Mesoscale Discussion 1046
   NWS Storm Prediction Center Norman OK
   0819 PM CDT Sun Jun 28 2020

   Areas affected...Far Eastern Nebraska and western/northern Iowa into
   southern Minnesota

   Concerning...Severe potential...Watch possible 

   Valid 290119Z - 290315Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Isolated severe thunderstorms could develop through
   mid/late evening within a corridor from east/northeast Nebraska and
   western/northwest Iowa into southern Minnesota. Although
   considerable uncertainty exists regarding the magnitude/spatial
   extent of the severe risk, convective trends are being closely
   monitored.

   DISCUSSION...Mid-level warming/subsidence has generally prevailed
   across the region through peak heating and early evening in the wake
   of an MCV across east-central Minnesota. Cumulus has begun to tower
   particularly across northeast Nebraska into northwest Iowa, with a
   modest increase in radar returns along with a couple of lightning
   flashes, although the initial development across northwest Iowa has
   recently diminished. The regional attempts at deeper convection are
   likely related to an early evening increase of a southerly low-level
   jet, whose axis extends into this region. Although there will
   continue to be a modest nocturnal low-level jet increase with a
   related increase in warm/moist advection, the extent of capping
   remains a key uncertainty within an otherwise unstable environment.
   Regarding this capping and the strength of the elevated mixed layer,
   the 00Z Omaha observed sounding reflected about a 6.5C 12-hr
   temperature increase around 700mb (13.6C) since this morning. 

   If/where convection can become rooted/sustained this evening, ample
   instability across the region could result in a severe risk.
   Deep-layer shear will not be overly strong (mid-level winds
   generally 20kt or less), but steep lapse rates and 4000+ J/kg MLCAPE
   would conditionally include a severe risk, including the possibility
   of a few initial supercells capable of severe hail.

   ..Guyer.. 06/29/2020

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...MPX...DMX...FSD...OAX...

   LAT...LON   42669635 43609550 43899455 43589373 43469379 42839365
               42199382 41339488 41999644 42669635