LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1141 PM CST Wed Nov 23 2022
Valid 241200Z - 251200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM
SOUTH-CENTRAL TEXAS TO SOUTHWEST LOUISIANA...
...SUMMARY...
A few strong to severe storms are possible Thursday from
south-central Texas into southwest Louisiana. Locally damaging wind
gusts are the primary threat.
...TX/LA...
Upper trough continues to dig south across the central Rockies and
will soon develop a closed circulation over NM. This feature is
forecast to settle into far west TX by the end of the period as
strongest mid-level flow will not round the base of the trough until
later in the day2 period. As a result, meager height falls will
overspread the warm sector, and this will be primarily across the
Edwards Plateau region during the early-mid afternoon hours.
Late this evening, scattered-numerous showers/thunderstorms have
evolved within a zone of low-level warm advection beneath the LLJ
that extends from central TX-southeast OK-western AR. Latest
guidance suggests LLJ will weaken considerably through Thursday
evening then increase overnight across the lower MS Valley where it
should encourage another bout of concentrated convection during the
latter half of the period from LA into AL. Instability is expected
to remain meager within these warm advection zones and forecast
soundings do not favor organized severe.
In the absence of meaningful large-scale forcing spreading into TX
during the day1 period, boundary-layer heating is expected to prove
instrumental in potential robust thunderstorm development. One area
where a few strong storms may evolve will be ahead of the surging
cold front across the Edwards Plateau during the afternoon. Latest
data suggests partial heating across this region could aid
destabilization such that surface-based parcels become buoyant by
19z. NAM forecast sounding for Brownwood at 19z exhibits SBCAPE
around 1300 J/kg with 35kt surface-6km bulk shear and a veering wind
profile with height. This would seemingly support some supercell
potential and have extended low severe probabilities into this
region of TX to account for wind/hail with isolated afternoon
convection.
Downstream, extensive precipitation across eastern TX, along with a
weakening LLJ should allow a weak surface boundary to sag south into
the lower Sabine River Valley, arcing west across the upper TX
Coastal Plain. PW values should gradually increase across this
region but forecast buoyancy is not expected to be that significant.
Latest water-vapor imagery suggests a weak low-latitude short-wave
trough ejecting northeast across northern Mexico toward south TX.
This feature should encourage a considerable amount of convection
north of the boundary with scattered storms expected to spread
across much of the Coastal Plain. Strong, deep-layer flow and
adequate shear will exist for at least the threat of locally severe
wind gusts with this activity.
..Darrow/Squitieri.. 11/24/2022
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