SPC AC 031945

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0245 PM CDT Fri Jul 03 2020

   Valid 032000Z - 041200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS
   AFTERNOON INTO TONIGHT ACROSS PARTS OF EASTERN MONTANA...ADJACENT
   NORTHWESTERN SOUTH DAKOTA...AND WESTERN/CENTRAL NORTH DAKOTA...

   ...SUMMARY...
   Severe thunderstorms capable of producing mainly large hail and
   strong wind gusts are possible late this afternoon into tonight
   across eastern Montana and parts of the Dakotas.

   ...20Z Outlook Update...
   Categorical and probabilistic lines have been adjusted in an attempt
   to account for the gradual progression of synoptic and sub-synoptic
   features, and latest trends concerning destabilization, evident in
   latest observational data/imagery.

   For details concerning the severe weather potential through the
   remainder of this period, please refer the 1630Z discussion appended
   below, and the latest SPC Mesoscale Discussions (including recently
   issued MD 1092).

   ..Kerr.. 07/03/2020

   .PREV DISCUSSION... /ISSUED 1138 AM CDT Fri Jul 03 2020/

   ...Northern High Plains...
   Widely scattered to scattered thunderstorms are expected to develop
   this afternoon into tonight, with large hail and damaging winds
   expected. The most likely scenario will be for storm
   development/intensification to initially occur late this afternoon
   and early evening across southwest/south-central Montana within a
   corridor of post-frontal upslope flow and heating over the higher
   terrain/mountains. While some supercells can be expected
   particularly across southeast/east-central Montana, storms should
   aggregate and linearly organize this evening/tonight as they
   progress through the instability axis from far eastern Montana into
   North Dakota/northwest South Dakota.

   ...Central High Plains to southern Plains/Ozarks...
   Strong diurnal heating, acting upon both the higher terrain of
   central/northern Colorado and southeastern Wyoming, and composite of
   outflow boundaries across Kansas/Oklahoma, will combine with a moist
   boundary layer to weaken MLCINH through the afternoon.  Widely
   scattered to scattered thunderstorms should develop across the
   region, aided by an MCV across eastern Kansas. These storms will
   predominantly be multicellular, but with transient/localized
   supercell characteristics possible. The main concerns should be
   isolated severe gusts and large hail. 

   ...Northeast States...
   A relatively moist/moderately unstable air mass resides along/south
   of a southward-sagging cold front. Widely scattered thunderstorms
   are expected to develop and intensify this afternoon, initially
   across eastern/southern New York and western
   Massachusetts/Connecticut, with the strongest storms capable of
   isolated damaging wind gusts. Modest mid-level lapse rates will keep
   peak MLCAPE in the 500-1200 J/kg range over much of the area. Weak
   low/middle-level winds and a related lack of substantial deep-layer
   shear will limit organization and should keep the overall severe
   potential relatively marginal/isolated.

   ...ArkLaTex/Louisiana...
   Moderate to strong destabilization will continue to occur this
   afternoon on the western/southern fringes of ongoing early day
   thunderstorm clusters across the region. Thunderstorms should
   diurnally intensify within the moist/unstable air mass and modestly
   enhanced mid-level northerly winds could contribute to some
   organization/sustenance. A few instances of locally damaging winds
   could occur through the afternoon/early evening hours.

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