699
ACUS01 KWNS 191244
SWODY1
SPC AC 191242

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0742 AM CDT Sat Apr 19 2025

Valid 191300Z - 201200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
WEST-CENTRAL TEXAS...

...SUMMARY...
Scattered severe thunderstorms are likely from parts of Texas into
southern Missouri, mainly this afternoon and evening. Large to very
large hail, damaging winds, and a few tornadoes all appear possible.
Isolated to scattered damaging winds may also occur across portions
of the Ohio Valley into the Northeast.

...Southern Plains to the Ozarks...
Multiple bands/clusters of convection are ongoing this morning from
parts of eastern OK northeastward to the Ozarks and mid MS Valley.
Much of this activity should remain elevated, with isolated
hail/wind potential in the short term. In the wake of these
thunderstorms, an upper trough/low will eject from the Southwest
across the southern High Plains through the period. A front should
generally remain stalled across the southern Plains and towards the
Ozarks today, as surface cyclogenesis occurs over far west TX. As
large-scale ascent spreads eastward over the southern High Plains,
additional robust thunderstorms will likely develop by mid afternoon
along/near the front, and a dryline extending southward across west
TX into northern Mexico.

Daytime heating of a moist low-level airmass, combined with the
presence of steep mid-level lapse rates, are expected to support
moderate instability across the warm sector, with peak MLCAPE values
potentially reaching up to 1500-2500 J/kg. Strong deep-layer shear
around 50-70 kt will support intense updraft organization with
convection that develops along/near the front and dryline this
afternoon. Initial supercells will likely pose a threat for very
large hail around 2-3 inches in diameter, along with damaging winds.
By early evening, convective mode should become messier as a
gradually strengthening low-level jet and the front encourage
thunderstorm interactions/mergers. Still, a continued large hail and
damaging wind threat will likely persist for much of the evening.
Strengthening low-level shear in tandem with the increasing
low-level jet should also support some threat for a few tornadoes
with any supercells/clusters that can remain surface based this
evening. Given increased confidence in multiple intense supercells
developing this afternoon, an Enhanced Risk has been introduced
across parts of west-central to western north TX with this update.

...Mid Mississippi/Ohio Valleys to the Northeast...
Instability is expected to remain fairly weak along/ahead of the
surface front extending from southern MO across the OH Valley and
into the Northeast. Even so, strong west-southwesterly winds through
low/mid-levels may support a threat for isolated to scattered
severe/damaging winds as the boundary layer gradually destabilizes
through the day. Multiple ongoing clusters of elevated convection
from the Ozarks to the mid MS and lower OH Valleys may become
surface based over the next several hours with filtered daytime
heating. Have therefore expanded the Slight Risk for damaging winds
northeastward across these areas in a narrow zone along/near the
front.

A rather strong mid-level jet will overspread the northern
Mid-Atlantic into the Northeast today, as an upper trough develops
eastward over the Great Lakes and eastern Canada. Although low-level
moisture is forecast to remain limited, cold temperatures aloft
should aid in modest destabilization by early afternoon in a narrow
corridor along/ahead of the eastward-moving cold front. Deep-layer
shear will be strong enough to conditionally support supercells,
although there should be a tendency for convection that develops
along the front to become more linear with time. Based on recent
guidance trends, have expanded the Marginal Risk for hail/damaging
wind potential eastward across these areas. Greater severe wind
probabilities may be needed if confidence increases in a organized
cluster developing.

..Gleason/Broyles.. 04/19/2025

$$