SPC AC 192002

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0302 PM CDT Sun Jul 19 2020

   Valid 192000Z - 201200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
   THE OHIO VALLEY...NORTHEAST U.S. AS WELL AS THE CENTRAL HIGH
   PLAINS...

   ...SUMMARY...
   Thunderstorms with isolated strong to severe gusts will continue
   across the Ohio Valley into a portion of the northeast states this
   afternoon. Other strong to severe storms with isolated large hail
   and damaging wind gusts are expected to develop over the central
   High Plains this afternoon into the evening.

   ...Discussion...

   Adjustments have been made to previous outlook across the OH Valley,
   mainly to remove areas that have been overturned by earlier storms
   and to expand slightly farther east. Elsewhere, Storms should
   develop within the upslope regime across the central High Plains
   this afternoon. A few supercells are expected initially, but storms
   should evolve into lines and clusters as they spread southeast,
   posing a threat for large hail and damaging wind into the evening.

   ..Dial.. 07/19/2020

   .PREV DISCUSSION... /ISSUED 1120 AM CDT Sun Jul 19 2020/

   ...IL to OH...
   A broken band of showers and thunderstorms extends from northern IL
   eastward across southern Lower MI.  This convective zone is ahead of
   the primary surface cold front, but has become the effective zone of
   lift/convergence.  One fast-moving cluster of thunderstorms over
   northern IL has developed a bowing structure, and poses the threat
   of persistent strong/damaging winds as it moves eastward through the
   Chicago area into northern IN and southwest Lower MI.  Please refer
   to MCD #1274 and WW #384 for further details.

   Relatively strong heating/destabilization will likely result in
   afternoon thunderstorms intensification along the convective
   boundary from central IL/IN into southeast Lower MI and western OH. 
   Westerly flow aloft weakens with southward extent, but moderate CAPE
   values will be sufficient for a few strong/severe wind gusts in the
   stronger cells.

   ...Western NY...
   Storms over Ontario will track eastward into parts of western NY
   this afternoon, where strong heating is also occurring.  Deep
   westerly flow aloft and linear nature of convection suggest some
   risk of locally damaging wind gusts this afternoon, although models
   vary on how far east convection remains strong. Please refer to MCD
   #1275.

   ...Central Plains...
   Morning visible satellite imagery shows low clouds eroding across
   northeast CO and vicinity.  A moist low-level air mass is present
   here with dewpoints in the 60s and weak easterly/southeasterly low
   level winds.  Strong heating will lead to moderate CAPE values over
   northeast CO and eastern WY, leading to scattered thunderstorm
   development.  Activity will form by early afternoon over the
   foothills of CO and spread eastward into instability axis, where a
   few severe storms are expected to develop.  Vertical shear is
   marginal, suggesting that multicell storms capable of locally large
   hail and gusty winds are possible.  Storms will develop eastward
   this evening into southeast SD/western NE/northwest KS with a
   continued risk of hail/wind.

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z