Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 241023

Area Forecast Discussion
National Weather Service Las Vegas NV
223 AM PST Sat Feb 24 2018

.SYNOPSIS...An upper level disturbance moving through northeast
Nevada into Utah will cause strong winds in western San Bernardino
County and snow showers in Lincoln County late this afternoon and
this evening. Otherwise, dry and warmer conditions are expected
this weekend. Southwest winds will increase area wide Monday ahead
of the next storm which will bring a chance of rain and snow to
the region Monday night and Tuesday.

.SHORT TERM...A dry northwest flow will be over the forecast area
this morning with mostly sunny skies and fairly light winds. A
shortwave trough dropping southeast across northeast Nevada into
Utah will bring a pretty good chance of snow showers to Lincoln
County late this afternoon through this evening. Precipitation
amounts will be fairly light but some of the higher terrain could
see 1-2 inches of snow. The only other significatn impact from
this shortwave will be increasing westerly winds in western San
Bernardino County. NAM and GFS MOS guidance along with several hi-
res models are indicating sustained winds of 25-30 knots
beginning about 22z this afternoon and continuing through about
06z this evening. I decided to go ahead with a wind advisory for
that time frame with moderate confidence. The ECMWF MOS and
several other hi-res models are not quite so strong so we`ll see.
A dry northwest flow will resume following the exiting shortwave
overnight into Sunday. The forecast area will have mostly sunny
skies and warmer temperatures with generally light winds. The
exception will be locally breezy north winds down the Colorado
River from Laughlin- Bullhead City down to Havasu as is typical
behind exiting shortwave troughs. By Monday, the next upper trough
will be dropping down into northern California with an increasing
southwest flow over the area. We should see increasing surface
winds with breezy to locally windy conditions. Temperatures will
warm up some more but clouds will start to increase across the
northwest portion of the CWA with a chance of snow showers
developing across far northern Inyo County and northern Esmeralda
County. The models are in pretty good agreement deepening the
upper trough into a closed low Monday night and tracking it
southward along the southern California coast. This will result in
increasing clouds and spreading precipitation chances to areas
roughly northwest of I-15. With the low dropping that far south,
we will likely see some gusty northwest wind start to develop over
Esmeralda and northern Inyo Counties.

.LONG TERM...Tuesday through Friday.
A closed upper-level low pressure system is forecast to form over
the northern California coast late Monday and dive southward
toward the area. The exact trajectory of the upper low will be
critical to the sensible weather we see on Tuesday. The GFS model
brings this low around the base of the larger trof and across the
southern part of the CWA. In contrast, the ECMWF is slower with
this progression and further south. The GFS solution will bring
better chances for precipitation across the area. In fact, as
forecast right now, the GFS is indicating a pattern that is
favorable for more convective (high rate) precipitation. Given
temperatures with this system, low level valley snows are possible
in many areas. Certainly mountain snows will be possible and may
be enhanced with easterly flow in locations like the Spring
Mountains. The ECMWF solution may still bring precipitation to the
southern half of the CWA, but it is a bit less favorable for
impactful weather. Tuesday has the potential to be an interesting
day and will be monitored closely over the weekend. For the rest
of the period, the area remains under a broad upper level trof
with deep westerly winds. This is a pattern that favors dry and

.AVIATION...For McCarran...A northwest flow is expected through
early morning with speeds generally around 10-15 kts. Few-sct
clouds expected Saturday around 8-10k feet with southwest winds
around 9 kts in the afternoon.

For the rest of southern Nevada, northwest Arizona and southeast
California...West to northwest winds will remain in place with
speeds generally between 10-20 kts. Improving conditions will be
seen on Saturday.


SHORT TERM...Harrison

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