Clearpost.online It's your post, so post it!

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0736 AM CDT Fri Aug 12 2022

Valid 121300Z - 131200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE NORTHERN ROCKIES AND VICINITY...

...SUMMARY...
Isolated severe gusts and hail are possible over parts of the
northern Rockies and vicinity.

...Synopsis...
The main synoptic upper-air features for this period will remain a
progressive trough near the East Coast, a southward-drifting
anticyclone over the central High Plains, and a currently
quasistationary cyclone centered about 250 nm west of the Columbia
River mouth.  A series of upstream shortwave troughs -- located
south of a different cyclone over the Gulf of Alaska -- will spread
height falls across parts of the northeastern Pacific.  As that
occurs, the closer cyclone will eject north-northeastward today,
devolving into a strong, open, shortwave trough by the time the
associated vorticity max crosses northern Vancouver Island late
tonight.  By 12Z tomorrow, the shortwave trough should be negatively
tilted, extending along Vancouver Island and over western WA.  

The 11Z surface analyses showed a cold front extending from a low
east of NJ, southwestward across the Carolina uplands to northern
portions of GA/AL/MS, beco*ing quasistationary and more diffuse
west-southwestward over north-central TX and southern NM.  Another
cold front was drawn from the Champlain Valley across eastern parts
of PA/WV/KY to northeastern MO, beco*ing a warm front northwestward
to a low over north-central SD.  The eastern part of this boundary
will overtake the southern frontal zone across the Southeast through
the period, from east to west.  The co*bined front will move
offshore from the Carolinas by 12Z, the extend westward over
southern parts of GA/AL/MS.  A surface low analyzed over
southwestern ID should remain in that area through most of the
period.  Meanwhile, a trough now extending from that low to eastern
WA will be overtaken gradually by the low-level cold front preceding
the ejecting mid/upper trough.

...Northern Rockies and vicinity...
Isolated to scattered thunderstorms are expected to develop this
afternoon into early evening over the mountains of central/northern
ID and western MT, as well as in a zone of boundary-layer heating
and convergence near the southwestern ID surface low.  Isolated
severe gusts and large hail will be possible from this activity, and
the wind potential may continue eastward across parts of central/
northern MT this evening with any co*plex(es) that evolve from the
afternoon convection farther west.

Height falls and an eastward spread of favorably strong, difluent
upper/anvil-level winds are expected over the northern Rockies from
late afternoon through tonight.  This will occur as the northwestern
trough ejects toward/over the coast, and the mean ridge shifts
eastward across western/central MT.  Meanwhile, low-level warm
advection and surface heating will destabilize the boundary layer
and -- in concert with favorable existing low-level moisture --
preferentially over higher terrain and the enhanced lift near the
low/trough.  Insolation/vertical mixing will deepen the boundary
layer and reduce lower-elevation surface dewpoints from current
values mainly in the 50s to near 60 F.  Still, sufficient moisture
should remain, amidst nearly dry-adiabatic surface-600-mb lapse
rates, to support areas of 500-1200 J/kg MLCAPE.  Modified 12Z RAOBs
and forecast soundings also suggest 30-45-kt effective-shear
magnitudes across much of the area -- locally higher where
orographically aided, boundary-layer flow backing can occur.  This
will contribute to a mix of early multicell and supercell modes.  

Mergers and cold-pool aggregation may lead to more clustering with
time across western MT, with ambient/mean-wind aided forward
propagation of the resulting convection onto the adjoining High
Plains of central MT.  Moistening of the inflow layer ahead of the
convection is possible, atop residual well-mixed subcloud profiles,
and over just a shallow nocturnal-cooling layer near the surface. 
This suggests activity may be maintained into central MT into
tonight, with at least isolated severe gusts possible.

..Edwards/Broyles.. 08/12/2022