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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



$$