Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 211004

Area Forecast Discussion
National Weather Service Reno NV
253 AM PDT Wed Apr 21 2021


Shower coverage mainly south of Highway 50 this morning will
diminish as breezy north winds spread drier air into the region.
After a cooler day, warmer conditions return Thursday and Friday
with more typical afternoon breezy conditions. A late season
winter storm will bring strong winds and periods of valley rain
and mountain snow this weekend into early next week.



Latest satellite imagery showed the compact upper low finally
beginning to track southward at a little faster clip as the next
shortwave upstream approached the Pacific Northwest. Showers and
associated gusty outflow winds along the I-80 corridor will
gradually taper as new shower development occurs farther south
from Alpine/Mono Counties eastward to Mineral/southern Churchill
counties (as the deformation zone shifts southward). Isolated
thunderstorms are still possible close to the core of the low,
mainly later this morning into the afternoon near the Sierra
crest, although overall shower coverage east of the crest will be
diminishing during the afternoon, as steering winds push most of
the showers out of the area (either west of the crest or into
central/southern NV.

It will be cooler today with breezy north winds and decreasing
cloud cover from north to south. Areas of blowing dust in the
Basin and Range should settle down early this morning as the very
tight pressure gradient relaxes a bit. While temperatures will be
cooler today and RH generally higher, the Chalfant/Hammil Valleys
and the Swall Meadows area could still experience near critical
fire weather conditions. Northerly flow will likely channel here
with gusts 30-35 mph.

A weak shortwave ridge moves across CA-NV Thursday and Friday with
warmer daytime temperatures and dry conditions. Modest northwest
winds aloft and good mixing will keep breezy winds going each
afternoon/evening. So the enhanced chop today on Pyramid Lake will
persist into Friday. Hohmann

.LONG TERM...Saturday through next week...

A late season Pacific storm system will move into the region this
weekend into early next week, bringing strong gusty winds, colder
temperatures, valley rains and mountain snow. Forecaster confidence
continues to increase regarding this pattern change.

GFS and EC ensembles continue to increase the chances of seeing the
storm make landfall in California and push precipitation into the
Sierra and even into western Nevada on Sunday. There is a low
chance (less than 25%) that the storm could split to the south,
with much less impact to our area, but at this time it`s most
likely that this storm will hit.

Winds will increase Saturday into Sunday, with widespread valley
gusts up to 40-50 mph. Saturday`s winds will be strongest north of
US-50, then shift to south of US-50 on Sunday. Impacts to air
travel, high-profile vehicles, and lake recreation are highly likely
(90% chance), with a low chance (around 20%) of damaging winds.

Some light precipitation will move into northeast California late
Saturday, but the bulk of the moisture will push into the region on
Sunday as the Pacific moisture plume moves inland. Latest model
consensus has the most likely precipitation in the Sierra around 0.5-
1.0", with up to around 1.5" along the Sierra Crest. We should see
some periods of shadowing and light spillover into western Nevada,
with generally less than 0.10" into the valleys of western Nevada
and up to 0.25" in northeast California.

With snow levels coming down to around 5500ft Sunday night, we could
see a few inches of snow down to Lake Tahoe level and higher amounts
of 6-12" of snow at Sierra pass level. Several inches of snow are
expected in the Eastern Sierra of Mono County as well, but the
heaviest snow will likely be north of Tioga pass.

Below normal temperatures are in store for Sunday and Monday, with
highs in the 50s for western Nevada and 40s in the Sierra.
Temperatures will start to warm back up to near average by the
middle of next week as a ridge builds back over CA/NV. -Hoon



Low pressure moving over the region will continue to bring scattered
showers, pushing south through the day with mainly areas south of
US-50 by later this morning. This includes a 30% chance for a
dusting of snow around KMMH this morning. Periods of LLWS are also
possible through this morning for KMMH, mainly before 15z.

Brisk north winds are in store for today across the region with
gusts up to 20-25kts. There is some blowing dust over west-central
Nevada this morning around KNFL with minor reductions to visibility.

Scattered showers will continue through the day in Mono-Mineral
counties, although focus will shift mainly west of the crest with a
slight chance of thunder for areas along and west of the Sierra
Crest this afternoon.

Quieter weather is expected for Thursday-Friday, with a stronger
Pacific storm system moving into the region this weekend. This storm
system will bring strong gusty winds, LLWS, mountain snow and valley
rain. -Hoon


.REV Watches/Warnings/Advisories...


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