High Wind and Strong Wind in California, April 16, 2018

Area Forecast Discussion
National Weather Service Las Vegas NV
915 AM PDT Mon Apr 16 2018

.SYNOPSIS...Very strong winds will affect the region today as
a potent Spring storm system moves through the region. Wind
Advisories and High Wind Warnings are in effect. Chances for rain
and snow today and tonight will remain north of Las Vegas.
Temperatures will fall back down below normal, especially west of
Las Vegas. The entire southern Great Basin and Mojave Desert will be
much cooler Tuesday. After a quiet and warmer day Wednesday, winds
will increase along with a chance of showers Thursday with next
storm system.
&&

.UPDATE...As of 9AM this morning, satellite is showing the shield
of mid/high clouds just south of I-15 slowly shifting to the
southeast. Updated sky grids to reflect the slower southeast trend
in cloud cover. The potent trough will continue to dig into the
southern Great Basin and California through today, increasing
southwest winds ahead of it and bringing slight chances of precip
across northern portions of the CWA. The latest MOS guidance is
little stronger than hi- res models with wind speeds, especially
for areas expecting high winds this afternoon. As such, increased
winds across portions of the region expecting to see peak wind
gusts this afternoon. &&

.PREV DISCUSSION... /issued at 315 AM PDT Mon Apr 16 2018/

.SHORT TERM...through Tuesday night.

Shield of mid/high clouds preceding potent trough off the northern
California coast covering areas south and east of Interstate 15 this
morning. The fetch of lower level moisture off the Pacific was
moving into the Sierra Nevada producing lgt-mod snow showers from
Mammoth Lake north to the Tahoe Basin.

As we have been advertising, concern from the passage of this trough
will be very strong winds later today/this evening. Based on hi-res
models and MOS guidance strongest period of winds will occur between
11 am and 8 pm this evening. Variety of High Wind Warnings and Wind
Advisories remain posted through late tonight. Cold frontal passage
will occur at Bishop and Tonopah late this afternoon. Frontal band
will slide southeast reaching Las Vegas between midnight and 3 am
Tuesday, and finally Kingman about 8 am Tuesday. Post-frontal
northwest winds will persist through the first half of Tuesday before
beginning to decrease during the afternoon.

The southern Sierra Nevada will continue to intercept much of the
moisture today with new snow accumulation of 3-6 inches possible
above 8500 feet, and a Trace-2 inches between 6000-8500 feet. Light
rain and snow showers will breakout along the cold front across
Esmeralda/central Nye County this evening, eventually reaching
Lincoln County late this evening and overnight. Higher terrain of
northern Lincoln may see a few inch of snow overnight. Kept a slight
chance in overnight as far south as the Spring Mountains.

Tuesday. Dry, but much cooler across the entire area.

.LONG TERM...Wednesday to Sunday.

The next system will churn down the west coast and pivot inland
Wednesday then close itself up over Nevada on Thursday. Sensible
weather response will be strong winds and increased precip chances.
Medium-range guidance has remained in good agreement with the
synoptic evolution. The main wind impact from this system will be
north winds on the backside on Thursday. Low-level forecast winds
between 35-45 kts across the southern Great Basin will aid in gusty
conditions across Esmeralda, Nye, and Inyo Counties. Large spread
still exists in north winds speeds between MAV and EC, mainly for
areas north of Interstate 15. Further south, breezy to locally
strong north winds will develop. With a warming cold pool, thermal
gradients aloft should weaken and decrease winds as the move south.
Overall, have taken the conservative approach to winds, with the
forecast favoring ECMWF solution.

In addition to wind, precip chances will increase along the southern
Sierra early early Thurs and spread eastward across the northern
zones Thursday. Precip on the backside of low - as it occludes - has
trended further south compared to previous runs, with 20 percent
PoPs being spread into the Las Vegas valley. Although precip is
expected to be light, will monitor these trends over the next
forecast cycles. There does appear to be slight destabilization
across Lincoln County Thursday afternoon, with CAPE values around
200 J/kg. This may support a few updrafts capable of a few claps of
thunder, but have not included any thunder at this time. Closed low
will progress east on Friday with precip chances tapering from west
to east as well. Northerly breezes will likely linger through Friday
across the region. By the weekend, ridging nudges inland bringing a
period of fair weather to area.

Temperatures will be around normal Wednesday, decrease Thursday
under height falls, then increase 3-6 degrees each day through
Sunday under the influence of an upper ridge.
&&

.FIRE WEATHER...Red Flag Warning remains in effect. Critical fire
weather conditions in the form of wind gusts greater than 35 mph and
relative humidity values less than 15 percent will occur across
northwest Arizona and the lower Colorado River Valley today. Due to
the dry Fall and Winter Seasons, critical fuels are primarily across
southern half of Mohave County.
&&

.AVIATION...For McCarran...South to southwest winds
are likely to persist through the morning. Stronger winds will
develop this afternoon with gusts to 40 kts possible. Mechanical
turbulence blo 18 kft at least through this evening. Shield of
mid/hi clouds will be shifting southeast this morning leaving behind
mostly clear skies. A cold front will push south through the area
later tonight, between midnight and 3 am Tuesday turning winds to
the northwest. FEW-SCT080-100 will accompany the front. As winds
decrease Tuesday afternoon the direction will shift more from the
northeast.

For the rest of southern Nevada, northwest Arizona and southeast
California...Widespread SW winds gusting 35-45 KTS expected this
afternoon with mechanical turbulence blo 18 kft downwind of
mountains at least through this evening. A cold front will push
south across the region tonight/early Tuesday morning. North winds
will then be favored through Tuesday. Chances of snow
showers/mountain tops obscured along the southern Sierra today. The
chance of light showers spread east across south central Nevada
tonight.
&&

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

UPDATE...Kryston
SHORT TERM/AVIATION/FIRE WEATHER...Pierce
LONG TERM...Boothe

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