320
ACUS02 KWNS 291733
SWODY2
SPC AC 291731

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1231 PM CDT Mon Apr 29 2024

Valid 301200Z - 011200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER SOUTHWEST
MN...WESTERN IA...FAR NORTHWEST MO...EASTERN KS...EASTERN NE AND FAR
SOUTHEAST SD...

...SUMMARY...
Severe thunderstorms will be possible on Tuesday from parts of the
mid/upper Mississippi Valley into the central/southern Plains. The
greatest threat is expected from eastern Nebraska into parts of
western Iowa and southwest Minnesota, with a risk of very large
hail, severe wind gusts, and a few tornadoes.

...Synopsis...
An upper cyclone is forecast to be centered over southeastern
British Columbia/southwest Alberta early Tuesday morning. A series
of shortwave troughs are expected to traverse the moderate mid-level
flow is extended throughout the base of this cyclone. The lead wave
in this series will likely move from the central High Plains
northeastward across the northern/central Plains into the Upper
Midwest throughout the day, accompanied by gradually strengthening
mid-level flow. A weak cold front and associated surface troughing
will precede this shortwave, with consolidation into more prominent
low anticipated from the Mid MO Valley into the Upper Midwest during
the afternoon and evening. Northern portion of this front near the
surface low will remain progressive, continuing eastward through the
Upper Midwest overnight. However, southern portion of the front will
slow and eventually stall across KS, with additional surface
cyclogenesis possible along the western portion of this boundary
over western KS and the eastern TX/OK Panhandles.

Farther east, a shortwave trough is expected to gradually shift
eastward from the Lower OH Valley/Mid-South across the TN Valley and
Southeast states, reaching the Mid-Atlantic States by early
Wednesday morning. Some phasing between this wave and a separate
low-amplitude shortwave farther north over the Lower Great
Lakes/southwestern Ontario is possible. Isolated thunderstorms are
anticipated ahead of both of these waves across much of the eastern
CONUS (i.e. from the Upper OH Valley/Northeast States into the
Southeast). However, limited buoyancy and weak shear should temper
the overall severe potential across the majority of the area,
although a locally increased risk is possible from central NY
through eastern PA and from eastern GA through SC.

...Mid MO Valley into Eastern KS...
Low-level moisture is expected to advect quickly northward
throughout the day, ahead of the approaching shortwave trough and
associated surface trough/cold front. Consensus among the guidance
brings low 60s dewpoints into the northeastern KS/northwest
MO/southeastern NE border vicinity by the mid afternoon, with upper
50s  northward along the NE/IA border. This low-level moisture
combined with modest daytime heating and steep mid-level lapse rates
will support moderate buoyancy (i.e. 1500 to 2000 J/kg).
Thunderstorm development is anticipated along the front during the
afternoon, beginning across eastern SD/southwestern MN then
extending southwestward across eastern NE. Given the moderate
buoyancy, robust updrafts should develop quickly, and vertical shear
will be strong enough to support organized storm structures. Large
to very large hail is likely with initial development before the
storms undergo a relatively quick upscale growth, with the
transition to a more linear mode favoring strong gusts. Some gusts
to 75 mph are possible. The tornado threat is a bit more complex.
There is enough low-level curvature to support tornadogenesis, but
the overall potential may be limited by the quick upscale growth and
relatively short time duration storms will be in a discrete mode.
That being said, some tornado threat is possible within the line as
well, particularly across western IA during the early evening (i.e.
around 00Z) as the low-level jet increases.

...Central KS southwestward across Western OK into Southwest TX...
Most of the stronger large-scale forcing for ascent is anticipated
farther north, but persistent low-level convergence along the
dryline could result in isolated to widely scattered thunderstorm
initiation. Any storms that mature could produce large to very large
hail and damaging downbursts. Guidance has trended towards a bit
more thunderstorm coverage from northwest into southwest TX, but the
lack of stronger large scale forcing limits forecast confidence,
precluding the introduction of higher probabilities with this
outlook.

..Mosier.. 04/29/2024

$$