No watches are valid as of Wed Feb 18 20:00:02 UTC 2026.No Mesoscale Discussions are in effect as of Wed Feb 18 20:00:02 UTC 2026.SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1029 AM CST Wed Feb 18 2026
Valid 181630Z - 191200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Organized severe weather is not expected today or tonight.
...Synopsis...
Recent satellite imagery shows a very active upper pattern with
numerous shortwave troughs embedded within the broad troughing that
covers the CONUS. Lead shortwave in this series is currently
maturing over the Upper Midwest, with evolution into a cyclone
expected by this evening. A pair of lower amplitude shortwaves exist
farther west, one entering the central Plains and another over the
southern Great Basin. Lastly, a strong shortwave is currently
dropping quickly southward through the northeast Pacific, preceded
by yet another low-amplitude shortwave moving into the central CA
Coast.
All of these waves are displaced either north or west of the better
low-level moisture, which is in place from central TX to the central
Gulf Coast. This displacement will mitigate the overall severe
potential, although thunderstorms are still expected across several
areas, including the central Intermountain West into the central
Rockies ahead of the southern Great Basin shortwave, and along the
West Coast as the northeast Pacific shortwave drops south along the
coast. Highest coverage ahead of the Great Basin wave will likely
occur along the UT/CO this evening. Highest coverage along the West
Coast is anticipated along OR coast where multiple bands should move
through during the period. A secondary max is likely farther south
in the Monterey Bay Vicinity late tonight/early tomorrow morning.
Isolated elevated thunderstorms also remain possible this afternoon
from Lower MI into northeast OH/northwestern PA as the vorticity max
currently over OH moves into the region. Mid-levels will be dry but
lapse rates will be steep, and there could be just enough low-level
moisture to support limited buoyancy and a few thunderstorms as the
vorticity max moves through.
Lastly, strengthening low-level flow within the moistening low-level
airmass could support a few isolated thunderstorms across Middle TN
and adjacent far south-central KY tonight.
..Mosier/Thompson.. 02/18/2026
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0156 PM CST Wed Feb 18 2026
Valid 182000Z - 191200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Organized severe weather is not expected today or tonight.
...20Z Update...
Only minor changes were made to the ongoing thunderstorm forecast
based on recent observational trends. See the previous discussion
for additional information.
..Wendt.. 02/18/2026
.PREV DISCUSSION... /ISSUED 1029 AM CST Wed Feb 18 2026/
...Synopsis...
Recent satellite imagery shows a very active upper pattern with
numerous shortwave troughs embedded within the broad troughing that
covers the CONUS. Lead shortwave in this series is currently
maturing over the Upper Midwest, with evolution into a cyclone
expected by this evening. A pair of lower amplitude shortwaves exist
farther west, one entering the central Plains and another over the
southern Great Basin. Lastly, a strong shortwave is currently
dropping quickly southward through the northeast Pacific, preceded
by yet another low-amplitude shortwave moving into the central CA
Coast.
All of these waves are displaced either north or west of the better
low-level moisture, which is in place from central TX to the central
Gulf Coast. This displacement will mitigate the overall severe
potential, although thunderstorms are still expected across several
areas, including the central Intermountain West into the central
Rockies ahead of the southern Great Basin shortwave, and along the
West Coast as the northeast Pacific shortwave drops south along the
coast. Highest coverage ahead of the Great Basin wave will likely
occur along the UT/CO this evening. Highest coverage along the West
Coast is anticipated along OR coast where multiple bands should move
through during the period. A secondary max is likely farther south
in the Monterey Bay Vicinity late tonight/early tomorrow morning.
Isolated elevated thunderstorms also remain possible this afternoon
from Lower MI into northeast OH/northwestern PA as the vorticity max
currently over OH moves into the region. Mid-levels will be dry but
lapse rates will be steep, and there could be just enough low-level
moisture to support limited buoyancy and a few thunderstorms as the
vorticity max moves through.
Lastly, strengthening low-level flow within the moistening low-level
airmass could support a few isolated thunderstorms across Middle TN
and adjacent far south-central KY tonight.
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CST Wed Feb 18 2026
Valid 191200Z - 201200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE MIDDLE MISSISSIPPI VALLEY AND LOWER OHIO VALLEY...
...SUMMARY...
Severe thunderstorms, with potential to produce a few tornadoes,
hail and damaging wind gusts, are possible across parts of the
middle Mississippi into lower Ohio Valleys Thursday afternoon into
early evening.
...Synopsis...
A progressive mid-level flow regime, characterized by multiple
low-amplitudes perturbations and strong west/southwesterly flow
aloft is expected over the CONUS Day2/Thursday. The primary
shortwave trough will move from the southern Rockies/Plains into the
Midwest by 00z, assuming a slight negative tilt as multiple weaker
preceding subtropical perturbation are absorbed. Strong ascent
associated with the trough a 100+ kt mid-level jet streak will
deepen a surface low over the eastern Plains, reaching the Great
Lakes by early Friday.
...Middle Mississippi and Lower Ohio Valley...
As the upper trough and surface low approach the Mid MS Valley early
Thursday, rapid low-level moistening is expected across parts of
eastern MO western IL and the lower OH Valley. While moisture
content is seasonably limited (surface dewpoints in the 50s to near
60 F), cooling mid-level temperatures ahead of the preceding
subtropical shortwave trough will support some destabilization
Thursday afternoon.
While instability will remain modest owing to limited boundary-layer
moisture, clearing ahead of a surging dryline tied to the surface
low will allow for diurnal heating. In combination with steepening
mid-level lapse rates, around 500-1000 J/kg of MLCAPE is exacted by
early afternoon. An arc of mainly cellular convection should develop
by mid afternoon across far eastern MO and western to south-central
IL and move quickly eastward. Amid very strong kinematic fields
(EBWD 55+ kt) a supercell mode is expected. Strong low-level shear
and the concentration of buoyancy in the lowest few km will favor
strong vertical accelerations and stretching with seasonably cool
mid-level temperatures. Hail is likely with the stronger rotating
storms. Additionally, with backed low-level flow near the low/warm
front and large low-level shear, (0-1 km BWD 25+ kt) a few tornadoes
are possible.
As ascent spreads eastward, thunderstorm activity may eventually
grow upscale enough to support increasing potential for damaging
wind gusts given the strong background flow. However, decreasing
buoyancy and weakening height falls with eastward extent should
gradually limit convective intensity into parts of the middle OH
Valley late Thursday evening.
..Lyons.. 02/18/2026
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