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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0754 AM CDT Sat Aug 06 2022

Valid 061300Z - 071200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
CENTRAL NEBRASKA NORTHEASTWARD INTO WISCONSIN...AND OVER PORTIONS OF
THE CENTRAL HIGH PLAINS...

...SUMMARY...
Marginal severe-wind and hail potential exists this afternoon and
evening from parts of central Nebraska northeastward into Wisconsin,
and over portions of the central High Plains.

...Synopsis...
The mid/upper-level pattern this period will be characterized
synoptically by these three positively tilted features:
1.  A weak, quasistationary trough from the lower Great Lakes down
the Ohio Valley to AR and south TX;
2.  A persistent and quasistationary anticyclone, centered over KS
with ridging extending toward IA and central parts of AZ/NM;
3.  A progressive trough -- initially evident in moisture-channel
imagery from the Canadian Rockies southwestward off the OR
coastline.

A series of shortwave troughs -- some convectively produced/enhanced
-- extend through the confluent-flow belt between the northwestern
trough and the central Plains ridge.  Those now over the Great Basin
region will be absorbed into the progressive trough as the latter
moves eastward to MT/WY by 12Z tomorrow.  As that occurs, height
falls are forecast over the central High Plains north of about I-80
and after 00Z.  Downstream, a perturbation with embedded MCV was
apparent in satellite and radar animations over eastern SD.  This
feature should cross southern/central MN today, reaching western WI
by 00Z. 

The 11Z surface analysis showed a cold front from the MN Arrowhead
southwestward through a weak low over southwestern MN to another low
near GLD, then across east-central CO.  This boundary is forecast to
move southeastward by 00Z to eastern Upper MI, central IA and
south-central NE, beco*ing quasistationary through the low (which
will move little from present location) and eastern CO.  The front
then should move little through the remainder of the period. 

...Central NE to upper Mississippi Valley...
Widely scattered to scattered thunderstorms are expected to develop
in clusters today into this evening, across parts of MN,
southeastern SD and northern IA.  Activity should occur on the
surface-850-mb front, near and south of the MCV where frontal and
MCV-related lift will be superimposed and relatively maximized. 
Isolated development is possible farther southwest across parts of
southwestern SD into central NE, where buoyancy will be favorable,
but large-scale and frontal ascent somewhat weaker.  Activity north
of the front will have a predominantly hail potential, but with some
strong gusts possible.  Convection along and south of the front
should post a threat for both marginally severe hail and isolated
severe gusts.  

A corridor of relatively rich low-level moisture, characterized this
morning by surface dewpoints in the upper 60s to low 70s, will
co*bine with diurnal heating to support MLCAPE in the 2500-3500 J/kg
range just south of the front.  Values will diminish further into
the warm sector where more/deeper boundary-layer mixing occurs. 
Steep lapse rates will exist in the subcloud layer, supporting
hail/gust maintenance to the surface in stronger cells.  However,
the overall organization of the event will be tempered by weakness
of mid/upper-level winds, and lack of stronger vertical shear
overall.  The predominant mode should be multicellular, with the
threat diminishing with eastward extent into more-stable air, and
after about 03-05Z. 

...Central High Plains...
Isolated to scattered thunderstorms are expected to develop over the
eastern fronts of the mountain ranges from CO-WY this afternoon,
with isolated development also possible on the eastward-extending
ridges and wherever convective temperature can be reached via
heating farther east.  Isolated hail/gusts to severe limits may be
expected.

Pockets of relatively dense short-term clustering/upscale
aggregations of convection are possible within this corridor. 
However, guidance is quite inconsistent on if/where this may take
place, which is not surprising considering the overall weak forcing
aloft.  The regime overall will be characterized by increasingly
moist, post-frontal upslope flow, contributing to somewhat favorable
storm-relative boundary-layer winds.  However, lack of more-robust
mid/upper-level flow will limit deep shear south of east-central/
southeastern WY.  Farther north, where effective-shear magnitudes
over eastern WY may increase to the 40-45-kt range, a narrower and
weaker corridor of favorable buoyancy will be available.  Forecast
soundings suggest peak preconvective MLCAPE ranging from around
1500-2000 J/kg over parts of northeastern CO to less than 500 J/kg
in northeastern WY -- all atop a well-mixed boundary layer.  The
severe potential appears strongly tied to afternoon heating, though
any clusters may persist into the evening with gradually diminishing
gust/hail risk.

..Edwards/Thompson.. 08/06/2022