622
FXUS65 KVEF 012120 CCA
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
210 PM PDT Mon Jul 1 2024

.SYNOPSIS...A dangerous long-duration heat wave is on the way to the
Mojave Desert and southern Great Basin. Excessive Heat Warnings go
into effect beginning Wednesday and Thursday and continue into next
week. Monsoonal moisture lingering over northwest Arizona though
this evening will be pushed away to the east by Tuesday.
&&

.SHORT TERM...through Wednesday.

The main weather story is the heat wave building over our forecast
by Wednesday and continuing through the holiday and into next week.
Temperatures will only increase 1-3 degrees across our forecast area
Tuesday as the trough over the Intermountain Region slowly pulls
away and allows the large Eastern Pacific ridge to begin nosing
inland. This will boost temperatures an additional 3-5 degrees
Wednesday and begin a long heat wave as the ridge amplifies and
parks over the western states. The Excessive Heat Warning remains in
effect for much of southeast California and southern Nevada
Wednesday through Monday then expands to include the Colorado River
Valley and much of Mohave County Thursday through Monday.

A lesser concern is moisture over eastern Mohave County which now
looks to be quite limited due to dry westerly flow aloft associated
with the aforementioned trough. Isolated light showers or a brief
thunderstorm can`t be completely ruled out, but chances are only
about 10 percent this afternoon. Increasingly dry flow will impede
convection Tuesday over Mohave County and the surface dewpoints in
the 50s and 60s today will drop into the 30s and 40s Tuesday.

.LONG TERM...Thursday through Monday.

The aforementioned ridge is forecast to be centered along the West
Coast Thursday then model ensembles are in good agreement that it
will slowly become centered over Nevada Saturday through Monday.
Preceding the ridge will be a dry north-northwest flow over our
region with very little potential for any moisture to work its way
into our region. This is the hottest synoptic pattern that we see
and this is reflected in the NBM forecast high temp of 117 in Las
Vegas Sunday and Monday...which would tie our all-time record high
that we have reached five other times. Although this is not a
certainty, there is a 56 percent probability that Las Vegas will
reach 117 degrees during this time, so there is no good reason to
adjust this downward simply because it is a fairly rare occurrence.
Death Valley should be about 10 degrees higher...around 127. The NBM
indicates a 25 percent probability that Furnace Creek could reach
130 degrees. 115-119 degrees can be expected from Laughlin to Lake
Havasu during this time.

There is no indication of a break in the heat for our region through
the middle of next week among the medium range ensembles.
&&

.AVIATION...For Harry Reid...South to southwest winds with
occasional gusts to 25kts will persist across the valley through
sunset.  Wind will drop below 10kts overnight, and speeds are
expected to remain less than 10kts through Tuesday.  VFR conditions
are expected through the week under mainly clear skies. Temperatures
will increase throughout the week, with readings around 115F or
higher, likely by the weekend.

For the rest of southern Nevada, northwestern Arizona, and
southeastern California...Gusty south-to-southwest winds will
continue across the Las Vegas Valley, Colorado River Valley, and
western Mojave Desert, including KDAG, through this evening.  KBIH
will see light northerly winds, becoming variable or even southerly
for a period late this afternoon and evening.   All sites should see
winds fall below 10kts overnight, and remain less than 12kts on
Tuesday.  VFR conditions are expected through the week under mainly
clear skies.  Temperatures will increase through the week, with
readings rising to 110F-120F by the weekend.
&&

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

$$

SHORT TERM/LONG TERM...Adair
AVIATION...Planz

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