Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0248 PM CDT Tue Aug 20 2024
Valid 202000Z - 211200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
CENTRAL MONTANA...
...SUMMARY...
Severe thunderstorm winds and large hail are possible today, mainly
over parts of Montana.
...Montana and the High Plains...
The previous forecast remains on track with only minor modifications
made to the Marginal risk/wind probabilities across southwest MT to
account for developing convection within a deeply-mixed environment.
See the previous discussion for additional details regarding the
severe risk across Montana, and MCD #1963 for recent convective
trends regarding CO/NM.
...South Carolina Coast...
A targeted Marginal risk was considered for the immediate SC coast
where convection is developing along a sea breeze boundary. The
thermodynamic and kinematic environment along the coast appears
conducive for a few strong, to perhaps severe, storms. However,
longevity of initial cells appears limited based on regional radar
imagery, and recent high-res guidance suggests any threat will
remain very localized to mainly coastal counties. Given these
concerns, risk highlights were withheld.
..Moore.. 08/20/2024
.PREV DISCUSSION... /ISSUED 1108 AM CDT Tue Aug 20 2024/
...MT...
Morning water vapor imagery shows a progressive shortwave trough and
associated mid/upper level speed max rotating across NV/ID. Lift
associated with this system will overspread the mountains of
ID/southwest MT this afternoon, where increasing mid-level moisture
and strong heating will lead to scattered thunderstorm development.
As these storms move off the higher terrain, they will encounter a
deeply mixed and marginally unstable air mass. Steep low-level
lapse rates and favorably strong westerly mid-level winds will favor
damaging wind gusts or perhaps hail with the more intense clusters
of storms. Activity will spread into eastern MT during the evening
and slowly weaken as diurnal cooling ensues.
...CO/NM...
A persistent upper ridge remains over NM, with several weak
perturbations rotating around the top of the ridge across UT/CO.
Widely scattered high-based thunderstorms are expected to develop
across central/southern CO later this afternoon and spread slowly
eastward into the Plains. A few of the storms may produce gusty
winds or hail.
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