Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0349 AM CDT Sat May 14 2022
Valid 171200Z - 221200Z
...DISCUSSION...
Agreement amongst global model solutions begins to break down Day
5/Wednesday over North America, particularly with the evolution of a
low centered over the Hudson Bay vicinity Day 4. The ECMWF lingers
this low in the vicinity of Hudson Bay through the period, while the
GFS weakens the low and ejects it across eastern Canada Days 7-8.
As a result of the differing evolutions of this low as depicted by
the various models, corresponding differences are evident over the
northern U.S. with respect to the upper pattern -- and thus the
surface pattern as well. Therefore, predictability precludes any
confident assessment of severe potential through middle and latter
stages of the period.
Meanwhile, on Day 4/Tuesday, and into Day 5, a series of subtle
cyclonic disturbances -- embedded within fast westerly quasi-zonal
flow over most of the CONUS -- will shift out of the Rockies and
across central and eastern portions of the country. With a lee-side
low over the central High Plains -- maintained by the westerlies
aloft -- forecast to drift into the Kansas/Oklahoma vicinity
overnight, with a warm front arcing northeastward and then eastward
into the Mid Mississippi Valley.
Capping associated with the eastward advection of an elevated mixed
layer is expected across the southern Plains, which will likely
limit warm-sector storms. However, in the vicinity of the warm
front, afternoon convective development is expected, which will
likely then be sustained through the evening as a southerly
low-level jet develops. With moderate CAPE across the area, and 30
to 50 kt mid-level flow contributing to ample shear for
organized/severe storms, a 15% area is being introduced at this
time.
Day 5/Wednesday, a continuation of at least some severe potential
will likely shift eastward across the Mid Mississippi and into the
Ohio Valley. However, evolving/increasing model differences with
time precludes an areal highlight for Day 5, and onward through the
end of the period.
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