Day 4-8 Outlook

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0345 AM CST Tue Feb 23 2021

Valid 261200Z - 031200Z

...DISCUSSION...
Medium-range models continue to suggest that, although blocking may
linger to some degree through much of this period, an initially
prominent mid-level high and amplified ridging across the eastern
Pacific will become suppressed by a series of short wave
perturbations emerging from the upstream Pacific.  As this occurs,
it still appears that a more pronounced split flow will evolve
downstream, across much of the U.S. and southern Canada.  This may
include mean mid-level troughing in the southern branch, across the
southern Pacific coast through the Southwest, from which one or two
significant perturbations may emerge late this weekend into early
next week.  At the same time, subtropical ridging, centered over the
southern Gulf of Mexico, may undergo a period of amplification, and
a deep mid-level low near/north of Hudson Bay may maintain some
influence, before perhaps returning northward across the Arctic
Circle vicinity by the end of the period.

This pattern could include potential for significant surface
cyclogenesis to the lee of the southern Rockies and a substantive
return flow of moisture off the western Gulf of Mexico by early next
week, accompanied by at least some increase in risk for severe
weather.  However, based on sizable differences evident among the
various models, and from run to run, the predictability of the short
wave developments throughout this period appears relatively low.

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