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

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1224 AM CDT Tue Sep 15 2026

Valid 161200Z - 171200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS WEDNESDAY
MORNING ACROSS THE GREAT SALT LAKE/SALT LAKE CITY VICINITY...

...SUMMARY...
A couple of strong to severe thunderstorms appear possible across
the Greater Salt Lake City vicinity Wednesday morning.

...Discussion...
Latest model output continues to indicate that an initially digging
short wave trough along the Pacific coast will contribute to the
evolution of a notable mid/upper low near or inland of the northern
California coast by 12Z Wednesday.  Cut off from the westerlies, to
the south of a belt of broadly anticyclonic flow shifting inland of
the British Columbia coast through the Canadian Prairies, movement
thereafter likely will be slow and mostly in response to
smaller-scale perturbations pivoting around its periphery.

Downstream of the broad ridging in the westerlies, at least a couple
of notable short wave perturbations will remain progressive
within a stronger, broadly confluent regime across the eastern
Canadian Provinces through northern mid-latitude Atlantic.  It
appears that this will include one rapidly shifting  east of
northern Quebec into the Atlantic, as another digs through northern
Manitoba and northwestern Ontario.

In lower latitudes, prominent mid-level ridging may maintain
considerable influence across much of the central and southern Great
Plains into the Mid Atlantic, as its center continues a slow
west-southwestward retrogression into and across the lower
Mississippi Valley/Mid South vicinity.  There remains more
uncertainty concerning an easterly wave approaching the southern
Atlantic Seaboard and a possible mid-level perturbation suppressing
the ridging across parts of the lower Great Lakes/upper Ohio Valley
vicinity.

...Great Basin...
Beneath a difluent regime, downstream of the evolving mid-level low,
latest model output is suggestive that a focused area of large-scale
ascent may overspread the Great Salt Lake/Salt Lake City vicinity
Wednesday morning.  Based on NAM, Rapid Refresh, and RRFS forecast
soundings and other guidance, it appears that this may be
accompanied by low-level moistening supportive of modest
boundary-layer destabilization, in the  presence of strengthening
deep-layer shear becoming conducive to the evolution of supercell
structures.  This activity will pose at least some risk for severe
hail and wind.  The potential for a brief tornado remains more
uncertain.

...Ohio into lower Missouri Valleys...
A moist environment along and south of a remnant surface frontal
zone, or perhaps a preceding outflow boundary, may contribute to 
the development of moderate mixed-layer CAPE with daytime heating. 
This destabilization may become supportive of scattered strong
thunderstorm development during the afternoon into evening. 
Although spread lingers in the model output concerning the location
and extent of this activity, this seems likely to remain focused
within a weakly sheared regime beneath this mid-level ridging.  Some
of the more vigorous cells may still pose a risk for localized
strong surface gusts, but the anticipated rather sparse coverage
continues to preclude introduction of 5 percent severe wind
probabilities at this time.

..Kerr.. 09/15/2026

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0230 AM CDT Tue Sep 15 2026

Valid 171200Z - 181200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
The risk for organized severe thunderstorms currently appears
negligible for Thursday through Thursday night.

...Discussion...
It appears that mid-level ridging will remain prominent across much
of the central and southern Great Plains, middle and lower
Mississippi and Ohio Valleys through this period. A wave migrating
on its southeastern periphery may gradually overspread portions of
the south Atlantic Seaboard by late Thursday night.  To its
northwest, a cut-off low, initially inland of the northern
California coast, may elongate north-northeastward through portions
of the northern Intermountain Region and Great Basin.

Within the stronger westerlies, consolidating large-scale mid-level
troughing is forecast to dig through northern Ontario, Quebec and
adjacent portions of the Northeast.  It appears that this will be
accompanied by a developing area of surface low pressure, trailed by
a reinforcing cool intrusion across the upper Great Lakes region and
adjacent portions of the Upper Midwest.  A preceding front may
progress southeastward across the northern Mid Atlantic and upper
into middle Ohio Valley, perhaps overtaking portions of an initially
quasi-stationary boundary across the lower Ohio through lower/middle
Missouri Valley vicinity.

Guidance suggests that seasonably high boundary-layer moisture
content along the southern-most baroclinic zone will once again
contribute to sizable CAPE with insolation Thursday.  However,
generally warm thermodynamic profiles and weak deep-layer mean
flow/shear probably will continue to inhibit the risk for organized
severe thunderstorm activity.  

If forcing for ascent, associated with a subtle perturbation
migrating through the northern periphery of the ridge, can support a
sufficiently upscale growing thunderstorm cluster, then the
environment might be conducive to the evolution of a meso-beta scale
cyclonic circulation with strengthening rear inflow and potential to
produce strong to severe surface gusts.  While the potential for
this remains uncertain at the present time, trends will continue to
be monitored in later outlooks for this period.

..Kerr.. 09/15/2026