ZCZC SPCSWOMCD ALL
ACUS11 KWNS 201617 
SPC MCD 201617 
OKZ000-TXZ000-201845-

Mesoscale Discussion 0699
NWS Storm Prediction Center Norman OK
1117 AM CDT Mon May 20 2019

Areas affected...southwest into central OK...western north-central
TX

Concerning...Severe potential...Tornado Watch likely 

Valid 201617Z - 201845Z

Probability of Watch Issuance...95 percent

SUMMARY...A Particularly Dangerous Situation Tornado Watch will
likely be needed for portions of central and western OK. 
Observational trends and short-term model guidance suggest a watch
being issued during the 1pm-2pm period.

DISCUSSION...Visible satellite imagery shows a bubbling cumulus
field over western north-central TX into southwest and south-central
OK.  Rapid moisture advection is occurring late this morning with
surface dewpoints rising into the lower 70s over southern OK. 
Upwards of 4000 J/kg MLCAPE is expected by early to mid afternoon
across western and central OK with intensifying wind profiles.  

Short-term model guidance appears to have a reasonable depiction of
free warm sector initiation occurring over southwest and
south-central OK during the 2-3pm period.  The observational trend
in visible satellite imagery showing more pronounced bands of low
cloud cover ---perhaps indicative of horizontal convective rolls
and/or low-level confluence zones is supportive evidence for this
model-based depiction.  The expectation is for storms to develop on
the northern half of these cloud features with explosive supercell
development likely thereafter.  Forecast soundings show a very rare
combination of intense low-level SRH, very moist boundary, and
extreme buoyancy.  As such, the risk for strong to violent tornadoes
appears to be increasing later this afternoon into the early
evening.

..Smith.. 05/20/2019

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...OUN...

LAT...LON   34199717 33829936 34169988 35509993 35899882 36029706
            35629678 34609685 34199717 

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