Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Las Vegas Nevada
230 PM PST sun Mar 1 2015
Synopsis...steady precipitation will continue to spread northeast
across San Bernardino, Mohave, Clark and Lincoln counties tonight.
Precipitation should taper to showers late Monday morning and
afternoon. Additional showers are possible mainly across the eastern
half of the area Tuesday. Gusty north winds are expected Wednesday
especially in the Colorado River valley. Otherwise dry and warming
conditions are expected from Wednesday through next weekend.
Short term...tonight through Tuesday night.
The middle and upper level low is sinking south of Point Conception
which is allowing a plume of subtropical moisture surge northward
into the southwest Continental U.S.. steady precipitation is spreading
northward across Southern California...western Arizona...and far
southern Nevada. Expect the intensity to increase a bit later this
evening...overnight and into Monday morning as stronger forcing
pushes into the area. Farther west..expect showery activity. Late
tonight another shortwave will dive south along the West
Coast...acting to push this system east. We should start to see the
steady precipitation edging east Monday morning...yet there remains
enough moisture and upper level forcing to keep shower chances going
late Monday morning through the afternoon. There is also enough
instability to warrant isolated thunder chances. By Monday night
precipitation chances decrease.
Snow levels as of this writing are around 4500-5000 feet in the
west...5000-5500 around Clark County...and 6500+ in our east. As the
moisture surge from a warm source region continues...snow levels
will increase a little more overnight...particularly across Mohave
County. We are still looking at snow amounts from now through Monday
of 3-6 inches above 5000 feet (locally higher possible) in Lincoln
County as well as the Sheep Range and Spring Mountains. Will
continue the Winter Weather Advisory for those areas. The Sierra and
White Mountains will also see some snow accumulations. Will keep an
eye on snow levels and accumulation amounts...but not anticipating
any headline products for that area at this time due to the steady
plume of moisture being well east. Highest liquid totals will be
across Mohave County...where some minor/nuisance flooding in urban
and poor drainage areas will be possible. Also expect running water
in normally dry washes. Be especially alert if driving tonight as
ponding water on roadways could be harder to see.
While the precipitation will be diminishing Monday...west to
southwest winds will be increasing. The strongest winds are expected
over the Mojave Desert, where gusts of 30-40 miles per hour are possible. By
Tuesday...the shortwave trough that kicks this upper low east will
be moving overhead. Given this forcing and lingering low-level
moisture...there remains a chance of showers mainly in the higher
terrain east and north of Las Vegas. Any precipitation accumulations
should be fairly light. As the trough and surface front track across
the area Tuesday...northerly winds will increase. So far...the
strongest winds appear to be across Esmeralda and Nye counties
perhaps getting into Lincoln County. As for temperatures...expect
highs to be about 6-12 degrees below normal Monday and Tuesday.
Long term...Wednesday through Sunday.
One last piece of upper level energy dives south along the West
Coast on Wednesday and forms a broad area of low pressure over
northern Baja California Thursday. It will help maintain cooler conditions
across the region with high temperatures still 8-10 degrees below
normal. Surface high pressure strengthens behind a cold front that
slices through the area early Wednesday bringing gusty north winds
to much of the area with enhanced north winds along the Colorado
A warming trend is expected beginning Thursday and continuing into
the weekend with high pressure building over the southwest.
Temperatures are forecast to be 3-5 degrees below normal Thursday
but quickly warm to above normal for the weekend. Las Vegas should
warm back into the 70s under mostly clear and light wind conditions
for the first full weekend of March.
Aviation...for McCarran...ceilings generally 5-7k feet through the
afternoon and overnight. Shower activity will begin to settle into
the valley by 22z with periods of steady rain possible at times
through the night. Ceilings could fall blw 5k feet and visibility
reduced in more moderate showers. Rain is still expected to taper
off to hit and miss showers by Monday afternoon. Winds will maintain
an easterly component through the evening then will either become
light or trend toward typical diurnal direction. South to southwest
winds of 8-16 kts after 15z Monday with gusts to 25 kts.
For the rest of southern Nevada...northwest Arizona...and southeast
California...winds generally 10 kts or less with favoring typical
diurnal directional trends through tonight. Low ceilings 5-8k feet
through tonight with periods of steady rain at times generally east
of a kdag-kely line with snow levels between 5500 and 6500 feet.
Isolated-scattered showers are expected west of this line. Ceilings below 5k feet
and reduced visibility to MVFR or lower at times possible. Mountain
obscurations are likely. Improving conditions by later Monday.
Spotter information statement...spotters are requested to report
any significant weather according to Standard operating procedures
today through Tuesday night.
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