Mesoscale Discussion 2079
NWS Storm Prediction Center Norman OK
0145 PM CDT Mon Sep 04 2023
Areas affected…Eastern WY…Western SD…Western NE Panhandle
Concerning…Severe potential…Watch possible
Valid 041845Z – 042115Z
Probability of Watch Issuance…60 percent
SUMMARY…Thunderstorm coverage is expected to increase from eastern
Wyoming into the eastern Dakotas this afternoon and evening.
Damaging gusts and isolated hail are possible with these storms, and
a watch may eventually be needed.
DISCUSSION…Recent surface analysis places a low over northeast WY
(in the GCC vicinity), near the intersection of a pre-frontal trough
that extends northeastward into western SD and the cold front moving
southeastward into the western Dakotas and northeast WY. A
well-defined shortwave trough is also moving through western WY,
with strong mid-level flow and large-scale forcing for ascent
associated with this system spreading eastward/northeastward into
eastern WY, and the western Dakotas. Despite favorable daytime
heating, destabilization downstream of this wave (and in the
vicinity of the northeast WY surface low) has been tempered by
limited low-level moisture.
Low-level moisture will remain limited, but cooling and moistening
mid-levels associated with the approaching shortwave should result
in modest buoyancy across the region. Strengthening mid-level flow
is expected to result in moderate deep-layer vertical shear as well.
These conditions should support a persistence of the ongoing cluster
of showers and thunderstorms currently moving across
east-central/northeast WY. Additional thunderstorm development is
also likely farther west, closer to the shortwave, as well as
farther south into southeast WY, as the airmass destabilizes and
ascent increases. Deeply mixed boundary layer and high cloud bases
suggest damaging gusts will be the primary risk, with some potential
for upscale growth along storm outflows into one or more bowing
segments. Some isolated hail is possible as well.
…Please see www.spc.noaa.gov for graphic product…
LAT…LON 42710650 45690402 44930166 42400205 41260405 41550564