acus03 kwns 190732
Storm Prediction Center ac 190730
Day 3 convective outlook
National Weather Service Storm Prediction Center Norman OK
0230 am CDT Wednesday Jun 19 2013
Valid 211200z - 221200z
..there is a slight risk of severe thunderstorms for parts of the northern/Central
Plains to the upper MS valley...
An upper-level trough should dampen slightly as it remains anchored
over the northern intermountain west into early Sat...with embedded
impulses rotating throughout it. A downstream middle-level anticyclone
should hold over the Southern Plains with a ridge emanating northward into the
upper Midwest. A belt of moderate middle-level west/swlys will persist
across the north-central Continental U.S....which may be enhanced by
convectively-induced impulses. At the surface...a Lee thermal low
should be centered over northestern Colorado Friday afternoon...with a
SW/NE-oriented weak surface front extending into the upper Midwest.
This front and perhaps additional outflow boundaries will likely be
modulated by a probable mesoscale convective system on d2.
..nrn/Central Plains to the upper MS valley...
Thunderstorm clusters may be ongoing over parts of the upper MS valley
within a low-level warm air advection regime. This activity may diurnally
strengthen and pose a risk for isolated severe wind/hail as it
spreads east/southeastward along the leading edge of the eml.
Farther west...A Reservoir of strong to extreme instability appears
likely to develop Friday afternoon along and S of the aforementioned
surface front within a plume of very steep middle-level lapse rates and
enriching low-level moisture beneath a capping inversion. Low-level
upslope flow to the north of the boundary and perhaps glancing influence
of a shortwave impulse rotating across the northern High Plains should
aid in afternoon thunderstorm development near the higher terrain in vicinity of
Black Hills. With strong effective shear...activity should mature
into supercells capable of producing very large hail and a few
tornadoes. As the low level jet strengthens over the Central Plains/mid-MO
valley Friday evening...consolidating cold pools should yield upscale
growth into an mesoscale convective system. Given the degree of instability on the fringe of
sufficient deep-layer shear...potential exists for bows capable of
significant severe wind.