441
FXUS65 KVEF 262016
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
1216 PM PST Tue Nov 26 2024

.SYNOPSIS...A potent Pacific storm will pull away toward the Rockies
Wednesday, allowing cooler and drier northwest flow to develop late
Wednesday into Thanksgiving Day. Aside from a few sprinkles possible
Saturday and Sunday, dry weather is likely through the holiday
weekend and into next week.
&&

.SHORT TERM...through Wednesday night. Midday satellite loop showed
moisture from the atmospheric river continuing to stream over our
area. The Sierra Nevada range was intercepting much of the moisture,
with enough spilling over to produce rain in the Owens Valley and a
mix of lenticular and trapped lee wave clouds farther east. Surface
obs showed high winds isolated to the higher elevations of the
Spring Mountains, with gusts around 40 mph as far down as Red Rock
Canyon. Low pressure near the CA/OR border will track ESE through
Wednesday, gradually veering the flow which is steering the AR,
which will pinch it off and shut off the precip chances in our CWA
from north to south tonight through Wednesday afternoon. The first
concern is the Winter Storm Warning in the Sierra. HADS and SNOTELs
showed that snow depth had been increasing very slowly through the
morning, but snow water equivalent had been increasing more rapidly,
suggesting that this morning`s snow was heavy and wet (snow-liquid
ratios as low as 4:1). High resolution models are in consensus that
precipitation on the eastern Sierra slopes this afternoon should be
similar to or lighter than this morning. This fact plus the slowly
increasing snow depths would suggest canceling the Winter Storm
Warning, but the heavy and wet nature of the snow suggests that the
situation may be more dangerous than snow depth alone conveys. Thus,
will keep the Warning going for now and continue to evaluate as the
day goes on. Precipitation is likely to end in the Sierra this
evening, but do not want to be too quick to cancel. Will, however,
cancel the Winter Weather Advisory for the White Mountains this
afternoon, as the Sierra interception has been very efficient. The
second concern is wind. The High Wind Warning for the Spring
Mountains looks good, as gusts over 70 mph continue at Angel Peak.
The Wind Advisories for much of the Mojave Desert are a bit more
nebulous. West winds have just cranked up at KDAG, so will continue
to monitor speed and coverage trends for a few hours before making
any decisions. The third concern is rain amounts in the Spring
Mountains. The highest 24 hour gauge total has been 4.02 inches in
Rainbow Canyon, but all gauges show rates of half an inch or less
per hour, which has meant no flooding reports thus far. This should
continue to be the case as the AR wanes through tonight. If the Las
Vegas Valley were to get any measurable rainfall, the most likely
time would be between midnight and sunrise Wednesday morning.

.LONG TERM...Thanksgiving Day through Monday.

A ridge develops along the Pacific Coast over Thanksgiving Weekend,
bringing dry northwesterly flow aloft and near average temperatures
to the forecast area. Low pressure to the south of the ridge near
the Southern California coast should moderate 500 mb height rises
and prevent temperatures from increasing at the surface. The north
to south pressure gradient between the ridge and the low may bring
an localized increase in northerly winds along the Colorado River
through the weekend. There is a 60 to 80 percent chance of wind
gusts over 40 mph between Laughlin and Needles on Thanksgiving. Most
moisture should be scoured out of the area by Thursday and no
precipitation is expected through the beginning of next week.
&&

.AVIATION...For Harry Reid...Southwest winds 15-25 knots with gusts
between 30-35 knots will remain through the afternoon before
diminishing to around 10-20 knots out of the southwest. There is
some indication that winds could briefly become southeast to south
between 01-03z this evening with speeds around 10-15 knots, but
overall confidence is low. A cold front will move through the region
overnight with winds shifting to the northwest between 09-12z with
sustained speeds between 10 and 20 knots and occasional gusts
between 20 and 25 knots through Wednesday morning. SCT-BKN050-070
through much of the day. When the cold front moves through, CIGS
could briefly drop to around 3-4k feet along with a few light
showers with the best chances (20-30%) between 09 and 14Z. Sky
conditions will improve Wednesday along with northwest-northeast
winds 8-14 knots.

For the rest of southern Nevada, northwestern Arizona, and
southeastern California...Gusty southwest winds will continue
through the afternoon across the Las Vegas Valley TAF sites this
with speeds between 20 and 30 knots. SCT-BKN050-070 all day. The
best chance of light rain showers will be overnight as a cold front
moves through the area. CIGS could briefly drop to around 3-4k feet
along with a few light showers with the best chances (20-30%)
between 09 and 14Z. Northwest winds at KBIH will range between 10
and 12 kts with occasional gusts to 20 kts this afternoon. Light
rain/snow mix, CIGs below 5 kft, and occasional visibility drops
below 6 SM will persist through 02Z. Around 08Z, northwest gusts
pick up at KBIH between 20 and 25 knots. Gusty west winds at KDAG
between 25 and 35 knots expected. Speeds will diminish around 12Z as
the direction shifts to north-northeast. South winds at KEED and
KIFP between 8 and 12 knots with occasional gusts to 20 knots. Not
expecting precipitation at KDAG, KEED, or KIFP terminals. CIGS will
improve Wednesday with generally FEW-SCT clouds around 8-12k feet in
the afternoon and Northwest winds 10-20 knots.
&&

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

$$

SHORT TERM...Morgan
LONG TERM...Meltzer
AVIATION...Gorelow

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