Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 211706
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
906 AM PST Wed Feb 21 2018

.SYNOPSIS...
A series of disturbances will bring continued cold temperatures and
periods of unsettled weather through the weekend and well into
next week. Periods of gusty winds and in some areas precipitation
which may fall in the form of snow where snow levels are low
enough.
&&

UPDATE... A band of high clouds continues to stream up across much
of San Bernardino County and into southern Nevada and Northwest
Arizona and will keep temps from rising significantly today. A
shortwave trough will push across the Sierra this afternoon and
across Lincoln County later this afternoon and into the early
evening hours. I have increased clouds and introduced a slight
chance of snow showers in northern Lincoln County during the
afternoon and early evening. Otherwise, no other changes made.
&&

.PREV DISCUSSION...
410 AM PST Wed Feb 21 2018

.SHORT TERM...Today through Friday Night.

High clouds moved in across the region overnight, keeping
temperatures a few degrees warmer than previously forecast across
portions of the area. As of 4 AM temperatures had already dropped
to 20 degrees in Kingman, so the Hard Freeze Warning remains in
effect. For the rest of today expect temperatures similar to
yesterday, gradual clearing, and light winds.

Conditions become more active on Thursday into Friday as the next
wave moving through the mean trough plunges south along the west
coast. The system will move east of the area by Friday night.

WIND: The incoming system will result in gusty winds across the
Sierra and along the typical Mojave Desert I-15/I-40 wind
corridor. Widespread gusts of 35-50 MPH can be expected and Wind
Advisories have been issued for these areas Thursday. Winds will
turn to the north late Thursday into Friday with gusts of 25-40
MPH in its wake. We`ll have to monitor for potential advisory
level north winds across central Nevada on Friday.

PRECIPITATION: While not a moisture laden system, low snow levels
and dynamic forcing may result in higher snowfall amounts than
seen with the last system, particularly over Lincoln and Mohave
counties. Snow levels will vary across the region with this
system, but a rain snow mix will be possible in some valley
locations, including the higher edges of the Las Vegas Valley on
Thursday afternoon/Thursday night. That said, accumulations are
not expected in the Las Vegas area. Meanwhile across Lincoln and
Mohave County at elevations above 4000 feet, amounts of 1-5" will
be possible with higher amounts in the mountains. As a result,
Winter Weather Advisories were issued for those areas from mid-day
Thursday through mid-day Friday. Confidence is moderate at best
with how quickly precipitation ends from west to east Thursday
Night into Friday, but by Friday night the entire region should be
dry.

.LONG TERM...Saturday through Tuesday.

A broad troughing pattern over the western U.S. is keeping the
area under northerly flow. Passing upper level disturbances are
dominating the weather pattern through the extended period as a
result. Each of these passing disturbances are not expected to be
major weather producers, but will serve to increase winds and
bring low chances of precipitation, mainly to higher terrain
areas. The first of these passing waves occurs on Saturday/Sunday.
This is the weaker of the two during this period. It is expected
to pass to the north and east of the area. Therefore, increased
chances of precipitation have been introduced into the forecast
for Lincoln County and northern Mohave County in the Arizona
Strip. The second system is slated to begin moving in on Tuesday.
This wave is a bit more potent. Both the GFS and ECMWF are eluding
to a cutoff low over southern California. There are differences
in timing between the two. The ECMWF is a bit earlier with the
arrival of the system as the low cuts off over southern California
by Tuesday night. The GFS not until later Wednesday. In either
case, the winds are expected to be stronger with this system and
may warrant an advisory.
&&

.AVIATION...For McCarran...Mainly light and variable winds are
expected today, favoring typical diurnal trends by this afternoon.
CIGS of 10-15kft are expected to gradually improve today.
Southwest winds will increase again Thursday morning, with gusts
to 35-40 KTS by Thursday afternoon. This will be accompanied by
lower CIGS and a slight chance of precipitation. Conditions will
improve somewhat on Friday with north winds gusting to around 25
KTS.

For the rest of southern Nevada, northwest Arizona and southeast
California...Mainly light winds across the region today, with CIGS
of 10-15kft. Southwest winds will increase across the region
Thursday, with gusts of 30-45 KTS across the Sierra and Mojave
Desert. Lower CIGS and chances for precipitation will accompany
this next system. North winds gusting 20-30 KTS are expected
Friday.
&&

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

$$

UPDATE................Czyzyk
SHORT TERM/AVIATION...Wolcott
LONG TERM.............Lericos

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