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Severe Weather 4/17/26

N0mz

N0mz

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Currently outlined 15% with the attached disco:

Medium range guidance has been consistently showing an upper trough
over the western U.S. developing eastward toward the High Plains
Friday/Friday night. As this occurs, increasing deep-layer
southwesterly flow will overspread a seasonally moist and unstable
airmass. A lee low will deepen over the central/southern High
Plains, with a dryline extending across western OK/TX during the
afternoon. By evening and into the overnight hours, a cold front
will spread southeast across the central/southern Plains and Lower
MO Valley. This pattern will support a risk of severe storms across
the warm sector from OK to IA.

Andrew Shearer thread:
 
Cyclonic Paracosm said:
they did go 30% and they are expecting sig tors as the initial threat....
Click to expand...
D4:

"A strong upper trough oriented from Montana to the Southwest will
eject eastward to the Plains on Friday/Friday night. Southwesterly
mid/upper flow will intensify ahead of this feature, with 40-60 kt
850-700 mb flow forecast by late afternoon into the nighttime hours.
A somewhat complex surface pattern is forecast, with a lee low
deepening over the central/southern High Plains to western OK, and a
second surface low near the Mid-Missouri Valley developing northeast
into Ontario. A surface dryline will extend from the High Plains low
to near the western OK/TX panhandle border into central TX by
midday. Meanwhile, a cold front will be oriented from eastern MN
into central KS at midday.

Ahead of these surface features, a broad warm sector characterized
by mid/upper 60s F dewpoints will be in place as temperatures warm
into the 80s F. A plume of steep midlevel lapse rates will
overspread the region, resulting in moderate to strong
destabilization. Forecast soundings indicated impressive wind
profiles supporting supercells. Initial supercell storms capable of
all hazards (including very large hail and strong tornadoes) are
expected. During the evening, convection may grow upscale into a
squall line as storms near the Mississippi River, with an
accompanying increase in damaging wind potential."
 




...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF NORTHERN OKLAHOMA AND EASTERN KANSAS...MISSOURI...IOWA...AND FAR
NORTHWEST ILLINOIS...

...SUMMARY...
Widespread severe thunderstorms are expected from parts of the
southern Plains to the Middle and Upper Mississippi Valley vicinity
on Friday and Friday night. All severe hazards will be possible.

...Southern Plains to MS Valley...

A robust upper trough will eject eastward from the northern High
Plains and central Rockies to the Upper Midwest and central Plains
on Friday. As this occurs, strong deep-layer southwesterly flow will
overspread portions of the central/southern Plains to the Mid/Upper
MS Valley and Great Lakes. Flow at 850-700 mb around 40-60 kt will
be common. At the surface, a cold front will extend from northern MN
to a low over eastern NE Friday morning. Meanwhile, a dryline will
extend southwest from the NE low into central KS, northwest OK and
western TX. A warm front initially arcing across central IA into
south-central IL will lift northward through the period ahead of the
eastward-advancing surface low tracking across northern IA/southern
MN into WI. A warm sector characterized by mid/upper 60s F dewpoints
will be in place across the southern Plains to the Mid-MS Valley by
midday, with a narrow plume of low 60s F dewpoints extending north
into portions of eastern MN and WI. Steep midlevel lapse rates (7-8
C/km) will overspread this moist boundary layer, resulting in
moderate to strong destabilization.

As strong ascent overspreads the aforementioned surface boundaries
by mid afternoon, widespread thunderstorm development is expected.
While initial supercells are possible given a favorable
thermodynamic environment and supercell vertical wind profiles,
linear forcing along the front combined with strong deep-layer
southwesterly flow parallel to the initiating boundary may result in
rapid upscale development into a QLCS, particularly from northeast
KS/northwest MO into IA. A well-organized line of convection will
pose a damaging wind risk along with possible QLCS tornadoes as
convection develops eastward through the afternoon/evening. If any
discrete supercells develop, an all-hazards risk will also accompany
that activity.

Further south across southern KS into OK, supercell development may
be more probable, at least initially. Convection will initially
develop along the dryline prior to the cold front overtaking this
boundary later in the evening. Any supercells that develop and can
maintain discrete characteristics will pose a risk for very large
hail, strong tornadoes, and damaging winds. With time, the cold
front will overtake the dryline during the evening and move
southeast overnight. Linear convection is expected along the front,
posing a damaging wind and isolated tornado risk during the
nighttime hours.

Capping, weakening large-scale ascent and more modest vertical shear
with southern extent may limit storm potential along the dryline in
western/west-central TX.

..Leitman.. 04/15/2026
 
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