SPC Mar 14, 2025 0600 UTC Day 1 Convective Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1238 AM CDT Fri Mar 14 2025

Valid 141200Z - 151200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS THE
MID-MISSISSIPPI VALLEY AND PORTIONS OF THE LOWER OHIO VALLEY...

...SUMMARY...
A regional outbreak of severe storms is likely across the
Mid-Mississippi Valley to the Lower-Mississippi Valley, including
portions of the Lower Ohio Valley. Tornadoes, several of which could
be strong, widespread damaging winds with gusts from 70 to 90 mph,
and scattered large hail up to baseball size will be possible.

...Discussion...

Satellite imagery depicts a well-defined upper trough over the
southwestern U.S./northwest Mexico. This feature is forecast to
advance into the southern Rockies by sunrise as a 115kt 500mb speed
max translates across southern NM. This jet max should increase to
near 125kt as it translates into southwest OK by 18z, then weaken to
near 100kt overnight over northern IL. Water-vapor/radar data
suggest the leading edge of large-scale forcing is currently
spreading across western NM. Latest model guidance suggests intense
12hr mid-level height falls (on the order of 240-270m) will spread
across the southern Plains into IA as left-exit region of the
aforementioned jet shifts into the mid-MS Valley. At the surface, a
pronounced dry line will surge across the central Plains, arcing
from a very deep surface low over northwest KS-eastern OK by 18z.

Strong boundary-layer heating is forecast ahead of the cyclone, and
convective temperatures will easily be breached as temperatures warm
into the lower 70s. While surface dew points will remain a bit low,
SBCAPE should exceed 1000 J/kg and robust convection will readily
develop along the wind shift. Of particular concern will be the
efficiency of mixing very strong flow downward within this
convection. Forecast soundings exhibit 50kt just off the surface,
and very steep lapse rates will prove favorable for severe gusts
with any convection today. Widespread wind damage, with speeds
likely exceeding 70 mph are expected. Severe squall line should
organize and surge northeast across the mid-MS Valley during the
afternoon/evening hours.

Farther southeast, LLJ is forecast to strengthen markedly across
eastern AR/MO into IL. This will allow somewhat higher
boundary-layer moisture to advance across the lower into the middle
MS Valley prior to thunderstorm development. Latest thinking is
supercells should develop ahead of the fast-moving 500mb speed max,
with some propensity for activity lingering across the mid-South as
the right-entrance region of the jet influences longevity of
convection. Forecast soundings strongly favor organized convection
with supercells expected. Higher moisture content into eastern
MO/southwest IL will contribute to higher tornado probabilities with
these strongly sheared supercells. Longer-lived updrafts may produce
strong tornadoes, in addition to very strong winds and large hail.

Southern extent of the regional outbreak will likely be influenced
by the lack of stronger forcing across the lower MS Valley. Even so,
isolated severe supercells are expected within the less-forced
environment. This activity may linger well into the overnight hours.

..Darrow/Moore.. 03/14/2025

Read more