ACUS01 KWNS 112001
SWODY1
SPC AC 112000

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Sat Apr 11 2026

Valid 112000Z - 121200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
NORTH-CENTRAL KANSAS AND SOUTHEASTERN NEBRASKA...

...SUMMARY...
Scattered thunderstorms producing hail and strong wind gusts are
possible across portions of the southern High Plains and into parts
of Kansas and Nebraska this afternoon and evening. More isolated
strong to severe thunderstorms are expected across parts of the
central Rockies, upper Mississippi Valley, and portions of the
California coast.

...20z Update KS/NE...
An MCV evident in visible imagery over southwest/central KS is
forecast to shift northeastward this afternoon toward a differential
heating zone associated with a modifying remnant outflow boundary
across northern KS and southern NE. Ample heating south of this zone
has warmed temperatures ~5-7 degree above model guidance, with
observation trends suggestive of locally stronger buoyancy and
vertical shear on modified 12 and 18z RAOBs (1500-2000 J/kg of
MLCAPE). While overall mid-level flow is modest, some enhancement in
the low and mid-levels ahead of the MCV is also evident in area
VADs, bolstering bulk shear to 30-35 kt. Backed low-level winds
along the retreating boundary are also aiding in maintaining sizable
clockwise curved low-level hodographs. This could support the
development of small supercell structures with potential to produce
tornadoes, particularly near and just north of the retreating
outflow boundary, and perhaps in close proximity to the MCV.

Otherwise, some hail and localized strong wind gusts are possible
with any more robust storms able to develop and maintain themselves
into this evening. Deep-layer shear is progged to increase after
dark, as a 40-50 kt low-level jet develops, supporting an increase
in storm coverage along and north of the boundary tonight. Hail and
damaging winds would be the primary threats. Given the local
increase in severe potential, a small zone ahead of the MCV and
along the boundary has been upgraded to a level 2/5 Slight Risk.

...TX and NM...
Scattered strong to severe thunderstorms remain likely tonight
across West TX, the Rio Grand Valley and southeastern NM.
Eventually, one ore more lines or clusters may emerge and spread
east/northeast into central TX/west-central OK. A risk for damaging
gusts or a tornado remain possible with these storms into early
Sunday morning. High-res guidance suggests these storms may maintain
intensity slightly farther east. The 5% wind are was moved eastward
to account for the overnight/early morning risk for a few damaging
gusts.

Elsewhere, severe storms remain possible over parts of the Rockies
and West Coast. The outlook remains largely unchanged. See the prior
discussion for additional information.

..Lyons.. 04/11/2026

.PREV DISCUSSION... /ISSUED 1205 PM CDT Sat Apr 11 2026/

...Synopsis...
Recent satellite imagery reveals two shortwave troughs, one moving
through the Great Basin and the other moving into central Mexico,
progressing through the southwesterly flow aloft between the
subtropical ridging that extends through the Southeast states and a
deep upper low off the central West Coast. Steep mid-level lapse
rates precede the northern shortwave (i.e. from the northern/central
Rockies northeastward) and low-level moisture continues to advect
northward across the southern and central Plains. Both of these
factors will increase buoyancy ahead of these two shortwaves, which
are expected to become increasingly phased as they progress
northeastward throughout the day. This evolution will support a
large area of thunderstorms from the northern Rockies through the
southern Plains this afternoon/evening. Environmental conditions
support strong to isolated severe thunderstorms across these areas,
with a relatively higher chance of severe from the southern High
Plains into central TX and along the eastern NE/KS border vicinity.

Additionally, the West Coast upper low is forecast to progress
east-southeastward into southern OR and northern/central CA this
evening and overnight, supporting the potential for thunderstorms, a
few of which could be strong.

...Southern High Plains into Central Texas...
Scattered to numerous thunderstorms are expected to develop this
afternoon across the southern High Plains as a shortwave trough
lifts out of central Mexico and interacts with the moist and
modestly buoyant airmass in places over the region. A few initially
discrete storms are possible, and adequate deep-layer wind shear
around 35 kt could result in a few instances of severe hail.
However, weak capping and strong ascent should promote increasing
thunderstorm coverage, resulting in a transition to a more clustered
storm mode. Eventual evolution into one or more line segments is
possible, particularly over southwest TX as low-level flow
nocturnally strengthens and low-level moisture increases. As this
transition occurs, damaging gust potential will become the
predominant hazard. The strengthening low-level flow will also
lengthen low-level hodograph, supporting the potential for an
embedded circulation or two, particularly along the southern extent
of whatever line develops.

...Central Plains into the Upper Mississippi Valley...
Recent surface analysis places a warm front across central KS. This
warm front is forecast to progress northward throughout the day amid
persistent southerly flow and resulting moderate/strong low-level
moisture advection. Given the ongoing cloud cover across the region,
as well as the showers and thunderstorms over northwest MO, there is
some uncertainty to how this surface boundary will evolve. General
expectation is for this front to extend from the central NE vicinity
into north-central MO by this evening.

Large, looping low-level hodographs are anticipated in the vicinity
of this warm front. These profiles, along with dewpoints in the
low/mid 60s and modestly steep mid-level lapse rates, result in an
environment that is conditionally favorable for supercells. However,
some capping will likely linger across the region and large-scale
forcing will be negligible, casting doubt to whether convective
initiation will be realized. This uncertainty is matched by the CAM
guidance, none of which establishes meaningful convection during the
afternoon and evening. All that to say, if an updraft does mature in
this environment, all severe hazards are possible, including a
tornado.

More certain (but less intense) thunderstorm potential is
anticipated as low-level warm air advection becomes increasingly
focused from the central Plains into the upper Mississippi Valley
this evening and overnight. Moderate elevated buoyancy and
deep-layer shear support the potential for a few stronger updrafts
capable of hail as thunderstorms expand northeastward from IA into
the Upper Midwest.

...Northern/Central Rockies...
Scattered thunderstorm development is anticipated across the
northern and central Rockies, ahead of a shortwave trough
progressing northeastward into the region. Deep boundary-layer
mixing ahead of this system coupled with steep mid-level lapse rates
and moderate deep-layer vertical shear will result in an environment
that supports the potential for strong to severe gusts across much
of the region.

...Northern/Central California Coast...
A frontal band, associated with an upper low moving over the
northern California coast tonight, is expected to progress
southeastward through the central CA coastal vicinity this evening.
Thermodynamic profiles appear marginally supportive of isolated
convection deep enough to produce lightning. Winds within the lowest
1-2 km AGL should increase to around 40 kt as the wave moves
onshore, which will contribute to the potential for convective
downdrafts to produce a few locally damaging wind gusts.

$$