SPC AC 160704

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0204 AM CDT Sun Aug 16 2020

   Valid 181200Z - 191200Z

   ...NO SEVERE THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   Chances for severe weather on Tuesday appear too limited at this
   time to introduce any areal highlights.

   ...Synopsis...
   While the overall large-scale flow pattern aloft is expected to
   change little on Tuesday, some hints of a bit of a breakdown of the
   upper ridge is evident across the Northwest/northern Intermountain
   region, as repeated/weak vorticity maxima progress anticylonically
   eastward around the northern periphery of the ridge.  Otherwise, the
   general western ridge/eastern trough configuration of the flow field
   will persist.

   At the surface, the pattern will again remain relatively
   diffuse/subtle, though a weak front may shift southeastward out of
   Canada and across the north-central U.S. through the second half of 
   the period.  Otherwise, high pressure is expected to prevail across
   much of the country.

   ...Minnesota/upper Midwest region...
   The GFS and NAM forecast that a short-wave trough will dig
   southeastward out of Canada and across the north central U.S. during
   the afternoon and evening, accompanied by a cold front advancing
   across the Upper Great Lakes/upper Mississippi Valley/Dakotas
   through the second half of the period.  However, the latest run of
   the ECMWF is much slower -- and less vigorous, with this evolution. 
   While storm development near the front -- aided by moderate
   northwesterly flow aloft -- could result in local late
   afternoon/evening risk for severe weather with a few stronger storms
   should the NAM/GFS solution prove reasonably accurate, confidence in
   degree/location/timing of risk precludes highlighting a risk area at
   this time.

   ...Portions of the Northwest...
   With fast southwesterly flow aloft to prevail over the Northwest, on
   the western periphery of the ridge, and a series of small cyclonic
   disturbances continuing to move through the flow field, widely
   scattered afternoon/evening thunderstorms are again expected.  While
   fast flow aloft, combined with a deep mixed layer, could again
   promote gusty/locally damaging winds with a couple of the strongest
   storms, risk appears too limited/isolated to warrant initiation of
   an outlook area at this time.

   ..Goss.. 08/16/2020

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