Flooding and Heavy Snow in Nevada, March 9 to 22, 2023

Area Forecast Discussion
National Weather Service Elko NV
248 PM PST Thu Mar 9 2023

.SYNOPSIS...An atmospheric river event is set to bring strong
gusty winds, warmer temperatures, and valley snow changing over to
rain tonight into Friday. Snow levels will lower on Friday night
as scattered rain and snow showers continue through the weekend.
Mountains are expected to receive moderate to heavy snow amounts
through the weekend. A wet pattern continues through next week
with periods of rain and snow showers and closer to normal
temperatures.

&&

.SHORT TERM...This afternoon through Friday night

The Atmospheric River event is on our doorstep. Southerly winds
will be on the increase this afternoon into this evening and Wind
Advisories will go into effect starting at 10 pm in most of
northern and central Nevada as winds of 25 to 35 mph are expected
with gusts up to 50 mph. This will continue into late Friday
evening. The exception will be in Humboldt County, where winds by
late morning Friday will increase to 35 to 45 mph with hazardous
wind gusts to 70 mph and the advisory there will upgrade to a High
Wind Warning at that time and continues through the late evening.

Showers will also be on the increase this evening into the night
as the system begins to push into Nevada. Snow levels will start
off on the valley floors before steadily rising during the
overnight hours into the early morning hours on Friday. This will
allow for some light valley snow accumulations from about I80
north before the changeover to rain occurs. A Winter Weather
Advisory is in effect beginning at 4pm this evening in both
Humboldt and northern Elko counties for elevations above 6500 feet
for moderate to heavy snow amounts through Friday evening. The
Ruby mountains will be under a Winter Storm Warning for this
period as well. Lows will occur early in the evening and then rise
overnight as some valleys climb into the 30 and 40's.

Friday into Friday night will see the main rain event and a Flood
Watch remains in effect for Elko County on Friday through Monday
due to the expected rain on snow coupled with strong gusty
southerly winds and warming temperatures. Please see the Hydro
section below for more details. Snow levels will be from 7000 to 7500
feet in northern Nevada and 7500 to 8500 feet in central Nevada.
Snow levels will begin to drop on Friday afternoon in evening in
northern Nevada as a cold front moves in. The cold front is strong
and there will be enough instability to create snow squall
conditions along the front. The precipitation, however, will
starts to decrease behind the front and snow amounts in the
valleys Friday night will be an inch or two. This will also slow
down the snow melt. The cold front, however, will stall in central
Nevada, and snow levels of 6500 to 7500 feet are expected there
overnight as precipitation continues. Lows will be in the 20's
and 30's as winds decrease, though coldest valleys in Elko County
could drop into the teens behind the front.

.LONG TERM...Saturday through next Thursday.

By Saturday a mostly zonal flow pattern will be situated over the
Great Basin. Perturbations embedded within the upper flow will
provide ample energy to keep isolated to scattered showers in the
forecast thru the weekend. At the surface, what can best be
described as a stationary front, will be draped west to east thru
the middle of the forecast area. This will provide a notable south
to north temperature gradient. Most of the weekend precip
activity will be focused across N. Nevada. Precipitation type is
currently indicated to be valley rain/snow during the day with
snow levels lowering enough overnight to bring snow showers into
the valleys. Valleys of northern Elko County, and to a lesser
extent northern Humboldt County, may be cold enough to observe
snow showers thru the day, but will ultimately depend on how far
south the frontal boundary sets up. Any valley snow accumulations
that take place overnight look to generally be around an inch or
less each night. Locations that maintain light snow showers thru
the day may trend closer to one to two inches per day. Winds will
be generally light yet breezy at times. Daytime high temperatures
Saturday will be mid 30s to mid 40s for northern Nevada with low
40s to low 50s across central Nevada. Overnight lows will be
mostly in the low 20s to low 30s, mid teens for the usual cold
locations. Daytime highs Sunday look to warm a couple of degrees
with a similar distribution as Saturday, while overnight lows
maintain low 20s to low 30s for most.

By Monday a strong upper trof is indicated to dig into the
western U.S. from the west/northwest. Another robust moisture
plume will be associated with this boundary and surface cold front
and is expected to move into the forecast area in the Tuesday
time frame. This currently looks to be another warm spring season
system and is expected to bring more measurable valley rain and
mountain snow along with gusty winds. Indications are that precip
totals and wind gusts will be slightly more modest than tomorrows
(Fridays) event, but confidence is not strong at this time given
some discrepancies among numerical guidance on how the upper trof
and upper pattern in general evolves. Temperatures will be near
average Monday and Tuesday, likely cooling several degrees for
Wednesday post frontal with weather remaining active.

Weather finally breaks in the Thursday time frame with an upper
ridge potentially moving over the region. This would bring dry
weather and clearer skies along with warming temperatures.

&&

.AVIATION...Active weather moves in this evening
from the west with impacts forecast to be present at all
terminals during the next 24 hours. -SHSN overnight will give way
to some combination of -SHRASN, -SHRA, -RA, and VCSH at times
during the day tomorrow. MVFR and IFR conditions are forecast
thanks to reductions in visibility and low ceilings. Winds will
also be gusty with gusts around 40kts expected.

&&

.HYDROLOGY...A warm atmospheric river event will move into most
of northern and portions of central NV Friday. The combination of
rain on snow, afternoon high temperatures warming into the mid
40s to low 50s, and strong gusty southerly winds will all
accelerate the melting of the current (and well above normal)
snowpack.

The heavier rainfall amounts are expected Friday into Friday night
across most of Humboldt, Elko, Lander and Eureka, and White Pine
counties, where valley areas should receive between a quarter and
a half inch of rain, with some locally higher amounts possible.
Snow levels Friday afternoon will rise to between 7000 to 7500
feet across northern NV, with snow across higher elevations.
Lighter precipitation will linger into the weekend with up to an
additional tenth to a quarter inch of rain possible.

This warm, rain on snow event with the strong gusty winds will
result in accelerated melting of snow, the extent of which is
still uncertain. At a minimum, ponding of water, muddy roads, and
rises to creeks, streams and rivers is likely. Rivers will be on
the rise and there is an elevated risk for river flooding. A Flood
Watch is in effect from Friday through the weekend in Elko County
to account for these conditions.

&&

.LKN Watches/Warnings/Advisories...
Wind Advisory from 10 PM this evening to 10 AM PST Friday
Humboldt County.

High Wind Warning from 10 AM Friday to 1 AM PST Saturday
Humboldt County.

Winter Weather Advisory from 4 PM this afternoon to 10 PM PST
Friday ABOVE 6500 FEET in Northern Elko County.

Wind Advisory from 10 PM this evening to 1 AM PST Saturday
Northern Elko County...Northern Lander County and Northern
Eureka County...Northwestern Nye County...Ruby Mountains and
East Humboldt Range...South Central Elko County...Southern
Lander County and Southern Eureka County...Southwest Elko
County...White Pine County.

Flood Watch from late tonight through Monday evening Northern
Elko County...Ruby Mountains and East Humboldt Range...South
Central Elko County...Southeastern Elko County...Southwest Elko
County.

Winter Storm Warning from 4 PM this afternoon to 10 PM PST
Friday ABOVE 6500 FEET in Ruby Mountains and East Humboldt Range.

&&

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