Day 4-8 Outlook

Day 4-8 Outlook Image

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0335 AM CST Thu Dec 10 2020

Valid 131200Z - 181200Z

...DISCUSSION...
A progressive/moderate amplitude flow field aloft is progged across
the U.S. through Day 8, with medium-range models in reasonably good
agreement through Day 6 (Tuesday Dec. 15), with respect to
synoptic-scale evolution.  

During this first three days of the period, low-amplitude troughing
-- rotating around the eastern fringe of a large northern Canada
polar vortex -- is forecast to gradually depart northeastward/away
from the northeastern states.  Meanwhile, a second short-wave trough
-- initially over the Plains -- is forecast to move quickly eastward
across the Southeast Day 4 (Sunday Dec. 13) and then off the
Atlantic Coast through the first half of Day 5.  This feature will
be followed by the next in a series of troughs, which will move
inland over the West Day 4, across the Intermountain region and
eventually into the Plains through Day 5, and then eastward to the
Mississippi Valley region through Day 6.

Both of these two, aforementioned troughs will be accompanied by
associated surface cyclogenesis.  However, at this time it appears
that a cool/stable boundary layer will remain across the southern
Plains/Southeast, and thus the primary surface low tending to evolve
just offshore of the Gulf Coast -- along the main west-to-east zone
of baroclinicity (separating the cool continental air from the Gulf
airmass).  

Given this evolution, any severe weather potential would appear to
be limited to the Florida Peninsula, and that risk appears too low
at this time to warrant any introduction of severe-weather
probabilities.

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