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1 2 3 4 Severe Storm Outlook Narrative (AC)
000
acus02 kwns 190553
swody2
spc ac 190551
day 2 convective outlook
nws storm prediction center norman ok
1251 am cdt wed jun 19 2013
valid 201200z - 211200z
... there is a slgt risk of svr tstms for the upper midwest...
... synopsis...
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 nrn rockies at 12z/thu should shift nwd across the
srn 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 nwd from an
anticyclone over the srn plains to the upper midwest. at the
surface ... a cold front /perhaps enhanced by convective outflow on
d1/ should stall invof cntrl dakotas. trailing portion of this
boundary should advance wwd late d2 in the nrn high plains as
low - level mass response occurs.
... upper midwest...
isolated to widely scattered tstms should be ongoing across parts of
the dakotas into mn within a broad low - level waa regime and along
the leading edge of the plains eml. some of this activity may
intensify during the diurnal heating cycle as it progresses ewd and
could pose an isolated severe threat.
more robust surface - based tstms 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 tstms.
an initially stout capping inversion will probably limit
surface - based development with srn extent in sd/neb ... suggesting
that parts of nd/mn will be the focus for afternoon tstms. by late
afternoon/early evening ... sufficient surface heating and convergence
should initiate at least isolated tstms into parts of sd/neb where
the air mass should be very unstable. moderate wlys and steep lapse
rates in the mid - levels will support potential for supercells
producing very large hail along with isolated severe wind and a few
tornadoes.
low - level waa will strengthen thu evening as a robust llj develops
from the srn plains to the upper midwest. within modest upper - level
flow ... pattern would support diurnally - induced convection growing
upscale into a sewd - propagating mcs with a predominant risk of
severe wind.
.. grams.. 06/19/2013