891
FXUS65 KREV 152031
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
131 PM PDT Sun Sep 15 2024

.SYNOPSIS...

* Windy conditions will persist into early evening, then winds
  decrease overnight with more typical breezes Monday.

* Well below average temperatures expected Monday, in addition to
  widespread rain showers and high elevation snow.

* Another cold system expected Tuesday night and Wednesday,
  bringing additional chances for rain and high elevation snow.

&&

.DISCUSSION...

* Winds have increased this afternoon with surface gusts 30-35
  mph, locally to 40 mph and ridges around 60 mph. These winds are
  on track to continue into this evening before diminishing
  overnight. Fortunately, RH has remained elevated and generally
  above 20% in the Sierra and along the Hwy 395 corridor. Cannot
  rule out some locally critical conditions the remainder of the
  afternoon before winds decrease and moisture increases further
  this evening/overnight.

* Latest guidance has not departed much from previous thinking
  with a couple of colder storm systems in line to bring much
  cooler weather and good chances for wetting precipitation
  through Wednesday (60-80% chance of seeing at least 0.25" by
  late Wednesday in any one spot). The first storm drops into
  northern CA tonight and moves across the Great Basin Monday-
  Monday night while the second one drops into the region Tuesday
  night and Wednesday. Temperatures will be much below normal for
  Monday and Wednesday when rain chances are highest. Where bands
  set up, afternoon highs will struggle to reach 50 degrees in the
  Sierra and 60 degrees for lower elevation sites. Highs both days
  will be around 20-25 degrees below average (more like late
  October) with hard freezes returning to Sierra valleys Tuesday
  morning as we see a brief clearing in between storms.

* For the first storm, showers will increase late tonight across
  far western NV and the Tahoe Basin then shift into western NV
  during the afternoon/evening Monday. Latest blended guidance
  continues to favor west central NV, but some CAMS (particularly
  the HRRR) are bullish with convective bands over Reno-Tahoe
  Monday morning. This could result in some thunder as well as a
  brief lowering of the snow levels (as low as 6000 feet) -
  possibly bringing an inch or two of snow and impacts to higher
  passes. Antecedent conditions are quite warm, so accumulations
  would be brief - still worth watching if you have travel plans
  across Sierra passes in the morning. Otherwise, a good wetting
  rain is likely, especially across western NV east of Hwy 95 and
  over NW NV where the chance of seeing 0.50" of rain is 40-60%,
  locally higher near any storms. Lesser amounts are expected
  along the eastern Sierra towards Mammoth with this first storm.
  Snow levels outside convection will range between 7500-8000 feet
  with several inches of accumulation on the higher peaks of the
  Sierra above 8000 feet.

* The second storm drops a bit farther west and south with
  showers/isolated storms favoring the Sierra and areas south of
  Hwy 50 Tuesday night/Wednesday as it tracks across southern NV.
  Snow levels are not as low with this system, so rain will be the
  predominant precipitation type outside elevations above
  9000-9500 feet. Quite brisk northeast winds are possible across
  the Sierra ridges/higher terrain Wednesday night as the upper
  low exits. A drier and milder pattern returns late week into the
  weekend.

Hohmann

&&

.AVIATION...

* Strong gusty southwest winds will persist into early evening
  with gusts at area terminals 20-30 kts through 01-03Z. FL100
  winds will remain elevated 30-35 kts through 06-09Z (Mt top
  gusts 50-55 kts), then decrease overnight. This will lead to
  some moderate turbulence along with a short period of LLWS along
  the eastern Sierra (KMEV-KMMH) as surface winds weaken first
  (02-07Z).

* Moisture and instability increase 06-12Z with an expanding area
  of showers near the Tahoe Basin/far western NV terminals,
  lasting through 16-18Z Monday. There is about a 10-15% chance of
  a thunderstorm in this area with heavier showers and cannot rule
  out light snow accumulation of 1-4 inches above 7000 feet.
  Higher terrain obscurement with periods of MVFR down at terminal
  levels where heavier bands develop. Showers and isolated storms
  (15-25% chance) then transition to western NV, favoring KLOL-
  KNFL-KHTH Monday afternoon/evening.

* A second cold system will bring another round of rain and high
  elevation snow Tuesday night-Wednesday with daytime breezy
  conditions. We will have to watch Wednesday night for potential
  strong northeast ridge winds/increased turbulence as the
  systems exits.

Hohmann

&&

.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.

&&

$$