545
ACUS02 KWNS 290611
SWODY2
SPC AC 290610

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0110 AM CDT Mon Apr 29 2024

Valid 301200Z - 011200Z

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

...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 amplified mid/upper-level shortwave trough is forecast to move
eastward from the northern Rockies into parts of the northern Plains
on Tuesday, as an attendant strong mid/upper-level jet overspreads
the central Plains. A surface wave is forecast to move from the
central Plains toward the upper MS Valley, with a separate low
expected to largely remain in place across the southern High Plains.

...Upper MS Valley into the southern Plains...
An active severe weather day appears possible from eastern
NE/southeast SD into western IA/southwest MN, though uncertainty
remains regarding the quality of moisture return and primary storm
mode.

Modest low-level moisture will stream northward through the day from
the southern Plains into the central Plains and upper MS Valley, in
response to the approaching shortwave trough. While the richest
moisture will likely remain displaced southward of the shortwave
track, 50s to near 60F dewpoints could spread as far north as
eastern NE/western IA and southern MN by Tuesday afternoon. This
moistening beneath steep midlevel lapse rates will support diurnal
destabilization, with peak MLCAPE ranging from around 500 J/kg
across southern MN to greater than 1500 J/kg across the
central/southern Plains.

Thunderstorm development is expected along a cold front by mid
afternoon across northeast NE into southeast SD, with somewhat later
initiation possible southward into southeast NE/northeast KS, as
strong ascent overspreads the region. Quick evolution into
supercells will be possible due to very favorable deep-layer shear,
though some evolution toward a linear or cluster mode will be
possible with time as storms move eastward.

Any persistent supercells will pose a threat of potentially very
large hail (greater than 2 inches in diameter). Any notable upscale
growth could also be accompanied by severe wind gusts (potentially
in excess of 75 mph), especially in areas where stronger heating
occurs prior to storm arrival. Some tornado threat would also
accompany any stronger supercells, though the magnitude of the
tornado risk will be dependent on the quality of low-level moisture
return, which remains uncertain at this time. Greater severe
probabilities may eventually be needed once confidence increases
regarding moisture and primary storm mode.

More isolated development appears possible into the southern Plains,
where a supercell or two could develop with a threat of hail and
localized severe gusts.

...Parts of PA into central NY...
A weakening upper-level trough will move across parts of the OH
Valley on Tuesday. While the surface pattern will be rather
nebulous, modest low-level moisture will support at least weak
diurnal destabilization. Modestly supportive deep-layer shear could
support a few strong storms during the afternoon from parts of PA
into central NY. No probabilities were added due to uncertainty
regarding the magnitude of destabilization, but some isolated severe
threat could eventually evolve depending on trends regarding the
extent of heating and low-level moisture across the region.

..Dean.. 04/29/2024

$$