SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Tue Jun 28 2022
Valid 282000Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
UPPER MIDWEST...AND ALSO OVER CENTRAL MONTANA...
...SUMMARY...
Widely scattered severe thunderstorms remain possible over parts of
the upper Midwest and Montana into this evening.
...20Z Update...
Severe probabilities have been expanded slightly westward across
east-central MN, in advance of thunderstorms developing along a cold
front this afternoon, and also expanded slightly eastward over
southern upper MI. The northern edge of severe probabilities across
the upper Midwest has been trimmed in the wake of
southeastward-moving convection. Otherwise, the previous outlook
reasoning remains valid, with thunderstorms capable of hail and
locally damaging wind expected to continue into early evening from
southeast MN into much of WI and southern parts of upper MI.
Storms capable of isolated to widely scattered severe wind gusts
also remain possible across parts of MT into this evening. See the
previous discussion below for more details.
..Dean.. 06/28/2022
.PREV DISCUSSION... /ISSUED 1057 AM CDT Tue Jun 28 2022/
...Upper Midwest...
Water vapor imagery shows a progressive low-amplitude shortwave
trough over ND. This feature will track into the western Great
Lakes region this afternoon, and into Lower MI tonight. Ahead of
the trough, mostly clear skies are evident over northern WI and
western Upper MI, with dewpoints in the 50s expected to yield
afternoon MLCAPE values around 1000 J/kg. Increasing forcing for
ascent will lead to scattered thunderstorms by mid-afternoon.
Deep-layer shear is sufficient for a few rotating storms, and cool
temperatures aloft will support a risk of hail in the stronger
cells. Several 12z CAM solutions suggest that the western flank of
this activity will build southward across western WI into southeast
MN this evening, with a continued threat of hail and locally
damaging winds.
...MT...
A large upper ridge is present across much of the southwestern
states and Great Basin today, with the main ridge axis extending
northward into central MT. This part of the ridge will weaken this
afternoon as a subtle shortwave trough over eastern WA/OR
approaches. Scattered high-based showers and thunderstorms will
develop by mid-afternoon over the mountains of southwest
MT/southeast ID/northwest WY and track east-northeastward.
Instability and low-level moisture will be quite limited, and the
overall coverage of severe storms is in question. However, a few
cells will pose a risk of locally damaging wind gusts until
mid-evening.
Read more CHECK UPDATE ZOOM GRAPHIC
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