ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 061000
   SPC AC 061000

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0400 AM CST Sat Mar 06 2021

   Valid 091200Z - 141200Z

   ...DISCUSSION...
   ...Tuesday/Day 4 and Wednesday/Day 5...
   The medium-range models are in good agreement to start the Day 4 to
   8 period. On Tuesday, the models show west-southwesterly mid-level
   flow across much of the continental United States. Low-level
   moisture advection is forecast from east Texas northward across
   Oklahoma and Kansas. Although convective potential appears on the
   low side, isolated thunderstorms can not be ruled out Tuesday night
   across parts of the lower Missouri Valley within warm advection.

   On Wednesday, the models continue to have west-southwest mid-level
   flow in place from the Desert Southwest northeastward to the Great
   Lakes. At the surface, a cold front is forecast to move into the
   central Plains and upper Mississippi Valley. Thunderstorms would be
   possible along and ahead of the front Wednesday afternoon and
   evening. Weak instability is forecast near the front suggesting that
   any severe threat would be isolated. Differences in the model
   solutions suggest uncertainty on Wednesday is substantial.

   ...Thursday/Day 6 to Saturday/Day 8...
   On Thursday, the models maintain southwest mid-level flow across the
   south-central and eastern U.S. At the surface, a cold front is
   forecast to advance southeastward into northern portions of the
   southern Plains and into the mid Mississippi Valley. Surface
   dewpoints are only forecast to reach the 50s F near the front
   suggesting that instability will remain relatively weak Thursday
   afternoon. In spite of this, strong deep-layer shear is forecast
   along the front, which could be enough to support organized
   thunderstorm development. The greatest chance for strong storms
   would be from northeastern Oklahoma into central Missouri and
   central Illinois Thursday afternoon and evening. However,
   uncertainty is substantial due to instability concerns and timing
   issues with the front.

   On Friday and Saturday, model solutions strongly diverge. For
   example, the ECMWF keeps an upper-level low across the western U.S.
   while the GFS moves the upper-level low eastward into the High
   Plains. THE GFS ensemble has a large spread and shows both the
   faster and slower solution. The ECMWF deterministic solution is much
   less aggressive concerning a potential severe threat, keeping a
   moist airmass located along the western Gulf Coast. The GFS
   deterministic solution is more aggressive, advecting a moist airmass
   into the southern Plains and Arklatex. Thunderstorms, with some
   severe, would be possible in parts of the southern and central
   Plains eastward into the mid Mississippi Valley both Friday and
   Saturday. At this time, am favoring the slower ECMWF solution which
   keeps the upper-level low further west. Due to model differences,
   uncertainty is at high for Friday and Saturday.

   ..Broyles.. 03/06/2021

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