SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0348 PM CDT Sun Jun 12 2022
Valid 122000Z - 131200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PORTIONS
OF THE NORTHERN HIGH PLAINS EAST TOWARD CENTRAL PARTS OF SOUTH
DAKOTA AND NEBRASKA...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MID
MISSISSIPPI/LOWER OHIO VALLEYS...AND PORTIONS OF THE VIRGINIA/NORTH
CAROLINA VICINITY...
CORRECTED TO REMOVE SPURIOUS POINT IN TORNADO GRAPHIC
...SUMMARY...
Scattered severe thunderstorms across the northern and central High
Plains late this afternoon into tonight will be capable of producing
large hail and damaging winds. Isolated severe storms also remain
possible across the lower Ohio Valley and parts of the southern
middle Atlantic.
...Discussion...
Overall/prior forecast reasoning -- and associated risk areas --
continue to appear to adequately reflect severe-weather potential
this afternoon and tonight. The primary change in this update is to
expand the SLGT risk/15% wind area across the northern Plains area
southeastward, to include the remainder of southeastern South
Dakota, portions of northeastern Nebraska, northwestern Iowa, and
the rest of southwestern Minnesota. Model guidance has become more
consistent in suggesting that despite capping currently indicated
across this area, that an evolving/southwesterly low-level jet
nosing into the Mid-Missouri Valley will sustain convection across
this region overnight.
..Goss.. 06/12/2022
.PREV DISCUSSION... /ISSUED 1215 PM CDT Sun Jun 12 2022/
...Northern/central Plains to Upper Midwest...
Regional upper-air analysis reflects an axis of moderate low-level
moisture extending west/northwestward across the north-central High
Plains this morning. This coincides with a belt of strong mid/high
winds that precede an amplifying trough over the Pacific Northwest,
with the aforementioned stronger winds extending over the northern
Rockies east-northeastward into the Dakotas/Minnesota.
Influenced by increasing larger-scale forcing for ascent and
orographic lift in vicinity of mountains/higher terrain, increasing
thunderstorm development is likely by mid-afternoon across northern
Wyoming/southern Montana, and a bit later toward the Black Hills
vicinity and southward along the lee trough/boundary into western
Nebraska/northeast Colorado. Initial supercells capable of large
hail can be expected, along with some tornado risk and a higher
probability of very large hail particularly across northeast
Wyoming/far southeast Montana into western South Dakota.
Confidence has increased that a higher probability corridor of
severe storms including upscale growth into one or more MCSs should
evolve this evening across western/central South Dakota as well as
western Nebraska. An Enhanced Risk has been added to these areas.
...Missouri/Kentucky and southern Illinois/Indiana...
Complex short-term scenario across the region with multiple residual
influences (MCV etc.) from last night's middle Missouri Valley MCS.
A consequential reservoir of moisture exists across the region per
12z upper-air 850 mb analysis, extending from northern/eastern
Kansas into Missouri and southern portions of Illinois/Indiana into
northern Kentucky. This will contribute to a very unstable air mass
with upwards of 4000-6000 J/kg MLCAPE. However, a major complicating
factor, in terms of uncertainty, is expectations for steady
mid-level warming via the eastward-advecting elevated mixed layer.
12z Topeka, KS observed sounding featured a 15.2 C 700 mb
temperature, while Springfield, MO was 13.6 C. Short-term model
guidance varies considerable in this modest forcing/prevalent
mid-level warmth scenario.
However, storm persistence/development through this afternoon will
likely regionally favor the cooler side of this notable mid-level
thermal gradient, with more probable storms across downstate
portions of Illinois/Indiana into Kentucky. It is plausible that a
severe risk, at least on an isolated basis, impacts at least parts
of the region through the afternoon into evening, with potential
late-night redevelopment on the eastern edge of the cap. Damaging
winds and large hail will be possible in what could be a
multi-round-related storm risk for parts of the region.
...Virginia/North Carolina...
A cluster of strong/severe storms will continue to impact far
southeast Virginia vicinity through early afternoon. Otherwise, a
relatively moist and potentially unstable air mass is present to the
west of these early day storms. Forecast soundings suggest
sufficient deep-layer shear for convective organization and perhaps
a supercell or two. Overall, locally damaging winds are the main
threat through the early evening.
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