Valid 260100Z – 261200Z
…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THE CENTRAL
DAKOTAS ARCING INTO NORTHEAST WYOMING…
…SUMMARY…
Thunderstorms with isolated large hail and severe gusts are expected
over the central Dakotas arcing westward into northeast Wyoming this
evening.
…Northern Great Plains…
Water-vapor imagery this evening shows an amplifying mid-level
trough over MT which is forecast to reach the Dakotas late tonight.
A couple of strong to severe thunderstorm clusters are over the
central Dakotas this evening near a pre-frontal surface trough and
other intensifying severe storms are located near a cold frontal
segment over northeast WY. Both boundaries are forecast to move
southeast tonight. The 00z North Platte, NE raob sampled a
moisture-rich boundary layer (13 g/kg lowest 100mb mean mixing
ratio) which likely extends into the central Dakotas. Moderate
instability and the increasing westerly flow moving east through the
base of the shortwave trough, will combine to favor storm
organization and intensity through the evening. A longer-term risk
for severe storms will probably occur with the northeast WY storms
as they move east-southeastward into western SD and towards far
northern NE on the leading edge of stronger mid-level forcing for
ascent. Large hail and severe gusts are the primary risks with the
stronger storms. A gradual diminishing in storm coverage and
intensity are expected by the late overnight hours.
..Smith.. 08/26/2019
$$