SPC AC 260559

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1259 AM CDT Tue Jun 26 2018

   Valid 261200Z - 271200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERN
   KANSAS INTO A PORTION OF THE MIDDLE MISSISSIPPI VALLEY...

   ...SUMMARY...
   Severe storms are forecast across the lower Missouri and middle
   Mississippi Valley this afternoon and evening. Other strong to
   severe storms are possible from the Tennessee Valley into a portion
   of the Southeast States.

   ...Synopsis...

   Shortwave trough initially over the middle MS Valley region by 12Z
   will move east into the OH Valley tonight. Attendant weak surface
   low will develop into east IA this afternoon with warm front
   extending east through IL and IN. Trailing cold front will extend
   southwest through northern MO and central KS and move slowly
   southeast during the period. Upstream shortwave trough will advance
   east through southern Canada, glancing the international border of
   northern MT, reaching northern ND this evening. 

   ...Central and eastern KS through the middle Mississippi Valley
   region...

   Early storms will likely be ongoing across southern MO along warm
   conveyor belt. This activity will shift east and southeast during
   the day. A few other storms may be ongoing over northern MO in
   closer proximity to upper low circulation. Richer low level moisture
   with surface dewpoints near 70 F will advect through east KS and MO
   beneath eastern periphery of elevated mixed layer resulting in
   destabilization with a corridor of 2000-3000 J/kg MLCAPE from
   eastern KS through central MO. Ascent with several lobes of
   vorticity rotating through upper low circulation will contribute to
   the development of storms anywhere from central KS east through
   central and northern MO today. Belt of stronger winds along southern
   periphery of the upper low circulation will contribute to 30-40 kt
   effective bulk shear supportive of both multicell and some supercell
   structures, but storms may have a tendency to evolve into clusters
   and line segments with damaging wind and large hail the main
   threats. 

   ...Iowa through northern Illinois and southern Wisconsin...

   Modest instability is expected in warm sector. Storms will continue
   developing in association with vorticity maxima rotating through
   upper low circulation, and 35-40 kt effective bulk shear will
   support some supercell structures. If sufficient boundary layer
   destabilization occurs, threat will exist for a few tornadoes as
   storms move northeast and interact with warm front across eastern IA
   into northern IL and southern WI this afternoon into early evening. 


   ...Southeast States...

   Several clusters of multicell storms will develop through the TN
   Valley and southeast states where the thermodynamic environment will
   support a threat of wet microbursts during the afternoon.

   ...Northern Plains...

   Storms are expected to develop along progressive cold front,
   especially across western and central ND this afternoon and evening.
   Moderate instability and steep lapse rates with inverted-V boundary
   layers will support a threat for a few instances of downburst winds
   and hail. At this time, it appears coverage of severe events will
   remain too isolated for more than a marginal risk category.

   ..Dial/Nauslar.. 06/26/2018

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