Area Forecast Discussion
Issued by NWS Las Vegas, NV

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718
FXUS65 KVEF 241011
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
310 AM PDT Fri Mar 24 2017

.SYNOPSIS... Tranquil weather will briefly hold today under a high
pressure ridge before a fast moving system moves over the region
from the Pacific tonight into Saturday. This will bring a quick shot
of showery weather and light high elevation snow along with gusty
winds. Unsettled weather is expected through next week as an active
pattern brings additional disturbances across the western states.
&&

.SHORT TERM...through Saturday night.

A ridge between systems extending from southern California up over
the Great Basin and Intermountain Region will quickly move over the
Rockies by this evening ahead of an incoming Pacific trough. The
base of the trough was well off the West Coast this morning and was
directing a substantial moisture plume toward northern California
and Oregon. The moisture will slide to the southeast later today and
tonight with the tail end of it impacting the southern Sierra.
Considerable moisture will also make it across the Sierra into
central Nevada for numerous showers late tonight through Saturday
morning over central Nye and Lincoln counties. The center of the
trough is forecast to move across southern Nevada by 18Z Saturday
with sufficient moisture for a quick shot of isolated to scattered
showers extending down around I-40, but any precipitation is
expected to be quite light. Showers will diminish across southeast
Nevada and northwest Arizona Saturday afternoon on the back side of
the trough axis. Snow levels will be near 6500 feet over northern
Lincoln County Saturday morning so Pioche may see some snow or a
rain/snow mix, but significant accumulations are not expected below
8000 feet so travel impacts are not likely. The east slopes of the
southern Sierra will pick up a few inches and the Spring Mountains
could see an inch or two Saturday in spots. Accumulations are not
expected to warrant any advisories.

Aside from showers, winds will again be noticeable with this fast
moving open wave, with gusty south to southwest winds preceding it
later today and tonight then northwest winds following it on
Saturday. General sustained speeds of 15 to 25 mph can be expected
with gusts 30-35 mph, especially over the western Mohave Desert of
San Bernardino County Saturday.

.LONG TERM...Sunday through Thursday. Active pattern continues as
two storms are likely to affect the region during the period. Models
have come into better agreement with the first storm Monday and
Tuesday, so confidence is increasing then, but agreement is poor for
the second storm Thursday, so confidence is below average then.
Sunday should be dry areawide until the first storm rolls in from
the west, with precip chances increasing in the Sierra in the
afternoon and possibly spreading into the southern Great Basin
overnight. The models have come into better agreement this morning
on what is essentially a compromise solution between the weaker and
faster ECMWF of the past few days and the slower and stronger GFS of
the past few days. This compromise shows the shortwave trough
passing through Monday, with precip chances limited to areas near
and north of Las Vegas, before deepening and digging over the Four
Corners region Monday night. This will keep precip chances going
mainly in Lincoln and Mohave counties Monday night, but the biggest
impact will likely be gusty north winds beginning over the northwest
zones Monday afternoon and spreading areawide by Tuesday. Wind
Advisories may be needed. After a dry period Tuesday and Wednesday,
the next storm could start to bring precip chances back to the area
Thursday. The models agree on the existence of this storm, but do
not agree on its track or timing, so confidence in where to put the
best precip chances is very low. Temperatures should stay close to
late March averages through the period, with areas of well below
normal temps possible wherever precip and/or thick clouds persist
through the day on Monday or Thursday.
&&

.AVIATION...For McCarran...Light winds this morning will
become east-southeasterly this afternoon with speeds 8-12 kts. Gusty
south-southwest winds will then develop this evening and persist
overnight ahead of a fast moving trough moving in from the West
Coast. Clouds will increase tonight with bases of 8-10 Kft and
showers around the Las Vegas Valley by early Saturday morning along
with developing northwest winds of at least 10-20 Knots.

For the rest of southern Nevada, northwest Arizona and southeast
California...Light and variable winds this morning will become gusty
from the south-southwest across much of the region this evening
ahead of system moving in from the Pacific. Precipitation and strong
winds will spread across the southern Sierra later today and tonight
and showers will develop over southern Nevada and surrounding states
by Saturday morning along with lowering cloud bases and mountain
obscurement. Showers will be most numerous over central Nevada.
&&

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

$$

Short Term/Aviation...Adair
Long Term...Morgan

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