Severe Storm Outlook Narrative (AC)
Issued by NWS
ACUS01 KWNS 161628
SPC AC 161627
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1027 AM CST Mon Jan 16 2017
Valid 161630Z - 171200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
ARKLATEX AND MIDDLE MISSISSIPPI RIVER VALLEY...
A few severe thunderstorms are possible this afternoon and evening
from the Arklatex region to the Mid-Mississippi Valley. Damaging
winds, a brief tornado, and small to marginally severe hail are
possible on an isolated basis.
...East Texas/Arklatex/middle Mississippi Valley...
A closed upper low over KS/northern OK at late morning will continue
northeastward and reach the Lake Michigan vicinity by early Tuesday
morning. Heights will rise across east TX coincident with a stalling
front, while the cold front will remain more eastward progressive
across the Ozarks/middle Mississippi River valley. Moderately strong
south-southwesterly winds just above the surface will continue to
transport a seasonally moist air mass northward, with near 60 F
surface dewpoints reaching as far north as Memphis/northeast AR by
early evening as air mass modification steadily occurs.
Cloud cover may remain semi-prevalent across the warm sector today
coincident with weak warm/moist advection amid a confluent
pre-frontal regime. Even so, increasing moisture and cloud
breaks/pockets of stronger heating could lead to MLCAPE around 500
J/kg this afternoon. As at least some afternoon intensification of
updrafts occurs, 35-45 kt of effective shear would support
semi-organized updrafts and line segments, potentially capable of
marginally severe hail, damaging winds, and/or a brief tornado
through the afternoon and evening. Aside from cloud cover, a
sub-optimal phasing of large-scale ascent and more prevalent
moisture/surface-based instability (to the south) should limit the
overall severe risk today.