Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0234 PM CDT Sat Apr 19 2025
Valid 192000Z - 201200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHWEST AND CENTRAL TEXAS...
...SUMMARY...
Scattered severe thunderstorms are expected to continue across Texas
into southern Missouri 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.
...20z Update..
No changes are needed to the D1 Convective Outlook.
Thunderstorm activity has initiated within the Enhanced near the
dryline and front intersection across southwestern Texas. Initial
supercells across this area will be capable of large hail and
damaging wind. As the low-level jet increases through the
afternoon/evening, the threat for a few tornadoes may increase. See
MCD483 for more information.
Convection will continue intermittently along the cold front draped
from the Mid-Mississippi Valley, Ohio Valley, to the Northeast.
Strongly sheared profiles and continued heating through the
afternoon will support some intensification of activity at times,
with potential for damaging wind. See previous discussion and MCD484
for more information.
..Thornton/Moiser.. 04/19/2025
.PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Apr 19 2025/
...Southern Plains to the Ozarks...
Morning surface analysis places a cold front from just south of MAF
(in west Texas) northeastward through ARG (in northeast AR).
Widespread showers and occasional thunderstorms are currently
ongoing north of this front across OK and AR, and associated outflow
is still aiding in more eastward/southeastward progression of this
boundary across northern/central AR. This eastward/southeastward
progression is expected to slow with time as additional surface
cyclogenesis occurs across west TX ahead of a deep shortwave trough
progressing across Southwest. Low-level southerly/southeasterly flow
will persist south of the stalling boundary, leading to a sharpening
of the gradient through this afternoon/evening. By this afternoon,
dewpoints are expected to be in mid 60s along this boundary from
southwest TX into the Mid-South. This low-level moisture combined
with modest heating will result in airmass destabilization. As
large-scale ascent spreads eastward over the southern High Plains,
robust thunderstorms will likely develop by mid afternoon along/near
the front, and a dryline extending southward across west TX into
northern Mexico.
Strong deep-layer shear around 50-70 kt will support updraft
organization with convection that develops along/near the front and
dryline this afternoon. An initial supercell mode is anticipated,
with large hail as the primary risk. Storms will likely remain
elevated from northwest TX into the Ozarks, but surface-based storms
are more likely across southwest TX. Here, some very large hail
around 2-3 inches in diameter is possible. Strong outflow is
possible as well.
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.
The strengthening low-level jet and resultant increase in low-level
shear could also support some threat for a few tornadoes with any
supercells/clusters that can remain surface based this evening.
Additionally, another round of storms appears likely across Permian
Basin/southwest TX late this evening as the shortwave trough ejects
into the southern High Plains. These storms should have a more
linear orientation, with damaging gusts as the primary risk as they
progress eastward toward central TX late tonight/early tomorrow.
...Mid Mississippi/Ohio Valleys to the Northeast...
Current surface analysis places a cold front extending southwestward
from central Ontario through far southern IL and far southeast MO.
Showers and thunderstorms are ongoing in the vicinity of this front,
with much of this activity elevated behind the front across the Mid
MS and OH Valleys where the deep-layer flow is more parallel to the
boundary. A trend towards a more surface-based structure is
anticipated this afternoon as daytime heating promotes modest
airmass destabilization ahead of the front and the flow become more
orthogonal to the boundary, particularly across the Upper OH Valley
and Northeast.
Mid-level flow is expected to strengthen this afternoon and evening,
and despite modest buoyancy, deep-layer shear will be strong to
support linear structures capable of damaging gusts, especially as
convection that develops along the front becomes more linear with
time. Overall storm coverage is expected to be high enough to merit
15% wind probabilities along the front into southern NY.
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