Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 300426 AAA
AFDREV

Area Forecast Discussion...UPDATED
National Weather Service Reno NV
926 PM PDT FRI JUL 29 2016

.UPDATE...

Thunderstorm activity is waning across the area and we have
allowed the Red Flag Warning to expire at 9PM as expected. Gusty
and erratic outflow winds up to 30 mph were observed across much
of the region this afternoon and evening, along with several new
fire starts from lightning.

There are still a few isolated showers and thunderstorms around
the area, mainly north of Pyramid Lake, and are expected to
continue until around midnight with a few light showers continuing
overnight. We have also cancelled the Heat Advisory as well, as
temperatures are dropping off across western Nevada. Hoon

&&

.PREVIOUS DISCUSSION... /Issued 206 PM PDT FRI JUL 29 2016/

SYNOPSIS...

Afternoon and evening thunderstorms will wane early next week
as a drier westerly flow moves into northeast California and
western Nevada. Winds will increase across northeast California
and northwest Nevada this weekend as a trough moves through the
Pacific Northwest. The hot temperatures will ease early next week
but will remain slightly above average.

DISCUSSION...

A number of concerns to address over the next few days as the
ridge of high pressure gradually weakens and shifts south and east
of the region. This is in response to an incoming trough over the
Pacific Northwest. Here are the highlights.

..Heat...

Only a slow cooling trend is expected this weekend through
Monday with temperatures still remaining above average. 100+
degree temps will still rule a large area across western NV
Saturday but should be confined to the Basin and Range Sun-Mon.

..Thunderstorms...

Thunderstorm coverage will be most pronounced today with latest
satellite imagery showing cumulus buildups developing along the
eastern Sierra, as well as up north along the Lassen Convergence
zone. While thunderstorms will be moving a little more than they
were Thursday, anchoring and training of storms will still be
capable of heavy rain with a few flash floods/rock slides possible
along the steeper terrain. There is plenty of moisture with the
KREV sounding near 0.90" PWAT. As storms push off the eastern
Sierra and into western NV, deep mixing layer will promote strong
outflow gusts that will be capable of spreading out and well away
from storm cells. Gusts to 50+ mph will accompany stronger storms,
and blowing dust across the Basin and Range is a possibility by
this evening.

For the rest of the weekend and next week, a drier west flow will
begin to limit storms to mainly south of Hwy 50 Sat-Sun and mainly
near the White Mountains for Monday. Right now it appears Tue-Thu
will be storm free with the only possibility of any change in far
southern Mono-Mineral Counties, which will be near the edge of the
monsoon moisture over the Desert Southwest/Four Corners regions.

..Smoke...

Smoke will be highly dependent on fire activity with strong plume
already this afternoon from the Tule Fire. Smoke plume models
indicate this smoke will be push eastward into the Basin and Range
overnight with haze settling across much of western NV by Saturday
morning. If other fires start in different locations, this
forecast could change. For now, we have placed smoke and haze from
just north and east of Reno into the Fallon/Lovelock areas through
Saturday morning.

..Wind...

Winds will generally be light although multiple thunderstorm
outflows will probably disrupt our wind pattern by this evening.
Some models are showing gusty west flow across western NV in the
wake of storms which we have incorporated, but with only a
moderate confidence. As the ridge gets suppressed southward,
westerly flow will begin to increase, especially closer to the
Oregon border this weekend into early next week. Right now it
appears that in the Sat-Mon time frame the windiest day will be
Monday as a shortwave moves into the Pacific Northwest. Wind gusts
will be strongest north of Hwy 50 where gusts will be around 30
mph Sat-Sun afternoon and evening, enhancing slightly Monday when
gusts could reach 35 mph.

Hohmann

AVIATION...

Thunderstorms/cumulus buildups are already developing along the
Sierra and nearby higher terrain and will continue to intensify
this afternoon before lifting off to the east/northeast at 10-15
kts.

TRK/TVL may see storms in the vicinity but 10% or less chance of
direct impact due to westerly zephyr wind kicking storms east soon
after development. RNO/CXP 20-30% chance of seeing storms sometime
in the 22Z-02Z time frame. Strong erratic outflow winds to 35+
kts possible along with lightning. For MMH, similar impacts
possible through 00Z with activity pushing east early this
evening. For NFL/LOL/HTH the main risk of storms is after 00Z with
gusty winds and blowing dust.

A few other notes: Thunderstorms may cluster enough between KCXP-
KBIH to impact enroute travel over the Sierra into and out of SFO
region. Temperatures will be hot enough again today to potentially
result in some performance issues for aircraft due to density
altitude at peak heating 20Z-00Z. We have some fires ongoing in
the mountains north of RNO. These could result in reduced approach
or slantwise visibility in smoke and haze through Saturday and
possibly beyond. Chris/Hohmann

FIRE WEATHER...

Thunderstorms are developing and will be most widespread this
afternoon and evening. Storms will affect the eastern Sierra
initially with abundant lightning strikes. While locally heavy
rain will accompany some of the stronger storms, lightning strikes
outside the cores could be abundant with new starts likely. As the
afternoon and evening progresses, storms will begin to push off
the Sierra and toward the Hwy 95 corridor which includes the
Virgina/Pah Rah ranges and current fires north of Reno. Due to the
intense heating of valley floors, strong outflow winds will likely
accompany storms, and these outflows could occur well away from
storm cores. Gusts in excess of 40-50 mph will be possible.
Farther north from eastern Lassen into northern Washoe Counties,
storms should begin to develop by late afternoon. Continue all
warnings.

A drier westerly flow will develop north of Hwy 50 this weekend
and spread a little farther south into Mono-Mineral Counties early
next week. This will allow for storms to be confined mainly to
southern areas over the weekend although a few strikes may still
be possible Saturday over northwest NV. The main impact will turn
to breezy winds for ongoing fires and holdovers. A more typical
zephyr wind will return Sat-Sun from the Sierra Front northward to
the Oregon border, with some enhancement to these winds possible
on Monday as a shortwave trough moves through the Pacific
Northwest. Winds and low RH may be sufficient in these northern
areas for another round of critical fire weather headlines.
Hohmann

&&

.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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