Flash Flood in Arizona, July 13, 2017

Area Forecast Discussion
National Weather Service Las Vegas NV
825 AM PDT Thu Jul 13 2017

.SYNOPSIS...Limited monsoonal moisture remains in place promoting
isolated to scattered thunderstorm activity again this evening.
Activity will continue to become more isolated over the next few
days before monsoon moisture ramps up again over the weekend.
Temperatures will continue to be above normal with afternoon highs 5
to 8 degrees above normal by Friday and Saturday before modest
cooling arrives with increased clouds and thunder chances Sunday
into next week.
&&

.OUTLOOK...Only minor adjustments made this morning.  While this
mornings Las Vegas sounding continued to show adequate moisture for
another day of thunderstorm development, dry air aloft is quite
evident on water vapor imagery and much of this is likely to mix
down by mid afternoon supporting a dryer outlook today than past
days. Additionally...convective allowing models suggesting limited
convection across the region today, mainly focused across Lincoln
county.

&&

.SHORT TERM...Thru Saturday Morning

Didnt make many changes to the forecast through Saturday morning.
Moisture will become more and more limited the next 2 days, and will
keep afternoon thunderstorm activity isolated at best. Best chance
for will be over the higher terrain. In addition to the drying
conditions, temperature will be warming each day, with high
temperatures running 5-10 degrees above normal for this time of the
year as we head into the weekend. Friday will be the driest day of
the week as high pressure nudges westward and keeps skies mostly
sunny and shower and thunderstorm activity confined to the high
terrain. Enjoy it, because a weather pattern change looks to be
setting up over the weekend and into next week, bringing more
unsettled weather to the area as monsoonal moisture returns.
&&

.Long Term...Saturday through Thursday

Key feature during the period is the inverted trough presently over
the Big Bend region of Texas this morning. As I've stated all week
models have been quite consistent in their handling of this feature.
On Saturday inverted trough will be over northwest Mexico/southern
Arizona with deeper monsoon moisture pooling across southwest
Arizona and the lower Colorado River Valley. Moisture spreads north
into San Bernardino, Clark and Mohave Counties Sunday-Tuesday
leading to an increasing unstable airmass. The ECMWF slows the
westward progression of the inverted trough by Monday keeping the
feature more intact which could continue to produce additional
dynamics. Heavy rainfall and flash flooding will be a concern based
on available moisture. Models start diverging after Wednesday with
the ECMWF pattern suggesting a downward trend in convection while
the GFS suggests no change. Hottest day will be Saturday while the
rest of the period temperatures will be at or below normal from
the clouds and better precipitation chances.
&&

.FIRE WEATHER...Dry southwest flow will persist through the rest of
the week, keeping shower and thunderstorm chances mainly confined to
the higher terrain. Monsoon moisture will begin to make a comeback
over the weekend and into next week with thunderstorm intensity and
coverage on the increase each day starting Saturday. Otherwise...hot
temperatures are expected with occasional southwesterly breezes of
10-15 mph expected during the afternoons. &&

.HYDROLOGY...Creeks, streams and rivers in northern Inyo County
continue to run high and fast from snow melt. Some road closures
continue in the area. Bishop Creek Bypass and Big Pine Creek Bypass
continue to be utilized to minimize flows through Bishop and Big
Pine. Isolated thunderstorms over the mountains may aid snowmelt
runoff and keep some drainages elevated over the coming days as
well. Remember, never drive through flooded roadways or around
barricades. Also, pastureland or farmland adjacent to creeks,
streams or rivers could experience areas of standing water.
&&

.AVIATION...For McCarran...Typical diurnal set up with east
winds veering south-southwest after 18Z today. Winds should be
lighter today than yesterday, though over 8kts looks likely this
afternoon. Also expect it to be dry across the airspace today and
tomorrow.

For the rest of southern Nevada, northwest Arizona and southeast
California...Typical summertime diurnal winds continue through into
Friday. Thunderstorm activity will mainly be across higher terrain
and across Lincoln and Mohave counties. Though, isolated
thunderstorms may drift into surrounding valleys creating variable
and gusty winds. Storms should dissipate by 07-09Z tonight. FEW to
SCT above 10 kft through the forecast period.
&&

.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&

SHORT TERM/FIRE WEATHER/AVIATION...Allen
LONG TERM...Pierce

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LAS VEGAS NV
240 PM PDT THU JUL 13 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0545 PM     FLASH FLOOD      10 SSW STOVEPIPE WELLS  36.47N 117.21W
07/10/2017                   INYO               CA   PARK/FOREST SRVC

            DEATH VALLEY ROAD CONDITIONS FB PAGE REPORTS
            EMIGRANT CANYON ROAD AND WESTSIDE ROAD HAVE
            BEEN CLOSED DUE TO ROCKS, MUD, AND WATER
            OVER THE ROADWAYS FROM STORMS ON JULY 10TH.
            THE AMARGOSA RIVER WAS ALSO REPORTED FLOWING
            OVER THE SOUTH END OF WEST SIDE ROAD, AND
            THE RANGER COULD NOT CROSS IN THEIR 4WD
            VEHICLE.

&&

CO