SPC Oct 2, 2017 Day 4-8 Severe Weather Outlook

Day 4-8 Outlook

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0350 AM CDT Mon Oct 02 2017

Valid 051200Z - 101200Z

...DISCUSSION...
What appears to be an inherently difficult-to-predict pattern
continues to manifest in the medium-range period, as a
closed/cut-off low lingering over the Intermountain West begins to
eject eastward early in the period -- being kicked out by a strong
upper jet digging southeastward toward western North America out of
the Gulf of Alaska.

As this Rockies low ejects eastward, differences in
timing/amplitude/location become readily apparent -- which has
substantial influence on the evolution of the surface pattern east
of the Rockies.  While the GFS appears a bit more bullish with
respect to some convective/severe risk over portions of the central
U.S. Day 5 (Friday 10-6), with a deepening surface low over
Minnesota/Wisconsin, the ECMWF depicts only a weak frontal wave near
the Ozarks -- directly due to the differences in evolution of the
ejecting western U.S. upper feature.

Given such differences -- reflective of pattern unpredictability,
severe risk across the U.S. in the day 4-8 period cannot be
confidently assessed at this time.

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