ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 090956
   SPC AC 090956

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0356 AM CST Tue Mar 09 2021

   Valid 121200Z - 171200Z

   ...DISCUSSION...
   ...Friday/Day 4 and Saturday/Day 5...
   The medium-range models are in decent agreement on Friday, with an
   upper-level low in the Desert Southwest. Southwest mid-level flow is
   forecast over the southern Rockies and southern Plains. Elevated
   thunderstorms may be ongoing at the start of the period in parts of
   Oklahoma, Kansas and Missouri. The southwestern U.S. upper-level
   trough is forecast to move eastward during the day. In response, a
   moist airmass should advect northward into parts of Oklahoma where
   60+ surface dewpoints will be possible. A dryline is forecast to
   take shape by afternoon across far western Oklahoma and west Texas.
   To the east of the dryline, thunderstorms may develop during the
   late afternoon and evening along a corridor of instability. Strong
   deep-layer shear is forecast which may result in a potential for
   supercells. Large hail and wind damage would be the primary threats.
   Further to the east from northeastern Oklahoma into southern
   Missouri, thunderstorms may also develop during the late afternoon
   and evening. Although deep-layer shear may support an isolated
   severe threat, the threat may remain marginal due to weak
   instability.

   On Saturday, the models continue to be in reasonable agreement, with
   the upper-level low moving across the Four Corners area. A strong
   low-level jet is forecast to develop in the southern Plains as the
   exit region a 80 to 100 kt mid-level jet overspreads the southern
   High Plains. In response, deep-layer shear will be favorable for
   supercells with large hail. The current thinking is that a band of
   strong to severe storms will develop from western Oklahoma southward
   into northwest Texas Saturday afternoon. This band of storms could
   continue to be severe, moving into central Oklahoma and north Texas
   during the mid to late evening. All three hazards can not be ruled
   out Saturday afternoon and evening.

   ...Sunday/Day 6 to Tuesday/Day 8...
   The models continue to be in reasonably good agreement on Sunday and
   there is not too much spread among GEFS members. An upper-level low
   is forecast to move into the central High Plains as the mid-level
   jet moves across the southern Plains. To the east of the jet, a
   squall-line may develop and move into the Ozarks and Arklatex Sunday
   afternoon. This squall-line may remain intact across the lower to
   mid Mississippi Valley during the overnight period.

   On Monday and Tuesday, model solutions diverge. Although a cold
   front is expected to move across the Ohio/Tennessee Valleys and Gulf
   Coast states, substantial uncertainty exists concerning the
   upper-level level pattern. Strong thunderstorms will be possible
   along and near the front but uncertainty is high. This uncertainty
   continues into Tuesday due to very large differences among model
   solutions.

   ..Broyles.. 03/09/2021

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