SPC AC 220529
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1229 AM CDT Fri May 22 2020
Valid 221200Z - 231200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTHERN TEXAS AND OKLAHOMA...
...SUMMARY...
Severe storms will be likely today across parts of the southern
Plains northeastward into southeast Kansas and the Ozarks. An
enhanced threat for tornadoes, very large hail and wind damage is
expected from north Texas into southern and eastern Oklahoma.
...Southern and Central Plains/Ozarks...
An upper-level low will move east-northeastward across the central
Plains today as an associated trough moves across the southern
Plains. At the surface, a cold front will move into central Oklahoma
with a moist airmass located ahead of the front. A line of
thunderstorms is forecast to move across northern Oklahoma this
morning into the Ozarks this afternoon. South of the outflow
boundary, a moist and unstable airmass will remain in place from
north Texas into eastern Oklahoma, where moderate to strong
instability is expected to develop by early afternoon. MLCAPE values
should peak in the 3500 to 4500 J/kg range from near Wichita Falls,
Texas northeastward to south of Tulsa, Oklahoma. Convection is
forecast to initiate along this corridor during the late afternoon
with several discrete storms moving eastward across eastern and
southern Oklahoma. During the early evening, storms will also likely
develop in north and west-central Texas.
In addition to strong instability, RAP forecast soundings in parts
of the southern Plains show a favorable wind profile for supercells.
In southeast Oklahoma and north Texas, winds are forecast to veer
with height in the lowest 3 km AGL with speed shear in the
mid-levels. This combined with 700-500 mb lapse rates near 8.0 C/km
will be favorable for large hail with the stronger updrafts.
Hailstones of greater than 2 inches in diameter will be possible
with supercells co-located with the greatest instability. A tornado
threat is also expected to develop as low-level shear gradually
increases during the late afternoon and early evening. A couple
strong tornadoes may occur with the more dominant supercells, with
the greatest potential from between Wichita Falls and Fort Worth
northeastward to near McAlester, Oklahoma. An Enhanced Risk has been
added along this corridor.
The severe threat is expected to extend eastward into northern
Arkansas during the evening where large hail and wind damage will be
possible. Further north into western Missouri and eastern Kansas,
weaker instability should keep any severe threat more isolated. An
isolated severe threat is also expected in west-central Texas where
storms are expected to be very widely spaced.
...Southern Appalachians/Georgia/Carolinas...
An upper-level low will move northeastward across the Ohio Valley
today as an associated trough moves into the southern Appalachians.
Thunderstorms are expected to develop near the trough around midday
and move eastward into the Carolinas during the mid to late
afternoon. More isolated storms may also develop across parts of
northern Georgia. A moist airmass will be in place from Georgia into
the Carolinas where surface dewpoints are forecast to be in the 60s
F. As surface temperatures warm during the day, pockets of moderate
instability appear likely to develop. This combined with 0-6 km
shear of 30 to 40 kt and steep low-level lapse rates, should be
favorable for isolated severe storms. Marginally severe wind gusts
and hail would be the primary threats.
..Broyles/Lyons.. 05/22/2020