Flash Flood Warning 68, NWS Las Vegas, NV

126 
WGUS75 KVEF 192147
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
247 PM PDT Sat Aug 19 2023

CAC027-192345-
/O.CON.KVEF.FF.W.0068.000000T0000Z-230819T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Inyo CA-
247 PM PDT Sat Aug 19 2023

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 445 PM PDT THIS 
AFTERNOON FOR CENTRAL INYO COUNTY...

At 247 PM PDT, local law enforcement reported a road washout at the 
junction of State Route 190 and State Route 136.

HAZARD...Life-threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Law enforcement reported.

IMPACT...Life-threatening flash flooding of low-water crossings,
         creeks, normally dry washes and roads.

Some locations that will experience flash flooding include...
  Highway 190, Darwin and Panamint Springs.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3645 11784 3637 11731 3629 11728 3624 11762
      3631 11784

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

SM

121 
WGUS75 KVEF 192337
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
437 PM PDT Sat Aug 19 2023

CAC027-192347-
/O.EXP.KVEF.FF.W.0068.000000T0000Z-230819T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Inyo CA-
437 PM PDT Sat Aug 19 2023

...FLASH FLOOD WARNING WILL EXPIRE AT 445 PM PDT THIS AFTERNOON FOR 
CENTRAL INYO COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat for Highway 190, Darwin, and Panamint Springs. Please 
continue to heed remaining road closures.

A Flood Watch remains in effect until 500 AM PDT Tuesday for a 
portion of southeast California.

LAT...LON 3645 11784 3637 11731 3629 11728 3624 11762
      3631 11784

$$

SM

Area Forecast Discussion
National Weather Service Las Vegas NV
322 AM PDT Sat Aug 19 2023

.SYNOPSIS...Rich moisture related to approaching Tropical Cyclone
Hilary will begin to advance into the Mojave Desert today with
increasing shower and thunderstorm activity expected. This trend
will continue into Sunday as the remnants of Hilary lift
northward. Widespread heavy rain, gusty winds, and instances of
major flooding are expected. Hilary's remains will exit the
region by Monday but moist monsoonal conditions will persist much
of the week with daily storm chances and temperatures remaining
below normal.

&&

.SHORT TERM...through Monday.

Still on track for a rare and highly impactful weather event
unfolding this weekend across the southwestern US as the remains
of what is currently Hurricane Hilary lift through Southern
California and the Mojave Desert. The details of the forecast are
largely unchanged, and model guidance remains in very tight
agreement on the track of Hilary's remnant circulation and the
general swath of heaviest precipitation.

While Hilary is currently a category 4 hurricane roughly 260
miles west of Cabo San Lucas, she will weaken quickly on approach
of the northern Baja and will either be a weakening tropical storm
or depression by the time she reaches the US border and into our
deserts. Nonetheless, a tremendous amount of tropical moisture
will funnel into the region from the Gulf of California, aided by
a very strong southeasterly mid and low flow which will begin to
ramp up today. Best chance for excessive rainfall and flash
flooding today will be focused in western San Bernardino County
as well as Inyo County, though the flash flood risk exists
everywhere.

Integrated Water Vapor transport ahead of Hilary ramps up
dramatically tonight and blasts up the Colorado River Valley,
with widespread precipitation breaking out and increasingly heavy
rainfall rates likely. The WPC has continued a High Risk for
excessive Rainfall across much of Inyo and San Bernardino Counties
Sunday, which is where the greatest threat for catastrophic and
damaging flash flooding exists. We are especially concerned for
historical rainfall occuring in Death Valley National Park which
will greatly challenge regional infrastructure.

By Monday morning, a swath of 2-5+ inch rainfall totals are
expected across the western Mojave Desert, which could result in
catastrophic flooding in Death Valley, the Morongo Basin and
Barstow areas. Areas of orographic enhancement such as the
Panamint Range, Spring Mountains, and southern Sierra could
squeeze out event higher rainfall totals exceeding 5-7+ inches.

Further east, across the eastern portions of the Mojave Desert
including the Mojave Preserve and Las Vegas Valley, significant
rainfall is likely in these areas as well, though the heaviest
precipitation is currently favored in the aforementioned western
zones closer to Hilary's remnant circulation. Nonetheless,
southeasterly upslope flow over the McCullough Range and Spring
Mountains will aid in heavy precipitation generation which could
result in significant precipitation accumulations and flash
flooding. Additionally, with precipitable water values climbing to
near 2" or more from Las Vegas south, even brief rain showers can
produce extremely intense rainfall rates causing rapid flash
flooding.

The driest part of our forecast area will be Mohave County but the
very moisture rich airmass will still support very efficient
rainfall with shower and thunderstorm activity that occurs, and
locally impressive rainfall totals will be possible here as well,
especially near the Hualapai Mountain range.

In addition to the rain threat, as Hilary's remnant circulation
lifts through southern California, strong winds may spread
northward out of the Sonoran Desert and into the Mojave Sunday
afternoon and evening, spreading into the Southern Great Basin by
Monday. There is uncertainty in how strong these winds will be and
they will be dependent on how quickly Hilary weakens in the next
48 hours, but wind advisories or even a short fused high wind
warning may be needed for areas along the Colorado River and
south of I-40 for Sunday evening. With additional advisories
possible Sunday night into Monday for areas further north.

Whats left of Hilary, which will become unrecognizable by this
time, will lift into the Great Basin Monday. Rich tropical air
will remain in place with a rather strong southerly flow
continuing, which will tend to favor the higher terrain of
southern Nevada for heavy rainfall Monday, with drier and more
stable air tending to work in further south.

Temperatures through the short term period will be well below
normal thanks to the abundance of clouds and moisture, with high
temperatures Sunday likely to challenge record daily low maximum
temperatures for many areas.

.LONG TERM...Tuesday through Friday.

Following the exit of what is left of Hilary on Monday, widespread
low level moisture will remain in place. Synoptically, an
expansive ridge will remain parked over the central US with a
southerly flow featured across the southwestern states. This will
result in at least low-grade monsoonal conditions persisting most
of next week, with daily storm chances favored in the higher
terrain, but possibly drifting into the lower elevations in the
afternoon and evening hours. Subtle shortwave features embedded
in the flow may also result in some days being more active than
others and promote more lower elevation activity. For now, NBM
PoPs keep fairly generous storm chances going through the week
across Northwest Arizona and southern Nevada, with slight chances
across most of southeast California. With the abundance of
moisture and continued daily storm activity, temperatures remain
cooler than average by 5-10 degrees, but should trend warmer
heading into the end of the week.

&&

.AVIATION...For Harry Reid...Light and variable winds early this
morning will turn southeast by late morning.  Prevailing winds
should remain less than 10kts, but scattered thunderstorms are
possible after 20Z, and any that do develop will be capable of
producing gusty, erratic winds.  More steady light to, at times,
moderate rain is expected after 04Z as moisture from Hilary spreads
across the area.  In addition to the rainfall, reduced visibilities
of 5mi or less and CIGs less than 4kft are also expected by daybreak
Sunday.   The rain and reduced CIGs and visibilities will likely
continue into Sunday evening.

For the rest of southern Nevada, northwest Arizona and southeast
California...Scattered thunderstorms are expected across the region
once again today.  The best chance is after 20Z, and any storms that
do develop will be capable of producing gusty, erratic winds.  Away
from thunderstorm activity, winds of less the 10kts generally from
the east and southeast can be expected. Moisture from Hilary will
begin to spread across the area this evening into tonight, resulting
in steady rain developing from south to north. In addition to the
moderate to, at times, heavy precipitation, reduced visibilities
down to 2 to 4 SM at times and CIGs less than 2kft will be possible,
with the degraded conditions continuing into Sunday night.
&&

.SPOTTER INFORMATION STATEMENT...Heavy rain, high winds, and
flash flooding reports are requested through the weekend as the
remains of Hurricane Hilary lift through the Western Mojave
Desert.

&&

DISCUSSION...Outler
AVIATION...Planz

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