- Day Three
acus03 kwns 130724
Storm Prediction Center ac 130723
Day 3 convective outlook
National Weather Service Storm Prediction Center Norman OK
0223 am CDT sun Oct 13 2019
Valid 151200z - 161200z
..no severe thunderstorm areas forecast...
thunderstorms are expected across portions of the central and
southern U.S. On Tuesday. Severe potential is uncertain, but could
develop across parts of East Texas toward the lower Mississippi
A somewhat complex forecast is in store for Tuesday with regard to
severe weather potential from eastern Texas toward the lower MS valley
vicinity. A seasonally strong mid/upper shortwave trough over the
northern plains will track eastward and deepen over the central U.S.
Meanwhile, weak perturbations will migrate through westerly
southern-stream flow across the southern U.S. Ahead of a weak
mid/upper trough ejecting eastward from the southern High Plains.
These two troughs will merge over the southern U.S. By the end of
the period. A cold front associated with a strengthening surface low
pressure system over the upper Great Lakes/Midwest will surge
eastward across the Southern Plains and mid-MS valley through the
evening, and become oriented from lower Michigan to the Tennessee Valley
southwestward to the Upper Texas coast by Wednesday morning.
Strong warm advection will occur ahead of the cold front from the
Southern Plains to the deep south, with a warm front lifting as far
north as northern Alabama/Georgia Tuesday night. Deep southerly boundary-layer
flow beneath strong mid/upper level westerlies will produce
effective shear values capable of sustaining strong to severe
thunderstorms. However, instability will generally be weak due to
abundant cloud cover, and lapse rates will remain poor.
Additionally, thunderstorms will likely be ongoing Tuesday morning
along/north of the warm front due to this strong warm advection
regime. This may overall preclude severe convective development
through peak heating across much of the southern U.S. In favor of
mainly heavy, training rainfall.
There may be a greater opportunity for isolated strong/severe storms
during the late afternoon/evening across the arklatex/East Texas/Sabine
valley vicinity where some guidance suggests stronger heating will
occur and more favorable instability may align with favorable shear
ahead of the southeastward-surging cold front. Other guidance shows
a less favorable scenario with convection become undercut by the
fast-moving front. As such, uncertainty remains too high to include
severe probabilities at this time, but may become necessary in
subsequent outlooks depending on guidance trends.