Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Tue May 26 2026
Valid 261200Z - 271200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
WEST AND SOUTHWEST TEXAS...
...SUMMARY...
Thunderstorms with large hail, severe wind gusts and a couple
tornadoes are expected this afternoon and evening across parts of
west and southwest Texas. Isolated severe gusts and a marginal
tornado threat will be possible in parts of Kentucky. Isolated
severe gusts and hail may also occur in parts of the Upper Midwest
and northern Rockies.
...West and Southwest Texas...
A mid-level shortwave trough will move eastward today across far
west Texas. At the surface, a low will deepen near Big Bend as an
axis of low-level moisture sharpens from the Rio Grande Valley
northward into west Texas. Along this axis, surface dewpoints will
be in the upper 60s and lower 70s F, which will contribute to
moderate instability by afternoon. Near the moist axis, a
north-to-south corridor of low-level convergence is forecast, along
which thunderstorm development is expected by late morning. Storm
coverage is forecast to expand and move eastward from west Texas
into southwest Texas this afternoon.
Along the instability axis, MLCAPE is forecast to peak in the 2000
to 3000 J/kg range during the mid to late afternoon. RAP forecast
soundings near the instability axis at 21Z have 0-6 km shear in the
30 to 40 knot range with 700-500 mb lapse rates around 7.5 C/km.
This will be favorable for supercells with large hail. Hailstones
greater than 2 inches in diameter will be possible with the more
intense storms. In addition, forecast hodographs are curved and 0-3
km storm-relative helicity is forecast to increase to above 200
m2/s2, which will support a tornado threat. Cells are expected to
merge into a line during the late afternoon, potentially increasing
the threat for severe gusts. This line is forecast to move across
southwest Texas during the early evening.
...Kentucky...
South-southwesterly mid-level flow will be in place over the Ohio
and Tennessee Valleys today. At the surface, a mesolow is forecast
to develop over far western Kentucky this afternoon. To the east of
the low, moisture advection will increase surface dewpoints to near
70 F across much of Kentucky, where MLCAPE is forecast to peak
around 1000 J/kg. Within this unstable airmass, low-level flow over
southern and central Kentucky will be backed to the south-southeast.
This, combined with increasing low-level flow, will create curved
hodographs. Forecast soundings at 21Z south of Lexington have 0-3 km
storm-relative helicity increasing to 150 m2/s2 by mid afternoon,
which should support a marginal tornado threat. Isolated severe wind
gusts will also be possible.
...Upper Midwest...
Mid-level flow will be westerly today across much of the Upper
Midwest. At the surface, a quasi-stationary frontal boundary will be
in place from eastern North Dakota to northern Wisconsin. South of
this front, surface dewpoints in the 60s F will contribute to
pockets of moderate instability by afternoon. Scattered
thunderstorms will develop across this unstable airmass and move
east-southeastward during the afternoon. MLCAPE in some areas are
forecast to peak in the 1500 to 2500 J/kg range, with low-level
lapse rates becoming steep. This will be sufficient for isolated
severe gusts. Hail will also be possible, mainly from southeast
Minnesota into Wisconsin, where some models suggest instability will
be stronger.
...Northern Rockies...
A mid-level low will move southward across northern California
today. To the northwest of the low across the northern U.S., flow
will be from the south-southeast. At the surface, a low will deepen
across western Montana with upslope easterly flow located over much
of western Montana. As surface heating takes place today, an axis of
instability is forecast from northwest Montana extending
southeastward into far northwest Wyoming. Scattered thunderstorms
will develop in the higher terrain and move northward along and near
this axis of instability. Low-level lapse rates will be very steep,
which will contribute to a potential for severe wind gusts. Hail
will also be possible, mainly over western Montana where instability
is forecast to be the strongest.
..Broyles/Chalmers.. 05/26/2026
Read more CHECK UPDATE ZOOM GRAPHIC
http://dlvr.it/TSk6BV
