This is a multi-part message in MIME format...

------------=_1564078093-118394-660
Content-Type: text/plain

AWUS01 KWNH 251808
FFGMPD
AZZ000-UTZ000-NVZ000-CAZ000-260000-

Mesoscale Precipitation Discussion 0673
NWS Weather Prediction Center College Park MD
207 PM EDT Thu Jul 25 2019

Areas affected...Southern Sierra Nevada, Southern Great Basin,
Southwest Utah

Concerning...Heavy rainfall...Flash flooding likely

Valid 251800Z - 260000Z

Summary...Convection blossoming across Southern Nevada and Utah
will expand in coverage through the afternoon. Locally heavy
rainfall rates exceeding 2"/hr are possible, and as storms move
slowly to the N/NE, flash flooding will become likely.

Discussion...GOES-17 visible 1-min imagery this morning shows
cloud cover lifting slowly northward associated with dual MCVs in
the vicinity of southern Nevada. North of these, morning clouds
have begun to erode, representative of waning CIN, and diurnal CU
are beginning to bubble in the increasingly unstable environment.
Recent RAP analyzed SBCape is exceeding 1500 J/kg in the clear
regions, and will continue to rise to above 2000 J/kg and expand
across much of the discussion area as CIN erodes fully in the next
1-2 hours. This instability is combining with PWATs which were
observed to be 1.56" at VEF, 0.95" at FGZ, and 1.91" at YUM on the
12Z U/A soundings, all at or above the 90th percentile for the
date, and a record for the date at VEF. This anomalous moisture
combined with the increasing instability is producing a
thermodynamic environment which is extremely favorable for heavy
rain.

Ascent through the afternoon will be primarily driven via
low-level convergence in the vicinity of the MCVs and any
subsequent outflow boundaries. However, a 50kt jet streak is
present to the N/NW placing the region beneath the favorable RRQ
for ascent, and at least subtle PVA will exist above the
convectively enhanced MCVs. There will also persist 850-700mb
southerly flow east of an elongated trough axis across California
which will drive moisture flux northward along a boundary layer
theta-e ridge axis extending from Southern Nevada northeast into
central Utah.

Recent runs of the HRRR are very consistent showing a signal for
heavy rainfall from the Southern Sierra where S/E low-level flow
may provide upslope enhancement, through the Southern Great Basin
of Nevada, and into the canyons and National Parks region of
Southwest Utah. Although placement of the heaviest QPF is
difficult to discern due to the expected scattered nature of
thunderstorms, there will likely be pockets of QPF exceeding 2".
This heaviest rain will occur where rates of more than 2"/hr can
exhibit long temporal duration due to storm motions of 5 kts or
less as noted by very short Corfidi vectors. HREF exceedance
probabilities for 1-hr reach 40-50% due to FFG as low as
0.5-0.75"/1hr. Although convection should become widespread, flash
flooding may remain localized, and focused in the sensitive
terrain, dry washes, or slot canyons, across the region.

Weiss

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...FGZ...GJT...HNX...LKN...REV...SLC...STO...VEF...

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

LAT...LON   39731485 39631459 39211369 39081314 38951237
            38811153 38621106 38441090 38191067 37881041
            37501042 37231070 37071116 36981175 36961230
            36601323 36181401 35851444 35541490 35281555
            35121654 35121753 35621852 38181967 38631877
            39191723 39571588


------------=_1564078093-118394-660
Content-Type: text/plain; charset="US-ASCII"
Content-Disposition: inline
Content-Transfer-Encoding: 7BIT

= = =
To unsubscribe from WX-STORM and you already have a login, go to
https://lists.illinois.edu and use the "Unsubscribe" link.  Otherwise email
Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.
------------=_1564078093-118394-660--

--- SBBSecho 3.07-Linux
 * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)