Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 220546
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
946 PM PST Tue Feb 21 2017

.SYNOPSIS...An unsettled weather pattern will continue through
the end of the week with gusty winds over the lower deserts with
precipitation confined to mainly the Sierra and central Nevada.
Above normal temperatures will remain through Wednesday then cool
to below normal readings Thursday through the weekend.
&&

.UPDATE...Winds continue to be the main concern in the near term,
with gusts up to 52 MPH in Red Rock in the last hour where a Wind
Advisory remains in effect. Gusts over 40 MPH have also worked
their way into the west side of the Las Vegas Valley, with North
Las Vegas airport seeing a brief gust to 48 MPH. High-res models
indicate that these winds should retreat toward the mountains
overnight and therefore have held off on issuing any products.
Made some adjustments to the wind forecast to better account for
the current trends. Also tweaked sky and PoP based on the latest
guidance.
&&

.AVIATION...For McCarran...Southwest winds with gusts 20-30 kts
expected tonight, gradually diminishing early in the morning.
Southwest winds will increase again Wednesday with gusts around
20-25 kts. FEW-SCT clouds around 8-10k feet at times and BKN
around 20k. Areas of mechanical turbulence should be expected near
the mountains through tonight. A cold front will push south across
the region Wednesday evening with gusty northwest winds in its
wake.

For the rest of southern Nevada...northwest Arizona...and southeast
California...Gusty southwest to west winds over most areas through
tonight and Wednesday. Gusts 20-30 kts expected. Clouds generally
FEW-SCT 8-10k feet at times with BKN 20k feet. Stronger west
winds are forecast on Wednesday across San Bernardino County with
gusts around 35-40 kts. A cold front will sweep south across the
region Wednesday afternoon through Wednesday night bringing gusty
northwest winds in its wake.
&&

.PREV DISCUSSION...
Issued at 315 PM PST Tue Feb 21 2017

.SHORT TERM...through Friday night.

A light showers associated with a weak disturbance moving through
southern Mohave county this afternoon. A few rain gages around
Kingman did manage to pick up a few hundredths, but these showers
are moving fairly quickly east and should be out of the region by
6pm MST. Still also seeing a few light rain/snow showers over the
Sierra but any accumulations will be light and precipitation is
expected to end this evening. Gusty winds are occurring this
afternoon across the northern zones of Esmeralda, central Nye and
Lincoln Counties and those are expected to continue until early this
evening before diminishing. The winds in the Spring Mountains have
not been too significant so far, but the hires models are indicating
the strongest winds occurring overnight. Some of the stronger winds
may sneak into the western parts of the Las Vegas Valley including
Mountains Edge, Summerlin and Centennial Hills with gusts
approaching 40 mph. At this time a wind advisory has not been issued
for the Las Vegas Valley, but it will need to be monitored.

Winds are expected to increase Wednesday across western and eastern
San Bernardino County by late morning and afternoon. It seems like a
marginal event, but gusts over 40 mph do seem likely. Have gone
ahead and issued a wind advisory for zones 523 and 524 from 9am-8pm.
The gusty winds look to also work into the Morongo Valley area by
late afternoon and early evening with the strongest winds expected
to develop around and just after sunset. The advisory for that area
runs from 3pm until midnight. Gusty northwest winds will occur over
the remainder of the region, but most areas will remain below
advisory levels.

Trough moving into the forecast area Wednesday evening with
precipitation mainly confined to the northern zones. Showers
associated with a cold front look to move through Lincoln County
late afternoon with mainly isolated showers across the Sierra,
Esmeralda, and central Nye Counties. Amounts look to be fairly light
over most areas with just a few hundredths expected. Snow levels
should drop down to around 4500 feet across northern Lincoln County,
but snow amounts are expected to amount to maybe a couple of inches.
Trough will gradually move east Thursday with cooler temperatures
and mainly dry conditions Thursday afternoon through Friday. Just a
few showers will remain across the far northern CWA Thursday
afternoon, but Friday looks to remain dry and cool.

.LONG TERM...Saturday through Tuesday.

There is the potential for a Pacific system to bring widespread
precipitation to much of our region, and the entire southwest
states, Sunday through early next week if the operational GFS
solution is to be believed. However, the ECMWF depicts quite a
different track and evolution of two eastern Pacific troughs and an
associated moisture plume. Also, the GEFS appears to be quite a bit
more subdued than the GFS solution, so confidence is not high in any
details yet. Suffice it to say a broad Pacific trough is forecast to
move inland Sunday and Monday followed by another one dropping in
quickly behind it from the northwest. If the trough digs offshore
and merges with another trough between Hawaii and the West Coast, it
will be an impressive storm...which is what the GFS depicts. If it
takes a more inland track like the ECMWF solution, it will shear and
shunt the Pacific moisture plume down the southern California coast
without as much inland penetration, but plenty of cold air moving
overhead. 30-40 percent PoP values for much of our forecast area
Sunday reflect this uncertainty for now and will hold off on getting
too detailed about impacts.
&&

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

$$

Update/Aviation...Wolcott
Short Term........Gorelow
Long Term.........Adair

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