SPC AC 211630
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1030 AM CST Wed Feb 21 2024
Valid 211630Z - 221200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TONIGHT OVER
PORTIONS OF THE MID MISSISSIPPI VALLEY...
Areas of strong thunderstorm development are possible across parts
of the Ozark Plateau and adjacent Great Plains and across central
Illinois to far western Indiana late Wednesday evening into early
Thursday, with some risk for severe hail.
Morning water vapor loop shows a fast-moving shortwave trough over
southern CA. This feature and its associated mid-level jet max will
track across the southern Plains and into the mid MS valley by late
tonight. Ahead of this system, strengthening southwesterly
low-level winds will enhance warm/moist advection into parts of
MO/IL, leading to a zone of modest instability after dark from
southeast KS across much of southern MO. Forecast soundings from
several 12z models indicate the boundary-layer remains capped,
suggesting the prospects for robust thunderstorm development are
rather low. However, a few morning CAM solutions do show a storm or
two overnight, which given the steep mid-level lapse rates and
strong shear would be capable of hail. Therefore, will maintain the
ongoing MRGL risk area to denote the conditional risk.
A surface warm front is expected to become established from central
MO into central IL later today. Low-level winds are expected to be
rather weak in vicinity of the boundary, but flow into the
mid-levels should result in elevated warm-advection and the
initiation of a few thunderstorms after midnight. Forecast
soundings suggest the potential for hail in the strongest cells,
although the potential for severe-caliber hail appears marginal.
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