SPC Jul 10, 2017 0100 UTC Day 1 Convective Outlook

SPC 0100Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0747 PM CDT Sun Jul 09 2017

Valid 100100Z - 101200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS TONIGHT ACROSS
PARTS OF SOUTHEASTERN MINNESOTA...NORTHEASTERN IOWA...SOUTHWESTERN
WISCONSIN AND ADJACENT PORTIONS OF NORTHWESTERN ILLINOIS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SURROUNDING
AREAS OF THE UPPER MIDWEST...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS
SURROUNDING AREAS OF THE UPPER MISSISSIPPI VALLEY AND ADJACENT GREAT
LAKES REGION...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TONIGHT ACROSS
PARTS OF SOUTHERN ARIZONA...

...SUMMARY...
One or two clusters of severe thunderstorms may develop across parts
of the Upper Midwest tonight.  Initial storms this evening across
parts of southern Minnesota may include the risk for severe hail and
perhaps a couple of tornadoes.  Later this evening into the
overnight hours, the risk for potentially damaging wind gusts may
become more prominent.

...01Z Outlook Update...
On the  nose of a plume of warm elevated mixed layer air advecting
east southeast of the northern Rockies (on the southern fringe of
the westerlies), forcing for ascent associated with lower/mid
tropospheric warm advection appears to be in the process of
supporting a general increase in convective development across the
Upper Midwest region.  Stronger boundary layer instability is still
generally focused in a corridor near/east of the mid Missouri
Valley, particularly near the intersection of the pre-cold frontal
thermal ridge axis and the axis of higher surface dew points, which
is now roughly oriented along/east of the Minnesota/South Dakota
border.  This may tend to advect eastward into/across the Upper
Midwest this evening, with the inflow of this air expected to
provide support for considerable further convective development and
intensification through the 02-04Z time frame.  This will coincide
with nocturnal strengthening of a west southwesterly low-level jet
(30-40 kt at 850 mb), beneath 40+ kt northwesterly 500 mb flow.  The
environment still appears potentially conducive to the evolution of
one or two organized, but perhaps compact, convective systems
eventually predominantly accompanied by the risk for potentially
damaging wind gusts.

Elsewhere, ongoing thunderstorm development appears largely diurnal
in nature, and already in the process of weakening/diminishing to
the east of the Rockies, with similar trends likely by 02-03Z across
the West.

..Kerr.. 07/10/2017

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