SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Sun Jul 03 2022
Valid 032000Z - 041200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PARTS OF
CENTRAL/EASTERN MONTANA AND SOUTHWEST NORTH DAKOTA...
...SUMMARY...
The most concentrated corridor of severe storms, including potential
for significant severe wind/hail and a few tornadoes, is forecast
across parts of Montana into southwest North Dakota through this
evening.
...20Z Update...
Prior forecast reasoning remains largely on track. Only minor
adjustments were made based on current observations. See MCD #1340
and #1341 for short-term details on the northern Rockies and
northern High Plains, respectively.
..Wendt.. 07/03/2022
.PREV DISCUSSION... /ISSUED 1121 AM CDT Sun Jul 03 2022/
...MT to western ND...
Primary mid-level low just off the OR coast is embedded within a
broader Pacific Coast trough. Multiple waves of ascent are evident
downstream of this trough, with the ones most impactful for severe
potential across southwest MT this morning and the next across
southwest ID. Guidance differs on the degree of intensification of
convection with the initial wave, while greater consistency exists
on convective evolution emanating out of the latter one.
With easterly low-level winds to the north of the effective surface
front beneath 35-45 kt mid-level southwesterlies, enlarged and
elongated hodographs will be favorable for several supercells, a few
of which could become long-tracked. Primary uncertainty is how
quickly storm-scale consolidation/upscale growth will occur.
Supercell bow-echo evolution does appear probable as convection
rides along the surface front given a deeply mixed thermodynamic
environment to its south. A forward-propagating MCS is increasingly
likely this evening as low-level winds and convergence strengthen
across eastern MT.
The full spectrum of severe threats is expected with significant
large hail most likely from mid-afternoon to early evening, and
significant severe wind potential centered on this evening. The
tornado threat is more nebulous and convective mode dependent, but
will be conditionally favored in a west/east-oriented corridor north
of the front.
...Northern/central Great Plains...
While most of the region will remain under the influence of
low-amplitude mid-level ridging, a broad plume of moderate to large
buoyancy is expected at peak heating with relative maxima centered
near northwest SD and the KS/NE border. Remnant outflow boundaries,
the lee trough over the High Plains, and the warm front across ND
and the Red River Valley should all focus scattered to widespread
thunderstorms from late afternoon into tonight. Stronger deep-layer
shear will generally be confined to the ND/Red River Valley regime
within the belt of enhanced mid-level westerlies, suggesting that
supercell potential farther south will be tied to mesoscale
boundaries with broader multicell clustering tending to dominate.
While all severe hazards are possible, wind should become the
overall primary threat, especially this evening into tonight as
multiple MCSs spread east.
...Carolinas...
Scattered thunderstorms are expected across much of the Southeast,
but potential for loosely organized multicell clustering is most
apparent across NC into parts of SC. The latter will be supported by
the presence of differential heating across a southward-sagging cold
front and the fringe influence of a trough over QC maintaining 15-20
kt mid-level westerlies. With 2000-2500 J/kg of MLCAPE along the
coastal plain, strong to locally severe gusts will be possible in
wet microbursts through early evening.
Read more CHECK UPDATE ZOOM GRAPHIC
http://dlvr.it/STHpNx
