LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Mon Sep 14 2026
Valid 141300Z - 151200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN NEBRASKA INTO WESTERN/CENTRAL IOWA...
...SUMMARY...
Scattered strong to severe thunderstorms should occur across parts
of eastern Nebraska into western/central Iowa this afternoon and
evening. Large hail, severe gusts, and a few tornadoes all appear
possible.
...Central Plains into Iowa...
A seasonably strong mid-level shortwave trough with 50-70+ kt
mid-level jet will advance quickly east-northeastward across the
northern Plains and south-central Canada today. Mid/upper-level
ridging will remain prominent over much of the Southeast and OH
Valley. Between these two features, a belt of around 30-50 kt
mid-level west-southwesterlies will persist across the central
Plains into the lower/mid MO Valley. The primary surface low over
the northern Plains this morning will develop into southern
Saskatchewan/Manitoba by this evening, with a secondary surface low
likely to form along/near the NE/SD border by late afternoon.
Greater low-level moisture across KS will attempt to lift northward
along a warm front today across the central Plains ahead of a cold
front that will sweep southeastward across the northern/central
Plains through the period.
Ongoing convection this morning across the central Plains/mid MO
Valley is being aided by warm/moist advection associated with a
strong south-southwesterly low-level jet. This activity should tend
to remain elevated and sub-severe as it tracks quickly
east-northeastward through the late morning before eventually
weakening. In its wake, destabilization is forecast to rapidly occur
across eastern NE/western IA as rich low-level moisture quickly
streams northward. There is still some variability in short-term
guidance with the degree and northward extent of low-level moisture
return through late afternoon across this region, which introduces a
fair amount of uncertainty regarding how unstable the warm sector
will become. Even so, a narrow corridor of moderate to strong
instability (MLCAPE 2000-3000+ J/kg) appears plausible across
eastern NE/western IA and vicinity by 21-00Z, assuming surface
temperatures can warm into at least the low to mid 80s.
Robust thunderstorms should develop along or just ahead of the cold
front by late afternoon/early evening across eastern NE, with
strengthening/favorable deep-layer shear for supercells initially.
Large hail may occur, but modest lapse rates aloft and a quick mode
transition to mainly clusters/line segments will probably limit the
spatial/temporal extent of the hail threat. Nearly all guidance
continues to show a favorable environment for tornadoes across
eastern NE/western IA as the supercells/clusters spread quickly
eastward this evening, with a 40-50 kt low-level jet aiding the
development of ample effective SRH. But, various RAP forecast
soundings across this region show lingering low-level inhibition,
and it remains unclear whether convection will be able to fully take
advantage of the strong low-level shear. Even with this uncertainty,
a sustained surface-based supercell in this environment would
conditionally be capable of producing a strong tornado.
Otherwise, severe/damaging winds should become an increasing concern
as clusters develop and spread east-northeastward. Weak instability
with eastward extent in eastern IA and vicinity should limit the
severe risk tonight. While deep-layer shear will be somewhat weaker
with southward extent across the central Plains, at least isolated
severe gusts may also occur with high-based/loosely organized
convection that develops this afternoon from eastern CO into
western/northern KS along a surface trough. Confidence remains too
low in a more focused corridor of severe wind potential across this
region to include greater probabilities with this update.
...Northern Plains...
A band of elevated thunderstorms is occurring this morning across
the Dakotas as large-scale ascent preceding the shortwave trough
overspreads the northern Plains in tandem with strong low-level warm
advection. Latest surface observations and recent RAP forecast
soundings across this region show cool and stable conditions in the
boundary layer, which limits confidence in an isolated severe wind
threat this morning as convection moves quickly northeastward.
Still, small hail and gusty winds may occur given the enhanced
background/gradient wind field and sufficient MUCAPE present, with
some convective enhancement possible.
...Southwest/Four Corners...
Scattered thunderstorm development will occur later today from
western CO and southeast UT into parts of AZ/NM as a fairly moist
low-level airmass gradually destabilizes. Modestly enhanced
mid-level westerly flow should be present this afternoon over parts
of UT/CO, though it is uncertain if diurnal heating and related
instability will be sufficient for an organized severe risk. Still,
isolated gusty winds and small to perhaps near-severe hail could
occur with the strongest thunderstorms. Farther south, flow will be
weaker across AZ, resulting in mostly disorganized convection. Even
so, localized strong gusts appear possible, especially where
stronger heating occurs and steeper low-level lapse rates develop
during the afternoon. Overall, confidence in an organized severe
risk is too low to include 5% hail/wind probabilities at this time.
...Eastern North Carolina...
A cold front will move southward across NC today. Large-scale ascent
will generally be weak, though isolated convective development may
occur as the front encounters greater low-level moisture and sea
breeze boundaries over coastal/eastern NC. Deep-layer shear within a
northwesterly mid-level flow regime will be sufficient for organized
thunderstorms, but poor mid-level lapse rates should tend to limit
updraft intensity and the overall severe threat. Regardless, any
thunderstorms that can develop and be sustained in this regime could
produce locally gusty winds and small hail.
..Gleason/Lyons.. 09/14/2026
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