- Day Three
acus03 kwns 200731
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
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