Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 211023

Area Forecast Discussion
National Weather Service Reno NV
323 AM PDT Sat Sep 21 2019


Temperatures will be warmer today with the warmest of the weekend
on Sunday before another cold front brings gusty winds, shower
chances, and a slight cool down into Monday. A warmup will occur
Tuesday-Thursday before another colder weather system moves into
the region late next week.



Tranquil weather across the region this morning with a clear sky,
calm winds, and average temperatures as a shortwave ridge builds in
from the west. Some freezing fog is anticipated in the Sierra
valleys of Plumas/Lassen counties as well as areas around the Tahoe
Basin, including Truckee and Martis Valley due to the clear skies
and efficient radiational cooling. This should dissipate by
sunrise. High temperatures this afternoon will be warmer compared
to yesterday`s with highs in the high 60s in the Sierra and low to
mid 70s for western Nevada. These conditions are expected to take
us through early Sunday before our next active weather system
makes its way from the northwest.

By Sunday afternoon, cloud cover along with southwest winds are
likely to increase ahead of a shortwave trough coming in from the
northwest. As for temperatures, they look to be the warmest of the
weekend with highs in the 70s to low 80s. As mentioned in the
previous forecast, the timing of the trough and its associated cold
front passage has slowed down a bit. This still looks to be the case
according to updated model guidance from this morning.

Breaking down the timing:

*Sunday afternoon: Cloud cover increases northwest to southeast with
a pick up in southwest winds. Winds do not look impressive with
sustained of 15-20 mph and gusts of up to 30 mph forecast. As
always, winds in wind prone areas such as the Sierra ridges, the US-
395 corridor, and US-95 near Walker Lake could see stronger gusts.

*Sunday evening: The gusty west-southwest winds continue with rain
showers moving in along the cold front. Better chances for showers
mainly for areas north of I-80.

*Early Monday morning: Winds shift to the north-northwest decreasing
a bit and showers migrate to the southeast into Mineral County as
the cold front moves through the region.

*Monday morning/early afternoon: Rain showers are possible due to
upslope flow along the eastern Sierra in Mono County. Winds still
breezy from the north-northeast with cloud cover clearing.

*Monday`s Temps: With the cold frontal passage, high temperatures
will once again be 5-10 degrees below normal for this time of year.
Western Nevada in the low 70s and the Sierra in the 60s. As for
lows, no major freezes anticipated with temps around average.

Weather conditions continue to improve for Monday evening into
Tuesday as high pressure tries to build over the region from the
west. -LaGuardia

.LONG TERM...Tuesday through Friday...

All of the changes in the extended portion of the forecast were made
in the Thursday/Friday time frame. These include increasing POPs for
Friday and adding some small POPs as early as Thursday afternoon to
account for a little quicker timing with the next system.

With a ridge to the west and a trough to the east...the first part
of the extended forecast should be rather quiet. Weak west-northwest
flow aloft and light surface winds will stick around Tuesday and
Wednesday. There should be a warming trend as well. Highs could
reach the lower to mid 80s for the lower valleys each day; Wednesday
should be a little warmer than Tuesday.

Changes start Thursday as the next longwave trough begins to drop
south from just off the Pacific Northwest coast into our area by
Friday. Some model solutions are now indicating the leading edge of
a band of showers moving south of the Oregon border by late Thursday
afternoon. This is a bit faster than previous models showed...but it
has good support from a broad spectrum of solutions. We added some
low end POPs for late Thursday into Thursday night to account for
this possibility.

The main trough gets into the region Friday. This is a rather cold
system and taps copious moisture. We have lowered temperatures a bit
more for Friday and increased both POPs and QPF during the day and
into Friday evening. Snow levels are likely to drop as low as 5500
feet in northeast California. That is where the heaviest QPF is as
well. This could result in some of the higher elevations north of
Interstate 80 picking up an inch or two of snow by late Friday
evening. Farther south into the Sierra total precipitation amounts
look lighter and snow amounts should be rather sparse...especially
south of Highway 50.

The changes Friday could be rather sudden with temperatures falling
through the afternoon. Gusty winds are possible as early as Thursday
night into Friday morning with some valley locations exceeding 35



Light winds and clear skies are forecast for all area terminals for
today as high pressure moves into the region. Some FZFG lowering
visibility down to LIFR/IFR conditions is still possible early this
morning mainly for KTRK due to the clear sky and calm winds. If fog
does develop... it should dissipate ~16Z.

Weather conditions worsen starting Sunday afternoon with increasing
southwest winds, cloudy skies, and chances for showers through
Monday afternoon as a cold front moves through the region.


.REV Watches/Warnings/Advisories...


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