SPC AC 250554

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1254 AM CDT Thu Jun 25 2020

   Valid 261200Z - 271200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
   GREAT LAKES REGION SOUTHWESTWARD TO THE MIDDLE MISSOURI VALLEY...

   ...SUMMARY...
   Scattered posing a risk for damaging winds and hail are expected
   from the central Plains east-northeastward across the Midwest to the
   Great Lakes Friday afternoon and evening.

   ...Synopsis...
   Gradual evolution of quasi-zonal flow aloft will occur Friday, as
   eastern U.S. troughing shifts offshore.  A positively tilted,
   low-amplitude short-wave trough within the westerlies will cross the
   central portion of the country through the period.

   At the surface, a cold front initially stretching from Minnesota to
   western Kansas will become elongated in a more
   northeast-to-southwest manner, as front moves eastward across the
   Great Lakes region, while lingering over Kansas.  Meanwhile, a
   second cold front is forecast to work its way inland/across the
   Pacific Northwest, ahead of a mid-level short-wave trough digging
   southeastward out of the Gulf of Alaska.

   ...Mid MO/Mid MS Valleys to the Great Lakes...
   Scattered thunderstorms are forecast to be ongoing across portions
   of the upper Mississippi Valley/Upper Great Lakes region
   area at the start of the period, ahead of the advancing cold front. 
   As diurnal heating drives afternoon destabilization, new storm
   development is expected near the advancing cold front, first over
   the Wisconsin vicinity and then stretching southwestward along the
   cold front into Kansas.  

   Flow aloft through the lower and middle troposphere across the
   region will be sufficient for organized storms -- likely evolving
   locally into fast/eastward-moving bands.  Along with hail potential,
   damaging winds will likely to be the favored severe risk.  Depending
   upon degree of destabilization which can occur across the Great
   Lakes area in the wake of early-period convection, a more
   organized/bowing-type wind risk could evolve, which could require
   higher wind probability/greater categorical risk in later forecasts.

   Convection should continue through the overnight hours -- spreading
   as far east as parts of Pennsylvania and New York, but
   with severe risk likely waning gradually as the airmass stabilizes
   with time.

   ...Central and southern High Plains...
   Isolated to widely scattered, late afternoon/early evening
   thunderstorm development is expected over the Front Range, as
   low-level easterly upslope flow evolves north of the cold front
   becoming more west-to-east oriented across Kansas through the day. 
   Moderate westerly flow aloft atop low-level southerlies will likely
   result in sufficient shear organized/rotating updrafts.  A deep
   mixed layer which will evolve through the afternoon over the High
   Plains suggests that storms moving off the higher terrain
   will be capable of locally strong wind gusts.  An isolated
   landspout-type tornado also cannot be ruled out, though potential
   for greater tornado risk should remain limited by a dry/deep
   boundary layer.  At this time, will maintain only marginal/level 1
   categorical risk, due to anticipated storm coverage being sparse. 
   Risk may be upgraded to slight risk in future outlooks if a bit more
   widespread development becomes more likely.

   Evening development of a southerly low-level jet could permit some
   upscale growth as storms move southward/southeastward during the
   evening, with some wind risk possibly lingering locally through the
   evening hours.

   ...East Texas and the Arklatex vicinity...
   Model forecasts of a weak upper low drifting northward across East
   Texas will likely support an increase in afternoon storm development
   across the Texas/Arkansas/Louisiana vicinities.  Slightly enhanced
   southerly low-level flow ahead of the low may promote rather fast
   northward storm motion, possibly resulting in a stronger wind gust
   or two.  However, risk appears too low to warrant inclusion of a
   risk are at this time.

   ..Goss.. 06/25/2020

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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z