- Day Three
acus02 kwns 261728
Storm Prediction Center ac 261727
Day 2 convective outlook
National Weather Service Storm Prediction Center Norman OK
1227 PM CDT Thu Apr 26 2018
Valid 271200z - 281200z
..there is a marginal risk of severe thunderstorms across the
eastern Oregon/western Idaho vicinity...
Isolated strong thunderstorms capable of downburst winds may occur
from parts of eastern Oregon into southwestern Idaho later Friday
afternoon and evening.
A large upper trough -- comprised of numerous smaller-scale features
-- is forecast to affect the eastern half of the U.S. Day 2, while
ridging prevails across a large portion of the intermountain west
and into western portions of the Great Plains. Still farther west,
an upper low moving east across the eastern Pacific is progged to
move onshore over the northern California/Oregon vicinity.
At the surface, a cold front is forecast to shift eastward across
the West Coast states into the Great Basin with time, ahead of the
advancing upper low. Meanwhile in the east, a cold front is
expected to shift southward across the Great Lakes and plains
states, and into the Midwest/Ohio Valley areas through the end of
..eastern Oregon/western Idaho vicinity...
Modest, high-based instability is forecast to develop through the
afternoon in conjunction with daytime heating, supportive of
isolated thunderstorm development over the region. Though degree of
cape will remain limited, and thus storms largely weak/disorganized,
a deep, dry sub-cloud layer (inverted v-type boundary layer
thermodynamic profile) expected across the area may support
evaporatively aided downdrafts -- possibly reaching severe levels
locally. Greatest risk will be in the late afternoon time frame,
with convection diminishing after sunset.
..maximum risk by hazard...
Tornado: <2% - none
wind: 5% - marginal
hail: 5% - marginal