Special Weather Statement, NWS Reno, NV

Area Forecast Discussion
National Weather Service Reno NV
353 AM PDT Thu Aug 8 2019

.SYNOPSIS...

Low pressure approaching northeast California and western Nevada will
bring chances for showers and thunderstorms today, with a few showers
or storms possibly lingering Friday in far northeast California and
far western Nevada. Dry weather and below average temperatures are
expected for the weekend with gusty winds Friday and Saturday. Warmer
temperatures and lighter winds return next week.

&&

.SHORT TERM...

Main change to the short term forecast was to increase coverage of
showers and thunderstorms Friday in far western NV and extreme northeast
California.

One upper disturbance has moved up into far northern Nevada this morning
while another near Point Conception, California is moving north ahead
of a main upper low off the Oregon and California coasts. In between
the disturbances, clear to partly cloudy skies are found across most
of western Nevada and the Sierra at this hour. However, there are
already signs of lift from the incoming southern wave, with clouds
developing south of Highway 50 in Mono and Mineral counties.

Today, there are expected to be two waves of forcing for showers and
thunderstorms. The first wave of forcing (currently moving into central
CA) is expected this morning, with the best shot for showers or a few
thunderstorms mainly well south and east of Reno where instability
appears greatest per SPC mesoanalysis and current satellite/radar trends.
Convection should be moving along rather quickly so there is still a
chance for some dry lightning strikes out in the Basin and Range this
morning. The second wave is expected with daytime heating and the onset
of convergent low-level forcing by midday or shortly after as west-
southwest flow kicks out into the Great Basin. Those storms could be
much wetter and stronger than the morning convection given convergence
and instability between 500-1000 J/KG over western and west-central
Nevada per simulated soundings. There does not appear to be any major
shear aloft although there is sufficient flow that could bring longer-
lived cells with hail 0.5" to 1" in diameter and heavy rainfall, as
well as some outflow winds in excess of 45 mph (especially in west-
central NV).

With forcing exiting this afternoon, thunderstorms should taper off
fairly quickly after sunset today. Attention then turns to another wave
due in Friday morning which will bring a chance of showers and
thunderstorms, mainly north of Highway 50 and northwest of I-80 out
in the Basin. Once again there will be a chance for a few thunderstorms
outside of the normal peak heating hours, with the morning favored
over most of western/northwestern NV. Besides convection, another
feature of interest Friday will be winds. They will kick up as
gradients maximize in the afternoon, with gusts 25-35 mph possible
over western Nevada/the Sierra Front. This could bring concern for
rapidly spreading fires; see the fire discussion below for more.

Saturday, drier and more stable west-southwest flow aloft finally
arrives as the main upper low moves into Oregon. This will mean dry
weather, with the exception of far northern Lassen and Washoe counties
and the Surprise Valley where a low chance of showers will exist closer
to the upper low. There will also be another round of gusty afternoon
winds. Temperatures will bottom out Saturday with highs around 10
degrees below average, or mid 70s to mid 80s in the lower valleys
and upper 60s to mid 70s in the Sierra valleys. -Snyder

.LONG TERM...Sunday through Friday...

Low pressure slowly lifts out of the Sierra and western Nevada and
leaves behind much cooler temperatures. High temperatures will be
much colder, running about 7-10 degrees below normal. Model guidance
is showing some Sierra locations dropping into the low 30s for Sunday
morning so frost wouldn't be out of the question for some areas.

Flat ridging settles in across the West for early in the week, with
a drying and a warming trend. By the middle of next week, ensemble
guidance suggests another trough may move into the West with the
return of increased winds. -Edan

&&

.AVIATION...

There will be greater coverage of thunderstorms this afternoon along
with an increased potential for stronger storms with heavy rain.
Terrain obscuration will also be likely.

Chances for storms to reach terminal sites today:

KRNO/KCXP/KMEV: 25%
KTVL/KTRK: 15%
KMMH: 40%
KNFL: 60%

Winds will pick up on Friday and Saturday, but thunderstorm
chances will persist for some areas through Friday morning. -Edan

&&

.FIRE WEATHER...

*  Isolated to scattered thunderstorms through Friday. Storms will
   be drier through early this morning and then wetter by this
   afternoon.

*  Gusty southwest to west winds and cooler Friday and Saturday,
   especially north of Highway 50. Locally critical conditions
   Friday afternoon/early evening Sierra Front to BLM lands of
   eastern Lassen and northern Washoe Counties.

High confidence for thunderstorms through today with a mix of wet
and dry storms through early this morning then storms will transition
to more wet storms by this afternoon.

Showers persisted overnight across Pershing and Churchill counties
through around 1 AM. Simulations keep isolated showers/storms
picking up again in just a few hours. As of 1AM, there are already
showers and thunderstorms across Inyo county. As this stronger
disturbance approaches, these showers/storms will increase in
coverage with storms remaining elevated at least through mid-
morning. There is still potential for more lightning starts
overnight into Thursday morning.

Gusty and erratic outflow winds (to 50+ mph) are possible with these
showers/storms. As storms continue to develop through the day,
multiple outflow wind gusts could produce erratic winds even far
away from the thunderstorms. Fire officials should remain vigilant
of the location and movement of organized outflows. Some storms may
linger tonight into Friday. Some simulations were showing a
significant drying trend for Friday, but it appears that the
moisture and chances for thunderstorms will persist into Friday for
areas north of Interstate 80.

Drier and more stable conditions will be present on Friday and
Saturday as a stronger jet along with westerly flow pushes into the
region. Gusty southwest to west winds Friday-Saturday could reach to
around 35 mph in some areas with sustained winds 15-20 mph. Humidity
levels will still be quite low on Friday, so there may be some areas
with critical fire weather conditions. A fire weather watch may be
needed for gusty winds and dry conditions for some areas on Friday.
So while it will cool down and humidity levels will rise, these
winds would pose a risk to ongoing fires. -Edan

&&

.REV Watches/Warnings/Advisories...
NV...Red Flag Warning until 11 AM PDT this morning NVZ453-459.

CA...None.
&&

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

Special Weather Statement
National Weather Service Reno NV
1206 PM PDT Thu Aug 8 2019

CAZ072-073-NVZ001>004-082100-
Greater Lake Tahoe Area CA-Mono CA-
Western Nevada Basin and Range including Pyramid Lake NV-
Greater Lake Tahoe Area NV-Greater Reno-Carson City-Minden Area NV-
Mineral and Southern Lyon Counties NV-
1206 PM PDT Thu Aug 8 2019

...STRONG THUNDERSTORMS CONTINUE FOR THIS AFTERNOON AND EVENING...

Doppler radar continues to track strong thunderstorms mainly for
areas south of US-50, including the eastern Sierra. Heavy rain,
nickel sized hail, cloud-to-ground lightning and winds in excess of
40 mph will be possible with these storms. This development is
expected to continue into the early evening hours before the storms
begin to dissipate.

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.

&&

LAT...LON 3758 11901 3774 11913 3773 11925 3788 11920
      3795 11932 3804 11931 3820 11963 3845 11968
      3881 12003 3885 12016 3942 12037 3948 11762
      3935 11777 3910 11778 3900 11819 3889 11817
      3847 11770 3789 11842 3747 11783 3746 11878
TIME...MOT...LOC 1858Z 240DEG 0KT 3864 11917

EL

Special Weather Statement
National Weather Service Reno NV
112 PM PDT Thu Aug 8 2019

NVZ002>005-082215-
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-
112 PM PDT Thu Aug 8 2019

...Strong Thunderstorms Developing over Northwestern Nevada...

At 110 PM PDT, Doppler radar was tracking a strong thunderstorms
over Washoe County Nevada, moving northeast at 20 mph.

Dime size hail, frequent hail, and wind gusts up to 50 mph will be
possible with this storm. This development is expected to continue
into the early evening hours before the storms begin to dissipate.

Locations impacted include...
Reno, Carson City, Pyramid Lake, Lahontan Reservoir, Incline Village,
Gerlach, Virginia City, Sparks, Fernley, Dayton, Spooner Summit,
Wingfield Springs, Northwest Reno, Spanish Springs, Golden Valley,
Virginia Peak, Carson City Airport, Verdi-Mogul, New Washoe City and
Hidden Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If on or near Pyramid Lake, get out of the water and move indoors or
inside a vehicle now. Don't be caught on the water in a
thunderstorm. Strong wind gusts and lightning pose an immediate
danger to boaters. Gusty winds will cause a rapid increase in wave
heights which may capsize small boats.

Heavy rainfall is occurring with this storm. Expect ponding of water
on roadways. In areas of steep terrain, minor rock slides are
possible. Drivers should slow down and turn on their headlights if
encountering heavy rains.

&&

LAT...LON 4096 11933 4096 11901 3919 11900 3923 11914
      3910 11930 3909 11997 4198 11996 4198 11932
TIME...MOT...LOC 2010Z 219DEG 17KT 3985 11970

AH