Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Las Vegas Nevada
224 PM PST Friday Dec 20 2013
Synopsis...a weak disturbance is expected to pass across Nevada and
Utah tonight into Saturday bringing increased clouds to the area and
the possibility of a few snow showers to northern Lincoln County.
Otherwise dry conditions with near to slightly above normal
temperatures are expected through next Friday.
Short term...tonight through Sunday.
North winds did picked up across the Colorado River valley late this
morning and remain gusty this afternoon especially near Laughlin and
Bullhead City. Surface pressure gradients are forecast to relax
early this evening and the wind fields become not as well aligned
with height which would support winds decreasing here in this time
frame. Gusts of 25-35 miles per hour can be expected here for the rest of this
afternoon and early this evening.
A weak disturbance is forecast to drop southeast tonight across
Nevada and move into Utah on Saturday. Models show some increase in
moisture especially above 500 mb. For most of the area, this will be
marked by an increase in clouds although looking at cross sections
it does not appear the moisture will be thick enough for any lengthy
duration to carry anything more than mostly cloudy in the east with
less clouds expected the further west and south one GOES. We may see
a few snow showers late tonight and tomorrow in the higher
elevations of northern Lincoln County. Temperatures tonight should be close
to what we saw last night in most areas. For Saturday, forecast
soundings generally show cooling below 850 mb (except for the gfs)
so highs should be around what we saw today or a degree or two
Once the disturbance exits to the east Saturday evening, we should
see a relatively clear sky for Saturday night and Sunday. Low temperatures
again show little change for Saturday night with a degree or two of
warming expected on Sunday.
Long term...Monday through Friday...a dry northwest flow will be in
place on Monday along the front side of a ridge of high pressure.
The ridge axis will slowly move to the east and reach the West Coast
by Thursday. A weak wave may push through the eastern periphery of
the forecast area on Tuesday...which will increase northerly
winds... particularly down the Colorado River valley on Wednesday.
Several members of the gefs ensemble...including the operational run
break of a weak low over central California and drop it down and off
the Southern California coast on Thursday. Main impacts from that
potential low would be to provide some enhanced cloud cover...mainly
over the eastern Sierra. Overall the period should be dry with
temperatures near to slightly above normal.
Aviation...for McCarran...northwest winds should decrease this
evening to 5-10 kts and then shift to the southwest around 09z
Saturday. Afterwards winds should favor typical diurnal directions
at 3-6 kts. Variable cloud cover mainly at or above 20k feet with a few
clouds as low as 10k-15k feet.
For the rest of southern Nevada...northwest Arizona...and southeast
California...gusty north winds should decrease this evening in the
Colorado River valley. Otherwise expect northwest to north winds in
most locations tonight 5-10 kts. On Saturday winds should favor
typical diurnal directional trends at 5-10 kts except across
Esmeralda and central Nye counties where northwest winds of 7-14 kts
with gusts to 25 kts are expected. Variable clouds at or above 15k-20k feet
with bases as low as 10k feet are expected. Cloud cover should be
greatest over the eastern half of the area. Isolated shsn possible
in northern Lincoln County tonight and tomorrow with the potential
for mountain obscurations. Bases near any shsn may be as low as
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