spc ac 121733
day 2 convective outlook
nws storm prediction center norman ok
1233 pm cdt tue may 12 2026
valid 131200z - 141200z
...there is a slight risk of severe thunderstorms for north-central
montana...
...summary...
scattered severe thunderstorms are possible across portions of the
northern high plains wednesday afternoon and evening. severe wind
gusts are the primary hazard.
...northern rockies and high plains into northern utah...
a potent mid-level shortwave trough over western or/wa will move
east across the northern rockies into the northern high plains as a
downstream ridge shifts east into the upper midwest by early
thursday morning. an attendant 80-90 kt 500 mb speed max will
overspread id/mt by peak heating as a cold front sweeps east across
portions of the northern rockies into the northern parts of the
great basin. forcing for ascent and diurnal destabilization will
lead to scattered thunderstorms developing by mid afternoon.
forecast soundings show large surface temperature-dewpoint
depressions and inverted-v thermodynamic profiles. increasing flow
through the cloud-bearing layer will result in relatively swift
storm motions within pre-conditioned, dry-adiabatic 0-3 km lapse
rates. isolated to scattered storms developing over the higher
terrain will move into the lower elevations and increase in coverage
as a couple of linear clusters evolve towards early evening across
central mt, and to a lesser degree, across eastern id. the primary
risk will be severe gusts (60-80 mph) accompanying the stronger
cores and outflow. farther south, very deeply mixed boundary layers
evident in forecast soundings across northern ut into southern id
will favor severe gusts with the stronger cores.
...ohio valley/central appalachians...
an upper-level trough initially over the central great lakes will
move east-southeastward to the lower great lakes and mid-atlantic
states vicinity during the period. strong cyclonically curved,
500-mb flow (50+ kt) will move through the base of the trough. a
surface low will move eastward across southwestern ontario as a cold
front advances east-southeastward into the central appalachians.
ahead of the front, surface dewpoints in the lower to mid 50s f will
contribute to weak instability as surface temperatures warm during
the day. increasing low-level convergence near the front will lead
to scattered thunderstorm development, with additional storms
forming due to topographic forcing in the central appalachians.
ahead of the front, low to mid-level lapse rates are forecast to
steepen by midday/early afternoon, lending the potential for several
stronger thunderstorms capable of an isolated risk for wind damage
and localized severe gusts.
...tx panhandle...
despite a 500-mb ridge overhead, very strong boundary layer heating
may sufficiently erode convective inhibition and yield a couple of
thunderstorms developing near the caprock (22-00 utc). very steep
lapse rates will support an isolated risk for hail/wind if sustained
storms develop. this activity will likely dissipate by mid evening.
..smith.. 05/12/2026
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note: the next day 2 outlook is scheduled by 0600z