Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 252013
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
113 PM PDT Tue Sep 25 2018

.SYNOPSIS...

Warm days and cool nights can be expected the next several days
with generally light winds. A pattern change is looking more
likely for the weekend going into the first week of October with
periods of stronger winds, cooler temperatures, and increasing
chances for wet weather.

&&

.DISCUSSION...

Warm and very dry conditions to continue as a ridge strengthens
across the west. This will push high temperatures back around 90
degrees Thursday and possibly Friday in western Nevada valleys.
Lows will continue to be cool thanks to the dry airmass allowing
for excellent radiational cooling.

Changes are on tap for this weekend into next week as the ridge
pinches off and allows jet energy to undercut it and bring an area
of low pressure into the western CONUS. This will bring increasing
winds beginning Friday with the strongest winds likely to be
Saturday and breezy conditions continuing into Sunday. The track of
the main area of low pressure keeps the deeper moisture into the
PacNW, which means much of northeast CA and northwest NV will
remain dry outside of light sprinkles near the Oregon border. The
combination of gusty winds and low humidity could bring increased
fire weather danger on Saturday along with choppy conditions on
area lakes. Please see the fire weather section below for
additional details.

Going into next week, uncertainty remains high due to how, what is
currently Tropical Storm Rosa, will evolve over the upcoming
days. The storm is currently located off the coast of Southern
Mexico and is slated to evolve into a hurricane and then
potentially curve toward Baja (GFS) or remain in the Pacific with
some moisture advected into the longwave western trough (EC). A
system of this magnitude could greatly affect the pattern across
the west, however it`s far too early to tell exactly how this will
evolve, especially given the significant model ensemble spread.
What does appear likely, is a cooler and potentially wetter
pattern going into the start of October with general troughiness
over the west and ridging in the east. -Dawn

&&

.AVIATION...

With high pressure strengthening above, VFR conditions with east-
northeast winds around 5-10 kts can be expected for this afternoon
into the early evening hours. Even lighter winds are forecast for
tomorrow afternoon through Thursday as the high sits directly
overhead western Nevada and the Sierra.

Southwest winds pick up a bit, along with an increase in cloud
cover, for Friday afternoon and will strengthen through the weekend
as a low pressure trough sweeps through towards the north.
Precipitation looks minimal and confined to the northern portions of
the California coast.

As the shortwave trough exits to the northeast, the weather pattern
looks to be more active with chances for precipitation and gusty
winds as we enter into October. -LaGuardia

&&

.FIRE WEATHER...

Main concern is this weekend with the upper low moving onto the
coast. The models have trended toward more of a glancing blow and
into the Pacific Northwest. As a result, northeast California and
western Nevada will be more in the sweet spot for gusty winds and
low RH. In the meantime, it will continue to be very dry ahead of
the low with poor overnight RH recovery, but winds will be light
into Friday morning.

Winds increase a little Friday afternoon, but the main event will be
Saturday. The potential is there for some gusts 35-45 mph Saturday
afternoon with the strongest winds west of Highway 95. RH will
increase a bit as temperatures cool, but it still looks to be 10-20%
for minimums. The models have not been all that consistent with this
low, but if these trends continue and there is more consistency, a
Fire Weather Watch may be warranted.

Sunday winds remain gusty, but it will be cooler. There will still
be some concerns over fire zones 273/459 that day if the winds
remain strong. Those southern areas do not look to see much
cooling with it remaining very dry. X

&&

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

$$

For more information from the National Weather Service visit...
http://weather.gov/reno


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