ACUS02 KWNS 091712
SWODY2
SPC AC 091711
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1211 PM CDT Fri Aug 09 2024
Valid 101200Z - 111200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE CENTRAL AND SOUTHERN HIGH PLAINS...
...SUMMARY...
Isolated severe thunderstorms, capable of damaging gusts and perhaps
hail, are possible during the afternoon into early evening over
parts of the central and southern High Plains.
...Synopsis...
Upper cyclone centered over northeast Ontario Saturday morning is
forecast to progress gradually eastward/east-northeastward
throughout the day, ending the period centered over the central
Ontario/Quebec border vicinity. Several shortwave troughs will
rotate through the enhanced mid-level flow within the base of this
cyclone, which stretches cyclonically from the Upper Midwest across
the Upper Great Lakes/OH Valley and into the Northeast/St. Lawrence
Valley.
A cold front is expected to extend from ME southward off the coast
of southern New England before then arcing back more southwestward
through the Carolinas and GA into the central Gulf of Mexico. The
series of shortwave troughs rotating around the cyclone will help
reinforce the continental airmass cover much of the eastern CONUS,
with little change in the location of the cold front from the
Carolinas into the central Gulf. Isolated thunderstorms are
anticipated east/southeast of this front, but weak shear should keep
the severe potential low.
Farther west, low-amplitude ridging will remain centered over the
Far West TX/southeast NM vicinity, with westerly flow aloft
extending throughout the northern periphery of this ridging from
OR/northern CA through the central Plains. This westerly flow aloft
will help support a sharpening lee surface trough and resulting
low-level moisture advection across the High Plains.
...Central/Southern High Plains.
Tightening surface pressure gradient between this troughing and high
pressure over the central/southern MO Valley will support low-level
southerly flow and associated moisture return across the
southern/central High Plains. Afternoon thunderstorm development is
anticipated across the Rockies, with the westerly flow aloft then
taking these storms away from the higher terrain into the High
Plains. Deep boundary-layer mixing is anticipated, but the
anticipated low-level moisture advection should still keep at least
modest moisture in place. Current expectation is for afternoon
dewpoints to range from the low 50s across eastern WY to the low 60s
in the northeast NM/southeast CO/southwest KS/western OK Panhandle
vicinity.
This low-level moisture will help support moderate buoyancy, with
MLCAPE from 500 J/kg over eastern WY to 1500 J/kg in southeast CO.
Low-level southeasterlies veering to westerly aloft will also
support moderate vertical shear, even though overall magnitude of
both the surface winds and the westerly flow aloft is modest. These
environmental conditions could support persistent multicells and
perhaps brief supercells, with isolated severe gusts and hail.
..Mosier.. 08/09/2024
$$
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