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

Day 4-8 Outlook

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0338 AM CDT Tue May 02 2017

Valid 051200Z - 101200Z

...DISCUSSION...
Through the upcoming weekend into early next week, the large-scale
mid/upper pattern will remain amplified, with a pair of closed lows
evolving over the contiguous US -- one over the Northeast and
another over the Pacific Coast. While organized, widespread severe
events appear unlikely with this pattern (precluding 15-percent
probabilities during the extended period), several localized, at
least marginally severe events appear possible through this weekend.

...D4/Friday -- Eastern North Carolina/Virginia...
Ahead of a cold front advancing towards the coastline Friday
morning, a small corridor of modest buoyancy may favor a few strong
surface-based storms. Moderate/strong southerly low/mid-level flow
may encourage transient updraft organization, as well, supportive of
isolated stronger gusts and/or a tornado before the front moves
offshore.

...D4/Friday - D5/Saturday -- Eastern Washington to central
Montana...
Diurnal heating and increasing boundary-layer moisture with the
arrival of front will yield modest/moderate buoyancy across parts of
the region Friday afternoon and evening. Additionally, deep-layer
shear will increase as south/southwesterly mid-level flow
strengthens through the day. Aided by orographic circulations and
broad large-scale ascent, a few storms are forecast to develop by
afternoon/evening, and the aforementioned environmental conditions
may encourage a few to be strong/marginally severe.

While more uncertain, some low-end severe potential may persist
across parts of western/central Montana on Saturday.

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