438
ACUS48 KWNS 270916
SWOD48
SPC AC 270914

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0414 AM CDT Sun Sep 27 2026

Valid 301200Z - 051200Z

...DISCUSSION...
...Wednesday/Day 4 to Friday/Day 6...
During the mid-week, an upper-level low is forecast to move slowly
eastward from the southern Rockies into the southern Plains.  As the
system approaches, low-level moisture will advect northward into the
southern and central Plains.  A pocket of moderate instability may
develop over the southern High Plains by Wednesday afternoon.  As
surface heating is maximized Wednesday afternoon, thunderstorms are
expected to form along and near the instability axis.  A mid-level
jet, associated with the approaching system, is forecast to move
into the southern High Plains in the afternoon. This feature will
increase deep-layer shear.  The timing of the mid-level jet is still
in question, but if the mid-level jet can move into the southern
Plains soon enough, then a severe threat could develop.  Under this
scenario, isolated supercells with large hail and severe wind gusts
will be possible.

From Thursday into Friday, the upper-level trough is forecast to
remain over the southern High Plains.  Ahead of the slow-moving
system, a moist and somewhat unstable airmass is forecast to be in
place both Thursday and Friday over parts of east-central Texas.  On
these two days, deep-layer shear may be strong enough for an
isolated severe threat, mainly with storms that form near the
instability axis.

...Saturday/Day 7 and Sunday/Day 8...
Over the weekend, an upper-level trough is forecast to move across
the central U.S.  Ahead of the trough, a moist and somewhat unstable
airmass is forecast to be in place over much of the Southeast, where
scattered to numerous thunderstorms will be possible each day.  Of
the two days, the strongest instability is forecast to be on Sunday,
when an isolated severe threat will be possible.  Uncertainty
regarding the spatial extent and magnitude is substantial at this
range.

..Broyles.. 09/27/2026