466
ACUS03 KWNS 171908
SWODY3
SPC AC 171907

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0207 PM CDT Thu Apr 17 2025

Valid 191200Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE
SOUTHERN PLAINS TOWARD THE OZARKS...

...SUMMARY...
Scattered strong to severe thunderstorms are possible from central
Texas into the Ohio Valley on Saturday.

...Synopsis...
An upper trough will move eastward across Ontario and Quebec,
deepening all the while. Meanwhile, a southern-stream low/trough
will move from AZ/NM into the southern Plains. This system will take
on a negative tilt into Sunday morning.

At the surface, a front will stall from PA westward to the middle MS
Valley, and southwestward into northwest TX. Upper 50s F to lower
60s F dewpoints will be common along and south of this boundary,
with the most substantial instability developing from west-central
TX into OK. Winds around 850 mb will initially be out of the
southwest across the entire warm sector, but backing and
strengthening will occur over the southern Plains late as the upper
trough approaches. At that time, a cold front will further increase
lift over TX and OK.

...From parts of OK across MO/IL/IN/OH/PA...
Substantial rain and thunderstorms are likely to be ongoing early on
Saturday north of the stationary front and aided by theta-e
advection just off the surface with 30+ kt southwest 850 mb winds.
While the low-level lapse rates will initially be poor, sufficient
elevated instability combined with strong deep-layer shear may
support marginal hail during the day. Indications are that heating
will be most prominent from the central Appalachians into parts of
the upper OH Valley and into PA, and a few diurnally driven cells
may produce marginal hail over OH and PA.

...TX/OK into the Ozarks...
Scattered storms may redevelop from northern TX into OK during the
day, as low-level moisture advection is maintained across the warm
sector and north of the boundary. Lapse rates will likely be poor
due to extensive clouds and persistent showers/storms.

Later in the day, strong heating over southwest TX and lift near the
cold front should allow for new development over west-central TX
during the late afternoon, with increasing storm coverage as the
low-level jet increases through the night. A few supercells may
develop in this region, producing large hail. The front may tend to
undercut the activity, but a brief tornado cannot be ruled out.
Farther north, batches of elevated storms will spread out of TX and
into OK, with both periodic hail and heavy rain threat (see WPC Day
3 Excessive Rainfall Product).

..Jewell.. 04/17/2025

$$