Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 100407
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
807 PM PST Fri Dec 9 2016

.SYNOPSIS...Mainly dry weather along with a warming trend
is on tap through the remainder of the week and into the weekend.
However...there will be considerable high cloudiness at times and
also a chance of light snow for the Sierra and far northern Lincoln
County at times through the weekend. Mild and dry conditions are
expected through the middle part of next week.
&&

.UPDATE... Updated sky grids to account for scattering out of lower
clouds as well as the more scattered coverage of higher clouds this
evening. Tweaked wind grids through tomorrow, with the main outcome
of limiting advisory level winds, but will leave it to the overnight
shift to make any major changes.
&&

.PREV DISCUSSION...
Issued at 230 PM PST Fri Dec 9 2016

.SHORT TERM...Through Monday Night...

Considerable low clouds hung over much of the area today keeping
temperatures cooler today. However, looking at satellite imagery,
these clouds are expected to be out of the area by late this
afternoon with mainly high clouds overnight. A trough moving into
the Pacific Northwest is expected to drag some moisture into central
California and as far south as the southern Sierra starting late
tonight through early Sunday. With the flow being nearly
perpendicular to the Sierra crest most of the moisture will remain
over the western slopes, but a few inches could fall over the higher
peaks of the eastern Sierra. The high elevations of Esmeralda and
central Nye Counties could also see some light isolated showers. The
models have been a little more aggressive in dragging a piece of
energy across northern Lincoln County Saturday night. Although
precip amounts will remain light we could see a bit more coverage
across that area and possibly 1-2 inches of snow by Sunday morning
for the higher mountains. Models are indicating that weak ridging
will build Sunday afternoon, pushing any moisture north of our area
leaving the CWA dry through Monday.

Winds ahead of this weak disturbance will increase a bit Saturday
afternoon with gusty west winds likely across western San Bernardino
County. Speeds should generally remain in the 30-40 mph range with
some isolated gusts over 40 mph, but it does not look widespread
enough to warrant any wind advisories. We could also see some
enhanced downslope winds over the eastern Sierra Saturday afternoon
and night, but those also look isolated and are expected to remain
below advisory levels. The remainder of the area will see a slight
increase in winds, but generally 10-20 mph. Lighter winds Sunday and
Monday are expected.

With less cloud cover Saturday we should start to see temperatures
increasing across the area. Readings are expected to climb above
normal and will remain above normal through Monday.

Nearly zonal flow will continue through the short term with
considerable high cloudiness at times. Some lower level moisture has
even worked into the area but due to rising heights and minimal
synoptic lift I do not expect any precipitation today except
possibly near the Sierra Crest. Temperatures should warm a little
today but warming could be somewhat limited due to cloud cover and
valley inversions. A shortwave trough moving through the Pacific
Northwest will bring a chance of precipitation to northern portions
of Esmeralda, central Nye and Lincoln Counties Saturday afternoon
and evening while light snow continues near the Sierra crest.
Precipitation chances now look to make it as far south as northern
Mohave County overnight Saturday night into Sunday morning as the
shortwave trough pushes across Utah. Precipitation amounts in our
forecast area should remain pretty light with this feature. Another
impact from this shortwave trough will be an increase in west to
southwest winds Saturday and Saturday night, especially in the
Sierra and western Mojave Desert of San Bernardino County. At this
time MOS guidance keeps winds at the Barstow-Daggett airport below
advisory levels but it will be something to monitor. It looks like
we should see dry conditions area wide on Sunday with perhaps a
little more sunshine leading to high temperatures 5-8 degrees above
normal in most locations.

.LONG TERM...Tuesday through Friday.

Northwest flow will prevail Tuesday and Wednesday, with mid-high
level moisture streaming across the region. This will continue the
trend of considerable high clouds. Temperatures will run several
degrees above normal. Any precipitation chances will remain limited
to the Sierra and central Nevada.

Models continue to indicate a possible change in the pattern
beginning Thursday with a Pacific trough digging off the California
coast. Model agreement isn`t great out that far (GFS deeper and
slower, ECMWF more progressive), so any details are very low
confidence. At least breezy conditions with chances for
precipitation will spread across much of the region late in the week
and possibly some very cold air moving through sometime during the
weekend.
&&

.AVIATION...For McCarran...Lower clouds around 5k feet are expected
to diminish late this afternoon leaving mainly high clouds this
evening and overnight. Varying amounts of high clouds are expected
to remain through Saturday. Light and variable winds will transition
to a southwest direction after 03z with speeds around 5 kts. We will
see a slight increase in south to southwest winds after 21z Saturday
with speeds around 10 kts.

For the rest of southern Nevada...northwest Arizona...and southeast
California...Lower clouds will gradually diminish this evening with
mainly high clouds expected overnight through Saturday. Variable
winds under 10 kts will remain through mid day Saturday, but will
increase during the afternoon. West winds 20-30 kts are possible
across western San Bernardino County with generally 10-20 kts
elsewhere. Some enhanced downslope winds will also be possible
Saturday afternoon and night across the eastern Sierra slopes where
gusts to 50 mph will be possible.
&&

&&

$$

Update...Steele
SHORT TERM/AVIATION...Gorelow
LONG TERM...Wolcott

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