Mesoscale Precipitation Discussion 0578
NWS Weather Prediction Center College Park MD
543 PM EDT Wed Aug 01 2018

Areas affected...Central and Southern Sierra Nevada

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

Valid 012141Z - 020300Z

Summary...A concentrated area of thunderstorms will continue to
develop over the central and southern Sierra Nevada, and may
persist into the late afternoon. These storms may be nearly
stationary at times and could produce flash flooding.

Discussion...GOES-15 visible and IR satellite, as well as MRMS
composite reflectivity, show a concentrated area of convective
development over the central and southern Sierra Nevada range,
generally to the south of Topaz Lake and Mt. Patterson.
Precipitable water values were elevated across parts of central
and southern California, and were generally analyzed to be above
the 90th percentile for this time of year by the global models.
Thus, despite only modest instability at higher elevations, the
available moisture should be sufficient to drive the potential for
locally heavy rainfall. MRMS rainfall estimates have been as high
as 1-2 in/hr, as have some of the dual pol estimates from KHNX and
KRGX. These storms should be able to persist for at least a few
hours, and where they remain relatively stationary, some flash
flooding could develop. The convection should begin to wane after
01-02Z as available instability decreases and the sun begins to
set.

The greatest chances of flash flooding appear to be from naer the
central Inyo-Tulare County border north into Mono County.

Lamers

ATTN...WFO...HNX...REV...VEF...

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

LAT...LON   39041870 38391777 36261737 35651825 37321929
            38661964