Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0255 PM CDT Tue Sep 15 2026

Valid 152000Z - 161200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING ACROSS PARTS OF THE CENTRAL PLAINS AND MIDWEST...

...SUMMARY...
Strong to locally severe thunderstorms may occur from the
south-central Plains into parts of the Midwest this afternoon and
evening, with at least isolated damaging wind gusts possible.

...20z Update...

...Southern Great Plains into parts of the Midwest...
The forecast remains generally on track with only minor adjustments
made to the existing outlook. Locally greater potential for a couple
of damaging/severe wind gusts may exist across portions of
south-central Kansas and northern Missouri where guidance continues
to depict greater storm coverage in the vicinity of a surface cold
front. The general displacement of enhanced deep-layer shear to the
north of the boundary and better thermodynamic profiles farther to
the south limits confidence regarding the occurrence of more than
isolated damaging/severe wind gusts, however. Thus, have opted
against a categorical upgrade with this outlook cycle. See MCDs
#2300 and #2301 as well as the discussion below for additional
details.

...Great Basin...
Isolated to widely scattered thunderstorms have formed across
portions of the Four Corners region as of 1930 UTC. Latest objective
analysis and regional observed 18z soundings indicate that weak
buoyancy has developed amid deep, well-mixed boundary layer
profiles. While these thermodynamic profiles may support an isolated
strong to perhaps severe thunderstorm or two this afternoon,
relatively weak low-level flow and fairly nebulous synoptic forcing
for ascent are expected to preclude a more concentrated area of
severe potential.

..Chalmers/Weinman.. 09/15/2026

.PREV DISCUSSION... /ISSUED 1117 AM CDT Tue Sep 15 2026/

...Central Plains into Midwest...
Moderately fast zonal flow remains across the northern US today,
with the primary surface boundary extending from the TX Panhandle
east-northeastward into parts of KS/MO/IL.  This boundary will be
enhanced by daytime differential heating, and will provide the focus
for scattered thunderstorms along its length.  Most of this activity
will be relatively disorganized, but in an environment of moderate
CAPE and steep low-level lapse rates favorable for occasional
strong/severe downdrafts.

One area of greater concern extends across northern MO into
west-central IL.  Morning CAM solutions suggest higher confidence in
storm coverage in this area, and forecast soundings show sufficient
deep-layer shear for organized multicell or occasional supercell
structures.  However, much of this activity may occur on the north
side of the baroclinic zone with slightly weaker support for intense
downburst winds.  Warm temperatures aloft should limit hail concern.
Therefore, have opted to maintain the MRGL risk category and
re-evaluate at the 20z update.

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1208 PM CDT Tue Sep 15 2026

Valid 161200Z - 171200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
NORTHERN UTAH...

...SUMMARY...
A couple of strong to severe thunderstorms appear possible across
northern Utah on Wednesday.

...UT...
An upper low will move slowly southward across northern CA, with low
pressure and gusty south winds developing over NV. Substantial
moisture will exist east of this trough, with precipitable water
around 1.00" over much of UT. Temperatures aloft will be coolest
early in the day, with gradual height rises over time which may
mitigate destabilization somewhat. However, mid to upper level shear
will be strong due to the upper jet, and may support cellular storm
mode and marginal hail. Storms may develop early in the day, with
additional activity during the afternoon.

...Northern MO/IA eastward into OH...
A 600 dm high at 500 mb will remain over the TN Valley, with
generally weak winds aloft south of the Great Lakes. A weak
east-west oriented surface trough is forecast to stretch from MO
into OH, with 70s F dewpoints present. Daytime heating will result
in an uncapped air mass, with scattered thunderstorms within this
zone. The poor lapse rates aloft and building upper ridge should
result mainly in non-severe thunderstorms. However, sporadic strong
gusts cannot be ruled out.

..Jewell.. 09/15/2026

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0210 PM CDT Tue Sep 15 2026

Valid 171200Z - 181200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
The risk for severe thunderstorms appears low on Thursday.

...Discussion...
On Thursday, a large upper trough will move into eastern Canada,
with height falls with the base of the trough moving across the
Great Lakes and into the Northeast. Meanwhile, heights will fall
over the Southeast as the upper high center shifts back west into
the southern Plains. To the west, an upper low will drift from
northern CA into southern OR, with cool temperatures aloft over much
of the Great Basin.

At the surface, high pressure will remain over the northern Plains
to Great Lakes, with a weak surface trough extending from the
central Plains into the OH Valley and toward the Mid Atlantic. Upper
60s to lower 70s F dewpoints will remain along this zone, resulting
in areas of moderate instability. Weaker instability will exist
ahead of the Pacific Northwest low, and ahead of a cold front
pushing across northern NV, eastern OR, and western ID.

Severe storm chances appear relatively low over the Pacific
Northwest given weak instability and marginal shear, while the zone
from MO into PA suffers from poor lapse rates aloft and/or minimal
shear.

..Jewell.. 09/15/2026