SPC AC 140548

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1248 AM CDT Tue Jul 14 2020

   Valid 151200Z - 161200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
   THE MID-MISSISSIPPI VALLEY AND PARTS OF THE CENTRAL AND SOUTHERN
   HIGH PLAINS...

   ...SUMMARY...
   Severe storms are expected on Wednesday across parts of the middle
   Mississippi Valley, and over portions of the central and southern
   High Plains. Damaging winds and hail will be the main hazards with
   these storms.

   ...Mid-MS Valley vicinity...

   An upper trough centered over the northern/central Plains Wednesday
   morning will shift eastward to the Great Lakes by Thursday morning.
   This will bring a belt of moderate southwesterly midlevel flow
   across portions of the lower MO/mid-MS Valleys to the Great Lakes.
   At the surface, a seasonally moist and unstable air mass will reside
   across the region ahead of a southeastward advancing cold front.
   Convection associated with one or more decaying MCSs from the Day
   1/Tue period will likely be ongoing Wednesday morning from eastern
   KS/NE into parts of IA and perhaps MO. The location of this
   activity, how quickly it diminishes and/or lifts northeast, and any
   remnant boundaries/MCVs left behind will influence the breadth and
   location of afternoon convection.

   Most guidance suggests strong destabilization will occur across the
   mid-MS Valley vicinity from central MO into central IL along a sharp
   temperature gradient amid upper 60s to low 70s F surface dewpoints.
   Semi-discrete cells are possible initially with vertical wind
   profiles conducive of supercell structures. However, midlevel lapse
   rates will remain modest, and strong downburst winds appear possible
   given PW values near 2 inches. As frontal forcing increases and
   interactions among outflows occur, some upward development into one
   or more forward-propagating clusters/bowing line segments appears
   possible, especially as a southwesterly low level jet increases
   during the evening. Damaging wind will be the main hazard, though
   favorable vertical shear and instability could support severe hail
   in strongest cells. 

   ...Southern/Central High Plains vicinity...

   A shortwave impulse will eject eastward across CO/NM Wednesday
   afternoon/evening. At the surface,  moist upslope easterly low level
   flow will transport mid 50s to mid 60s F surface dewpoints westward
   across western KS, the OK/TX Panhandles and eastern CO/NM beneath
   steep midlevel lapse rates. Strong heating during the afternoon will
   result in thunderstorm development initially over the mountains. As
   storms move off higher terrain into the adjacent High Plains,
   vertically veering supercell wind profiles should aid in maintaining
   organized, albeit high-based, cells. There is some uncertainty
   regarding how far east convection will be maintained, as a stronger
   cap will be in place eastward toward the CO/KS border, extending
   southward into the OK/TX Panhandles. Nevertheless, isolated to
   scattered storms capable of strong winds, and perhaps hail, are
   expected along a narrow corridor from southeast CO into northeast NM
   and possibly parts of the OK/TX Panhandles. 

   Some guidance develops storms northeastward along the surface cold
   front into northeast OK and southern KS overnight Wednesday/early
   Thursday. Forecast soundings suggest this activity would likely be
   elevated, but could pose at least a marginal threat of hail and
   gusty winds.

   ..Leitman.. 07/14/2020

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