SPC Jul 4, 2022 1630 UTC Day 1 Convective Outlook
[html]SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1127 AM CDT Mon Jul 04 2022
Valid 041630Z - 051200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE UPPER
MS VALLEY/SOUTHWEST GREAT LAKES AND MT TO THE WESTERN DAKOTAS...
...SUMMARY...
A few tornadoes and scattered damaging are possible from late
afternoon through this evening centered on a portion of the Upper
Mississippi Valley and southwest Great Lakes regions. Scattered
large hail and isolated severe wind gusts are possible across parts
of Montana into the western Dakotas from late afternoon through
tonight.
...Upper MS Valley and southwest Great Lakes...
A non-severe MCS is ongoing from western WI to the IA/IL border
area. While the northern portion will likely further decay, remnants
of the southern portion may persist across northern IL into IN this
afternoon. Weak mid-level lapse rates and just-in-time moisture
return should limit more widespread intensification potential, but
isolated damaging wind gusts will be possible into late afternoon as
the boundary layer further destabilizes.
In the wake of the MCS and its attendant convectively induced
shortwave impulse, large-scale ascent should be suppressed to the
northwest of the low-level warm theta-e advection regime that is
expected to persist from the Mid-MO Valley to southern WI. While
there is low confidence in timing of redevelopment, areal extent
will likely be focused near the IA/MN/WI/IL border. The degree of
boundary-layer destabilization is questionable and its plausible
that redeveloping convection will remain slightly elevated atop it.
In addition, convective mode should tend to evolve into a
west/east-oriented cluster. But rather enlarged low-level hodograph
curvature owing to the southwesterly jet and modest surface
temperature-dew point spreads favor a conditional threat for a few
tornadoes. Consolidation of clusters into a forward-propagating MCS
is possible tonight across northern IL into northwest IN with
scattered damaging winds beco*ing the primary threat until
convection weakens overnight.
...MT to the Dakotas...
Despite minor weak mid-level height rises, presence of 50s surface
dew points banked up to the northern Rockies will foster scattered
thunderstorm development by late afternoon off the higher terrain in
MT. More isolated thunderstorms will likely initiate off the Black
Hills and are possible in north-central/northeast ND near a weak
surface low. A belt of enhanced mid-level southwesterlies to
westerlies will be maintained downstream of the weakening closed low
near northwest WA. This will foster 40-50 kt effective bulk shear
supporting potential for several supercells with mid-level updraft
rotation. Larger buoyancy should be confined to southern SD into
southeast ND, more muted values from 750-1500 J/kg are expected to
the northwest. This will likely be a limiting factor to greater
intensities with significant hail and wind potential expected to be
very isolated/conditional. Large hail should be the primary threat
with more isolated swaths of severe wind gusts focused on eastern MT
into southwest ND this evening/tonight.
..Grams/Wendt.. 07/04/2022
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Source: SPC Jul 4, 2022 1630 UTC Day 1 Convective Outlook (http://ht**://www.spc.noaa.gov/products/outlook/day1otlk_1630.html)