U.S. Severe Weather Forecast (Convective Outlook)

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Day Three

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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 
the country. 


... 
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 
the period. 


..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 
evening. 


..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 
forecasts. 


.Goss.. 08/23/2014