Severe Storm Outlook Narrative (AC)
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ACUS48 KWNS 290817
SWOD48
SPC AC 290815

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0215 AM CST Mon Nov 29 2021

Valid 021200Z - 071200Z

...DISCUSSION...
Medium-range models indicate that several strengthening
perturbations will emerge late this week through next weekend, from
a strong mid/upper jet initially rounding the crest of broad ridging
(across the eastern Pacific through the northern U.S. Great Plains),
into broad troughing (east of the upper Mississippi Valley through
the western Atlantic).  As they dig through the mid-level troughing,
it appears that they will contribute to strengthening surface
cyclogenesis across the St. Lawrence Valley and parts of northern
New England into the Canadian Maritimes.  In its wake, it appears
that another intrusion of cold/dry air will overspread most areas
east of the Rockies by late next weekend.

Preceding the cold front, latest guidance is suggestive that a
corridor of modest destabilization is possible on Friday, associated
with boundary-layer moisture return along a weak surface trough,
roughly near/east of the Interstate 35 corridor of south central
through north central/northeast Texas.  This may coincide with
increasing forcing for ascent, associated with a perturbation
emerging from persistent weak upper troughing across the subtropical
eastern Pacific/northern Mexican Plateau, to support some risk for
strong thunderstorm development.  Although a mid-level speed maximum
might contribute to sufficient deep-layer shear for organized
convection (given sufficient destabilization), low-level wind fields
are forecast to remain generally weak, which probably will tend to
minimize the severe weather potential.

..Kerr.. 11/29/2021


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