810
FXUS65 KVEF 221613
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
913 AM PDT Sat Jun 22 2024

.SYNOPSIS...Daily temperatures are expected to peak around 6 to 8
degrees above normal through Monday leading to hot conditions
across the region but not excessively hot. Increasing moisture
over the weekend will lead to increasing chances for showers and
thunderstorms over Mohave County although activity could spread
into Clark and San Bernardino counties on Sunday. Over our
northern areas, hot and dry conditions will persist through next
week.

&&

.UPDATE...Moisture will continue to gradually creep into Mohave
County throughout the day today, with far eastern Mohave County
having a 10 to 20% chance of seeing precipitation this afternoon.
During the overnight hours we will see moisture begin increasing in
San Bernardino and Clark Counties with more widespread 20 to 30%
chances for isolated showers and thunderstorms in southern Clark
County as well as southern and eastern San Bernardino County
tomorrow afternoon. Mohave County will also see increased chances
for showers and thunderstorms tomorrow afternoon and evening with 15
to 30% chances increasing to 50 to 60% as you go east. As the
moisture begins its retreat on Monday, we will also see
precipitation chances begin decreasing with it. Temperatures will
continue to run around 5 to 8 degrees hotter than normal through at
least the middle of next week.

&&

.SHORT TERM...Saturday through Monday.

SPC meso analysis shows dry conditions across our area this
morning - generally under 0.50 inch precipitable water values.
There is a slightly higher moisture gradient ranging from 0.50
inch PWAT at the triple point where Nevada, California, and
Arizona meet to 0.80 inch PWAT at the far southeast corner of
Mohave County. However, moisture transport is weak and there is
really no indication of any moisture surge towards our area at
this point. Satellite imagery shows a definite southwest component
to the flow aloft which will help in keeping our skies mostly
clear with the exception of some scattered mid level clouds over
southeast Mohave County.

As we go through the day today, a deep pool of moisture currently
residing over southern Arizona, Baja, and the Gulf of California,
is directed northward by an inverted trough embedded in the
700-500mb flow along the western periphery of high pressure to our
east. This inverted feature is forecast, by the HREF, to drive
higher moisture between 1-1.50 inch PWATs into our southern areas
by late this afternoon. PWATs between 0.75 and 1.00 inches reach
into far northern Clark County and western San Bernardino County,
as well as Death Valley National Park. The HREF is forecasting
little cloud cover today and mean CAPE values between 250 and 500
joules/kg over far eastern San Bernardino and far southwest Mohave
County with a probability of CAPE exceeding 500 joules/kg at
30-40% in this same area. So we have 2 of 3 ingredients in place
for thunderstorm development...moisture and instability. The HREF
is forecasting very little storm activity today and its
probability for thunder is 0%. This could be due to the lack of
any lifting mechanism outside of daytime heating and to warm
temperatures aloft which would tend to cap convection. The HRRR
holds off until late this afternoon in developing storms over the
eastern part of Mohave County which then are forecast to move west
to around Golden Valley in the evening before dissipating.
Interestingly, a couple of HRRR runs develop isolated showers or
storms in Clark County over the southeastern Las Vegas Valley this
afternoon. Will have to see if this trend holds.

Sunday is still looking like our most active day out of this
initial monsoon moisture surge. Conditions across the southern
regions of our area are forecast to moisten further - partly due
to the westward progression of moisture from thunderstorms the
previous evening. The HRRR has storms developing by late morning
on Sunday with widespread isolated cells through the afternoon and
early evening. The HREF forecasts 10-12 degree Celsius dewpoint
temps over the southeast CWA suggesting heavy rain producing
thunderstorms are possible there on Sunday. Monday, the storm
activity is largely confined to Mohave County although moisture
remains in place across much of our southern desert areas.

Temperatures through Monday should be similar to what we had
yesterday although they could be a touch cooler on Sunday
depending on how much shower/storm activity we get. The latest
probabilities of 110 degrees in Las Vegas is 50% today, dropping
to 38% Sunday, then back to 50% on Monday. Heat Risk is generally
in the moderate range through Monday with a small area of major
heat risk in southern Inyo County and the Amargosa Valley. No heat
related products are in effect or are anticipated through Monday.

.LONG TERM...Tuesday through Friday.

An extended period of hot weather is the main story though much of
the week as an expansive area of high pressure sets up and holds
across the Desert Southwest as is typical for this time of year.
There are indications the high flattens a little Thu-Fri in response
to a trough swinging across the Intermountain Region. The latest
NBM indicates daily high temperatures across the Mojave Desert
zones will generally be in the 108-112 degree range which is
several degrees above normal...but not uncommon for late June. The
official forecast for Las Vegas holds at 108-109 for most days
except peaks at 110 on Wednesday. Overnight lows will be in the
mid to upper 80s. While this is hot, the latest HeatRisk grids
have backed off slightly on indicating areas of major HeatRisk
(level 3) for Tue-Wed and mainly keep moderate across most of the
region.

In addition, moisture will not be too far away over Arizona, and
afternoon thunderstorms that develop over central or western Arizona
the next few days could push outflow into southern Nevada and
southeast California which would increase humidity/cloud cover and
bring temperatures down a few degrees. This is already showing up in
the latest HRRR and NBM which indicate outflow pushing into southern
Clark and southeast San Bernardino County Saturday evening. It`s
the time of year when a lot can change from day to day due to
distant thunderstorms and we will continue to monitor the
potential for moisture intrusions into our area. Meanwhile, Mohave
County will see the best potential for isolated to scattered
afternoon thunderstorms.

&&

.AVIATION...For Harry Reid...Winds start of variable this morning.
Gusty southeasterly winds develop for a few hours in the late
morning and early afternoon, transitioning to the south-southwest
later in the afternoon. After sunset, wind speeds fall to less than
10 knots out of the southwest. There is a 40 to 50 percent chance of
southwesterly gust development after midnight on Sunday morning.
Skies remain clear through the forecast period besides FEW cloud
development over the Spring Mountains in the afternoon.

For the rest of southern Nevada, northwest Arizona and southeast
California...Gusty southerly winds develop across most of the area
this afternoon, decreasing in the evening. There is a 40 to 50
percent chance of another round of southwesterly gusts after
midnight in the Las Vegas Valley. Overall peak gusts between 15 and
20 knots are expected at Las Vegas Valley and Colorado River Valley
terminals, and up to 25 knots at KBIH. At KDAG, gusty easterly winds
pick up later this morning, shifting to the southeast in the early
afternoon and eventually the west in the evening. Skies remain
clear through the forecast period besides FEW cloud development over
mountain peaks in the afternoon.

&&

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

&&

$$

UPDATE...Stessman
SHORT TERM...Salmen
LONG TERM...Adair
AVIATION...Meltzer

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