689
FXUS65 KREV 172125
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
225 PM PDT Tue Sep 17 2024

.SYNOPSIS...


* Well-below average temperatures continue through most of the week.

* Another storm system brings additional precipitation chances for
  Wednesday and Thursday.

* A warming and drying trend starts on Friday and continues into
  the weekend as the storm leaves the area.

&&

.DISCUSSION...

Our radar today has shown fewer precipitation returns as yesterday`s
showers exit to the east. In the GOES-18 regional infrared satellite
imagery, there are two distinct circulations rotating nearby. One,
associated with yesterday`s showers, is centered near the OR/ID/NV
borders and will continue to move out of our area today. The other,
associated with our incoming system to arrive Wednesday, is
progressively moving over northern California. With these storms
hanging out so close together, we may see only a bit of filtered
sunshine through clouds today.

Overnight tonight, showers will start to arrive, first to Modoc,
Lassen and northern Washoe counties. During the overnight period,
chances in these areas range 20-65%, with the greater chances found
along the OR border. For this timeframe at these locations, a few
hundredths of additional moisture is possible. Once the system slides
a bit further south, the precipitation will follow. Rain or snow
showers along the Sierra have a 25-35% chance to hear a rumble of
thunder embedded in active showers. By mid-morning, showers will be
heading along and south of I-80. Snow levels will be hovering around
9,500 feet, so accumulating snow in the northern Sierra is less
likely, unless the peaks are above 9,500 feet, such as Mt. Rose. The
bulk of the precipitation will arrive late Wednesday, ans will
remain along and south of I-80 through Thursday afternoon. By the end
of this round of showers and snow, we can expect nearly an inch of
liquid equivalent for the higher Sierra ridges, with leeside valleys
and foothills gathering anywhere from a half an inch to an inch of
liquid. Snow accumulations will mostly be found south of US-50, and
Ebbetts, Sonora and Tioga passes are a focus for this snowfall.
Tioga Pass and Mammoth Mountain both have 30-40% chance to see up to
4 inches of fresh snow. Things will start to dry out late Thursday.

Friday we will be shaking off the chilly air from the exiting
system, as temperatures climb back into seasonal average territory.
The weekend is shaping up quite nicely as a ridging pattern brings
clearing skies, lighter winds and pleasant conditions to get out and
see some fall colors! HRICH

&&

.AVIATION...

* Today we will see variable conditions between VFR to MVFR near
  active rain and snow showers. Some clearing this afternoon will
  give way to increasing clouds this evening. Winds will generally
  remain light, but gusty outflow winds are possible near shower
  activity.

* Lightning is possible (25-35% chance) near active showers for
  KTRK, KTVL, KMMH, with some lower chances (25-30%) for leeside
  terminals KRNO, KCXP, KMEV. Snow showers are expected near KMMH,
  so a rain/snow mix may be possible on the runway. Terrain
  obscuration is likely. Sierra ridge winds will increase late
  Wednesday evening to around 30 kts. HRICH

&&

.REV Watches/Warnings/Advisories...
NV...None.
CA...Winter Weather Advisory from 2 PM Wednesday to 8 PM PDT Thursday
     CAZ073.

&&

$$