Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 190912

Area Forecast Discussion
National Weather Service Reno NV
212 AM PDT Sun Aug 19 2018


The streak of 90 degree days will continue across the Nevada
valleys over the next few days, with the warmest temperatures
expected today. Cooler overnight lows will provide some relief
from what could be the hottest summer on record. Gusty afternoon
and evening winds may produce short periods of critical fire
weather conditions the next few days.



A generally quiet weather pattern will prevail for the next few
days, although some breezes are expected each afternoon and
evening. Monday looks to have the best chance for a bit of
enhanced wind gusts beyond the typical zephyr--see the Fire
Weather segment below for more details.

The warmest temperatures of the upcoming week are expected today,
with Reno having a chance of reaching 100, which would be a daily
record high and the 20th 100+ degree day in this summer of many
heat-related records (although with all of these days of triple
digit heat, Reno never reached 105 degrees this year). We will
then see a slow cooling trend with highs easing back to the lower
90s in lower elevations by Tuesday.

Dry weather will prevail regionwide through Monday, with some
afternoon cumulus mainly south of US-50. However, with the latest
guidance dropping the low farther south into far northern CA
Tuesday afternoon, a small deformation zone with lift and
instability could set up and produce a few showers and
thunderstorms near the Oregon border. While confidence is still
relatively low in this possibility due to variance in the low`s
projected location, we will increase cloud cover over this area
with precip chances raised to around 10% from Cedarville northward
for Tuesday afternoon-evening.

As for smoke and haze, it is probable (mainly haze) over most
areas this morning, but with the increasing southwest to west
winds, many areas will clear out later today. The areas most
likely to be affected by smoke and haze for the next few days will
be far northeast CA-northwest NV, and portions of Alpine, Douglas,
Lyon, Mono and Mineral counties downwind from the Donnell and
Lions fires. Some smoke from the multiple Oregon/Northern CA fires
could settle into areas as far south as Susanville and Lovelock
during the next couple of nights, before being pushed out by the
wind during the day. As always, this smoke/haze projection assumes
similar activity levels on the existing fires, and no new large
fire starts. MJD

.LONG TERM...Wednesday through next weekend...

No wholesale changes this morning. An upper level shortwave will
be exiting Wednesday with a general southwest to west flow keeping
things dry across the Sierra and western NV. Models continue to
indicate troughiness redeveloping along the west coast next
weekend, which would suggest more dry weather on tap with
temperatures not getting excessively warm but remaining above
normal for mid-late August. This translates to upper 70s/lower 80s
Sierra valleys and mostly 90s for western NV valleys. With the
main jet stream to the north, winds will remain typical with
gusts 20-25 mph each afternoon. Hohmann



Increasing southwest flow early this week will have a tendency to
clear the air across the Tahoe Basin and much of western NV while
areas north of Susanville and Gerlach as well as immediately
downwind of the Lions and Donnell fires in Alpine/Mono/Mineral
Counties will continue to see haze and periods of smoke which
could reduce slantwise visibility. Besides these concerns, expect
dry conditions with typical afternoon winds today enhancing both
Mon/Tue when gusts could approach 25-30 kt. Hohmann



We are more confident tonight in an upper level trough over the
Pacific Northwest dropping southward across northern CA and OR
Monday and Tuesday with a 70+ kt jet max extending from northern
CA eastward along the northern NV border Monday afternoon and
evening. 700 mb winds increase to 25 kts across the northern
Sierra which translates to ridge gusts around 50 mph. Surface
thermal gradients are not very tight between the northern Sierra
valleys and the Basin and Range. So forecast parameters suggest
winds will not reach widespread critical conditions despite winds
aloft getting very close. The upper jet weakens Tuesday although
700 mb winds will continue to be near 25 kts. We will continue
with a general headline for breezy winds and dry conditions
through Tuesday and fire officials should be prepared for short
durations of localized critical fire weather conditions, mainly
north of Highway 50 Monday afternoon and evening and possibly
Tuesday afternoon as well.

Dry air will continue to infiltrate the region ahead of this
trough with low afternoon humidity levels and poor overnight
recoveries on mid and upper slopes. Even the Sierra of Mono County
which has seen moderate recoveries in recent days should see a
noticeable drop by Tuesday. Hohmann


.REV Watches/Warnings/Advisories...


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