Mesoscale Discussion 0461
NWS Storm Prediction Center Norman OK
1239 PM CDT Sat May 19 2018
Areas affected...Northern Oklahoma into southern Kansas
Concerning...Severe potential...Watch likely
Valid 191739Z - 192015Z
Probability of Watch Issuance...80 percent
SUMMARY...Storms are expected to form across northern Oklahoma into
southern Kansas, with very large hail and a tornado or two possible.
A watch will likely be needed by 20-21Z.
DISCUSSION...Surface analysis shows a quasi-stationary boundary from
northwest OK into southern MO, with a cold front just northwest from
the TX Panhandle into east-central KS. Meanwhile, earlier storms
have left behind an outflow boundary, close to the synoptic front
along the KS/OK border.
Visible satellite imagery shows heating is occurring in the
post-outflow air mass, along with strong warming south of the main
front where temperatures are rising into the mid 80s F. Although
morning soundings showed a rather shallow moist layer from TX into
OK, some deepening of the moist boundary layer is expected near the
fronts, also aided by evapotranspiration. The presence of cold
temperatures aloft combined with this warming air mass is resulting
in strong instability with 700-500 mb lapse rates around 8.5 C/km.
This suggests vigorous updrafts which will support very large hail.
In addition, a tornado or two is possible in this region due to the
locally backed surface winds near the modifying outflow, and aided
by slight warm advection/lift atop this boundary.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 37279811 37719681 37789582 37619547 37169529 36709560
36439690 36289810 36259846 36449870 36699879 36989860