Graphic for MPD #0610
Mesoscale Precipitation Discussion 0610
NWS Weather Prediction Center College Park MD
940 PM EDT Tue Aug 07 2018

Areas affected...Central Arkansas...

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

Valid 080140Z - 080600Z

SUMMARY...Colliding outflows to support broad areas of ascent and
quick downdrafts with totals of 1.5-2.5" in very short duration. 
Secondary fast moving cluster to track through same areas adding
more rain, increasing some isolated flash flooding.

DISCUSSION...Regional RADAR mosaic depicts chaotic outflow driven
quick up and down thunderstorms in the vicinity of the old outflow
boundary bisecting AR toward Memphis.  Moisture pooled along the
boundary supports total PWATs near 2".  However, 00z LZK sounding
denotes a solid inverted v boundary layer and inflow region across
central/southern AR is the local minimum in surface Tds though
still in the mid to upper 60s.  Weak mid-level flow and these dry
pockets support the strong wet microbursts capable of 1.5-2.5" in
less than 30 minutes nearing but not necessarily eclipsing the
high 1hr FFG values that are in the 2.5-3" range.  FFG only
further increases and the overall duration is limited due to the
cold pools/outflow. 

With that stated, MCV vorticity center is dropping Southeast out
of SE KS and is supporting a more organized convective cluster
across NW/West Central AR...that will track through the same
areas.  The forward propagation is very fast, but capable of an
additional 1.5" in short duration.  Waning GOES-16 visible imagery
and 3.9um SWIR depict and outflow boundary from dying convection
across northern LA, that will help surge some unstable air
northward to feed the cluster to maintain it, and as the outflow
converges will allow for one last stronger updraft surge before
ingesting more worked over air. 

Flash flooding remains possible but very isolated over the next
few hours as the limiting factors toward FF conditions continue to
compound, as such flash flooding is considered possible but on the
low end and more isolated in nature.

Gallina

ATTN...WFO...LZK...MEG...TSA...

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

LAT...LON   35909069 35209040 34759160 34679284 34849406
            35309421 35699375 35699263


Last Updated: 940 PM EDT Tue Aug 07 2018