ACUS01 KWNS 240551
SPC AC 240549
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1249 AM CDT Mon Jun 24 2019
Valid 241200Z - 251200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE GREAT LAKES SOUTHWARD INTO THE SOUTHERN APPALACHIANS AND IN
PARTS OF THE SOUTHERN PLAINS...
Scattered storms, some severe with hail or wind, are expected today
the southern Great Lakes southward across the Ohio Valley into the
Southern Appalachian Mountains. Other severe storms may occur across
parts of the southern Plains.
...Ohio Valley/Southern and Central Appalachians...
An upper-level trough will move eastward across the Mississippi
Valley today as southwest mid-level flow remains over east-central
U.S. At the surface, a cold front will advance eastward into the
Ohio and Tennessee Valleys as a corridor of maximized low-level
moisture sets up ahead of the front. Surface dewpoints in the upper
60s F should result in moderate instability by midday across much of
the moist sector. As surface temperatures warm and low-level
convergence increases along the front, scattered convection is
forecast to initiate along and ahead of the front. Linear MCS
development will be possible as storms increase in coverage and move
northeastward across the moist sector during the afternoon. RAP
forecast soundings ahead of the front by 21Z from northern Kentucky
southward into the southern Appalachian Mountains show MLCAPE values
from 1000 to 2000 J/kg with steep low-level lapse rates. This along
about 30 kt of 0-6 km shear should be favorable for isolated
damaging wind gusts. Hail will also be possible with the stronger
cells embedded in the any line that becomes established.
...Southern Great Lakes/Upper Mississippi Valley...
An upper-level trough will move across the upper Mississippi Valley
today as a cold front advances eastward into the region. Surface
dewpoints in the mid 60s F ahead of the front should contribute to
the development of a pocket of moderate instability by afternoon
from southern Wisconsin into northern Illinois. Scattered cells are
forecast to initiate along and ahead of the front in the vicinity of
the upper-level trough around midday. Many of the cells should
become thunderstorms, moving eastward across southern Wisconsin and
northeastern Illinois during the afternoon. Steep lapse rates
associated with the trough and moderate deep-layer shear should be
sufficient for isolated supercell formation and a large-hail threat.
A few damaging wind gusts will also be possible with the stronger
cells. The greatest severe threat should occur near peak heating.
Westerly to west-northwesterly mid-level flow will be in place today
from the southern Rockies into the southern Plains. At the surface,
a corridor of maximized low-level moisture should set up across
west-central Texas. This will likely contribute to a corridor of
moderate to strong instability by afternoon. Convection is expected
to initiate along the instability axis during the mid to late
afternoon, although warm temperatures aloft and limited large-scale
ascent should keep thunderstorm activity isolated. However, the
instability combined with steep mid-level lapse rates and 30 kt of
deep-layer shear should be sufficient for supercell development.
Large hail and wind damage will be possible, mainly during the late
afternoon and early evening as the storms mature and move eastward
across west-central Texas.