433
FXUS65 KVEF 142102
AFDVEF
Area Forecast Discussion
National Weather Service Las Vegas NV
102 PM PST Thu Nov 14 2024
.SYNOPSIS...Conditions will turn unsettled Friday and Saturday as the
region will be under an area of low pressure. Strong winds with
gusts exceeding 40 mph will occur in the western Mojave Desert of
southern California Friday. Also, isolated to scattered showers will
favor the higher terrain Friday and Saturday, while Saturday will be
the coldest day. Another system clips the area early next week
setting the stage for persistent, gusty north winds down the lower
Colorado River Valley next week.
&&
.SHORT TERM...Through Saturday night.
After another quiet weather day today, a more unsettled and
transient weather patten sets up for the next few days with multiple
quick hitting systems digging into the region that will bring
increasing winds, cooler temperatures, and a low risk for
precipitation.
The first trough is progged to dig into the Southwest US tonight and
Friday. The main forcing arrived late tonight into early Friday
morning as the trough axis moves inland and potent vorticity
advection punches into the area ahead of it. This along with an
increasing pressure gradient will increase winds, especially Friday
in the Western Mojave Desert where probability for impactful wind
gusts over 40MPH are 70% or greater. A wind advisory was issued for
this area to highlight the potential wind impacts and no changes
were made to this headline. Elsewhere, southwest to west winds will
gust 25 to 35 MPH at times on Friday.
Precipitation wise, area cross-sections show limited moisture in the
low levels Friday night as the best forcing moves into the region.
Probabilities for any precipitation (>0.01 inch of QPF) is low (less
than 20% tonight and limited to the Sierra and then the terrain of
Esmeralda County. So despite the robust forcing with the incoming
system, precipitation impacts will be limited tonight through Friday
morning. As the trough axis moves east, cold temperatures aloft will
settle into parts of the region by Friday afternoon. This set up
would support decent cold-core dynamics with scattered showers
developing during the afternoon with diurnal heating, especially
northwest of the I-15 where the coldest temperatures aloft will be
situated. Model reflectivities show this well as light showers
develop in that area after 1PM PST. Again, there is little to no the
signal for impactful precipitation Friday afternoon. Moisture at the
low levels will still be limited and any wind will help mix in that
dry air and lift cloud bases even further to hinder precipitation
from reaching the ground. Probability for precipitation amounts
Friday afternoon over 0.10inch peaks at 30% and favors the terrain.
PWATs through the region will also remain at or slightly below
normal. So even with some pseudo updraft reinforcement to better
organize the showers Friday afternoon, it wont result in widespread
impacts. Snow levels do drop to around 5000ft so light snow may fall
in the Spring Mountains and Sheep Ranges, as well in areas north of
Caliente in Lincoln County- but accumulations are not expected. In
addition, with a slight convective cold-core element combined with
the lower snow levels, graupel will be possible with any showers
Friday afternoon.
The trough will continue to move east Friday night and Saturday.
Precipitation is possible again Saturday afternoon in areas
southeast of the I-15 as the system slowly drags itself out and
brings the colder air further south. Similar impacts are expected
Saturday that will occur on Friday where showers can develop. Areas
further northwest will remain dry as anticyclonic flow sets up
behind the exiting trough. North winds will taper off Saturday and
be lighter than Friday with no wind impacts expected on Saturday.
Saturday will be the coldest day with north winds behind the system
pushing in cold air. Temperatures Saturday will be about 10 degrees
colder than today.
.LONG TERM...Sunday through next Thursday.
As the weekend comes to an end, our trough is forecast to close off
over far southern Arizona and/or northwestern Mexico. At the same
time, a shortwave ridge builds over the southern Great Basin ahead
of the next trough. As a result, the N-S pressure gradient tightens,
inducing northerly breezes across the area. Best chances of
impactful winds reside in the Colorado River Valley between Laughlin
and Needles (60% chance of 40+ mph gusts).
The next system pushes through the Great Basin on Monday in the form
of a broad trough. Ensemble guidance shows a tongue of anomalous
moisture ahead of the trough axis, but it largely dissipates by the
time it reaches our area. Latest NBM PoPs on Monday are only 10-20%
in the far northwestern and northeastern fringes of the CWA. Other
than the limited precip chances, this system also brings a
reinforcing shot of gusty and cool conditions. Impactful winds are
possible (10-40% chances) on Monday, but the northerly winds behind
the system have a better shot of impacts Tuesday and Wednesday,
particularly in the Colorado River Valley. This is because the
trough axis is expected to be well east of us while a high-amplitude
ridge builds over the West Coast, resulting in a tightened N-S
pressure gradient. This gradient will drive northerly winds for a
few days, with 50-70% chances of 40+ mph gusts in the lower Colorado
River Valley. As the ridge expands inland mid-week, winds gradually
weaken while temps warm.
&&
.AVIATION...For Harry Reid...Diurnal wind patterns are expected for
a majority of the forecast period, with generally light winds
forecast through this afternoon. After sunset, winds become variable
before veering to the southwest with speeds around 8KT. An
approaching system will result in an uptick in winds after 10z
Friday with sustained speeds around 10-15KT and intermittent higher
gusts. Southwest winds will increase even more after 18z with
sustained winds 14-18 knots and gusts between 25-30 knots. winds
will begin to diminish after sunset Friday. Occasional high clouds
through the period.
For the rest of southern Nevada, northwest Arizona and southeast
California...Winds will generally remain light and variable through
the afternoon and into this evening. There will be an uptick in
southwest winds affecting mainly KDAG/KLAS/KVGT/KHND after 06z with
speeds 8-10 knots with occasional gusts up to 18 knots. Stronger
winds are expected Friday, especially near KDAG where west winds 20-
25 knots and gusts 30-35 knots are expected during the afternoon.
Some isolated showers are possible after 10z Friday, affecting
mainly the Sierra and White Mountains in Inyo County along with the
higher terrain of Esmeralda and central Nye counties.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
SHORT TERM...Nickerson
LONG TERM...Woods
AVIATION...Gorelow
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