Area Forecast Discussion
Issued by NWS Las Vegas, NV
FXUS65 KVEF 300316
Area Forecast Discussion
National Weather Service Las Vegas NV
815 PM PDT SUN MAY 29 2016
.SYNOPSIS...Seasonal temperatures and light winds are expected for
Memorial Day with a slight chance of showers and thunderstorms for
the Sierra and southern Great Basin and dry conditions elsewhere.
Thereafter, a warming trend will commence with widespread triple
digit heat building over the deserts by midweek.
.UPDATE...Lightning trends suggest most of the convection has
diminished across the region this evening but some light showers
persist across the southern Great Basin and a few weak echoes are
showing up on radar across northern Mohave county. With the loss of
daylight, things should continue to decrease through the evening.
The current forecast has this well outlined and aside from some
minor cloud cover adjustments no update is needed this evening.
.SHORT TERM...Today through Tuesday night.
WV imagery currently shows a vorticity maximum moving into southwest
California with an elongated shear axis to the northeast into Utah.
Scattered convection has developed in the southern Great Basin into
southwest Utah in association with this feature. Some decent storms
developed in northeast Lincoln County earlier this afternoon, with
radar indicating spotty 0.25-0.75 inch totals in an hour`s time to
the north of Eagle Valley. Meanwhile, the Sierra has been much
quieter today than the past several days, with precipitation just
getting going near the crest in the past couple of hours. Expect
this convection to continue through sunset with a downward trend
thereafter. As the vort max slowly trudges into southwest Arizona
tomorrow, precipitation will favor eastern portions of the CWA
(namely eastern Lincoln and northern Mohave Counties) with a
noticeable upswing in activity during the late morning through early
evening hours. Aside from a stray shower in the Sierra, not much
precipitation is expected elsewhere. Temperatures are expected to be
near seasonal averages.
A weak front/wind shift will push through the area Monday afternoon
into Tuesday, with perhaps a few gusts just after frontal passage,
particularly in the southern Great Basin. Otherwise, the departing
upper low will slow to a crawl and sink into northern Mexico, with
upper-level ridging nudging into the region. Expect warming
temperatures and drier conditions on Tuesday, with temps near or
just slightly above normal.
.LONG TERM...Wednesday through Saturday night.
Big story in the long term is the developing heat wave. Upper-level
ridging becomes entrenched across the West Wednesday through
Saturday as an omega blocking pattern develops. Temperatures will
warm into the triple digits across the deserts during this period.
MOS values hit 107 or 108 in Vegas Friday and Saturday. Current high
temperature records are 107 and 109, respectively. Did not go quite
this high in the grids, as there may be some increasing high
cloudiness during this period. Overnight lows are expected to be
near 80, which will also be flirting with record high minimum
temperatures. Current forecast would suggest heat products may be
necessary during this period. Most certainly a good plan to start
ramping up heat safety/preparedness messaging, particularly given
that this is the first major heat wave of the year and the past
couple of weeks have been relatively cool.
By the weekend, an upper low approaches the California coast.
Extended models are in decent agreement on its presence but less so
on its eventual position and timing (anywhere from the northern
Great Basin to northwest Mexico). Main effects during the long term
period will be to enhance downstream ridging (and resultant surface
heating) Friday and Saturday, to increase high cloudiness, and to
increase the chances for orographic precipitation in the Sierra by
the weekend. However, this will be a system to keep an eye on
afterward given its anticipated proximity to the area.
.AVIATION...For McCarran...East to southeast winds around 10 kts with
occasional gusts to 20 kts will continue through sunset then start
to turn more toward the southwest. Southwest winds will then
continue through the overnight hours with speeds around 7 kts. Winds
Monday are expected to turn more northeast to east after 17z, with
wind speeds generally around 6-8 kts. Few clouds around 12-15k feet.
For the rest of southern Nevada...northwest Arizona...and southeast
California...A few showers and isolated thunderstorms possible
through early this evening across northern
Inyo...Esmeralda...central Nye...and Lincoln Counties. Gusty winds
up to 30 kts will be possible with any tstorm. Otherwise, few-sct
clouds around 12k feet through Monday afternoon. Winds will
generally be less than 10 kts most areas through tonight and
afternoon winds 10-20 mph Monday.
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather according to standard operating procedures.
Short Term/Long Term...Shafer
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