SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1016 AM CST Tue Dec 28 2021
Valid 281630Z - 291200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING OVER PORTIONS OF LOUISIANA AND MISSISSIPPI...
...SUMMARY...
Marginally severe thunderstorms are possible this afternoon and
evening over parts of the lower Mississippi Delta region.
...LA/MS...
A broad area of warm/moist surface conditions are present today from
east TX into the Mid-South, resulting in modest CAPE values over the
region. Large scale forcing for ascent across this region is weak,
and a mid-level capping inversion is present. This will greatly
limit the extent of thunderstorm activity in most areas. However,
there is a corridor from southern LA into central MS were model
guidance shows the capping inversion weakening through the day,
leading to a few robust storms this afternoon and evening.
Low-level shear profiles in this region are relatively strong,
suggesting some potential for rotating updrafts and a marginal risk
of a tornado, wind gust or hail report. Therefore will maintain the
ongoing MRGL risk area with no changes.
...Lower OH Valley...
Another area of some concern for gusty thunderstorm winds is over
the lower OH Valley. A band of fast-moving low-topped showers is
expected to develop this afternoon over southeast MO and track
across portions of southern IL, southern IN, and western/central KY.
Forecast soundings suggest that weak thermodynamic profiles (MUCAPE
only 100-200 J/kg) will limit the risk of lightning with this
activity. However, very strong wind fields may result in a few
locally strong wind gusts with the more intense showers or isolated
thunderstorms. Given the uncertainty and weak CAPE fields, will
maintain a less than 5% severe wind probability forecast.
..Hart/Squitieri.. 12/28/2021
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