U.S. Severe Weather Forecast for Tomorrow
Upcoming severe weather outlook.
acus02 kwns 211745
Storm Prediction Center ac 211744
Day 2 convective outlook
National Weather Service Storm Prediction Center Norman OK
1244 PM CDT Thursday Aug 21 2014
Valid 221200z - 231200z
..there is a slight risk of severe thunderstorms across northeast Colorado...Northwest
Kansas into Nebraska...
Scattered strong to severe storms will be possible from northeast
Colorado and northwest Kansas into Nebraska Friday afternoon and
into Friday evening and overnight across portions of the central and
northern plains. Large hail and strong wind gusts will be the
primary threats...though a tornado cannot be ruled out in the
western extent of the slight risk area. A few strong to severe
storms will be possible from Iowa to the Ohio Valley and perhaps the
central Appalachian Mountains.
A shortwave trough digging southeast today along the British
Columbia coast will amplify into a larger scale trough on Friday
across the northern intermountain region and Great Basin. The evolution
of this system into day 2 will further aid in dislodging the compact
lower Colorado River valley closed low on Friday. This low will track
northeastward from Arizona...reaching the Central High plains by late Friday
night. Meanwhile...models suggest weaker impulses will precede the
Arizona low...moving northeastward from the southern rockies into eastern Colorado to South Dakota by peak
heating Friday afternoon. Downstream...a strong ridge will be
maintained from the Gulf of Mexico into the Southern Plains and Lower-Middle
MS valley with height rises into the Great Lakes. At the
surface...a front becoming stationary today across eastern Nebraska to northern Kansas
should extend from central Iowa west-southwestward into northwestern Kansas and eastern Colorado at 12z
Friday. This boundary will shift a little northward into Friday afternoon
as a warm front and extend from central Iowa westward through east central
to southwestern Nebraska into northestern Colorado. A developing Lee low in eastern Colorado will track
along this boundary Friday night into central Nebraska.
..portions of the Central Plains...
Surface dewpoints in the 60s along the warm front Friday afternoon
combined with a plume of midlevel lapse rates around or greater than
7 c/km and surface heating will result in a moderately unstable
environment. Forecast soundings suggest surface based inhibition
should weaken by early-middle afternoon across northestern Colorado/northwestern Kansas and southwestern
Nebraska supporting convective development from the Lee low east-northeastward along
the warm front. Deep layer ascent will increase due to convergence
in vicinity of these surface features and attendant to the weak impulses
tracking northeastward across this region should prove supportive for deep
convection. Despite weaker low-level winds into the
afternoon...effective bulk shear of 30-40 knots across the slight risk
area suggests multicells and supercells can be expected with large
hail and damaging wind gusts the primary threats with the initial
storm development. A strengthening southerly low level jet into western/central Kansas to
southern Nebraska should enhance low-level shear and perhaps a tornado threat
early Friday evening. Further strengthening and veering of the
low-level jet across the Central Plains...increasing warm air advection...and
residual moderate instability suggests strong-severe storms could
persist through the evening and spread eastward across central/eastern Nebraska
and northward into South Dakota. Hail and gusty winds would be a threats with this
activity into the overnight period.
..OH valley to the middle MS valley...
Thunderstorms should be ongoing across portions of this region at the start
of day 2...with lingering cloud debris potentially limiting
destabilization. However...models suggest the environment should
become moderately unstable with the potential for a few strong to
severe storms Friday afternoon into the evening. Height rises from
the middle MS valley to the Great Lakes would suggest portions of the
Midwest /across Illinois/ may have a limited thunderstorm coverage.