Mesoscale Discussion 0561
NWS Storm Prediction Center Norman OK
0357 PM CDT Wed Apr 19 2023
Areas affected...Portions of southwestern and south-central Oklahoma
Concerning...Severe potential...Watch possible
Valid 192057Z - 192300Z
Probability of Watch Issuance...60 percent
SUMMARY...Conditional severe threat increasing. Potential for
supercells with large hail and a couple tornadoes late afternoon
into the evening. A watch will be possible in the next few hours.
DISCUSSION...A conditional severe threat is increasing across
portions of southwestern and south-central Oklahoma. A surface
dryline continues to mix eastward across Oklahoma and Texas. Ahead
of the dryline, mid 60s dew points have moved north of the Red River
across southern Oklahoma. 19z RAOB from OUN indicates moistening and
a weakening cap beneath an elevated mixed layer with steep lapse
rates (around 8 C/km). Temperatures have warmed into the 80s with
strong daytime heating, with MLCAPE around 2500-3000 J/kg. Further
indication of the weakening cap can be seen in satellite, as cumulus
fields continue to show increasing development. The 19z OUN RAOB and
surface objective analysis also indicate deep layer shear around
35-40 kts. The main risk with any initial storm development would be
large hail, given steep lapse rates. As the main wave approaches
from the west with deepening low pressure across the Central Plains,
850 mb flow will increase through the evening, further elongating
hodographs and increasing risk of a couple tornadoes. Trends will be
monitored closely with a watch will be possible within few hours.
..Thornton/Grams.. 04/19/2023
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