Mesoscale Precipitation Discussion 0661
NWS Weather Prediction Center College Park MD
700 PM EDT Tue Aug 14 2018

Areas affected...Central Oklahoma...

Concerning...Heavy rainfall...Flash flooding possible

Valid 142300Z - 150400Z

SUMMARY...Increasing convection will further intensify with
strengthening LLJ, increasing rates and favorable training profile
support possible flash flooding this evening into overnight.

DISCUSSION...GOES-16 Visible imagery depict a loosely organized
line of developing convection from Dewey to Panye county, OK
coincident with pooling of highest surface Tds (mid 70s).  This
along with solid isolation supports MLCAPEs of 2500-3000 J/kg
along this similar line.  Aloft, CIRA layered PWATs in the 7-5H
layer are maximized from SW MO across central OK generally
associated with a weak 5H trof that passed through and sparked
more isolated supercells.   A surface front remains further
northwest from HUT to P28 to GAG defined well with TCU line in
Visible imagery.

A secondary/stronger shortwave is noted in the GOES-WV suite
generally aligned with the frontal boundary...leading to some
increased ascent for this convective development. While cells are
still loosely organized at this time, they are aligned favorably
with mean cloud bearing flow (westerly at 20kts) that would
generally support some training in the short term, though there
appears to be some northward development trends noted.   Given the
vertical depth of the cells and available moisture, 1.7" west
along the line to the max of 2" near Wagoner/Rodgers county; rates
of 2"/hr are possible over the next few hours leading to totals of
2-3".  It is possible this may lead to isolated flash
flooding...but more likely will set the stage for the early
overnight.

RAP forecasts suggest slow backing of 850-925 flow with a steady
increase from 20kts to 35kts by 04z across much of central OK to
eastern OK.  The increased moisture flux will raise TPWs to over
2" to 2.25" and increase rainfall efficiency, allowing rates to
reach 2.5"/hr or greater in strongest cores.  OK Mesonet suggests
that soils are fractionally (.8 to 1) saturated at modest depth
(4-10") from Blaine to Creek counties suggesting if the line sets
up along that axis, flash flooding may be a bit more likely than a
county north where values are .2-.4" Majors to Rodgers county. 

Gallina

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

ATTN...RFC...ABRFC...

LAT...LON   36799573 36669534 35819550 35329771 35389947
            36329949 36649818 36739720