SPC Sep 15, 2026 1630 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1117 AM CDT Tue Sep 15 2026

Valid 151630Z - 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.

...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.

..Hart/Chalmers.. 09/15/2026


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SPC Sep 15, 2026 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0728 AM CDT Tue Sep 15 2026

Valid 151300Z - 161200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN/CENTRAL PLAINS INTO THE 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.

...Southern/Central Plains into the Midwest/Great Lakes...
The primary mid/upper-level trough over central/eastern Canada will
remain displaced well north of the surface warm sector today, with
upper ridging remaining anchored over the Southeast. A surface cold
front will make generally slow south-southeastward progress over the
central Plains and mid MS Valley/Midwest through this evening,
before eventually stalling late in the period. A seasonably moist
airmass characterized by surface dewpoints in the 60s to low 70s
will be in place ahead of the front from the southern High Plains
northeastward to the southern Great Lakes vicinity. While lapse
rates aloft will remain modest, daytime heating will support the
development of moderate instability by mid afternoon along much of
the length of the front (perhaps locally stronger across parts of
eastern KS into MO/IL).

Enhanced mid-level flow will tend to remain north of the cold front,
but some veering and gradual strengthening of the wind field with
height through mid levels should support sufficient deep-layer shear
for modest updraft organization, especially from parts of the
central Plains into the Midwest. Current expectations are for
thunderstorms to gradually develop by 20-23Z along/near much of the
length of the front as convective temperatures are reached. Loosely
organized clusters capable of producing mainly damaging winds should
be the primary concern as this convection spreads generally
east-northeastward through the evening, especially where low-level
lapse rates can become steepened. This appears more likely across
parts of the southern/central Plains where stronger heating is
forecast. Some chance for marginal supercell structures may exist
from parts of eastern KS into MO this afternoon, with isolated hail
possible. Considered greater wind probabilities and a Slight Risk
across this region, but potential for an organized cluster remains
too uncertain for an upgrade with this update.

...Southwest/Four Corners...
A rather moist low-level airmass (surface dewpoints generally in the
50s) will remain across parts of the Four Corners region today.
Modestly enhanced west-southwesterly mid-level flow will persist
from UT into western CO ahead of a mid/upper-level trough over the
Pacific Northwest. While occasional strong thunderstorms appear
possible, modest heating and overall weak destabilization are
currently expected to limit the magnitude of the severe threat.
Small hail and gusty winds could accompany the strongest cores, but
confidence in organized severe thunderstorms remains too low to
include any hail/wind probabilities at this time.

..Gleason/Mead.. 09/15/2026


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SPC Sep 15, 2026 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1226 AM CDT Tue Sep 15 2026

Valid 151200Z - 161200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
SOUTH-CENTRAL PLAINS INTO PARTS OF THE 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.

...South-central Plains into parts of the Midwest...
A vigorous mid/upper-level trough will move quickly eastward across
Ontario and the Upper Great Lakes region today, before reaching
southern Hudson Bay and Quebec by this evening. A deep surface low
will accompany this system, as a trailing cold front moves across
parts of the central Plains and Midwest. To the south of the
ejecting trough, an upper ridge is forecast to amplify over the
Southeast.

Persistent clouds and precipitation to the cool side of the front
will help to reinforce the baroclinic zone as it moves southeastward
through the day. The front will impinge on an increasingly warm and
unstable environment by late afternoon, and scattered storm
development is expected from the TX Panhandle into parts of the
Midwest. The strongest mid/upper-level flow will be displaced north
of the front, and low-level flow will tend to weaken through the
day.

This weakening flow regime, combined with gradual midlevel height
rises and an eventual tendency for storms to be undercut by the
front, results in uncertainty regarding the magnitude of the
organized severe threat this afternoon and evening. However,
seasonably strong heating and relatively large PW and buoyancy will
support potential for localized downbursts and outflow-driven
clusters, with attendant damaging-wind potential. Hail potential
appears generally limited by weak midlevel lapse rates and only
modest deep-layer shear, though small to near-severe hail may occur
with the strongest cells.

A relatively broad Marginal Risk has been maintained from the
south-central Plains into the Midwest. Corridors of locally greater
potential could eventually evolve within the broader risk area,
especially near any pre-frontal outflow boundaries generated by
early-day convection.

...Parts of UT/western CO...
Anomalous moisture will remain in place across parts of the Four
Corners region and Southwest today. The strongest deep-layer
flow/shear will reside from UT into western CO, in advance of a
mid/upper-level trough over the Pacific Northwest. While a few
strong storms will be possible, generally weak heating and
destabilization are currently expected to limit the magnitude of the
severe threat. Small hail and gusty winds could accompany the
strongest storms.

..Dean/Supinie.. 09/15/2026


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SPC Sep 15, 2026 0100 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 0100Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0756 PM CDT Mon Sep 14 2026

Valid 150100Z - 151200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
WESTERN/CENTRAL IA AND FAR NORTHWEST MO...

...SUMMARY...
Strong to severe storms remain possible tonight across parts of the
central Plains and Midwest, with the greatest remaining threat
expected from western into central Iowa.

...Western/northern KS into southeastern NE/IA/northwest MO...
A broken band of thunderstorms is ongoing this evening from western
KS into eastern NE and western IA. The western portion of this band
may pose a localized severe-wind threat through dusk across
western/northern KS, in the presence of a remnant well-mixed
boundary layer and moderate deep-layer flow.

Farther east, a narrow corridor of rich low-level moisture and
moderate buoyancy resides from northeast KS/northwest MO into far
southeast NE and southwest IA. Low-level shear/SRH remains locally
enhanced across in the vicinity of the effective warm front,
conditionally supporting tornadic supercell potential. However,
ongoing convection has already become outflow dominant, and residual
downstream MLCINH may continue to limit surface-based supercell
potential this evening. Even if tornado potential does not evolve,
the environment otherwise remains favorable for damaging winds and
isolated hail as storms move eastward through the evening.

Convection will become increasingly elevated with eastward extent
late tonight, though the strongest cells/clusters may remain capable
of producing isolated hail and localized strong/damaging gusts into
the early morning hours. Other bands or clusters of elevated storms
will also be possible in the wake of earlier convection across the
central Plains, with moderate elevated buoyancy potentially
supporting a brief/localized severe threat overnight.

..Dean.. 09/15/2026


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