Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 232100

Area Forecast Discussion
National Weather Service Las Vegas NV
200 PM PDT Tue May 23 2017

.SYNOPSIS..A strong ridge of high pressure over the region will
boost temperatures well above normal through Wednesday before giving
way to a trough moving down from western Canada which will bring
readings down around 10 degrees by Friday. A weak disturbance will
produce slight chances for afternoon and evening thunderstorms
across the southern Sierra and southern Great Basin Wednesday, along
with gusty southwest to west winds for the Mojave Desert Wednesday
afternoon through Thursday. Dry weather and a warming trend are
expected Saturday through Memorial Day.

.DISCUSSION...Skies were nearly clear over our area this afternoon,
with a few thin cirrus passing by and cumulus beginning to develop
over the Sierra as of 1 PM. Temperatures were rising well above
normal toward forecast highs today, with even a bit more warming
expected Wednesday. Heat Risk grids actually show a couple of areas
reaching warning recommendation Wednesday, but areal coverage is
quite small, so will continue with ongoing social media messaging.
Main concern is still wind over the Mojave Desert late Wednesday
afternoon through Thursday as a low pressure system rolls eastward
through southern Canada. Models have consistently shown winds right
around Wind Advisory thresholds for much of the desert through that
period. Since it is so marginal, chose to forgo any headlines for
now and let the night crew see one more model run. The trailing
trough will kick off a chance of thunderstorms in the Sierra and
southern Great Basin, but any extension into the Mojave Desert
should be limited to the higher terrain near and north of Las Vegas.
Although the parent low keeps moving east, weak troughing lingers
over the Great Basin through Friday. This will knock temperatures
down about ten degrees from Wednesday to Friday, and persistent
westerly flow should dry us out by Thursday evening. High pressure
moves overhead Saturday through Memorial Day, sending temperatures
back to several degrees above normal and keeping much of the area
dry, except for slight chances of thunderstorms over the Sierra each

.AVIATION...For McCarran....Light diurnal winds are expected to
continue through tonight. West downslope winds may pick up briefly
tonight but should remain under 10kts. Breezy to gusty southwest
winds should begin to reach LAS by 17-18Z tomorrow, but could begin
as early as 16Z. Sustained winds 15-22 kts with gusts around 30 kts
are likely from late morning through most of the evening tomorrow.
Clear skies are expected to remain throughout the forecast period.

For the rest of southern Nevada, northwest Arizona and southeast
California...Light diurnal winds are expected to continue through
most of tonight before breezy to gusty west to southwest winds
intrude the region tomorrow. Expected sustained winds of 15-25 kts
with possible gusts up to 35 kts for our westerly wind prone sites.
Clear to mostly clear skies are expected through the forecast

.SPOTTER INFORMATION STATEMENT...No significant weather is expected
today. A few thunderstorms will be possible over the southern Sierra
and central Nevada zones Wednesday afternoon and evening. Spotter
activation is not anticipated, but spotters are encouraged to
provide reports according to standard operating procedures.



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