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ACUS01 KWNS 161955

SWODY1

SPC AC 161954



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

0254 PM CDT Tue Apr 16 2024



Valid 162000Z - 171200Z



...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE

MIDWEST AND MIDDLE MISSISSIPPI VALLEY...



...SUMMARY...

Scattered severe thunderstorms are likely today, especially across

northern Missouri, Iowa, and northwestern Illinois. Large hail,

damaging winds, and tornadoes are expected. More isolated activity

could develop as far south as the Ozarks and Mid-South.



...Synopsis...

The previous forecast largely remains on track with only minor

modifications made to reflect convective trends across portions of

NE, KS, and western MO. Recent analyses show that the best kinematic

environment resides from central AR into MO and southern/southeast

IA. However, thermodynamic limitations (largely due to warm

temperatures in the 850-700 mb as sampled by the 18 UTC DVN and 19

UTC ILX soundings and modest mid-level lapse rates) and unfavorable

storm interactions have modulated convective intensity/organization

thus far. Further intensification remains possible through the

afternoon/early evening amid peak diurnal heating (see MCD 460 for

additional near-term details). Across far eastern NE into western

IA, cold temperatures aloft (supporting surface-based lifted indices

between -7 to -9 C) combined with plentiful ambient low-level

vorticity along surface boundaries continues to support a tornado

threat. See MCD 461 for additional details.



..Moore.. 04/16/2024



.PREV DISCUSSION... /ISSUED 1140 AM CDT Tue Apr 16 2024/



...Midwest/Middle Mississippi Valley...

Regenerative scattered showers and thunderstorms continue to occur

across western/northern Missouri into much of Iowa at late morning,

originating with a warm sector that narrows with north-northwestward

extent into southern Iowa and far east/northeast Nebraska in

vicinity of the surface low. Even while warm-sector cloud breaks

have been limited, steady early-spring heating and low-level

moistening is occurring with surface dewpoints rising through the

lower 60s F.



This development coincides with an intense/cyclonically curved 90+

kt polar jet and a low-level jet that will remain diurnally strong

(40+ kt). Modest cloud breaks aside, destabilization will be further

aided by a pocket of steep mid-level lapse rates and cold

temperatures aloft on the southeast side of the upper trough/low.

Scenario supports a risk for supercells especially across northern

Missouri into southern/eastern Iowa and northwest Illinois.



Steep mid-level lapse rates will aid in hail production, with a few

golf ball or 2+ inch diameter stones possible with the more robust

cores. Tornadoes will also be a concern, as the enhanced

boundary-layer flow and enlarged/curved hodographs associated with

the low-level jet will aid in updraft rotation. The main tornado

potential is still expected to be focused along/near the warm front

in southern/eastern Iowa where the stronger low-level shear is

forecast. A strong (EF2+) tornado is possible. Isolated to scattered

damaging winds are otherwise expected regionally.



Farther south toward the Ozarks and Mid-South, a potential for at

least isolated severe thunderstorms remains apparent into this

evening, with a moist/confluent regime near/ahead of the

eastward-advancing front. Mid-level lapse rates will remain limited.

However, steady low-level moistening will tend to counteract a

tendency for nocturnal boundary cooling, netting a scenario with

limited warm-sector inhibition tonight, supporting the possibility

of supercells capable of all severe hazards including a tornado

risk, even if severe storms remain relatively isolated overall.



$$