Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Las Vegas Nevada
246 PM PDT Friday Apr 18 2014 area of low pressure will move slowly east across the
area tonight and Saturday. Isolated thunderstorms will be possible
mainly in the mountains of California this evening. On Saturday...
thunderstorms will occur mainly over the mountains of the southern
Great Basin. As for the valleys sprinkles are possible. After a warm
up Sunday and Monday...a system will usher in strong winds Tuesday
followed by cooler temperatures Wednesday.

Short term...through Monday night...
satellite shows showers/isolated thunderstorms confined to the
southern Sierra and higher terrain of Esmeralda County. More
recently...starting to see buildups over the San Bernardino County
mountains. Cloud shield associated with vorticity center over the
remainder of the area is limiting convection and has only lead to
some sprinkles.

The isolated thunderstorms will dissipate this evening with the loss
of daytime heating. However...light rain showers or more likely
sprinkles will be possible tonight as the region remains under the
influence of an upper trough. Upper trough will continues its slow
migration east on Saturday with a broad area of weak
instability/cape again focused over the higher terrain. By
Sunday...any slight chance of showers will be confined to the higher
terrain of northeast Lincoln and northern Mohave counties.
Increasing westerly flow will mitigate any storms on the southern
Sierra Sunday. The westerly flow will continue to increase Monday
into Monday night ahead of a potent shortwave approaching the
California coast. Look for Ridgetop winds to increase Monday night
in the southern Sierra which will be the precursor to a windy
Tuesday. There should be little change in temperatures between today
and Saturday...then we warm back up to well above normal Sunday and

Long term...Tuesday through Friday...a return of windy weather is
expected on Tuesday as a strong low pressure trough pivots across
the Great Basin. Winds will first pick up across the Sierra and
Spring Mountains late Monday night and continue to strengthen across
the whole region Tuesday morning as pressure gradients tighten in
response to the approaching trough. Winds will be especially strong
in the Lee of the Sierra and Spring Mountains where gusts may exceed
60 miles per hour. Elsewhere wind gusts will likely fall closer to the 45-55
miles per hour range. With this magnitude of wind...areas of blowing dust are
likely Tuesday. While the storm system is mostly dry...low
probabilities of precipitation associated with the cold front do
exist for the Sierra and some our northern mountain zones.
Additionally...low relative humidities coupled with strong and gusty
winds will result in a period of dangerous fire weather Tuesday.

Much quieter weather is in store thereafter with calmer conditions
Wednesday through Friday. Temperatures will fall to slightly below
seasonal normals on Wednesday behind the departing cold front before
rebounding to near seasonal normals for Thursday and Friday. Long
range guidance hints at the possibility of another trough impacting
the west next weekend.

Aviation...for McCarran...southeast winds into this evening before
switching to a more southerly direction and diminishing tonight.
Light easterly flow expected by Saturday afternoon. Ceilings look to
stay above at or above 15 kft tonight. Some cumulus development with
possible showers over higher terrain (spring and sheep mountains)
Saturday afternoon.

For the rest of southern Nevada...northwest Arizona...and southeast
California...isolated thunderstorms near the southern Sierra crest
will dissipate this evening. There will be a repeat for a slight
chance of showers and thunderstorms Saturday afternoon over the
southern Sierra...mountains of southern Nevada and northwest
Arizona. Otherwise...there may be a few light showers or sprinkles.
Southeast-south winds will diminish this evening only to develop
again Saturday with speeds generally less than 15 knots.

Vef watches/warnings/advisories...



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