356
ACUS01 KWNS 141647
SWODY1
SPC AC 141645

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1145 AM CDT Mon Sep 14 2026

Valid 141630Z - 151200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN
KANSAS AND SOUTHERN/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 wind gusts, and tornadoes all appear
possible. Severe thunderstorm winds will also be possible across
northern/western Kansas.

...Central Plains to Iowa...
Well to the northeast of a warm front, semi-extensive elevated
convection continues at midday across Iowa and the eastern Dakotas
into western/southern Minnesota, although there has been a
diminishing trend, and cloud cover otherwise remains semi-prevalent
across Nebraska and western/northern Kansas.

A key forecast uncertainty remains the spatial location of primary
late-day surface-based destabilization and uncertain likelihood of
deep convective development toward/just after peak heating. The
semi-persistent convection, residual cloud cover, and
autumnal-approaching sun angle (and ramifications for air mass
recovery) may be factors for confining the most-favorable
environment/surface-based potential to eastern Nebraska and western
Iowa.

This will be as a seasonably strong mid-level shortwave trough and
50-70+ kt mid-level jet spread quickly east-northeastward across the
northern Plains and Canadian Prairies today. While the primary
surface low will likely persist across western Kansas, a secondary
surface wave may materialize across east-central/northeast Nebraska.
Greater low-level moisture across Kansas and the lower Missouri
Valley quickly spread north-northeastward in tandem with a warm
front, although its exact late-day disposition/placement is a bit
uncertain. This will precede a cold front that will sweep
southeastward across the northern/central Plains through tonight. A
narrow corridor of moderate to strong instability (MLCAPE 2000-3000+
J/kg) still appears plausible across eastern Nebraska and western
Iowa into the 21-00Z time frame, coincident and roughly dependent
upon surface temperatures warming into at least the low to mid 80s
F.

Robust thunderstorms should develop along or just ahead of the cold
front by late afternoon/early evening across eastern Nebraska, 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. Most guidance continues
to show a favorable conditional environment for tornadoes across
eastern Nebraska/western Iowa 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 this evening, with
other late-day high-based development also expected in vicinity of a
pre-frontal boundary across southern Nebraska and northern/western
Kansas. Regarding the eastern Nebraska/western Iowa regime, weak
instability with eastward extent in eastern Iowa and vicinity should
limit the severe risk deeper into the night. While deep-layer shear
will be somewhat weaker with southward extent across the central
Plains, at least isolated severe wind gusts may also occur with
high-based/loosely organized convection that develops this afternoon
from eastern Colorado into western/northern Kansas along a surface
trough.

...Southwest/Four Corners...
Scattered thunderstorm development will occur later today from
western Colorado and southeast Utah into parts of Arizona/New Mexico
as a fairly moist low-level airmass gradually destabilizes. Modestly
enhanced mid-level westerly flow should be present this afternoon
over parts of Utah/Colorado, 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 Arizona, 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.

...Eastern North Carolina...
A cold front will move southward across North Carolina 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
North Carolina. 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 mainly across near-coastal far eastern North
Carolina.

..Guyer/Weinman.. 09/14/2026

$$