Valid 222000Z – 231200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS EXTENDING FROM
PARTS OF OKLAHOMA NORTHEASTWARD TO INDIANA…
Isolated damaging winds, and perhaps a tornado or two, will remain
possible through this evening from parts of Oklahoma to Indiana.
No changes have been made to the Marginal Risk extending from
central OK northeastward to IL and far northwestern IN. A broad area
of persistent rain showers across parts of MO into IL has hampered
diurnal heating and the development of instability across this area.
Relatively better, but still limited, severe potential may exist in
a narrow corridor from parts of northern/central OK into
southeastern KS and far western MO ahead of a surface cold front.
MLCAPE around 500-1000 J/kg is in place across this region as some
cloud breaks have allowed for modest diurnal heating. Strong shear
remains over this region, which may support isolated strong/gusty
downdraft winds. An isolated/marginal severe risk may also exist
from the St. Louis metro area northeastward into central IL through
the rest of the afternoon, as a small increase in instability in the
presence of strong shear has occurred on the eastern edge of the
broad precipitation shield over MO.
.PREV DISCUSSION… /ISSUED 1117 AM CDT Sun Sep 22 2019/
…OK to IL…
No changes have been made to the ongoing forecast. A band of
relatively fast winds aloft extends from the southern and central
Plains into the mid MS valley and Great Lakes region today. A
strong shortwave trough embedded in this flow over western KS/OK
will track into MO/IL during this forecast period. Considerable
cloud cover and areas of precipitation will continue to affect the
MRGL risk corridor this afternoon. Despite the weak instability and
poor lapse rates, forecast soundings show sufficient vertical shear
to pose a limited risk of a storm or two becoming intense with
damaging wind potential and some tornado risk.