Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 211020

Area Forecast Discussion
National Weather Service Reno NV
320 AM PDT Fri Jul 21 2017


Areas of smoke from the Detwiler Fire could produce periods of
degraded air quality and haze for the Sierra and portions of
western Nevada today. Dry conditions will continue with
temperatures warming a few degrees over the weekend. Low pressure
off the West Coast may bring a chance for showers and
thunderstorms Sunday through the middle of next week.



Dry and stable southwest flow aloft will prevail across northeast
California and western Nevada through Saturday as an upper ridge
centered over southern Nevada strengthens over the region. With
the building ridge, high temperatures will edge up to the upper
90s to low 100s for the lower valleys of western Nevada by

As far as smoke impacts from the Detwiler Fire, as always it
depends much on fire intensity and wind flow. Currently, air
quality and airport sensors in the Reno-Tahoe area and down into
Alpine and far northern Mono County indicate improved conditions
versus yesterday morning at this time. Also, winds at ridgetop
are already much lighter than previous nights and GFS/NAM
simulations for winds near and below the Sierra crest show a
turning to light southeast to east tonight through Sunday morning.
This should allow for overall better air quality east of the
crest with a lessening of hazy conditions, especially away from
the immediate Sierra crest and on the west slopes of the Sierra.

Turning to Sunday, flow between low pressure off the California
coast and the upper ridge over central and eastern Nevada will
bring gradually increasing moisture with southerly flow aloft.
With slight cooling aloft in simulations (possible weak upper
wave) and hot afternoon temperatures, there is expected to be
sufficient instability for cumulus buildups with at least
isolated showers and thunderstorms. Favored initiation zones
currently look like Mono and Mineral Counties as well as north of
Susanville, with convection pushing off to the north and northeast
in the flow aloft by Sunday evening. -Snyder

.LONG TERM...Monday through Friday...

No major changes in the forecast thinking for next week. Shortwave
trough moving through far northern CA next week will keep a few
thunderstorms in the forecast for western Nevada. Increasing
southwest flow over the Tahoe Basin and northeast CA will help to
reduce thunderstorm chances for those areas. Temperatures will drop
a few degrees on Tuesday as the trough moves in. By Thursday and
into next weekend we will see temperatures increase once again as
the ridge builds back into NV/CA. There looks to be some progressive
zonal flow over the Pac NW late next week, which could mean
increasing winds in our area, especially north of I-80. Hoon


The main aviation concern for the next couple of days will be the
smoke and haze from the Detwiler Fire in Mariposa County, California.
Limited reductions to visibility area expected for today, with
mainly slantwise visibility being impacted especially during the
morning hours. Outside smoke/haze, generally VFR conditions with
typical west winds in the afternoon up to 20kts. Hoon


.REV Watches/Warnings/Advisories...



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