Winter Weather Advisory 14, NWS Reno, NV

Area Forecast Discussion
National Weather Service Reno NV
320 AM PDT Fri Apr 23 2021

.SYNOPSIS...

Dry weather with above average temperatures and typical afternoon
west breezes will prevail for one more day today. Then for the
weekend and into next Monday, a late season storm will bring
sharply colder temperatures, stronger winds, and periods of valley
rain and mountain snow. Dry and warmer conditions return by the
middle of next week.

&&

.SHORT TERM...

Main change in the short term was issuing wind-related advisories
across eastern CA-western NV for Saturday.

Here's the easy part of the short term period: We'll have one more
warm spring day before the incoming storm with highs in the 70s
for lower elevations and 60s for Sierra valleys, and typical
afternoon zephyr breezes into far western NV (gusts 25-30 mph).
This would be an optimal time to secure loose and wind-sensitive
items before this weekend's storm rolls in.

For Saturday, the main weather highlight will be stronger winds
with widespread gusts of 45-50 mph in most areas, with 55-65 mph
gusts in wind prone locations, and 80+ mph for Sierra ridges.
While for most areas the peak winds are likely in the afternoon,
there's a possibility of a short periods of enhanced downslope
wind gusts of 60+ mph in parts of Mono County early-mid Saturday
morning as an upper level jet streak moves overhead. Blowing dust
could produce areas of poor visibility over parts of western and
west central NV, especially downwind of deserts, sinks and dry
lake beds.

A leading shortwave and moisture band will push across northeast
CA-northwest NV Saturday morning, with mainly light precip
possibly extending into parts of the Tahoe basin. However, the
Surprise Valley and extreme northwest NV near the OR border could
receive a decent 0.25-0.50" with this feature.

The main precipitation looks to reach the Sierra Saturday night
through Sunday, with a colder air mass bringing chilly
temperatures more typical of February. Snow levels look to be
rather low for late April (down to 5000-5500 feet at times, and
even lower toward the end of the event). Snow accumulations below
the 6000-6500 foot elevations will be more iffy due to the higher
sun angle, but for main passes the snow will be more likely to
accumulate on roads (or at least be slushy) even during the
daytime. The heaviest snowfall rates are likely to occur during a
3-6 hour window from mid-morning through mid-afternoon, with up
to 2"/hour possible. Snowfall/precip totals have trended a bit
less but still the potential for a few inches at lake level around
Tahoe and higher elevations of northeast CA, 6+" inches for the
Sierra above 7000 feet, and locally 12+" along the crest.

Rainfall amounts will taper off into lower elevations of northeast
CA-western NV with shadowing present for much of the event, until
the cold front passage provides a short period of spillover
precip. Broader scale lift across parts of west central NV,
especially north and east of Lovelock, could yield totals closer
to 0.25". Otherwise, amounts look to be in the 0.10" or less
category, except isolated locations could receive higher amounts
as some heavier shower bands move through Sunday late afternoon-
evening. A rain-snow mix is possible down to 4500-5000 feet by
this time with patchy slick roads possible in foothills around
the Reno-Carson urban corridors in the pre-dawn hours on Monday,
as temperatures drop to near or below freezing.

Periods of gusty winds are again likely on Sunday, although the
duration, magnitude and location of the stronger gusts are less
certain, due to the timing of the cold front passage. An earlier
front passage could lead to more moisture spilling over into
valleys more quickly to reduce the wind effects, followed by
brisk post-frontal winds (but not as strong as the winds along
and ahead of the front). MJD

.LONG TERM...Monday through Friday...

The late season Pacific storm will slowly be making its exit out
of the region early next week with lingering rain and snow
showers for much of the Sierra and western Nevada. Temperatures
will remain on the colder side with highs in the 50s for Nevada
and 30s and 40s for the Sierra locations. Highest Sierra terrain
will be contending with very cold temperatures and likely wind
chills as well as the storm exits the region.

By late Monday into Tuesday, showers will dissipate across the
region as the low ejects eastward. Ensemble cluster forecasts in
decent agreement with high pressure amplifying across the West
from Tuesday through Friday. Simulations are pointing towards a
warming/drying trend for Tuesday through Friday, as well as more
typical afternoon west winds each day. -Edan

&&

.AVIATION...

Typical west breezes with VFR conditions for today, with increasing
cloud cover through the evening.

Rapidly changing conditions will begin tonight through the weekend
as a strong late season Pacific storm moves into the Sierra and
western Nevada. Gusty winds will ramp up for the Sierra terminals
tonight with gusty conditions spreading across western Nevada
terminals by early Saturday morning. There will likely be increased
turbulence with periods of LLWS late tonight through Monday.

From late Saturday through Monday there will be periods of
moderate to heavy mountain snow down to the KTVL/KTRK/KMMH
terminals, with the heaviest snowfall rates Saturday night through
late Sunday night. Lighter valley rain across western Nevada is
forecast with this storm by late Saturday night through early
Monday morning.
-Edan

&&

.REV Watches/Warnings/Advisories...
NV...Lake Wind Advisory from 5 AM Saturday to 3 AM PDT Sunday NVZ002.

     Winter Storm Watch from late Saturday night through late Sunday
     night NVZ002.

     Wind Advisory from 11 AM to 11 PM PDT Saturday NVZ001-004.

     Wind Advisory from 8 AM to 11 PM PDT Saturday NVZ003-005.

CA...Lake Wind Advisory from 5 AM Saturday to 3 AM PDT Sunday CAZ072.

     Winter Storm Watch from late Saturday night through late Sunday
     night CAZ072.

     Wind Advisory from 8 AM to 11 PM PDT Saturday CAZ070-071.

     Wind Advisory from 5 AM to 11 PM PDT Saturday CAZ073.

&&

For more information from the National Weather Service visit...
http://weather.gov/reno