SPC AC 190728

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0228 AM CDT Tue May 19 2020

   Valid 211200Z - 221200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THURSDAY
   AFTERNOON AND EVENING ACROSS PARTS OF SOUTHEASTERN
   COLORADO...SOUTHWEST KANSAS...NORTHWEST OKLAHOMA AND NORTHEASTERN
   PORTIONS OF THE TEXAS PANHANDLE...

   ...SUMMARY...
   Thunderstorms may develop and evolve into an organizing cluster
   across central portions of the higher Plains late Thursday afternoon
   and evening, accompanied by a risk for severe hail and strong wind
   gusts.

   ...Synopsis...
   Blocking within the mid/upper flow east of the Plains may undergo
   more substantive weakening during this period, as large-scale
   western U.S. troughing develops eastward across the northern Plains,
   toward the upper Mississippi Valley.  A vigorous short wave
   perturbation digging southeast of Hudson Bay, toward Newfoundland
   and Labrador, may also contribute to significant weakening of
   mid-level ridging extending across the upper through lower Great
   Lakes region at the outset of the period.  As this occurs, there may
   be some net northward motion of a remnant mid-level low toward the
   middle Ohio Valley.

   Within the Western large-scale troughing, the bulk of the initial
   perturbation emerging from the Intermountain West is forecast to
   pivot north-northwestward across the international border, through
   Alberta and Saskatchewan, around the northern periphery of a
   trailing short wave trough digging into the northern U.S.
   intermountain region.  At the same time, remnant short wave
   troughing, initially over the Four Corners states, is forecast to
   shift north-northeastward across the Rockies into the central Plains
   by late Thursday night.

   In lower levels, the primary surface cyclone appears likely to
   migrate northward away from the international border, through
   Saskatchewan, with surface troughing lingering across the western
   Dakotas into the immediate lee of the Front Range of the Rockies
   Thursday afternoon.  Southeast of the Front Range, a zone of
   strengthening differential surface heating near a remnant frontal
   zone will extend across parts of southwestern Kansas and the
   Oklahoma/Texas Panhandle vicinity, with a sharpening dryline across
   the Texas South Plains toward the Texas Big Bend.

   These features are expected to become the focus for modest to strong
   boundary-layer destabilization in the presence of at least moderate
   shear, providing potential for isolated to widely scattered strong
   to severe thunderstorm development Thursday afternoon and evening.

   ...Central High Plains...
   Moderately large CAPE (1000-2000+ J/kg) appears possible along the
   zone of stronger differential surface heating, as far north as
   southeastern Colorado.  Aided by forcing for ascent associated with
   the short wave emerging from the Southwest, there appears potential
   for convection to develop and consolidate within a zone of
   strengthening lower/mid tropospheric warm advection.  One or two
   organizing clusters of storms may evolve with a tendency to
   propagate eastward and southeastward across southwestern Kansas and
   the Panhandle region, aided by a modest southerly low-level jet
   Thursday evening.  This may be accompanied by a risk for severe wind
   gusts, in addition to large hail, before weakening overnight.

   ..Kerr.. 05/19/2020

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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z