SPC AC 131700
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1200 PM CDT Fri May 13 2022
Valid 141200Z - 151200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF LOWER MI AND THE OH AND TN VALLEYS...LOWER MS VALLEY...SOUTHERN
HIGH PLAINS...AND CENTRAL PLAINS...
...SUMMARY...
Strong/locally severe storms are expected across portions of the
central third of the U.S. -- particularly from the Kansas/Oklahoma
vicinity eastward toward the Ozarks.
...Synopsis...
A mid-latitude cyclone is forecast to be in place over the Canadian
Prairie Provinces early Saturday, with only modest northeastward
progress anticipated throughout the day. A strong shortwave trough
is expected to rotate through the base and eastern periphery of this
cyclone, while another follows in its wake into the northern/central
Plains late Saturday into early Sunday. Farther east, a large upper
low is expected to weaken as it moves gradually
eastward/northeastward into the Northeast.
At the surface, a weak cold front is forecast to extend from Lower
MI southwestward across southern IL, southeast MO, and northwest AR
into southern OK. Some southeastward/southern progression of this
front is possible throughout the day while it becomes increasingly
diffuse. Another cold front is expected to drop across the northern
Plains and into the Upper Midwest and central Plains. By 12Z Sunday,
this front will likely extend from Lower MI southwestward into
northern NE.
...Lower MI...Lower/Middle OH Valley...TN Valley...
Scattered to numerous thunderstorms are anticipated ahead of the
weak front mentioned in the synopsis. Dewpoints ahead of the front
will be in the low to mid 60s, supporting moderate buoyancy.
Vertical shear will be weak, limiting storm organization and
promoting a multicellular storm mode. However, a few more robust
updrafts are still feasible (particularly as a result of storm
mergers), with isolated damaging wind gusts and/or hail possible.
...Lower MS Valley...
Outflow from preceding thunderstorms may provide the impetus for
additional early afternoon development across southern AR/northern
LA. Uncertainty regarding the presence and location of this outflow
limits predictability. However, if storms do develop, a few
water-loaded downdrafts capable of isolated wind damage are
possible.
...Central Plains...
Elevated thunderstorm development is possible in the vicinity of the
front over southern Nebraska Saturday night into early Sunday
morning. Enough buoyancy and vertical shear will be in place to
support isolated hail within the stronger updrafts.
...Southern High Plains...
Afternoon heating/destabilization along a lee-trough/dryline will
likely support very isolated storm development. Modest flow aloft
should limit convective intensity overall, though a few
stronger/high-based storms may produce gusty winds locally.
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