zczc spcswod48 all
acus48 kwns 120845
spc ac 120845
day 4-8 convective outlook
nws storm prediction center norman ok
0345 am cdt wed mar 12 2025
valid 151200z - 201200z
...severe weather outbreak possible on d4/sat...
...discussion...
...day 4/sat - central gulf coast states to the ohio valley...
a strong large-scale upper trough is forecast to quickly move across
the plains to the ms valley on saturday. an intense jet streak will
move across the deep south into the oh valley as this occurs. at the
surface, a low secondary to the 980 mb low over the upper midwest is
forecast to develop during the late morning/early afternoon across
the mid-south. this will aid in further northward transport of rich
gulf moisture into portions of the lower ms valley and tn valleys.
atop this moisture-primed boundary layer, cold 500 mb temperatures
are forecast. this may support fairly steep lapse rates, which would
foster moderate instability across portions of ms/al amid supercell
wind profiles. however, some uncertainty remains tied to the
evolution of convection in the day 3/fri period into the morning
hours of saturday. some forecast guidance suggests a relatively
pristine warm sector will be maintained, or if only isolated
convection develops overnight/early saturday, recovery could occur.
if this scenario unfolds, a concerning severe weather setup
supporting all-hazard severe could unfold across portions of
la/ms/al through the day and into evening, and eventually spreading
east into ga overnight. trends will be monitored closely over the
coming days and further adjustments to the 30 percent/enhanced risk
area may be needed in future outlooks.
with northward extent, instability will become more limited.
nevertheless, sufficient moisture amid intense deep-layer flow will
support swaths of strong/damaging winds into the ohio valley and
portions of the central appalachians saturday and saturday night.
higher outlook probabilities may be needed in subsequent outlooks if
confidence increases.
...day 5/sun - north florida into the carolinas and mid-atlantic...
a strong upper trough will shift east across the midwest and
southeast on sunday. strong deep-layer southwesterly flow ahead of
the trough will overspread much of the eastern u.s. atop a moist
boundary layer. bands of convection will likely produce swaths of
strong to severe gusts ahead of an eastward-advancing cold front.
...days 6-8/mon-wed...
an upper trough will move offshore over the atlantic on monday,
while a broad upper ridge spreads across the plains in its wake.
another large-scale upper trough will move across the western u.s.
on tuesday, ejecting across the plains and into the ms valley on
wednesday. some severe potential could return to parts of the
central or south-central states toward the end of the period with
this system, but current model forecasts suggest moisture return in
the wake of the day 4/5 system will remain poor. trends will be
monitored over the coming days.
..leitman.. 03/12/2025
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