spc ac 091727
day 2 convective outlook
nws storm prediction center norman ok
1227 pm cdt mon mar 09 2026
valid 101200z - 111200z
...there is an enhanced risk of severe thunderstorms across central
illinois into northwest indiana and across the edwards plateau into
central texas...
...summary...
scattered severe thunderstorms are forecast on tuesday from the
southern plains into the southern great lakes vicinity. all severe
hazards are possible.
...synopsis...
a bi-modal severe weather event is expected tuesday afternoon and
evening across the mid-west and portions of central texas.
mid-morning surface observations/analyses reveal a surface low
migrating eastward across the upper great lakes with a trailing cold
front draped southwestward into the central plains. weakening winds
behind the front suggest that this boundary will begin to stall
later today across the midwest/central plains. meanwhile, returning
moisture is forecast to spread north over the next 24 hours as
surface pressure falls and southerly winds increase across the
plains with the approach of the upper trough currently meandering
over baja california and a slight amplification of the upper wave
over the north-central conus. this will help establish an expansive
warm sector from southern texas northward into the central plains
and great lakes region, bounded to the north by the stalled frontal
boundary and to the west by a weak dryline/pacific front. strong to
severe thunderstorms are expected within this warm sector as ascent
along the midwest frontal zone and across the southern plains
increases with the ejection of the upper trough late tuesday
afternoon into tuesday night.
...midwest...
the greatest regional severe threat will likely be focused along the
frontal boundary tuesday afternoon and evening. most guidance
suggests the stalled cold front will advance northward as a warm
front as low-level southerly flow increases within the warm conveyor
belt of a developing cyclone over ia/northern mo, but the exact
placement and orientation of the boundary, and any potential
influence by cool lake-breezes off lower lake michigan, remain
uncertain given spread between 12z cam and global guidance.
regardless, strong isentropic ascent over the frontal zone coupled
with ample low-level moistening and steepening mid-level lapse rates
will support a convective environment favorable for well-organized
convection along both the warm front and southwestward along the
cold front across northern mo and ks. effective srh on the order of
200-300 m2/s2 coupled with mlcape of 1500-2000 j/kg along/just south
of the boundary will support the potential for tornadoes - including
strong tornadoes - with any discrete supercell that can become
established. convection developing north of the surface fronts will
still reside in a very favorable environment for elevated supercells
capable producing large/very large hail (possibly in excess of 2
inches). upscale growth/clustering is expected through the evening
hours, which should support an increase in severe winds. it remains
somewhat unclear how quickly upscale growth will occur given
along-boundary flow through a deep layer, and this may curtail the
supercellular tornado threat if clustering occurs too quickly.
however, based on latest forecast soundings and cam guidance, the
tornado potential will likely be greatest along the warm front
across central il between 21-02 utc where low-level srh and surface
pressure falls/ascent will be maximized.
...southern plains...
12 utc soundings across the southern plains sampled steep mid-level
lapse rates already in place across the region. the onset of deep
moisture return is noted along the tx coastal plain, which should
spread north across central tx into ok by tuesday morning.
isentropic ascent within the warm sector may support isolated
thunderstorm development by late morning across north tx into the
texarkana region where capping should be weaker. by late
afternoon/early evening, more widespread thunderstorm development is
expected across central tx as strong height falls associated with
the ejecting upper wave overspread the region. initially discrete
supercells will be capable of all hazards, through very large (2+
inch) hail appears to be the most probable threat. strong forcing
for ascent will promote upscale growth through the evening with one
or more bowing segments possible. enlarging low-level hodographs
associated with an increasing nocturnal jet may support embedded
circulations within the developing squall line. 30% hail/wind
probabilities were introduced to highlight the corridor of higher
hail/wind threat from the edwards plateau into central tx.
..moore.. 03/09/2026
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note: the next day 2 outlook is scheduled by 0600z