228
ACUS01 KWNS 202000
SWODY1
SPC AC 201959

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0159 PM CST Thu Nov 20 2025

Valid 202000Z - 211200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN PLAINS TO ARKANSAS...

...SUMMARY...
Isolated strong to severe thunderstorms may occur today into this
evening across the southern Plains into Arkansas. Large hail,
damaging winds, and a tornado or two all appear possible.

...20Z Update...
No changes were made with this update. An upgrade to Slight Risk was
considered for parts of south-central into north-central TX ahead of
the northeast/southwest-oriented band of storms. Here, diurnal
heating has allowed temperatures to climb into the upper 70s to
lower 80s amid middle/upper 60s dewpoints -- resulting in a
moderately unstable warm sector. While this instability and around
50 kt of effective shear will conditionally favor embedded supercell
structures, current thinking is that deep-layer southwesterly
flow/shear parallel to the larger-scale cold pool will result in
undercutting and training of storms. Therefore, held off on an
upgrade at this time. Nevertheless, damaging gusts, sporadic large
hail, and perhaps a tornado or two will all be possible with any
longer-lived storms -- especially any that can form immediately
ahead of the convective band and related cold pool.

..Weinman.. 11/20/2025

.PREV DISCUSSION... /ISSUED 1031 AM CST Thu Nov 20 2025/

...Southern Plains to Arkansas...
Showers/thunderstorms remain common at late morning with widespread
cloud cover with the warm sector across most of Texas and Oklahoma.
This precedes a mid/upper-level trough currently located over
Arizona/New Mexico and far northern Mexico, which will continue to
eject northeastward toward the southern High Plains. A surface low
will gradually deepen across the south-central High Plains and
develop eastward through the period.

It still seems likely that convection and widespread cloud cover
will persist through the day, resulting in generally modest diurnal
heating and weakening mid-level lapse rates with time. While
enhanced deep-layer shear will remain across the warm sector owing
to persistent strong southwesterly mid-level flow, the potential for
organized thunderstorms downstream or in the wake of ongoing morning
convection remains uncertain, particularly in the context of
somewhat stronger low-level winds more likely to interface where
convective overturning has occurred.

Regardless, some potential for isolated supercells and/or organized
multicell clusters will exist this afternoon/evening particularly
across portions of central and possibly into parts of
North/northeast Texas. This includes isolated severe hail and
damaging winds, and a modest enlargement of low-level hodographs
could also support a tornado risk.

Farther west, some high-resolution guidance continues to show the
development of additional strong/locally severe storms across
east/southeast New Mexico into west Texas/southwest Oklahoma, in
closer proximity to the ejecting upper trough. This convection could
pose a threat of strong gusts and perhaps some hail, but it remains
uncertain as to whether sufficient instability will develop to
support anything beyond a very isolated/marginal-type severe risk.

$$