Subj : DAY48SVR: Nws Storm Prediction Center Norman Ok
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Mar 31 2023 09:01:56

ACUS48 KWNS 310901
SWOD48
SPC AC 310900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Fri Mar 31 2023

Valid 031200Z - 081200Z

....DISCUSSION...
Medium-range models indicate that mid/upper flow will undergo
substantial amplification across the northern and middle latitudes
of the Pacific during this period.  This appears likely to include
the evolution of a broad, deep mid-level trough which will support
strong cyclogenesis to the southeast of the Aleutians by the end of
next week.  Downstream flow is then forecast to split near the North
American Pacific coast, with ridging building across the far western
Canadian provinces and troughing across the U.S. Great Basin and
Southwest, before converging into broad troughing across the
northwestern Atlantic.

Prior to these developments, a significant mid-level short wave
trough is forecast to emerge from the Intermountain West Monday into
early Tuesday, before contributing to strong cyclogenesis across the
central Great Plains into the Upper Midwest Tuesday through Tuesday
night.  The mid-level perturbation may be accompanied by a 100 kt
cyclonically curved 500 mb jet, contributing to strong deep-layer
shear across the warm sector of the surface cyclone, where
intensifying southerly 850 mb flow may contribute to large,
clockwise curved low-level hodographs.

The GFS, ECMWF and their respective ensembles seem to be coming in
better agreement with the late afternoon and early evening track of
the surface cyclone across the northeastern Kansas into southeastern
Nebraska vicinity, with a warm front extending across southern Iowa
and the dryline extending trailing from the surface low southward
near the Missouri/Kansas border.  The dryline may become the focus
for the initiation of strongest storms, which will tend to propagate
northeastward before being overtaken by a surging cold front.

There is some concern that a more subtle mid-level impulse may
contribute to thunderstorm initiation over the warm sector, across
parts of the Ozark Plateau, early in the day and negatively impact
destabilization across that area, and perhaps areas to the north.
However, if this does not become a mitigating factor, a substantive
organized severe weather event may evolve, including potential for
strong tornadoes, large hail and damaging wind gusts Tuesday
afternoon into Tuesday night across the lower Missouri Valley
vicinity.

...Kerr.. 03/31/2023

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