Severe Storm Outlook Narrative (AC)
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000
ACUS01 KWNS 290103
SWODY1
SPC AC 290101

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0801 PM CDT Wed Jun 28 2017

Valid 290100Z - 291200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR NORTHERN IL
AND SOUTHEAST WI...

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR NORTHERN
MO...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
PLAINS INTO THE MIDDLE MS VALLEY AND SOUTHWEST GREAT LAKES...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR A SMALL PART
OF SOUTHEAST MN AND ADJACENT WI...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM WY INTO THE
CENTRAL PLAINS AND EAST INTO LOWER MI...

...SUMMARY...
Severe thunderstorms with large hail, wind damage, and a few
tornadoes are forecast across the middle Missouri Valley
northeastward to the west shore of Lake Michigan this evening.
Other more isolated severe storms may occur from Wyoming and the
north-central High Plains this evening and overnight in the central
Plains.

...IA/MO/WI/IL and adjacent areas this evening...
Ongoing strong to severe thunderstorm clusters will continue
eastward this evening as a shortwave trough over the Upper Midwest
moves into the northern Great Lakes tonight.  A corridor of richer
low-level moisture analyzed this evening from the lower central
Plains northeast into eastern IA/northern IL vicinity is
contributing to moderate to strong buoyancy.  A significantly strong
low-level wind profile sampled on area WSR-88D VADs and the 00Z
DVN/TOP raobs suggests organized storms, including supercells and
bowing segments, will yield a risk for low-level storm rotation and
the possibility for a few tornadoes during the early evening.  As
storms and associated cold pools continue to coalesce this evening,
it appears the risk for 50-65 kt gusts is highest across northern
IL/southeast WI ahead of a convective complex and farther southwest
over northern MO.  A large to very large hail threat may continue in
the near term for western flanking updrafts on the northern MO
complex before upscale growth lessens this threat.  As storms move
into southwest Lower MI and northwest IN, drier air in the low
levels and weaker buoyancy will lead to a corresponding weakening in
storms and a lowering severe risk.

...CO/WY Front Range to northern KS/southern NE...
Within a steep low to mid-level lapse rate environment, widely
scattered thunderstorms will spread eastward this evening across WY
and the north-central High Plains.  Isolated hail/wind will be the
threats with the strongest storms.  Later tonight, a 50-kt southerly
LLJ is forecast to develop over KS.  Some potential exists for at
least small-scale MCS development this evening/overnight as
strengthening warm air advection results in isolated to widely
scattered storms capable of sporadic large hail/localized severe
gusts.

..Smith.. 06/29/2017

$$



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