Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 05/18/20

Area Forecast Discussion

National Weather Service Las Vegas NV

 235 PM PDT Sun May 17 2020

.SYNOPSIS...Increasingly gusty conditions are expected today with
the strongest winds across eastern California and the Southern
Great Basin region. Gusty conditions will continue into Monday
before a weather system brings a brief shot of showers and
thunderstorms to parts of the area on Tuesday. Temperatures today
will be warm but cool sharply into Tuesday into below normal
territory. Temperatures will slowly rebound through the remainder
of the week with dry conditions resuming.
&&

.SHORT TERM...Through Tuesday Night.

Another round of gusty winds are expected Monday across the area.
It should be similar or slightly lower compared to today`s winds
for most locations. Didnt make significant changes to the Monday
wind forecast. However, there are a few concerns where winds may
have different impacts than today:

Hi-res models are starting to show downslope potential for the
Sierra east slopes again Monday afternoon. In fact, model cross
sections look a bit more favorable tomorrow compared to today as
strong ridgetop winds will be pushing in and hints of leeside waves
breaking downstream on the White/Inyo Mountains. Confidence remains
low that strong winds will make it into the Valleys. With the
potential for downslope winds continuing, decided to extend the Wind
Advisory for The Sierra and Owens Valley into Monday night. Much
like today`s methodology: the risk exists for stronger gusts and
higher impacts than what would be expected of a wind advisory and if
confidence in a downslope event increases the wind advisory can be
upgraded to a high wind warning. If downslope winds were to develop,
it would likely be between 18Z-03Z Monday.

The other area where downsloping winds is possible is the Spring
Mountains. The overall setup doesn`t look as favorable as the Sierra,
however there is still a slight chance. Hi-res wind models show a
quick burst of west winds after 03Z Tuesday. Confidence is way too
low currently for any headlines, but will need to how things
develop tomorrow.

Finally for the winds, decided against extending the Lake Wind
Advisory for Monday afternoon. Today`s winds have been marginal to
reach criteria, though there have been reports of impacts on the
lakes due to winds. With slightly lower winds tomorrow and since it
will be a Monday there should be less boats and lake-goers, there
should be overall less impacts.

Outside of the winds, the chance for precipitation increases Monday
and Tuesday as an upper level trough moves through the region.
Monday precipitation chances will be isolated and low impact, with
the main bulk of the moisture being blocked by the Sierra so most of
the precipitation should remain on the ridgetop. Monday night into
Tuesday, the center of the upper level cold low moves through
Central California and southern Nevada. Low level moisture will be
limited, but cold temperatures aloft and decent forcing with the
trough axis should allow for scattered precipitation to break out.
Models tend to struggle with cold core lows over the Southwest US,
so spread precipitation chances Tuesday afternoon further south and
west from previous forecast to highlight the area of coldest
temperatures aloft. Marginal instability will develop under the low,
especially if we get any daytime heating, so scattered thunderstorms
are possible over Inyo, Esmeralda, Nye, and Lincoln Counties. Cant
rule out a burst of wind from any of these showers and storms as
forecast soundings show inverted-V type soundings. Also could see
small hail since it will be so cold aloft. Best chances for
precipitation will be in Inyo and Esmeralda where some moisture
should spill over the Sierra crest, as well as in the higher terrain
of the Souther Great Basin.

Temperature will cool off to near normal Monday and bottom out on
Tuesday, when high temperatures will drop to about 10 degrees below
normal.

.LONG TERM...Wednesday through Saturday.

Heights will slowly climb starting Wednesday as formerly mentioned
trough lifts into the central Rockies. However, broad troughing will
remain across the West resulting in only a slow warm up to near
normal conditions by the end of the week. Another shortwave trough
may dig southward into the region Friday into Saturday resulting in
another round of gusty winds and a modest cool down.
&&

.FIRE WEATHER...Widespread dry and gusty conditions are expected
through Monday evening resulting in a period of critical fire
weather. Greatest fire danger Monday will be over zones NV-461
and AZ-102. Fire zones CA-227 and NV-460 and 462 may seen enough
of an increase in moisture to bring RH`s values to 20-25% and thus
reduce the fire weather risk. Confidence in Mondays RH`s values is
lower, so will wait to see more data before canceling any Red Flag
Warning areas. In CA-226, it will remain dry on Monday but less
confidence that winds will reach criteria. By Tuesday, winds
diminish and moisture will increase enough that the fire danger
will be lower.

A quick round of showers and thunderstorms will be possible
Tuesday across the Sierra and southern Great Basin. Lightning and
sudden erratic winds will be possible with the precipitation. Dry
and calmer conditions will follow for the remainder of the week.
&&

.AVIATION...For McCarran...Gusty south-southwesterly winds will
persist throughout the period. Gusts through the afternoon may
reach 35 knots at times before reducing to 20-25 knot gusts
overnight. Mountain waves will introduce minor to moderate
turbulence on aircraft across LAS airspace through Tuesday. Broken
mid and high level clouds will continue to stream overhead.

For the rest of southern Nevada, northwest Arizona and southeast
California...Gusty south to southwesterly winds will continue at all
airfields through the afternoon. Gusty conditions are likely to
taper off by late this evening for most airfields before resuming on
Tuesday. Downslope winds along the east Sierra may shift winds to
the west at KBIH and introduce periods of LLWS in the Owens Valley.
Elsewhere, mountain wave turbulence is expected through the period.
Dry conditions expected areawide, though cumulus buildups over the
Sierra and Spring mountains are possible Tuesday afternoon. VFR
conditions will continue.
&&

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

$$

DISCUSSION...Nickerson
AVIATION...Boothe

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