SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 PM CDT Sun May 08 2022
Valid 090100Z - 091200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
CENTRAL AND EASTERN SOUTH DAKOTA INTO FAR WEST-CENTRAL MINNESOTA...
...SUMMARY...
Isolated severe hail and/or wind gusts may occur this evening into
tonight over portions of the north-central Plains.
...Synopsis...
A broad cyclonic upper flow regime will persist across the western
and central U.S., with an embedded mid-level impulse approaching the
northern Plains from the intermountain West (per latest water vapor
imagery). As this impulse begins to overspread the northern Plains,
deep-layer ascent will increase, fueled both by divergence aloft,
and low-level convergence at the terminus of a 40-60 kt 850 mb jet,
which will also transport rich boundary layer moisture northward.
Convective coverage and intensity is expected to increase through
the night across portions of far northern Nebraska into the Dakotas,
with enough shear and instability to promote strong to severe
thunderstorm development.
...Northern Plains...
The low-level jet is expected to intensify through the evening
across the Plains states, transporting deep boundary layer moisture
in advance of an approaching mid-level perturbation and ongoing
showers/thunderstorms currently situated across the WY/NE border.
Given boundary-layer decoupling, most of the northward-advecting
buoyancy will be constrained above 850 mb, with some RAP forecast
soundings depicting LFCs as high as around 700 mb. Still, deep
moisture advection beneath 8 C/km 700-500 mb lapse rates will
promote over 2000 J/kg MUCAPE. After 06Z, 80+ kt west-southwesterly
500 mb flow will overspread the 60 kt low-level jet, supporting well
over 50 kts of effective bulk shear. Convergence at the nose of the
low-level jet will support convective initiation across portions of
central South Dakota. Given the steep mid-level lapse rates and
associated MUCAPE, robust elevated convection could develop and
propagate across the LLJ terminus with a severe hail threat, hence
the introduction of a Category 2/Slight risk. Several of the latest
HRRR runs and some of the earlier CAMs suggest that the greatest
chance for robust, elevated convection would be in the 06-12Z
period, from the NE/SD border into far west-central MN.
...Southeast North Dakota...
Relatively strong updrafts, including a supercell in the
Stutsman/Barnes County, ND vicinity are traversing a narrow but
moist and buoyant low-level airmass, where a residual boundary is in
place. Any storms that can favorably interact with this boundary may
support a brief severe threat. However, this threat is expected to
only last for a couple more hours. Please see MCD #0691 for more
details.
...Central Texas...
A couple of towering cumulus clouds have recently grown and have
begun to precipitate, with MRMS mosaic radar data showing 30 dBZ
echoes approaching 30 kft in the past hour. However, dynamic lift
across the southern Plains remains quite weak, and the dryline has
also begun to retreat to the west. As nocturnal cooling and
associated boundary layer stabilization sets in, robust convective
development becomes increasingly unlikely.
..Squitieri.. 05/09/2022
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