SPC AC 011946

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0246 PM CDT Wed Jul 01 2020

   Valid 012000Z - 021200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE THIS
   AFTERNOON INTO TONIGHT ACROSS PARTS OF THE NORTHERN
   ROCKIES...CENTRAL PLAINS...OZARK PLATEAU...MID SOUTH...SOUTHEAST AND
   MID ATLANTIC...

   ...SUMMARY...
   Strong storms may impact parts of the northern Rockies, the central
   Plains into the Ozark Plateau and Mid South, the Southeast, and the
   Mid Atlantic region region late this afternoon into tonight, posing
   at least some risk for severe hail and locally damaging wind gusts.

   ...20Z Outlook Update...
   Adjustments have been made to categorical and probabilistic lines in
   an attempt to better account for the gradual progression of synoptic
   and sub-synoptic features, and latest trends concerning
   destabilization which will impact convective potential late this
   afternoon through tonight.  This includes the southeastward
   advancement of convective outflow from the lower Missouri Valley
   into the Mid South, and across far southern Georgia and Alabama into
   northern Florida.

   Marginal Risk/5 percent severe probabilities have been added to
   southeastern Kansas and portions of adjacent states, near the
   stalled western flank of the convective outflow advancing into the
   Mid South, east of an area of low pressure within southern plains
   surface troughing. Beneath modestly steep mid-level lapse rates
   associated with warm and capping elevated mixed-layer air, heating
   of a moist boundary layer with surface dew points in the lower/mid
   70s is contributing to very large CAPE in excess of 4000 J/kg. 
   This, coupled with modest deep-layer shear (mainly due to pronounced
   veering of winds with increasing height) along the boundary, is
   contributing to an environment at least conditionally supportive of 
   organized convective development, including supercells.

   Initiation of storms across southeast Kansas might not be entirely
   out of the question late this afternoon or early evening.  However,
   probabilities for this still seem relatively low, with mid/upper
   support to contribute to weakening of inhibition still not obvious. 
   Somewhat more probable, increasing lift associated with warm
   advection, on the nose of the nocturnal low-level jet, may
   contribute to thunderstorm initiation and upscale growth late this
   evening into the overnight hours, with a tendency to develop
   southeastward along the remnant outflow boundary.

   ..Kerr.. 07/01/2020

   .PREV DISCUSSION... /ISSUED 1100 AM CDT Wed Jul 01 2020/

   ...Mid MS Valley...
   A relatively long-lived MCS continues to track southeastward across
   MO at around 30 knots.  The leading edge of the convection is moving
   into an axis of moderate/strong instability, where MLCAPE values
   will be over 3000 J/kg this afternoon.  Continued redevelopment
   along the leading edge of the cold pool, coupled with the degree of
   instability, will pose a risk of intensification later today.  Wind
   fields are weak, suggesting the overall severe threat will remain
   rather isolated/marginal.  However, locally gusty/damaging wind
   gusts are possible as storms track into parts of northeast AR,
   western KY/TN, and northwest MS.

   ...AL/GA...
   Another remnant MCV and associated weakly-organized MCS is moving
   across eastern AL and western GA.  Strong heating ahead of this
   system, coupled with 20-30 knots of 700-500mb flow shown on regional
   VADs and RAP guidance suggest the potential for a few gusty/damaging
   wind reports with this activity through the afternoon.

   ...Mid Atlantic...
   Scattered thunderstorms have begun to form over the Chesapeake Bay
   and eastern MD.  Other storms are expected through the afternoon
   over the region as daytime heating and slightly cooler temperatures
   aloft promote convective development.  MLCAPE values over 2000 J/kg
   and sufficient westerly flow at mid/upper levels may result in
   isolated strong/severe storms capable of gusty winds.

   ...TX...
   Similar to the last couple of days, strong heating and ample CAPE
   will develop along the surface dryline over west-central TX.  This
   will likely result in a 2-3 hour window of thunderstorm activity. 
   Mid-level winds are becoming progressively weaker each day, which
   should limit convective organization and overall severe threat. 
   Nevertheless, isolated strong storms are possible - mainly from
   22-01z.

   ...MT...
   A persistent upper trough remains over the northwest US today, with
   several weaker shortwave troughs rotating across the Great Basin and
   northern Rockies.  Relatively strong heating, sufficient mid-level
   moisture, and cool temperatures aloft will promote the development
   of afternoon thunderstorms over southwest MT.  Low level moisture
   and CAPE are weak, but a few organized cells may form and produce
   hail and gusty winds.  Storms are expected to develop northeastward
   toward the Saskatchewan border by evening.

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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