Mesoscale Precipitation Discussion 0929...Corrected
NWS Weather Prediction Center College Park MD
1008 PM EDT Sat Oct 06 2018

Corrected for summary section

Areas affected...Eastern CA...Far Southern NV...Central/Northern
AZ

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

Valid 070205Z - 070805Z

Summary...Areas of heavy showers and a few thunderstorms will
continue this evening and into the overnight hours. Some concerns
for flash flooding will persist as a result.

Discussion...The latest WV satellite imagery shows a strong trough
amplifying down across the Great Basin and into the Southwest U.S.
which is fostering an an area of locally heavy showers and
thunderstorms across areas of eastern CA, far southern NV and into
northern AZ.

PWATs across the region are quite modest with values of 0.50 to
0.75 of an inch, and instability profiles are weak with as much as
500 j/kg of MUCAPE. However, the nose of a 110+kt 250mb jet is
advancing southeast across southern CA and will be aiming into
western AZ overnight which will drive strong left-exit region jet
dynamics over much of the Southwest tonight. In fact, there is
already a strong mid to upper-level vort center moving across San
Bernardino County, CA where there is some locally concentrated
convection. The strong dynamics associated with the amplifying
trough will compensate for the relative lack of moisture and
instability and will continue to drive a threat for locally heavy
rainfall through the evening and into the overnight hours.

The latest hires model consensus, including recent runs of the
HRRR, gradually tend to focus the heaviest rainfall over central
and northern AZ, and including the Mogollon Rim. The
aforementioned large scale forcing/ascent over the region coupled
with orographics will likely yield as much as 1 to 2 inches of
rain with locally heavier amounts over the higher terrain. This
will maintain a threat for flash flooding going into the overnight
hours.

Orrison

ATTN...WFO...FGZ...GJT...PSR...SLC...VEF...

ATTN...RFC...CBRFC...CNRFC...

LAT...LON   37041086 36691001 35811007 34611131 34211233
            34061315 34061390 34121460 34291560 34681625
            35081663 35511672 35721636 35531566 35461491
            35601401 35921344 36501286 36931196