SPC AC 221959

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0259 PM CDT Mon Jun 22 2020

   Valid 222000Z - 231200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
   THE SOUTHERN PLAINS...MIDWEST AND MIDDLE ATLANTIC REGIONS...

   ...SUMMARY...
   Scattered severe thunderstorms with large hail and wind gusts are
   expected from late afternoon into tonight over the southern Great
   Plains. Isolated severe storms will persist across portions of the
   central Great Plains, Midwest, Deep South, Mid-Atlantic, and south
   Florida.

   ...Discussion...

   Introduced a small SLGT risk for the Middle Atlantic region for
   numerous multicell storms capable of producing locally strong to
   damaging gusts this afternoon. Otherwise no significant changes to
   previous forecast.

   ..Dial.. 06/22/2020

   .PREV DISCUSSION... /ISSUED 1152 AM CDT Mon Jun 22 2020/

   ...Southern Great Plains...
   Low-level upslope flow over the High Plains will aid in scattered
   storm development off the higher terrain, initially including
   southeast Colorado/northeast New Mexico Raton Mesa vicinity and
   farther south into additional parts of eastern New Mexico. Deeply
   mixed thermodynamic profiles amid 25-40 kt 500-300-mb
   northwesterlies will support initial high-based supercells with a
   primary threat of large hail early. Convection should tend to
   consolidate as it spreads east-southeast across the Panhandles and
   west/northwest Texas during the evening, likely aided by a ribbon of
   low-level easterlies. This should yield an increasing potential for
   severe wind during the early to mid-evening. Isolated to scattered
   severe wind gusts may persist tonight across western north Texas
   with an east/southeastwardward-propagating MCS. Severe hail will
   also be possible overnight farther east near the Red River Valley
   with any low-level warm-advection-driven convection.

   ...Illinois and eastern portions of IA/MO to western Indiana...
   Have upgraded portions of the region for a wind-related categorical
   Slight Risk. Decaying outflow and prevalent cloud cover complicate
   the scenario somewhat, but moderate destabilization is expected
   particularly across north-central Illinois into northwest Indiana
   ahead of a weak surface low/cold front. Damaging winds will be
   possible with the strongest storms through the afternoon/early
   evening. 

   ...Lower Mississippi Valley/Mid-South/Tennessee Valley...
   Modestly enhanced low/mid-level flow exists in association with an
   eastward-moving MCV across the region. Cloud cover/some outflow may
   hinder more appreciable destabilization, but wind profiles may be
   sufficient for weak/transient supercells and semi-organized linear
   clusters. Isolated damaging wind gusts should be the most common
   severe risk, but a tornado could also occur.

   ...Eastern Nebraska/Middle Missouri Valley...
   Mid-level perturbations over eastern MT and central SD, embedded
   within northwest flow should aid in isolated to scattered storm
   development this afternoon. The lack of steeper mid-level lapse
   rates should be a limiting factor to a greater severe risk. But
   isolated marginally severe hail and strong wind gusts appear
   possible with any storms that form.

   ...Mid-Atlantic...
   An MCV over Ohio will drift east with afternoon scattered storms
   expected near and south of this feature. While buoyancy should
   become moderate given robust boundary-layer heating and mid to upper
   60s surface dew points, weak flow throughout the troposphere
   suggests pulse to perhaps loosely organized multicells should
   dominate. Microbursts producing strong gusts may yield localized
   tree damage.

   ...South Florida...
   A few storms capable of producing wet microbursts and perhaps
   marginally severe hail should develop at peak afternoon heating
   along sea breeze boundaries. Large buoyancy with MLCAPE of 2500-3500
   will be the primary supporting factor as weak tropospheric winds
   suggest pulse to loosely organized multicells should prevail.

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