Mesoscale Discussion 0519
NWS Storm Prediction Center Norman OK
0241 PM CDT Fri May 25 2018
Areas affected...Much of western Oklahoma into northwest Texas
Concerning...Severe potential...Watch likely
Valid 251941Z - 252215Z
Probability of Watch Issuance...80 percent
SUMMARY...At least a few severe storms capable of very large hail
and damaging wind are expected to develop by 22-23Z.
DISCUSSION...Surface analysis shows a dying outflow boundary from
northwest TX into the eastern TX Panhandle. Strong heating continues
on both sides of the boundary, and surface winds remained
southeasterly and backed relative to areas to the west. Meanwhile, a
weak surface low was located across northwest OK, with a low
pressure trough generally extending southwestward into the South
The outflow may have caused some degree of drying of the air mass
emanating out of OK. However, GPS water vapor sensors indicate only
a slight drop in overall moisture content on the cool side of the
boundary, and, surface dewpoints continue to rise. Therefore, MLCAPE
values of 2000-3000 J/kg appear reasonable given the very steep
lapse rates aloft and strong heating.
Although surface convergence will remain weak, it should be
sufficient given the lack of CIN to initiate a few areas of severe
storms. The most likely area for initiation would appear to extend
from northwest OK into the eastern TX Panhandle. Northwest flow
aloft atop light but veering winds with height should result in
slow, southward-moving cells capable of very large hail and
localized wind damage.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 34990076 36140025 36670010 36699974 36489935 36079905
35039889 34399881 34049865 33769845 33309800 32999788
32619844 32599930 32690011 32900092 33260130 34010127