SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 AM CDT Thu Jun 23 2022
Valid 231300Z - 241200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
INTO TONIGHT NEAR THE KS/NE BORDER...
...SUMMARY...
Widely scattered severe thunderstorms are possible across portions
of the central Great Plains this afternoon and evening. Large hail
and severe gusts will be the primary threats with the stronger
storms.
...Northern KS/southern NE this afternoon through tonight...
Weak perturbations emanating from the monsoonal moisture plume will
drift eastward across the central Plains, around the northern
periphery of the southern Plains closed high aloft. At the surface,
a warm front will move slowly northward across KS, to the east of a
lee cyclone near the CO/KS border by this evening. A corridor of
68-70 F boundary-layer dewpoints will be maintained in the vicinity
of the warm front across KS/NE, with strong surface heating and deep
mixing expected to the southwest of the warm front across western
KS. The net result should be relatively weak convective inhibition
and the potential for surface-based thunderstorm development late
this afternoon/evening along the warm front close to the KS/NE
border, with the potential for elevated storm development persisting
overnight on the nose of a 30+ kt low-level jet.
There is some uncertainty regarding the role/persistence of morning
clouds/convection in late afternoon storm development, though there
should be at least some clearing along the northwest KS/southwest NE
border, where storm development is more probable by 22-00z.
Midlevel flow will not be strong (though 50 kt flow is expected
above the 300 mb level), so low-midlevel hodograph length will
depend on the degree of low-level easterly low-level flow component
in the warm advection zone along and north of the warm front. A few
supercells will be possible with large hail and damaging gusts, and
the tornado threat will depend on getting storms into the areas of
backed low-level flow and richer low-level moisture. Otherwise,
storms may coalesce into clusters overnight, with a continuing
threat for isolated hail/wind.
...Northeast SD into MN this evening into tonight...
A weak surface trough, associated with a shortwave trough over
western ON, will move southeastward into northeast SD and
central/northern MN by late afternoon. An increase in low-level
moisture from the south during the day, combined with daytime
heating and convergence along the trough, could support widely
scattered thunderstorm development by late afternoon/evening along
the surface trough. The specific degree of low-level moistening and
resultant increases in CAPE are a bit uncertain (some model guidance
appears to be a bit high with the 68+ dewpoints by evening), and
storm coverage is in question given the moisture and weak forcing
for ascent. Wind profiles appear to be on the lower margins for
organized/supercell storms. Given these factors, will maintain
Marginal risk for the conditional threat.
...Central MT this afternoon/evening...
A midlevel level closed low over southern BC will move eastward,
with the primary midlevel jet crossing northern MT through tonight.
The midlevel low will be accompanied by a surface cold front, which
will provide a focus for thunderstorm development across central MT
this afternoon/evening. Low-level moisture will remain limited
across MT (boundary-layer dewpoints in the low-mid 40s with daytime
heating/mixing), which will likewise limit buoyancy. Still,
inverted-v profiles and some increase in midlevel flow will support
the threat for isolated strong-severe outflow gusts from late
afternoon into this evening.
...Eastern NV/western UT this afternoon/evening...
A weak closed low over central CA will evolve into an open wave and
eject east-northeastward over NV/UT through tonight. Weak ascent
downstream from the midlevel trough, combined with daytime
heating/mixing, will result in weak buoyancy and inverted-v profiles
favorable for high-based thunderstorm development. A modest
increase in midlevel flow and the steep low-level lapse rates/DCAPE
greater than 1000 J/kg will support the threat for isolated severe
outflow gusts.
..Thompson/Jewell.. 06/23/2022
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