ACUS01 KWNS 291230
SWODY1
SPC AC 291228

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0728 AM CDT Sun Sep 29 2024

Valid 291300Z - 301200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not forecast for today.

...Synopsis/Discussion...
A highly amplified, slow-moving, mid/upper-level pattern will
persist over much of the CONUS, south of a progressive northern
stream near and north of the Canadian border.  A norther-stream
trough, nearly synoptic in scale, is apparent in moisture-channel
imagery from central/southwestern BC to near-coastal WA/OR.  This
feature should amplify and move eastward across southwestern Canada
and the interior Northwest through the period, reaching east-
central/south-central SK, central MT and western WY by 12Z tomorrow.
Weak, basal height falls and modest midlevel moisture will
contribute to the potential for isolated, high-based convection over
portions of UT, some of which may extend deep enough to generate
lighting and strong gusts, into a deeply mixed boundary layer.  Weak
moisture/buoyancy (MLCAPE generally less than 100 J/kg) precludes an
unconditional severe area.

As the northern-stream trough moves away from CA, a formerly cut-off
low now moving ashore into south-central CA will become cut off
again, and drift southward/southwestward back toward the Pacific by
the end of the period.  Ridging will weaken greatly over the
northern Plains and Upper Midwest ahead of the northern-stream
trough, but will persist at its root over the Four Corners region.
To its east, a longstanding, stacked, gradually filling cyclone will
drift erratically eastward over the TN/KY border area, possibly
devolving into an open-wave trough by the end of the period.
Associated convection to its east will encounter a relatively warm/
stable layer in mid/upper levels, limiting but not entirely
suppressing potential for convection to reach into icing layers
suitable for lightning.  As such, isolated thunder will be possible
from the central Appalachians to the Tidewater.  Although warm
midlevels will extend southward to most of FL, rich boundary-layer
moisture/theta-e south of a quasistationary frontal zone over
northern FL will support sporadic thunderstorm potential, mainly
from midday through early evening.

..Edwards/Broyles.. 09/29/2024

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