool side of
the front, potential for stronger thunderstorm development seems
likely to become focused along or just to the cool side of the
frontal zone.
While deep-layer shear near the front is likely to be strong and
potentially supportive of organized thunderstorm development, the
extent to which thermodynamic profiles become conducive to a risk
for severe weather remains unclear. It appears that
lower/mid-tropospheric lapse rates will be generally weak, and most
unstable CAPE is forecast anywhere from modest to weak. At the
present time the risk for severe thunderstorms Friday through Friday
night appears mostly conditional, and too conditional support a
forecast of 5 percent or greater severe probabilities. However,
this could still change in later outlook updates for this period,
particularly across parts of the Gulf Coast states.
..Kerr.. 02/18/2026
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