Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1229 AM CDT Wed May 13 2020
Valid 131200Z - 141200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN AND CENTRAL PLAINS...
...SUMMARY...
Isolated to scattered severe thunderstorms are expected across parts
of the southern and central Plains this afternoon through tonight.
The greatest threat for numerous severe wind gusts and perhaps some
very large hail will be across parts of west Texas and western
Oklahoma.
...Southern Plains...
West to southwest mid-level flow will be in place today across the
western half of the nation as a shortwave trough moves through the
flow into the southern High Plains. At the surface, a low will
deepen in eastern Colorado as a surface trough and dryline become
more focused in the southern High Plains. A moist airmass will
advect northward from the lower Rolling Plains into the southeast
Texas Panhandle this afternoon where surface dewpoints appear likely
to reach the lower 60s F. As surface heating takes place, moderate
instability will develop to the east of the dryline from west Texas
into the eastern Texas Panhandle and eastward across much of the Red
River Valley. The shortwave trough is timed to reach the dryline in
the late afternoon, which combined with increasing low-level
convergence, should result in scattered convective initiation from
near Amarillo northeastward into the northeastern Texas Panhandle.
These storms will move eastward into the enhanced risk area during
the late afternoon and early evening. Additional thunderstorms will
develop south-southwestward across west Texas during the late
afternoon.
RAP forecast soundings to the east of the dryline by late afternoon
show nearly dry adiabatic lapse rates below 700 mb with MLCAPE in
the 2000 to 3000 J/kg range. This combined with 0-6 km shear of 40
to 50 kt will be favorable for supercells with large hail.
Hailstones greater than 2 inches in diameter will be possible with
supercells that develop intense cores, from western Oklahoma and the
eastern Texas Panhandle south-southwestward into the Pecos River
Valley. As cell coverage increases during the late afternoon and
early evening, it appears a broken line segment will organize and
move eastward into western Oklahoma and northwest Texas. Wind damage
will be likely along the leading edge of the line segment. A few
tornadoes will be possible with the more dominant supercells as
well. The enhanced risk area has been adjusted to account for a
further west position of the dryline.