Technical Forecast Discussion

965
FXUS65 KREV 160949
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
249 AM PDT Mon Sep 16 2024

.SYNOPSIS...

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

* Another cold storm brings continued below average temperatures and
  additional precipitation chances Tuesday into Wednesday.

* A warming and drying trend follows for the remainder of the week.


&&

.DISCUSSION...

Current radar imagery depicts a band of stratiform precipitation
extending in a north-south orientation over Mineral, Churchill, and
Pershing counties early this morning. This band is attributed to
increased moisture transport around the eastern periphery of an
upper-level low moving inland into northern California this morning.
This low will slowly track east through the morning hours, with
widespread showers gradually wrapping around the low through the
remainder of the day. Latest high-resolution guidance shows this
band taking residence over the Basin & Range through a majority of
this morning, wrapping northwest into areas north of I-80 by the
early afternoon, then dropping south along the Sierra and western
Nevada through the evening. Given the residence time of the band
over the Basin & Range, heaviest precipitation accumulation is
expected in this area, with a 20-30% chance to see over an inch
of liquid through Tuesday morning for areas east of US-95. Wetting
rains (>0.10") are a good bet for western Nevada and northeastern
California with a 80-90% chance. Due to the mainly southeasterly
flow associated with this system, chances for wetting rains drop
off significantly for Sierra valleys, with recent guidance only
indicating a 20-30% chance. Some isolated thunderstorms are
possible through this evening, with a 15-20% chance mainly north
of I-80 and east of US-95.

This system has brought a much cooler airmass to the region, with
snow levels dropping to around 7500 ft this morning, then increasing
to 8000-8500 ft through the remainder of the day. With showers not
expected to impact the Sierra until the warmer parts of the day, any
snow accumulations will mainly be confined to the Sierra above 8000
ft. Brief lowering of snow levels is possible under heavier showers,
so some flakes mixing down to pass level is not out of the question.
Regardless, travel will be slick across the entire region given this
is the first rain we have seen in quite some time. Leave extra time
and space for your commutes today.

The upper-low swiftly exits the region on Tuesday, though some
showers may linger over the Basin & Range through Tuesday morning.
Another storm follows quickly on its heels, though digs a bit
farther west and south Tuesday into Wednesday. This system will
bring widespread precipitation chances once again, with early
high-resolution guidance showing showers spreading into the
Sierra early Wednesday morning, then sliding southeast. This
system will be a bit warmer, with snow levels around 9000-9500 ft.
As such, expect precipitation to fall mainly as rain, with the
exception of the high Sierra in Mono County.

Temperatures will be quite brisk through Thursday under the
influence of these two systems, with high temperatures struggling to
break the 70 degree mark even for warmest western NV valleys. The
coldest day will be Wednesday as skies clear behind the secondary
system, with temperatures 20-25 degrees below average. Ridging
developing over the eastern Pacific begins to nudge into the western
US through the remainder of the week, allowing for a gradual warming
and drying trend to prevail into next weekend. Whitlam

&&

.AVIATION...

Showers mainly impact areas east of the US-95 corridor through 18z,
before spreading westward through the remainder of the day.
Intermittent showers are expected between 21z Mon-12z Tue for KRNO-
KMEV-KCXP, 00z Tue-12z Tue for KTVL-KTRK, and 20z Mon-03z Tue for
KMMH. Expect mountain obscurement with periods of MVFR conditions
under heavier showers. Isolated thunderstorms are possible for
western NV this afternoon and evening. More typical westerly
afternoon breezes are expected today, with gusts to 15-20 kts.

FL100 winds increase overnight tonight through Tuesday ahead of
another storm system moving into the region, yielding increased
concerns for LLWS and mountain wave turbulence through early Tuesday
afternoon. Whitlam

&&

.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&

$$

NWS REV Office Area Forecast Discussion