(All days are valid from 12 UTC - 12 UTC the following day)
Note: A severe weather area depicted in the Day 4-8 period indicates 15%, 30% or higher probability for severe thunderstorms within 25 miles of any point.
PREDICTABILITY TOO LOW is used to indicate severe storms may be possible based on some model scenarios. However, the location or occurrence of severe storms are in doubt due to: 1) large differences in the deterministic model solutions, 2) large spread in the ensemble guidance, and/or 3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears unlikely (i.e., less than 15%) for the forecast day.
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 081000
SPC AC 081000
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CST Thu Dec 08 2016
Valid 111200Z - 161200Z
The 00Z GFS has trended closer to the ECMWF for day 4/Sunday with
less amplification of a Pacific shortwave trough as it reaches the
central Plains Sunday afternoon. These models maintain a broad,
cyclonic flow pattern across the contiguous U.S. until the start of
day 5/Monday, and then diverge greatly in amplitude. Although each
shows cyclonic flow across the U.S., the GFS suggests much lower
500-mb heights from the Rockies to the eastern states from day 5
through day 7/Wednesday.
Models suggest some strong to severe storm potential across the
northwest Gulf Coast to the central Gulf Coast states during day
5/Monday and day 6/Tuesday. However, given the uncertainty in both
the amplification of the upper flow pattern for the early part of
next week and overall destabilization, no severe-weather
probabilities will be included.
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