Mesoscale Precipitation Discussion 0690...Corrected
NWS Weather Prediction Center College Park MD
655 PM EDT Sat Aug 18 2018

Corrected for Areas Affected

Areas affected...Northeast NM...Southern/Eastern CO...Far
Southwest NE...Western KS...Portions of the OK/TX Panhandles

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

Valid 182245Z - 190445Z

Summary...Showers and thunderstorms will tend to become a bit more
numerous going into the evening hours. Some flash flooding will be
possible.

Discussion...A well-defined upper trough and associated closed low
crossing the central and northern Rockies will be interacting with
a very moist and unstable boundary layer this evening out across
the High Plains which is expected to generate a fairly organized
axis of convection. Showers and thunderstorms have been already
developing over the last couple of hours across portions of
eastern CO, western KS and down across northern NM given the
arrival of divergent flow aloft, and DPVA, while also interacting
with MLCAPE values of as much as 2000 j/kg.

The height falls will be strengthening this evening as the upper
trough begins to amplify out toward the central High Plains
region. Stronger deep layer forcing should yield sufficient ascent
for multiple organized convective clusters as the boundary layer
across the Plains this evening should remain moderately unstable
and with the aid of a moist southerly fetch ahead of a leeside
trough. In fact, PWATS are forecast to rise to 1.5 to 2 standard
deviations above normal by 00Z across far eastern CO and western
KS with values reaching 1.5 to 1.75 inches.

The recent radar trends and hires model output definitely appears
to be setting the stage for a couple of organized areas of heavy
rainfall. One cluster of organized convection should evolve over
northeast NM and southeast CO which may evolve into an
east-southeast propagating MCS across the OK/TX panhandles by late
evening. Meanwhile, the ongoing activity over east to northeast CO
and western KS will likely tend to consolidate as stronger
upstream height falls arrives and allows this convection to tend
consolidate or merge into at least a broken MCS that will
gradually propagate east across western/central KS overnight.

In both cases, heavy rainfall with rates of up to 2 inches/hr, and
storm totals of 3 to 4 inches can be expected. Some flash flooding
will be possible, and especially where merging cells occur.

Orrison

ATTN...WFO...ABQ...AMA...BOU...DDC...GJT...GLD...LBF...PUB...

ATTN...RFC...ABRFC...MBRFC...WGRFC...

LAT...LON   40900201 40300076 39140018 38180010 37280026
            36450082 35490194 35070342 35060459 35240558
            35970630 36470650 37050649 37570593 37860542
            38170472 38430392 38840325 39450296 40610281