Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1140 AM CST Mon Nov 25 2019
Valid 261200Z - 271200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
THE LOWER TO MIDDLE MISSISSIPPI VALLEY...
...SUMMARY...
Isolated severe storms with a threat for mainly damaging wind and a
couple of tornadoes will be possible over a portion of the lower to
middle Mississippi Valley region Tuesday.
...Lower to middle Mississippi Valley region...
A strong shortwave trough now approaching the Great Basin will
emerge over the central and southern Plains early Tuesday. A
mid-upper jet within base of this feature will strengthen to 120 kt
as the shortwave trough ejects negatively tilted through the middle
MS Valley region. Lee cyclone initially over the southern High
Plains will deepen within exit region of the upper jet as it
develops northeast through the middle MS Valley by Tuesday evening.
Trailing cold front will advance east and southeast through the
central and southern Plains and MS Valley. By the end of the period
the front should extend from a surface low over upper Great lakes
southwest through LA and the TX coastal area.
The boundary layer over the northwestern Gulf is in the process of
modifying with latest observations showing dewpoints already in the
upper 60s F. Positive theta-e advection promoted by southerly
low-level winds will persist through Tuesday contributing to surface
dewpoints near 70 F as far north as southern AR with upper 50s F
into central MO. Widespread clouds should limit diabatic heating in
warm sector, but MLCAPE should approach 1000 J/kg over the lower MS
Valley. Farther north from eastern KS into MO the development of
steeper lapse rates with colder air aloft (-14 to -16 C at 500 mb)
will contribute to marginal MLCAPE with 500-800 J/kg possible within
a more shallow convective layer. Two primary zones of surface based
thunderstorm development are possible Tuesday afternoon and evening,
including along the warm conveyor belt from northern LA into AR,
western MS and TN, and farther north within zone of stronger
pre-frontal forcing ahead of the cold front from eastern KS into MO
and western IL. Broken bands of storms including potential for a few
supercells and bowing segments will be possible in both of these
regimes where vertical shear profiles will be more than adequate for
organized structures with sizeable 0-1 km hodographs and 50+ kt
effective bulk shear. Primary limiting factor for higher severe
probabilities is the expected marginal thermodynamic environment.
Nevertheless, at least isolated damaging wind and a couple tornadoes
will be possible with the stronger storms.
...MAXIMUM RISK BY HAZARD...
Tornado: 5% - Slight
Wind: 15% - Slight
Hail: 5% - Marginal