Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 120909
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
209 AM PDT Tue Mar 12 2024

.SYNOPSIS...

Scattered, light snow showers will continue in the Sierra through
this afternoon, in addition to some spotty rain showers into western
NV. Otherwise, expect winds to continue ramping up regionwide into
this afternoon. Drier weather settles in Wednesday, though
confidence is increasing for a strong northeast-east wind event in
the Sierra from Wednesday to Friday.

&&

.DISCUSSION...

Current radar imagery reveals light snow showers ongoing in the
Sierra, mainly around the Tahoe Basin, with some scattered rain
showers developing over the Basin & Range. Webcams around the Tahoe
Basin show some accumulating snow on Sierra passes like Donner and
Echo, which may cause some minor travel delays for the morning
commute. Otherwise, main forcing with this weak system is expected
to last through around mid-morning, with precipitation becoming more
convective and spotty in nature through this afternoon. Signals for
enhanced CAPE values are evident in EFI guidance for eastern
Pershing & Churchill counties, prompting an introduction of 10-15%
chance of thunder for these areas this afternoon.

An upper-level jet associated with this weak system will also bring
a continued uptick in west-southwest winds through this afternoon.
700-mb winds peak around 40-50 kts this morning, indicative of 80-
100 mph gusts for Sierra ridgelines. Precipitation may dampen winds
through early morning for portions of the Sierra, but decreasing
coverage this morning will allow winds to quickly pick up and remain
elevated through this afternoon. Gusty winds are also expected down
to valley floors, with gusts 30-40 mph commonplace for most
locations.

The shortwave moving across the region today looks to close off over
the northern Intermountain region on Wednesday. This closed low then
undercuts a building ridge along the coast of British Columbia,
slowly drifting southwest into the Great Basin by Thursday. The
combination of this slow progression in addition to the favorable
northeast-east flow introduced over the region during this period
will create ideal conditions for a strong wind event along and west
of the Sierra crest. While winds will generally remain strong along
Sierra ridges for the entire period Wednesday through Friday, there
appears to be two distinct peaks in upper-level flow -- one early
Thursday morning and the other early Friday morning. The first peak
on Thursday looks the strongest, with current NAM guidance
indicating upwards of 70 kts at 700-mb, and the more "modest" GFS
showing 60 kts. Needless to say, damaging winds are likely along the
Sierra crest, with trees more vulnerable during this event as
easterly is not the typical prevailing wind direction. As such,
these strong winds may lead to downed trees and power lines, leading
to power outages for our Sierra communities.

Winds begin to quickly taper off overnight Friday as the low drifts
out of our region, with the aforementioned ridge taking its place
over the western US for the weekend. This pattern will promote
continued dry conditions, with a gradual warming trend to well-above
average temperatures by the start of next week. This warming trend
will be a stark contrast to the conditions early this month...we`ll
be trading powder for corn next week as blended guidance for Tuesday
is showing high temperatures in the low 70s for western NV and mid-
50s for Sierra communities. Whitlam

&&

.AVIATION...

* Tahoe Basin terminals including KTRK-KTVL will continue to see
  periods of MVFR conditions through around 14-15z as light snow
  showers bring lowered CIGS/VIS. Additional snow accumulations at
  these terminals will generally be a trace up to an inch. Precip
  becomes more spotty and convective through this afternoon. All
  other terminals will see generally dry conditions today, outside
  of convective rain showers across the west-central Basin & Range
  this afternoon.

* SW winds will continue to increase through this afternoon, with
  FL100 winds between 40-50 kts through around 00z leading to
  widespread areas of LLWS and turbulence. Surface wind gusts
  between 30-40 kts are possible for most terminals this afternoon.

* Clearing skies return Wednesday, but increasing NE-E winds bring
  renewed LLWS/turbulence concerns through Friday.

Whitlam

&&

.REV Watches/Warnings/Advisories...
NV...Lake Wind Advisory until 8 PM PDT this evening NVZ002.

CA...Lake Wind Advisory until 8 PM PDT this evening CAZ072.

&&

$$


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