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287
FXUS65 KVEF 190828
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
126 AM PDT Wed Jun 19 2024

.SYNOPSIS...Temperatures are expected to recover to near normal
today and then return to well above normal Thursday into next
week. Excessively hot conditions are possible as early as the
weekend in some of our valley locations. The first round of
showers and thunderstorms associated with the monsoon season is
possible by Friday and continuing through Monday as a shallow
surge of moisture reaches into the lower deserts and northwest
Arizona. Shower and thunderstorm chances are mainly in Mohave
County but could extend westward into parts of southern Nevada
and southeast California over the weekend.

&&

.SHORT TERM...
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Juneteenth.

To get some perspective on just how much relief from the heat there
was in Las Vegas yesterday, the high temperature of 91 degrees was
10 degrees cooler then Monday, 9 degrees below the normal high of
100, and 24 degrees below the record high of 115 set way back in
1940. Certainly, a welcome change of pace from the sweltering heat.

The weather pattern keeps our area under a mean trough today which
despite intense sunshine, will keep temperatures slightly below
normal. In addition to the abundant sunshine, we are expecting
afternoon breezes across the region today.

.LONG TERM...Thursday through next Wednesday.

A building ridge in the central US is expected to build back south
and west late this week through the weekend. This will bring warmer
temperatures back into the forecast. Temperatures should climb a few
degrees each day Thursday through Sunday, then Sunday onward the
daily high temperature spread shows little variation from Sunday
through the beginning of next week. HeatRisk by the end of the
weekend climbs into the `Moderate" category for most areas, and into
the "Major" or "Extreme" categories for the weekend into early next
week for most valley locations such as Death Valley, Las Vegas, the
lower Colorado River Valley, and southern Mohave County.  While
there may be a few degree fluctuations each day, above normal
temperatures and increased risk for heat related impacts are
likely this weekend into next week.

A decaying tropical cyclone that migrated from the Gulf of Mexico to
off the coast of Mexico could get pushed into the southwest US.
Probabilities for over 1 inch PWATs increase in the southern
Colorado River Valley and southern Mohave County, with over 50%
probabilities noted in that region this weekend on both the GEFS and
ECMWF ENS. So, increasing confidence there will be a surge of
moisture Thursday through Monday. However, instability currently
looks limited as probabilities for CAPE over 500 J/Kg through the
same period are little to none. Friday afternoon could have some
help in the form of extra forcing from the lingering trough that
will still be influencing our weather pattern as the transition to
ridging will be slow. This could provide enough forcing for some
precipitation to develop. Otherwise, it`s too early to say what
kind of impacts this moisture surge may result in and if showers
or thunderstorms will develop. If something were to develop,
Mohave County would have the best chance most of the period with
potentially precipitation a bit further north and west into
portions of the Colorado River Valley and eastern San Bernardino
County when the moisture will be most robust. The low levels of
the atmosphere remain very dry, so showers and thunderstorms that
form are likely to encounter substantial evaporation before
precipitation reaches the ground. The more likely scenario will be
dry lightning, which could increase chances of wildfire starts in
the area. Will continue to monitor this moisture flux through the
week and update the forecast accordingly.
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&&

.AVIATION...For Harry Reid...Winds will follow a diurnal pattern
today and tonight. Winds start off this morning out of the southwest
with speeds of less than 10 knots. Later this morning, they will
shift to the northeast, possibly taking a southeasterly direction at
times. Winds turn to the southwest and increase to over 10 knots in
the late afternoon. Occasional gusts to around 18 knots cannot be
ruled out and some uncertainty remains in the exact timing of the
wind shift. Speeds should fall to less than 10 knots overnight. Skies
will be mostly clear once high clouds exit this morning.

For the rest of southern Nevada, northwest Arizona and southeast
California...A diurnal wind pattern is expected across the area
today and tonight. Speeds should remain under 10 knots for most of
the forecast period, but increase to over 10 knots in the afternoon
becoming gusty at times, especially along the Colorado River Valley.
KDAG will experience gusty westerly winds this morning, followed by
a lull in the afternoon before picking up out of the west again in
the evening. Mostly clear skies are expected today besides
occasional high clouds.

&&

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

&&

$$

SHORT TERM...Salmen
LONG TERM...Nickerson
AVIATION...Meltzer

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