707
FXUS65 KREV 042231
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
231 PM PST Tue Feb 4 2025

.SYNOPSIS...

* Snow continues for higher elevations in the Sierra with periods
  of mostly rain over western NV for the rest of today and going into
  tomorrow.

* Gusty to strong winds will continue across the region through
  Friday, although the breezy winds on Wednesday should be
  lighter in comparison.

* A more significant and colder system is expected Thursday into
  Friday with heavy snowfall, strong winds, and colder conditions.

&&

.DISCUSSION...

The atmospheric river event continues to affect the region through
early tomorrow morning. After this system passes, the area
expects to see a break in activity on late Wednesday morning
through very early Thursday morning. The CWA remains with a mostly
southwesterly flow through around tomorrow morning, bringing
ample moisture and gusty winds to the region as the Pacific trough
slowly moves eastward. For tomorrow, forecast guidance shows the
CWA with a westerly flow aloft as the trough reorients itself
indicating a lull in precipitation chances. By Thursday, the upper
trough finally moves inland and bringing another shot at
precipitation and gusty winds. This system still shows signs of
being quicker than the early week`s system with impacts ending by
Friday evening.

Over the weekend and into early next week, the CWA will be at the
edge of the storm track. Therefore, the better chances for
precipitation and gusty winds will be north of the area. However,
breezes, and lingering showers are possible. In addition, the
forecasted angle of the trough will allow for a colder airmass to
advect towards western NV, NE CA and the Sierra with temperatures
10 to 15 degrees colder than usual for this time of the year.
Single digit low temperatures are currently in the forecast during
this time for a good portion of the region as a result.

Here are some updated details for the current system and the
following system later this week:

PRECIPITATION: With snow levels having risen this afternoon to
around 7000 to 8000 feet, Sierra snow continues while lower
elevations can expect to see rain chances through the rest of
today. The Sierra could see 1 to 3 feet of additional snow
snowfall through the rest of today into early Wednesday morning
with the Eastern Sierra crest seeing higher amounts of the range.
For more information on the current winter storm system, please
see the latest update of the Winter Storm Warning product for the
Sierra portions of the CWA. Snow water equivalent (SWE) through
tomorrow morning looks to be between 0.10 to 0.30 inches in the
western NV valleys, 1 to 3 inches in the Tahoe Basin and the
Sierra crest could see around 3 inches of new liquid. The
precipitation will taper for Wednesday morning (SWE around 0.10
inches or less along the Sierra through Wednesday night). On early
Thursday, snow levels will come down and close to the valley
floors during the morning commute, which could cause a rain/snow
mix that may hinder travel across the CWA. Snow levels still look
to come up for the afternoon and evening, changing the valleys
below 5000 ft over to rain, but will tumble back to valley floors
by Friday morning. Widespread snow showers will linger into Friday
(Please see Winter Storm Watch product for the Sierra Mountain
portions of the CWA for more info/potential snowfall timing and
amounts), while some light mountain snow shower chances may be
present through Saturday afternoon. Check the latest road
conditions at nvroads.com or quickmap.ca.gov as you plan your
travel this week. The latest snowfall forecast along with
potential winter weather impacts can also be seen at
weather.gov/rev/winter.

WIND: Models show a jet max moving over the CWA this evening
allowing for wind gusts up to around 45-50 mph in the forecast for
most of the NV portions of the CWA (See the Wind Advisory for more
information). Over the Sierra ridges, gusts could be up to around
85 mph with the highest portions pushing the triple digit mark.
The lull on Wednesday includes the decreased winds somewhat, but
winds will still be kind of breezy with gusts in the 20-30 mph
range. By Thursday with the next system, the focus will be from
the Quad counties and Tahoe Basin area towards Mineral and Mono
county.

IMPACTS:

* Be prepared for hazardous driving conditions in wind prone areas,
  especially for high profile vehicles, especially through early
  evening hours today.

* Travelers should anticipate chain controls, delays, and hazardous
  driving conditions over mountain passes. It is advised to check
  road conditions with Caltrans and NDOT 511 before traveling into
  the mountains.

* Aviation interests should be prepared for frequent periods of
  mountain wave turbulence, rotors, and LLWS.

* The windy conditions will also bring choppy lake conditions with
  wave heights of 2-4 feet for larger area lakes through tonight.

* Other potential impacts include downed trees, fences and
  powerlines, and power outages.

-HC/078

&&

.AVIATION...

* Mountain snow and valley rain continue through today with a
  potential lull by midday tomorrow. IFR/LIFR conditions with
  mountain obscurations and low visibilities due to wintry
  precipitation and some possible localized fog are likely in
  Sierra terminals. Additionally, there will be periods of
  moderate to heavy precipitation, turbulence, LLWS and gusty
  winds.

* WINDS: Turbulence and LLWS remain present through at least
  tomorrow afternoon. Wind gusts along Sierra ridges could exceed
  100 kts through tonight, with surface wind gusts for valley
  terminals ranging between 30-45 kts. Winds decrease tomorrow,
  but expect to remain breezy.

* PRECIPITATION: Snow continues over the Sierra through tonight with
  activity decreasing by Wednesday morning. Spillover periods of
  rain continue over western NV through tonight with no significant
  accumulations forecast, except for this evening.

-HC/078

&&

.AVALANCHE...

Strong winds, high elevation snow, and heavy rain are still
forecast this week for the Lake Tahoe area and southward. A lull
period tomorrow is sandwiched between today`s winter weather
system and another one later this week. Will continue to monitor
the late week system, but it still looks to be a fast moving
system compared to the first system.

* Snow levels: Area snow levels by the late afternoon and evening
  hours look to be between 7000 and 8000 feet, then start rapidly
  during the overnight hours going into Wednesday morning. The
  late week (Thursday-Friday) system`s snow levels currently look
  to start around 2500-4500 feet in the Northern Sierra Mountains
  before dropping down to 2000-3500 feet on Friday. The East-
  Central Sierra sees 5500-6500 feet on Thursday before crashing
  down on Friday.

* Snowfall totals: Additional snowfall amounts with the current
  system through Wednesday morning look to be around 12-16 inches
  for the Northern Sierra, with around 2-3 feet of additional
  snow expected along the highest peaks at Tahoe and southward. As
  of this forecast, the heaviest period of snowfall still are
  expected to take place on this evening and overnight with the
  Tahoe basin seeing up to 8 inches of snow in a 6 hour period.
  Locally higher amounts are also in the forecast towards Mono
  County (up to 12 inches in a 6 hour period) along the highest
  peaks. For the late week system, the latest forecast came down a
  little bit as it currently calls for around 20-30 inches in the
  Sierra crest.

* SWE and SLR: SWE appears to have crept up to between 1.5 to 3
  inches through tomorrow morning in the Sierra crest with some
  localized areas of around up to 4 inches. This system is
  relatively wet, so SLRs will be between 6:1 and 11:1. The late
  week system now looks to bring around 1 to 2 inches of SWE with
  SLRs of 9-16:1 between Thursday and Friday.

-HC/078

&&

.HYDROLOGY...

* A flood warning continues for the Pit River and tributaries in
  northwestern Lassen county. Prolonged moderate to major flooding
  is ongoing near Bieber in Big Valley. Levels are expected to
  increase slowly at the upstream Canby gage into Wednesday before a
  very slow recession. Impacted areas in and around Bieber are ~30
  miles downstream of the stream gage with numerous tributaries in
  between. As of this morning, levels in Bieber are slightly below
  the February 2017 crest. Levels in and around Bieber are expected
  to remain at very high levels for several days and increasing
  flows from Canby maybe counterbalanced somewhat by decreasing
  flows from lower tributaries.

* The Susan River at Susanville has receded about 4` from it`s peak
  Sunday night. While the Susan river is not forecast to return to
  flood stage, a second rise is likely with additional rain this
  afternoon and evening, and renewed minor flooding can not be ruled
  out if this afternoon precipitation comes in with higher rain/snow
  elevations then expected. A flood advisory remains in affect for
  the Susan River and remaining portions of Lassen County.

* Flooding potential is very low in other areas.

* Check cnrfc.noaa.gov for updated forecasts.

-Bardsley/078

&&

.REV Watches/Warnings/Advisories...
NV...Winter Storm Watch from Thursday morning through Friday morning
     NVZ002.

     Winter Storm Warning until 4 AM PST Wednesday NVZ002.

     Wind Advisory until 10 PM PST this evening NVZ001-003-004.

CA...Winter Storm Warning until 10 PM PST this evening CAZ071.

     Winter Storm Watch from Thursday morning through Friday morning
     CAZ071>073.

     Winter Storm Warning until 4 AM PST Wednesday CAZ072.

     Winter Storm Warning until 10 AM PST Wednesday CAZ073.

&&

$$