SPC AC 192000

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0300 PM CDT Thu May 19 2022

   Valid 192000Z - 201200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE UPPER MIDWEST AND MID MISSISSIPPI VALLEY INTO THE LOWER OHIO
   VALLEY...

   ...SUMMARY...
   Isolated very large hail, damaging winds, and a couple of tornadoes
   remain possible this afternoon into early tonight across northern
   Iowa, southeastern Minnesota and western Wisconsin.  Scattered to
   numerous damaging winds, large hail, and a couple of tornadoes
   should also occur this afternoon from southern Missouri into parts
   of Illinois, Indiana, and Kentucky.

   ...20Z Update...
   Primary change with this update was to expand the Enhanced Risk
   westward to account for the current position of a compact bowing
   cluster in southern MO associated with an MCV. Radar presentation of
   this cluster, especially recent velocity data from KSGF, shows
   potential for numerous severe winds, some potentially 75+ mph. Have 
   included a significant wind area across parts of southeastern MO and
   continuing into southern IL, as the airmass downstream has become
   moderately to strongly unstable. Father east, more cellular
   convection has developed over parts of southern IN into KY and
   northeastern TN to the south of a diffuse warm front. This activity
   should pose a threat for mainly large hail and damaging winds, but a
   couple of tornadoes will remain possible across this entire region,
   especially with the cluster tied to the MCV where low-level shear is
   locally enhanced. See Mesoscale Discussion 831 for more details.

   No changes have been made to the risk areas across the Upper
   Midwest. It appears likely that intense convection will develop by
   21-22Z, with an increasing threat for very large hail, damaging
   winds, and perhaps a couple of tornadoes. Mesoscale Discussion 830
   has more information on the short-term severe threat across MN/IA.

   ..Gleason.. 05/19/2022

   .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu May 19 2022/

   ...Upper MS Valley...
   Latest surface analysis shows a low over southeast SD, with a warm
   front extending eastward along the IA/MN border.  This boundary will
   lift slightly northward today, with a warm and moderately moist
   airmass along and south of the front.  A southerly low-level jet
   will strengthen by mid-afternoon, enhancing convergence/lift along
   the boundary and result in the development of intense thunderstorms.
   Supercells map develop across the ENH risk area, capable of very
   large hail and a tornado or two.  During the evening, storms will
   likely develop southwestward across western IA into eastern NE, with
   a more localized risk of large hail and damaging winds.

   ...Lower OH Valley...
   Satellite imagery shows a pronounced MCV over southwest MO.  A
   cluster of lead thunderstorms over eastern MO will limit northward
   destabilization this afternoon, but a corridor of moderate/strong
   instability will likely form ahead of the MCV from southern MO into
   southern IL/IN and western KY.  Thunderstorms are expected to form
   in this area, posing an initial risk of large hail and a tornado or
   two.  12z CAM solutions suggest the activity will grow upscale
   during the evening with an increasing risk of damaging winds as the
   storms move into IN/KY.  Activity may remain locally severe as far
   east as OH/WV later tonight before weakening as they track into the
   mountains.

   ...Carolinas...
   The environment from the western Carolinas to the coast will be
   moderately unstable this afternoon, with a conditional risk of
   damaging winds and hail in persistent/robust thunderstorm clusters. 
   However, 12z model guidance suggests very few storms will develop
   due to weak forcing aloft.  Therefore will maintain only MRGL risk
   for today.

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