Flash Flood Warning 19, NWS Reno, NV

Area Forecast Discussion
National Weather Service Reno NV
133 PM PDT Mon Aug 10 2020

.SYNOPSIS...
Showers and thunderstorms again this afternoon with increasing
thunderstorm coverage and intensity for Tuesday. Dry and breezy
conditions will develop for Wednesday. The rest of the week will
feature a rather typical summer time pattern with light afternoon
winds and a few thunderstorms possible over the weekend.

&&

.DISCUSSION...

No big changes to the forecast as we roll into mid August. Showers
and thunderstorms will be around again from Douglas-Alpine
Counties northward through Reno-Tahoe and northeast CA into this
evening. Heavy rain, hail and outflow winds of 40-50 mph the main
threats. Models are hinting a few light showers may develop late
tonight, but doesn't appear to be enough instability/forcing to
trigger any overnight storms despite an approaching trough.

For Tuesday, a trough hanging around the CA coast will move inland
and provide a boost to the instability and forcing. This will
allow for strong to severe thunderstorms to develop Tuesday
afternoon; outflow winds over 50 mph, blowing dust, hail and
heavy rain are possible. Storm motions should be around 10 mph
Tuesday which should reduce flash flood/debris flow potential.
Have a plan B for any outdoor activities tomorrow.

Drier air will move into the region behind the trough for Tuesday
night and Wednesday. This will clear out the thunderstorm chances
for a couple days and kick up some breezy winds Wednesday
afternoon. Strongest winds Wednesday should be over Lassen and
northern Washoe counites with gusts 30-35 mph. For Reno-Tahoe the
eastern Sierra and western NV afternoon winds should stay near
and below 30 mph with an occasional gust up near 35 mph for the
usual wind prone locations along US-395.

Thunderstorms may return for the weekend as high pressure rebuilds
over the desert southwest with some moisture and instability
returning to the region. Brong

&&

.AVIATION...
Thunderstorms about the region again today generally north of
Sonora Pass to Bridgeport to Reno-Tahoe terminals and into the
Susanville area. Outflows of 30-40kts, hail and heavy rain all
possible through 03z.

Stronger storms for Tuesday with 40-50kt outflows, blowing dust,
hail and heavy rain. Storms will fire a bit earlier over the
Sierra, perhaps as early as 19z, then push into western NV for the
afternoon and evening.

Thunderstorms chances within 10 miles rest of Today and Tuesday...
KRNO: 20% - 35%
KCXP: 25% - 35%
KTRK: 30% - 20%
KTVL: 30% - 20%
KMMH: 20% - 25%

Wind could be gusty for Wednesday perhaps a few gusts near 30 kts
for the Reno-Tahoe-eastern Sierra terminals. Stronger gusts are
possible for Susanville to Black Rock Desert. Brong

&&

.FIRE WEATHER...
Wet, slow moving storms again the rest of this afternoon and
evening with some hail and gusty outflow winds possible. Main area
of concern is roughly in the Sierra from Lassen County to Sonora
Pass and across western Nevada along US-395.

Tuesday continues to be an interesting day for thunderstorms.
Stronger thunderstorms are likely across the region with some but
not a lot of storm motion as winds aloft may not increase much
until Tuesday night. Storms should kick off in the Sierra and
northeast CA by early afternoon then push into western NV for mid
afternoon and evening hours. Tough call here with plenty of
moisture place as heavy rain remains a threat, however abundant
lightning could start new fires.

Conditions will dry rapidly for Wednesday with some afternoon
breezes. Not looking like a big wind event, but 30-35 mph gusts
are possible for the northern Sierra Front, northeast CA and
northern Washoe County after a potentially active thunderstorm
day. Duration of the 30-35 mph winds may limit the area for
critical conditions to eastern Lassen and northern Washoe
counties. Brong

&&

.REV Watches/Warnings/Advisories...
NV...Fire Weather Watch from Tuesday afternoon through Wednesday
     evening NVZ420-423-458.

CA...Fire Weather Watch from Tuesday afternoon through Wednesday
     evening CAZ270-271-278.

&&

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

Special Weather Statement
National Weather Service RENO NV
114 PM PDT Mon Aug 10 2020

CAZ071>073-NVZ002-110000-
Lassen-Eastern Plumas-Eastern Sierra Counties-
Greater Lake Tahoe Area-Mono County-
Including the cities of Portola, Susanville, Westwood,
Sierraville, Loyalton, South Lake Tahoe, Tahoe City, Truckee,
Markleeville, Bridgeport, Coleville, Lee Vining, Mammoth Lakes,
Stateline, Glenbrook, and Incline Village
114 PM PDT Mon Aug 10 2020

...Sierra Storms Starting to Build...

Isolated thunderstorms are starting to build over the high Sierra
as of 110 PM Monday. This trend will continue through the late
afternoon, with isolated-scattered storms along the Sierra
between Tioga Pass, Sonora Pass, Lake Tahoe, Donner Pass, and
Susanville. Storms will likely push into the Western Nevada
Sierra Front by late afternoon or early evening.

Storms will be slow moving so they will drop heavy rainfall in
spots. Strong outflow winds, lightning, small hail, and rapid
temperature drops are also likely with any storms.

With storms developing, now is the time to consider seeking sturdy
shelter if out in the mountains or on Sierra lakes.

http://weather.gov/reno

Special Weather Statement
National Weather Service Reno NV
527 PM PDT Mon Aug 10 2020

CAZ070>073-NVZ001>005-110215-
Surprise Valley California CA-Lassen-Eastern Plumas-
Eastern Sierra Counties CA-Greater Lake Tahoe Area CA-Mono CA-
Western Nevada Basin and Range including Pyramid Lake NV-
Greater Lake Tahoe Area NV-Northern Washoe County NV-Greater Reno-
Carson City-Minden Area NV-Mineral and Southern Lyon Counties NV-
527 PM PDT Mon Aug 10 2020

...THUNDERSTORMS CONTINUE OVER THE SIERRA, PORTIONS OF WESTERN
NEVADA, AND NORTHEAST CALIFORNIA...

Isolated thunderstorms look to continue through the early evening
over portions of western Nevada, much of the Sierra, and across
northeast California.

These thunderstorms will continue to be slow moving, so they will
have the propensity to drop heavy rainfall. Strong outflow winds,
lightning, small hail, and rapid temperature drops are the likely
threats with these storms.

Locations impacted include...
Reno, Carson City, South Lake Tahoe, Mammoth Lakes, Tahoe City,
Chalfant, Graeagle, Kings Beach, Plumas Eureka State Park, Crowley
Lake, Sonora Pass, Bieber, Gardnerville, Virginia City, June Lake,
Boca Reservoir, Nubieber, Pyramid Lake, Lee Vining and Twin Lakes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

During a thunderstorm, seek shelter inside a sturdy structure and
stay away from windows. Hikers and campers should seek shelter in a
vehicle if possible. Stay away from creeks and streams as water
levels may rise rapidly near thunderstorms.

&&

LAT...LON 3773 11926 3804 11931 3820 11963 3845 11968
      3885 12016 3960 12046 3971 12072 4019 12088
      4024 12104 4044 12106 4044 12122 4059 12132
      4118 12133 4121 11933 3907 11934 3805 11817
      3789 11842 3747 11783 3746 11784 3746 11878
TIME...MOT...LOC 0019Z 240DEG 0KT 3872 11978

CJ