Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 272024
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
124 PM PDT Wed Mar 27 2024

.SYNOPSIS...

Gusty winds will be followed by bursts of heavier Sierra snow
producing winter travel impacts this evening into early Thursday,
with a shorter period of rain for lower elevations. After a short
break, a more persistent storm will produce periods of rain and
snow Friday through this weekend, especially over the Sierra.
Drier and milder conditions return early-mid next week.

&&

.DISCUSSION...

Key Points:

* Quick moving storm produces gusty winds this afternoon-evening,
  with bursts of heavier snow bringing winter travel impacts over
  the Sierra tonight.

* A slower moving storm brings bands of Sierra snow Friday
  afternoon-Sunday with main winter travel impacts Friday night.
  Better chances for lower elevation rain or rain-snow mix for
  Saturday-Sunday.

* Finally some drying out for the first few days of April with
  temperatures warming to near seasonal averages.

A quick-moving but potent storm will push across CA-NV tonight
and clear the region by Thursday morning. Ahead of the precip,
wind gusts of 30-40 mph will be common for most lower elevations,
with gusts 50+ mph in wind prone areas and up to 90 mph for
Sierra ridges. As this system has similarities to last weekend`s
storm, enhanced gusts of 60+ mph could occur again (about 20%
chance) for 1-3 hours late tonight along US-95 between Hawthorne
and Walker Lake.

Meanwhile, precip will expand in coverage across northeast CA and
into the Sierra west of Tahoe this evening, with peak snowfall
rates of 1-2"/hour expected for a 4-8 hour period overnight.
Enhanced forcing along the cold front passage could even produce a
brief burst of 2-3"/hour snow rates for the higher elevations and
passes around Tahoe. It won`t be a pleasant trip over the Sierra
passes and Tahoe basin tonight, so if plans are flexible a more
favorable travel window would be this afternoon or during the day
Thursday. As the snow band moves south to Mono County, it will
lose some of its punch but areas along the crest could still
receive up to 1 foot. For more details on Sierra snow amounts,
check our latest Winter Weather Advisory statement. Snow levels
starting at 6000-6500 feet this evening will drop to below 5000
feet overnight, although for western NV/northeast CA valleys the
majority of precip will fall as rain (mainly between 0.10-0.25"
for the main urban areas, up to 0.40" for foothills and northward
into Lassen County/Surprise Valley, and lesser amounts for the
Basin and Range).

We get a brief break on Thursday as tonight`s storm exits and
before the next storm approaches on Friday. Isolated light snow
showers remain on tap near the Sierra crest and north of
Susanville-Gerlach Thursday afternoon-night as a subtle shortwave
sandwiches in between the two more notable storms, but impacts
will be more limited. Otherwise, cool conditions will prevail with
breezy west winds (gusts 25-35 mph, with Sierra ridge gusts up to
70 mph) during the daytime-evening hours on Thursday.

The storm for Friday through the weekend begins as an offshore
closed low with a subtropical moisture feed ahead of this low
spreading into the Sierra during the day on Friday, then pushing
into areas of western NV Friday night. Despite the subtropical
origin of this moisture, the air mass is relatively cool and snow
levels look to hover between 4500-5500 feet through much of this
event. So for Sierra communities, mostly snow is expected
although with the higher sun angles of late March, the amount of
snow that accumulates during the daytime will be limited to brief
periods with heavier snow rates. For Sierra/Tahoe area
communities, there`s about a 40-50% chance for storm totals of
6" or more, while higher elevations have a similar probability for
exceeding 1 foot of snow over a 48-hour duration from Friday
evening through Sunday evening.

Then by Saturday night-Sunday, a secondary area of low pressure is
projected to develop over western or central NV. This would lead
to areas of wrap-around precip across lower elevations, Easter
morning could be accompanied by a rain-snow mix for lower valleys,
and potentially a slushy 1-3" of wet snow in areas where heavier
precip bands persist in the hours prior to sunrise. Overall it
will be looking like a chilly and showery Easter Sunday with highs
mainly in the 40s-near 50. Many areas will be colder than it was
last Christmas (Reno`s high was 51 on 12/25/2023)!

Early next week it appears that we will finally get a reprieve
from the recent chilly and wet weather pattern as an upper ridge
develops in the Eastern Pacific next Monday and moves inland by
Tuesday. During this transition, a period of gusty northeast winds
is anticipated over the Sierra crest. While a couple of milder
days with near or slightly above average temperatures are on the
horizon for Tuesday-Wednesday, it appears to be a short lived
warmup as this ridge gives way to colder weather systems dropping
in from the northwest later next week, bringing increased winds
and chances for showers again. MJD

&&

.AVIATION...

South to southwest winds will continue increasing through this
afternoon-evening, with mountain wave turbulence and areas of
shear through late tonight along and ahead of a cold front
passage. Peak gusts of 25-35 kt are expected at most main
terminals thru 12Z Thursday, then become more west with gusts
20-30 kt through Thursday evening, with areas of mountain wave
turbulence continuing. Sierra ridge gusts to 80 kt are likely
through Thursday morning. The next storm Friday-Sunday doesn`t
appear to have as much wind, but more directional changes with a
east-southeast flow Friday-Saturday becoming west and then north
Saturday night-Sunday.

Conditions worsen at the Tahoe area terminals this evening, with
widespread IFR/LIFR conditions with SN most likely from 05-12Z,
and runway accumulations up to 4". Farther south at KMMH, the
potential for these degraded conditions arrives later, mainly
between 09-15Z with more variability in the CIGS/VIS due to the
passage of narrower snow bands. For the main western NV terminals
MVFR conditions due to rain are most likely from 06-12Z. Most
areas will see improved conditions through the day on Thursday
although leftover clouds will produce periodic mountain
obscurations. The next round of impacts to CIGS/VIS returns to the
Sierra terminals on Friday spreading to western NV Friday night,
with areas of rain and snow persisting through the weekend.

MJD

&&

.AVALANCHE...

For tonight`s quick hitting storm...

* Liquid totals (SWE): Generally from 1.0-1.7" for the Sierra
  crest west of Tahoe southward to Alpine County, and 0.75-1.2"
  for Mono County.

* Peak Snowfall Rates: Up to 2"/hour for a 4-8 hour period within
  the 8 PM tonight-4 AM Thurs time frame, with brief bursts up to
  3"/hour.

* Snow-Liquid Ratios: Starting wetter at 8-10:1, then trending
  somewhat drier at 10-13:1 toward end of event.

* Peak Ridge Level Wind Gusts: Southwest 80-90 mph.

MJD

&&

.REV Watches/Warnings/Advisories...
NV...Winter Weather Advisory from 2 PM this afternoon to 11 AM PDT
     Thursday NVZ002.

     Lake Wind Advisory from 5 PM this afternoon to 2 AM PDT Thursday
     NVZ004.

CA...Winter Weather Advisory from 2 PM this afternoon to 11 AM PDT
     Thursday CAZ072.

     Winter Weather Advisory from 5 PM this afternoon to 11 AM PDT
     Thursday CAZ073.

&&

$$


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