Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 270336 AAA
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
837 PM PDT Mon Jul 26 2021

.SYNOPSIS...Final day of widespread showers and thunderstorms is
among us before drier conditions return Tuesday and Wednesday.
Thunderstorm chances return for the region next weekend, as we gear
up for another easterly wave approach.
&&

.UPDATE...Satellite and radar trends indicate the threat for any
additional flash flooding or strong outflow winds/hail from storms
has greatly diminishing for the rest of tonight. Therefore, will go
ahead and cancel the Flash Flood Watch. Expecting less coverage in
storms Tuesday with at least isolated thunderstorms developing over
the higher terrain.

Thanks to hard work and some longer hours from our technicians the
radar was brought back into service late in the afternoon from last
nights lightning strike.

&&

.PREV DISCUSSION...1245 PM PDT Mon Jul 26 2021
.DISCUSSION...Today through next Sunday.

The KESX radar remains down this morning. Due to lightning proximity
as seen via satellite, our best guess is that it was struck by
lightning. Our electrical technicians are out at the radar now
assessing the damage. Will send an update via Twitter
(twitter.com/NWSVegas) when we learn more information.

Thankfully, the bulk of the weather this morning lies closer to KEYX
at Edwards Air Force Base. Today is the last day of widespread
showers and thunderstorms. We have long prepared for this easterly
wave to push into our region and tap into the monsoonal moisture.
Yesterday, widespread impacts were seen as severe thunderstorms
broke out across portions of northwestern Arizona and southern
Nevada. Downburst CAPE values hovered between 1000 and 1200 J/kg in
southern Mohave County. A storm moved through the area that resulted
in substantial flash flooding in Kingman, Dolan Springs, and Golden
Valley, as well as wind damage and a dangerous, albeit photogenic,
dust storm. Additionally, storms that moved from Mesquite down to
Las Vegas and Pahrump resulted in heavy rainfall and widespread wind
damage as well.

Today, DCAPE values are substantially lower, with the highest values
around 600 J/kg in portions of southern Nevada. Wind gusts, as a
result, are not our primary concern today. Today, the Flash Flood
Watch continues until 11pm PDT for southern and western Clark
County, western San Bernardino County, Inyo County, and southwestern
Nevada. This looks to be in good shape, so no changes have been made
to the product today. Storm motion looks to generally be to the west-
northwest, with slowest motions across western San Bernardino.

Additionally, we are talking about incredibly anomalous PWAT
values. PWATS range from 1.5 inches to 2 inches across San
Bernardino County this morning, which will stretch northward into
Inyo County this afternoon, where PWAT values in excess of 2 inches
will be seen over Death Valley National Park. This is over 250% of
normal for the region. Sunny skies this morning have allowed the
surface in Death Valley to warm, with max temperature of 97F. As the
inverted trough pushes across our area today, our primary concern
will be the flash flood threat in Death Valley.

[DEATH VALLEY] Death Valley received 0.21 inches of rain last night
at the Furnace Creek Visitor Center. According to local reports, no
flooding has been reported. Any additional rain that falls is likely
to act very hydrophobic, as the soil will not absorb much, if any,
additional rainfall. Hikers and tourists are discouraged to hike
this afternoon, particularly in areas with no cell service, canyons,
drastic elevation changes, and low level areas. Numerous roads
throughout the park have low water crossings, so always remember to
turn around, don`t drown. Wait for the water to recede before
attempting to cross it, or find an alternative route. Be very
careful when in Death Valley NP and searching for alternative
routes. Carry extra water in your vehicle in the event of a break
down, and stick to paved roads, if possible. If you are hiking,
ensure that you have a NOAA Weather Radio or other way to receive
weather alerts. When in doubt, if you see lightning or hear thunder,
seek shelter immediately. Shelter can be few and far between in
Death Valley, so please keep this in mind and stay weather aware if
in the park today.

Heavy rainfall will decrease with sunset, though isolated storms
capable of flooding will remain possible through 11pm PDT. Tomorrow
and Wednesday, the inverted trough continues to push northward, with
precipitation potential greatest across the Great Basin. Impacts
such as the ones that we`ve seen over the weekend and anticipate
today... are not expected tomorrow. Keep an eye on the forecast for
updates as we continue to monitor.

Going into the end of the work week and next weekend, a similar set
up is anticipated, with another easterly wave tapping into the Gulf
of Mexico and pushing westward into our area.
&&


.AVIATION...For McCarran...Thunderstorms have developed over the
Spring Mountains this morning, but this activity should remain west
of the terminal. The threat of storms should decrease as the
afternoon progresses and end after 1Z. Winds will turn more
southerly by this evening and then typical diurnal variations are
expected overnight and Tuesday. An isolated thunderstorm can not
be ruled out tomorrow, but the threat is too low to be included in
the TAF at this time.

For the rest of southern Nevada, northwest Arizona and southeast
California...A complex of showers and thunderstorms is moving
across San Bernardino county. KDAG will likely see some showers
and possibly a thunderstorm from this complex until about 22Z with
occasional gusty winds to 30kts possible. KBIH will also have a
chance of thunderstorms with the best chances between 23-03Z. For
the remaining TAF sites, storm risk remains low today with
typical diurnal wind patterns and variations prevailing.
&&


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

$$

UPDATE...Pierce

DISCUSSION...Varian
AVIATION...Planz

For more forecast information...see us on our webpage:
https://weather.gov/lasvegas or follow us on Facebook and Twitter


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