SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Thu Jun 23 2022
Valid 232000Z - 241200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
KS/NE/SD/MN...
...SUMMARY...
Scattered severe thunderstorms are most likely over parts of the
central Great Plains and the central portions of Minnesota to South
Dakota, mainly this evening.
...20Z Update...
The 2% and 5% tornado areas have been expanded slightly southward
across parts of north-central KS, based on the current position of
the effective warm front, but otherwise no major changes have been
made to the outlook. See MCD 1264 for more information regarding the
threat across NV/UT, MCD 1265 for more details across KS/NE, and the
previous outlook discussion below for details regarding the threats
in MN/SD and MT.
Isolated strong wind gusts will also be possible with storms across
parts of AZ/NM, though deep-layer flow/shear is quite weak across
this region, which should preclude a more organized severe wind
risk.
..Dean.. 06/23/2022
.PREV DISCUSSION... /ISSUED 1130 AM CDT Thu Jun 23 2022/
...Northern KS/southern NE...
Low-level warm theta-e advection has maintained a swath of elevated
convection centered on northeast to east-central KS, just northeast
of the surface warm front. To the south and west of this activity,
robust boundary-layer heating is underway, likely increasing
baroclinicity across the front by late afternoon. A low-amplitude
mid-level perturbation over the southern Rockies should be favorably
timed to aid in scattered high-based convection developing along the
lee trough in western KS to its intersection with the warm front
near southwest NE. While morning guidance varies substantially with
the overall thermodynamic environment, the 12Z HRW-NSSL/ARW and
NAM-Nest all suggest potential for at least a couple long-lived
supercells slowly spreading east-southeast from southwest NE across
northern KS. Midlevel flow will not be strong, although speed shear
into the upper levels will favor large hail growth. Hodographs will
depend on the degree of low-level easterly flow component in the
warm advection zone along and north of the warm front, which
guidance also varies substantially on. Even so, an increase in a
nocturnal southerly low-level jet will likely assist in potential
for a small MCS this evening. Given the conditionally favorable
setup, potential for sig hail and wind is apparent in addition to a
tornadic supercell or two.
...Central portions of MN/SD...
A weak surface trough, associated with a low-amplitude shortwave
impulse over northern ON, will drift southeast across northeast to
west-central MN, with a separate surface trough extending north from
western KS/NE into central SD. An increase in low-level
moisture from the south and southwest, combined with strong daytime
heating and modest convergence along the troughs, should support
isolated to scattered thunderstorm development during the late
afternoon to early evening. While model moisture forecasts are
likely overdone, and weak large-scale forcing for ascent limits
confidence, steep mid-level lapse rates and adequate deep-layer
shear will support conditional potential for a few supercells and
multicell clustering. Most morning CAM guidance suggests a narrow
corridor of cat 2/SLGT-risk caliber storms should form with a threat
for large hail and damaging winds.
...Central/eastern MT...
A mid-level closed low over southern BC will move eastward, with the
primary jet crossing northern MT through tonight. Associated surface
cold front will push east and provide a focus for isolated to
scattered thunderstorm development across central to eastern MT
during the late afternoon and evening. Low-level moisture will
remain limited with boundary-layer dew points in the 40s, yielding
MLCAPE to only around 500 J/kg. Still, inverted-v thermodynamic
profiles and some increase in mid-level flow will support the threat
for isolated severe gusts and small to marginally severe hail.
...Eastern NV/western UT...
A low-amplitude shortwave trough over the Sierra NV will gradually
progress east across parts of NV into western UT through tonight.
Moderate forcing for ascent ahead of this trough, combined with
daytime heating/mixing, will support scattered high-based
thunderstorm development. Limited boundary-layer moisture will
result in only meager MLCAPE and effective bulk shear will remain
weak. But deeply mixed inverted-v thermodynamic profiles and DCAPE
greater than 1000 J/kg will support a threat for isolated severe
gusts.
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