Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0144 AM CDT Mon Aug 17 2026

Valid 191200Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE CENTRAL PLAINS...

...SUMMARY...
Isolated strong to severe thunderstorms may produce large hail and
strong wind gusts from eastern Colorado into parts of Nebraska
Wednesday afternoon/evening.

...Central Plains...

Moderate northwesterly flow aloft will persist over the region on
Wednesday. In the wake of a prior cold frontal passage, easterly
low-level winds will maintain modest boundary layer moisture across
the High Plains, with somewhat deeper moisture further east into
central NE. A plume of steeper midlevel lapse rates will overspread
the region, and a corridor of moderate to strong instability is
forecast. Vertically veering wind profiles with 40+ kt effective
shear magnitudes and elongated/straight hodographs are evident in
forecast soundings. Isolated to widely scattered thunderstorms are
expected to develop within the low-level warm advection/upslope flow
regime during the afternoon into the evening. Isolated large hail
and strong outflow winds will be possible.

...Mid-South vicinity...

An MCV may be located over KS Wednesday morning. This feature will
migrate eastward as a surface boundary sags southward across parts
of the Ozark Plateau into the Lower OH Valley. A corridor of rich
boundary layer moisture will be in place near the surface boundary,
promoting a narrow corridor of moderate to strong instability.
However, forecast soundings indicated capping may rapidly increase
downstream of the Ozarks into southeast MO and western TN/KY. It is
possible that a narrow corridor of severe potential could develop
somewhere from the Ozarks into the Mid-South as the MCV and surface
boundary impinge on the area. However, confidence is low, precluding
severe probabilities at this time.

..Leitman.. 08/17/2026

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0248 AM CDT Mon Aug 17 2026

Valid 201200Z - 251200Z

...DISCUSSION...
An amplified upper pattern will persist during the Day 4-8/Thu-Mon
period. An upper trough will remain over the eastern U.S. while
strong upper ridging spreads from the western U.S. toward the Plains
late in the period. This pattern will result in moderate
northwestern flow aloft across portions of the Plains into the
Midwest. Beneath northwesterly flow aloft and on the eastern
periphery of upper ridging, a seasonally moist airmass will be in
place from the Mid/Lower MO Valley into the Upper/Middle MS Valley.
Some severe potential could develop over these areas through the
period. However, capping may limit this potential, and with no
notable features fostering focused large-scale ascent, uncertainty
is too high to include 15 percent severe probabilities at this time.

Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0140 AM CDT Mon Aug 17 2026

Valid 171200Z - 181200Z

...Synopsis...
Upper-level ridging across the western US will weaken as a trough
deepens across the Canadian Prairies. Increasing westerly flow
across the northern periphery of the ridge will bring an increase in
surface winds across portions of northern California and the Great
Basin with dry and breezy conditions possible.

...Northern Great Basin and Northeast California...
Warm afternoon temperatures are forecast to overlap with breezy
southwesterly surface winds across portions of northeastern
California into northern Nevada this afternoon. Relative humidity
reductions to 15-20% will overlap with sustained westerly winds
around 10-15 mph to support a few hours of Elevated fire weather
conditions. Fuels in this region remain critically dry, with little
to no recent rainfall.

...Northern Rockies...
Ascent from the trough sweeping across the northern Rockies into the
northern Plains will bring widely scattered thunderstorm activity
across portions of the northern Rockies this afternoon. Moisture
will be shallow and limited, with precipitable water values around
0.50-0.90". This in combination with faster storm motions may lead
to little in the way of wetting rainfall. However, several days of
wetting rainfall have tempered fuels such that dry storms and
lightning ignitions are expected to be sporadic. Several new starts
have been noted across southwestern ID and eastern OR. Depending on
the timing and location of the approaching shortwave trough, an
isolated thunderstorm over dry fuels further south into Idaho is
possible, albeit low (5-10% chance).

..Thornton.. 08/17/2026

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