- Day Three
acus03 kwns 230732
Storm Prediction Center ac 230730
Day 3 convective outlook
National Weather Service Storm Prediction Center Norman OK
0230 am CDT Sat Aug 23 2014
Valid 251200z - 261200z
..no severe thunderstorm areas forecast...
a few strong/isolated severe storms will be possible across the
upper Great Lakes region Monday...while additional storms evolve
farther to the west and west-southwest across the central portion of
As an upper low shifting northeastward away from the north central U.S. Continues
to weaken as it crosses Ontario...the large-scale ridge is prognosticated
to expand across a large portion of the southern and eastern Continental U.S..
meanwhile...a downstream trough will remain over the western portion of
the country through the period.
At the surface...a cold front -- trailing southwestward from a low moving
northeastward across Ontario toward Hudson Bay -- will advance eastward across the
upper Great Lakes region through the day. Meanwhile...the western
extension of this boundary will remain more quasistationary/W-E
oriented across the upper Midwest/Central Plains vicinity through
..upper Great Lakes region...
Ongoing storms are forecast ahead of the advancing cold front early
in the period...with some intensification of convection possible
during the afternoon as modest destabilization occurs. With
enhanced flow aloft -- on the southern fringe of the departing upper
system -- lying across the upper Great Lakes...shear sufficient for
storm organization is expected. Thus...a stronger storm or two may
become capable of locally damaging winds and/or hail through early
..Central High plains east-northeastward across the middle MO valley...
Relatively substantial model-to-model differences are evident with
respect to evolution of the western U.S. Trough...with the GFS showing a
more progressive feature crossing The Rockies and then approaching
the plains during the second half of the period while the NAM shows
a cut-off -- even slightly retrogressive -- low over the western Nevada/northern
California vicinity. Upstream differences across the plains are thus also
evident...with the NAM depicting rising heights across the central
U.S. And a weakening surface front...while the GFS suggests
cyclogenesis over the Central High plains along the western fringe of
the surface front. As such...the GFS is much more bullish with
respect to possible severe risk...while the NAM would suggest a
largely sub-severe/elevated convective event north of the front.
At this time...will opt to refrain from issuance of severe probabilities due
to uncertainty...with this area to be re-evaluated in later