U.S. Severe Weather Forecast (Convective Outlook)

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Day Three

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acus03 kwns 200731 
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Storm Prediction Center ac 200729 


Day 3 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0229 am CDT Wed Jun 20 2018 


Valid 221200z - 231200z 


..there is a marginal risk of severe thunderstorms across parts of 
the Central Plains and the southeast... 


... 
A few severe storms are possible on Friday across parts of the 
Central Plains, and from the lower Mississippi Valley toward the 
Ohio Valley. 


... 
An upper low is forecast to pivot from the mid MS valley across the 
Ohio Valley, with a cyclonically curved belt of 40+ kt midlevel winds 
from the Central Plains to the Ohio Valley. This feature will be 
accompanied by a weak surface low along with a northward spread of 
moisture supporting widespread thunderstorm activity. To the west, a 
secondary, low-amplitude shortwave trough will move across The 
Rockies and into the Central High plains late in the period with a 
surface low developing near the Texas Panhandle. Strong warm advection 
will materialize Friday evening across the Southern Plains in 
advance upper trough with 40+ kt at 850 mb out of the southwest. 


..eastern Colorado/western NE into OK... 
A plume of 50s f dewpoints are expected to spread northwestward 
toward the Kansas/Colorado border by 00z, supporting MUCAPE in excess of 2000 
j/kg with steep overall lapse rates. At least isolated storms are 
likely to form in advance of the upper wave, across western NE and 
northeast co, with severe hail and wind possible. However, the 
eastward extent of the severe threat at this latitude will be 
limited by a cool air mass to the east and subsequent capping. 


Farther south, other storms will be possible across the OK/Texas 
panhandles, which would then develop eastward across OK where the 
low-level jet will support lift. Some models indicate an MCS, in 
which case damaging winds would be possible. However, predictability 
of such a feature is too low for a slight risk at this time. 


..lower MS valley to the Ohio Valley... 
A large area of thunderstorm potential will exist from the MS river 
to the Appalachians with substantial moisture in place and 
relatively cool air aloft with the upper trough. The most likely 
area for severe storms appears to be from the arklatex into northern 
al, and northward into Kentucky. However, given the likelihood of 
antecedent outflows and early/ongoing storms, predictability is low. 
A slight risk may be needed in some parts of the area in later 
outlooks. 


.Jewell.. 06/20/2018 


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