SPC Jul 12, 2018 0100 UTC Day 1 Convective Outlook

SPC 0100Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0749 PM CDT Wed Jul 11 2018

Valid 120100Z - 121200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO
THE OVERNIGHT HOURS ACROSS PARTS OF NORTHERN AND CENTRAL MINNESOTA
AND ADJACENT PORTIONS OF THE PLAINS/UPPER MIDWEST...

...SUMMARY...
Strong to severe thunderstorm development remains possible this
evening into the overnight hours across parts of the upper
Mississippi Valley and northern Plains.

...01Z Outlook Update...
Seasonably high boundary layer moisture content is contributing to
moderate to strong potential instability within a corridor across
central Iowa through western/central Minnesota, and along ahead of a
surface cold front now advancing southeastward through the Dakotas. 
However, stronger mid-level height falls and 2-hour surface pressure
falls associated with a vigorous short wave trough and associated
cyclone are focused north of the international border, across
Manitoba, and are generally forecast to develop eastward into
northwestern Ontario overnight.  Forcing for ascent to overcome
inhibition and support appreciable convective development south of
the international border remains unclear, but model output continues
to generally suggest that this will eventually occur.

It is possible that an area of enhanced lower/mid tropospheric warm
advection, which now appears to be present across northeastern South
Dakota/southeastern North Dakota into west central Minnesota, may
provide the primary focus/forcing for thunderstorms while developing
eastward through the 03-06Z time frame.  Given the degree of
potential instability, and at least marginally sufficient shear for
organized convection, the environment appears conducive to the
evolution of an upscale growing convective system given thunderstorm
initiation.  If this occurs, activity is expected to tend to
gradually propagate southeastward.

Otherwise, at least attempts at thunderstorm initiation are ongoing
ahead of the cold front across areas to the west/north of Bemidji
MN.  Although near surface flow may gradually veer from an
easterly/southeasterly component to a south/southwesterly component
by daybreak, cold/cool and stable boundary layer air is expected to
remain prominent near the western shores of Lake Superior and tend
to suppress severe weather potential across that area.

To the west/southwest, across central South Dakota into the Black
Hills region, the front may become a focus for thunderstorm
development overnight (after 06Z) as it stalls ahead of an area of
developing mid-level height falls associated with a perturbation
emerging from the Wyoming Rockies.  If this occurs, thermodynamic
profiles may be supportive of thunderstorms capable of producing
widely scattered strong surface gusts.

..Kerr.. 07/12/2018

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