Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 141113
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
313 AM PST Thu Dec 14 2017

.SYNOPSIS....Breezy to windy conditions are expected across the
area today with continued dry and mild weather. Lighter winds but
cooler temperatures are forecast for Friday before another cold
front brings more wind to the area Saturday.
&&

.SHORT TERM...Today through Saturday.

A sharp upper level shortwave is sliding south along the eastern
edge of the forecast area. Surface pressure gradients are
strengthening and we have seen a 16 mb difference between Reno and
Las vegas and 13 mb difference between Ely and Needles. These
gradient numbers are impressive but have not translated to wind
speed strength...except in a couple of locations. The surface cold
front associated with the upper level disturbance has reached into
the northern portions of the Las Vegas Valley as of 2 am this
morning. Gusts have been up to 30 mph so far. A Wind Advisory went
into affect at 2 am and extends through this afternoon for areas
south of Las Vegas. In addition, Red Flag conditions are expected
along the Colorado River Valley today as strong wind gusts couple
with low humidity and very dry conditions to increase fire danger.
Temperatures are expected to be cooler today overall except in
isolated situations such as Death Valley National Park where
compressional heating due to elevated northeast winds will warm
temperatures around 10 degrees over Tuesday.

Advisory level winds and red flag conditions will end by evening
time as the system moves away and is replaced by shortwave ridging.
Light winds are forecast overnight and Friday except for lingering
north winds in the Colorado River Valley. Cooler temperatures in the
wake of the front for Friday will linger into Saturday as well.

The next Pacific trough reaches the Pacific NW coast Friday
afternoon and splits in two with he southern energy moving south
along the West Coast and becomes a closed low west of the southern
California coastline. The northern energy rolls into the
Intermountain Region and draws a cold front south through our area
on Saturday. This will bring another round of gusty northerly winds
to the region late Saturday. For the most part, mostly clear
conditions can be expected today through Saturday however, a thick
batch of high clouds will move over the area Friday night which may
help in keeping low temperatures warmer on Saturday morning.

.LONG TERM...Sunday through Thursday.

Models are in decent agreement that by Sunday morning a split
shortwave will be pushing south & east of the area, leaving gusty
north winds in its wake and cooler (closer to normal) temperatures.
It`s still unclear on whether northerly winds will reach advisory
levels, but the most likely location for that is down the Colorado
River Valley.

Things will calm and warm Monday and Tuesday as ridging tries to
build back in. However, that ridging will build a bit further west
over the eastern Pacific instead of the western US. This will keep
the door open for additional, deeper waves to ride down the eastern
edge of the ridge. Confidence is low in the details right now, but
the first of those waves may approach the region next Wednesday,
increasing southwesterly flow (and winds) across the area. This
system appears to be relatively dry, but could squeeze out a little
precipitation over the Sierra/southern Great Basin late next week.
Depending on the track and depth of the systems late next week, they
could usher in the coldest air of the season, as well as periods of
strong winds, and perhaps even some precipitation (again, for the
moment things continue to look mostly dry).
&&

.AVIATION...For McCarran...Gusty north winds will continue into the
afternoon then begin decreasing in the late afternoon and evening.
Wind speeds will generally be in the 12-25 kt range. Expect lighter
winds on Friday before another front brings gusty northerly winds
back to the terminal on Saturday.

For the rest of southern Nevada, northwest Arizona and southeast
California...Gusty north winds can be expected this morning with
decreasing wind speeds through the afternoon. Winds will generally
be in the 12-25 kt range through Thursday afternoon. The strongest
winds will develop down the Colorado River Valley with gusts around
40 kts. Some enhanced northerly winds are also possible over eastern
Lincoln County where gusts may approach 30 mph. Other than a few
high clouds, skies will remain mostly clear.
&&

.FIRE WEATHER...A cold front will produce more widespread stronger
north winds today along the Colorado River Valley with gusts over 35
mph expected. North winds will linger through the weekend as a
series of weak disturbances pass across the region. A Red Flag
Warning is in effect today for the Colorado River Valley due to
these strong winds, low humidity and dry conditions.
&&

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

$$

Short term/Aviation...Salmen
Long term...Wolcott

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