Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 202305
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
305 PM PST Tue Feb 20 2024

.SYNOPSIS...

The Sierra region continues to see periodic snow showers pass
through during the afternoon and evening causing some possible
travel impacts. Wintry precipitation chances then spread into
western NV going into Wednesday morning before tapering off across
the region by the afternoon hours. Dry conditions with a slight
warming trend is expected for the region going into the weekend
followed by a cold front bringing precipitation chances back early
next week.

&&

.DISCUSSION...

Rest of today through Wednesday Afternoon: With the REV CWA
having a southwesterly upper air flow due to an upper air low
residing to the west of OR, models depict wintry precipitation
chances continue for the Sierra portions of the region during the
afternoon and going through the night into Wednesday morning.
GEFS and ECMWF ensembles show higher amounts of IVT (>250 kg/m/s)
from the ongoing AR (Atmospheric River) event moving through
southern CA, southern NV, as well as northwestern AZ (where the
upper air jet is stronger) keeping better moisture south of the
REV CWA. A Winter Weather Advisory continues through Wednesday
morning for the northern portions of the Sierra region of the CWA
with Mono County having being added at 10 PM PST tonight for
potential winter weather impacts to travel. For more information
on this product: please visit www.weather.gov/rev/winter for the
latest updates as well additional forecast snowfall totals. But
generally around 3-6 inches of additional snow is expected for
the areas in the advisory with locally higher amounts possible.
Model forecast soundings are also showing the potential for south-
southwesterly winds gusting up to around 45 mph for the Greater
Tahoe Area. Forecast guidance keeps the higher CAPE values
(around 500 J/kg) west of the CWA during the late
afternoon/evening hours of Tuesday, but a rumble of thunder or two
cannot be completely ruled out. Precipitation chances spread into
western NV going into the evening and lasting through the
Wednesday morning hours. P-type looks to be mostly rain for the
valley areas though some light snow could be mixed in which might
make roads for the Wednesday morning commute a bit slick. Minimal
if any snowfall accumulation is anticipated at this time. By
Wednesday afternoon, models project the precipitation tapering off
and out to the east.

Wednesday evening through Saturday Night: Forecast guidance shows
an upper air ridge building over the REV CWA starting on Wednesday
night that starts to move out of the region on Saturday as an
upper air trough begins to progress down into the Pacific
Northwest. As a result, the region expects dry conditions to
prevail through remainder of the week with surface high pressure
in the western CONUS particularly on Thursday and Friday. Models
also show a slight warming trend going into the weekend with some
portions of western NV possibly hitting the 60 degree mark on
Saturday afternoon currently.

Next week: Extended models show the base of the aforementioned upper
air trough progressing southward and making it over the REV CWA on
Monday morning. Because of this upper air set up, the same models
show a cold front associated with a Canadian surface low starting to
push through the region during the morning hours. With this feature,
wintry precipitation chances are anticipated to return late
Sunday/early Monday. The best chances (around 40-50%) are currently
seen in the Sierra Mountain portion of the CWA on Monday afternoon.
Latest NBM snowfall probabilities show a 30-50% chance for greater
than 4 inches of snow for the Sierra crest in 48 hours by Monday
night. Will continue to monitor these precipitation chances as it
currently looks to be next chance for impactful weather. Beyond
that, the forward portion of an upper air ridge looks to move
into the area on Tuesday with the trough progressing eastward
which will lower precipitation chances once again.

-078

&&

.AVIATION...

The main weather concern will be periods of rain and Sierra snow
through Wednesday morning, lowering CIGS/VIS to MVFR/IFR thresholds.
Precipitation will be bimodal during this time, beginning with
spotty, hit-or-miss showers from 21-02Z this afternoon before
transitioning into a more steady rain/snow from stratified
upstream convection. Runway accumulation at KTRK/KTVL/KMMH will be
light with 1-3" possible through Wednesday morning. A rain to
rain/snow mix is favored for KRNO/KCXP/KMEV with only a 10% chance
of receiving 1" of snow. Other western Nevada terminals such as
KNFL, KHTH, KLOL will mainly see rain.

Shower activity will wane after 10-12Z Wednesday, allowing for
improved flight conditions for the remainder of Wednesday. Wednesday
afternoon may feature another bout of hit-or-miss type snow showers
in the Sierra, which would briefly lower CIGS/VIS and obscure
surrounding terrain. Ideal flying weather is expected after
Wednesday with widespread VFR conditions and light winds before
another storm arrives as early as late Sunday.

-Salas

&&

.AVALANCHE...

The previous forecast looks to be mostly on track through the
rest of today and going into tomorrow. Snow shower chances are
expected to continue through Wednesday morning bringing some
additional snowfall accumulation to the Sierra Mountain region before
tapering off during the afternoon hours.

Rest of today-Wednesday: SWE totals continue to be around 0.25-0.75"
along the crest north of US-50 while dropping to 0.10-0.25" south of
US-50 into Mono County. SLRs stay around 12-15:1 and snow levels
remain the same as well (4500-5500`). Additional snowfall totals
range between 2-5" with localized higher amounts possible along
the Sierra crest from Alpine to Mono Co. For the Tahoe area,
between 2-6" of additional snowfall is possible with some
localized higher amounts along the crest. Wind gusts are forecast
to be around 45 mph from the south-southwest through this evening
in the Tahoe area that should slow down by the overnight hours.

-078

&&

.REV Watches/Warnings/Advisories...
NV...Winter Weather Advisory until 10 AM PST Wednesday NVZ002.

CA...Winter Weather Advisory until 10 AM PST Wednesday CAZ071-072.

     Winter Weather Advisory from 10 PM this evening to 10 AM PST
     Wednesday CAZ073.

&&

$$


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