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acus02 kwns 190553
swody2
Storm Prediction Center ac 190551
Day 2 convective outlook
National Weather Service Storm Prediction Center Norman OK
1251 am CDT Wednesday Jun 19 2013
Valid 201200z - 211200z
..there is a slight risk of severe thunderstorms for the upper Midwest...
...
although there remains some spread...guidance is in better agreement
with the pattern for d2 lending greater confidence over delineating
higher severe intensity/coverage probabilities. A lead shortwave
impulse over the northern rockies at 12z/Thursday should shift northward across the
southern Canadian rockies...as upstream impulses rotate through the basal
portion of the broader upper-level trough over the northwest. This
will lend to continue gradual height rises emanating northward from an
anticyclone over the Southern Plains to the upper Midwest. At the
surface...a cold front /perhaps enhanced by convective outflow on
d1/ should stall in vicinity of central Dakotas. Trailing portion of this
boundary should advance westward late d2 in the northern High Plains as
low-level mass response occurs.
..upper Midwest...
Isolated to widely scattered thunderstorms should be ongoing across parts of
the Dakotas into Minnesota within a broad low-level warm air advection regime and along
the leading edge of the plains eml. Some of this activity may
intensify during the diurnal heating cycle as it progresses eastward and
could pose an isolated severe threat.
More robust surface-based thunderstorms should primarily be tied to
initiation along the cold front and/or outflow boundaries where
stronger insolation occurs in the wake of or south of morning thunderstorms.
An initially Stout capping inversion will probably limit
surface-based development with southern extent in SD/neb...suggesting
that parts of ND/Minnesota will be the focus for afternoon thunderstorms. By late
afternoon/early evening...sufficient surface heating and convergence
should initiate at least isolated thunderstorms into parts of South Dakota/Nebraska where
the air mass should be very unstable. Moderate westerlies and steep lapse
rates in the middle-levels will support potential for supercells
producing very large hail along with isolated severe wind and a few
tornadoes.
Low-level warm air advection will strengthen Thursday evening as a robust low level jet develops
from the Southern Plains to the upper Midwest. Within modest upper-level
flow...pattern would support diurnally-induced convection growing
upscale into a southeastward-propagating mesoscale convective system with a predominant risk of
severe wind.
.Grams.. 06/19/2013
