SPC AC 271729
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1229 PM CDT Wed Sep 27 2023
Valid 281200Z - 291200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe thunderstorms appear unlikely on Thursday.
...Synopsis...
Broad upper troughing is forecast to persist from the Pacific
Northwest/Great Basin into the northern High Plains on Thursday,
supported by a series of shortwave troughs moving through it base.
Lead wave in this series will begin the period extended from
southern Saskatchewan through central MT, before then progressing
quickly eastward. Surface low will take a similar track to this
shortwave, with an attendant cold front pushing eastward across the
Dakotas. Low-level moisture will be limited ahead of this front,
keeping thunderstorm chances low. Another shortwave trough is
forecast to move into the northern/central High Plains late Thursday
night/early Friday morning, resulting in a dynamically enhanced
low-level jet from the southern High Plains through the central
Plains. Isentropic ascent across the frontal zone will support
isolated thunderstorms. Vertical shear and buoyancy will remain
modest, limiting the overall severe potential.
Westerly flow aloft is expected to persist south of the primary
troughing as well, helping to support continued lee troughing across
the High Plains. Strong boundary-layer mixing is anticipated east of
the lee troughing, with the highest likelihood for isolated
thunderstorm development across the southern High Plains.
Across the eastern CONUS, a weakening upper low will likely begin
the period over southern Lower MI before gradually drifting
northeastward into southwestern Ontario. An associated surface low
is forecast to drift eastward across the OH Valley. A weak boundary
will extend southwestward/westward from this low, with showers and
thunderstorms reinforcing this boundary throughout the morning. Weak
convergence is possible along this boundary during the afternoon,
with some chance for afternoon/evening thunderstorm development from
central KY into southwest MO and western/middle TN. Modest buoyancy
and weak shear should limit the overall severe threat.
..Mosier.. 09/27/2023
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z
|