SPC Sep 15, 2026 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook

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.

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