FXUS65 KREV 290000 AAA

Area Forecast Discussion...UPDATED
National Weather Service Reno NV
500 PM PDT Thu May 28 2020


After some late discussion with the Great Basin GACC and fire
management officers in the Sierra Front and in Winnemucca, the
recent hot and dry conditions have pushed our fuels dry enough for
critical fire. We went ahead and expanded the Fire Weather Watch
for Saturday's winds to include the Northern and Southern Sierra
Front (below 7000ft), as well as the Lahontan Basin and West
Humboldt Basin in west-central Nevada. Fuels are transitioning
quickly, with the grasses and carry over grasses from last year
definitely the main carriers of fire. The sagebrush is drying out
quickly, but not quite to the severity of peak fire season just
yet. -Hoon


.PREVIOUS DISCUSSION... /Issued 236 PM PDT Thu May 28 2020/


High pressure will bring unseasonably hot temperatures through
Friday with some record highs possible. Chances for showers and
thunderstorms in eastern California and western Nevada develop later
Friday and continue Saturday as low pressure moves into the West
Coast. Windy and much cooler conditions are expected for Saturday
with cooler conditions and chances for showers continuing into
next week.


Another hot and dry day today thanks to a strong high pressure
ridge over much of the western CONUS. The forecast is on track to
reach temperatures well into the 90s across western Nevada and in
the 80s for the Sierra with records not out of the question once
again. Because of the very stable conditions and lack of mid to
upper-level moisture under the ridge, thunderstorm development will
be pretty much nonexistent for the region this afternoon/evening
with only a slight chance possible along the Sierra, south of Mono
County. Most of the Sierra and western Nevada region can see some
fair-weather cumulus clouds develop this afternoon accompanied by
the typical zephyr winds, but that's about it.

The weather pattern begins to change on Friday as the axis of the
ridge shifts towards the east making way for a cut-off low
pressure system to push up from the southwest. Temperatures will
continue to be 15-20 degrees above normal, but thunderstorm
chances increase for the afternoon through the evening. Short
range model guidance (NAM 3km, HREF, SREF, & NBM) all show some
convection starting to take place by early Friday afternoon over
the Sierra from the Tahoe Basin south into Mono County. As the
afternoon progresses, coverage looks to extend into northeast
California with slight chances along the Sierra Front possible...
this includes the Reno-Sparks and Carson City-Minden metro areas.
Typical impacts such as strong out flow gusts, brief downpours,
small hail, and lightning are anticipated with any storms.

Confidence in scattered thunderstorms forming over the
aforementioned areas increases as we enter into the evening hours
of Friday. Taking a look at multiple model soundings within the
region, a sufficient amount of CAPE (>1500 J/kg) and steep lapse
rates (~8-10 C/km) is forecast during this time. This, coupled
with some mid to upper level moisture and strong upper-level
divergence (lift) thanks to the approaching cut-off low from the
southwest, is a real confidence booster. It is important to note
that isolated storms that form in the afternoon could be more of
the dry microburst type leading to possible strong/severe outflow
gusts. As we enter into the evening and overnight hours, more
moisture is expected to be dragged up from the south as the low
migrates northeast into northern California resulting in nocturnal

Thunderstorm chances look to continue into Saturday morning with
wetting rains (>0.10") for the Tahoe Basin into northeast
California a good bet. Rain showers are likely for western Nevada,
but mainly confined to areas west of US-95 and NV-447 near Pyramid
Lake. Besides for the thunderstorms and precipitation, southwest
winds for Saturday afternoon/evening will most likely be
moderately strong region-wide with gusts reaching in the 35-45
mph range thanks to the passing low towards the west. Stronger
winds are anticipated along the Sierra ridges and across Mineral,
Churchill, and Pershing counties where blowing dust is possible.
Conditions on area lakes, including Tahoe and Pyramid, will also
be rough during this time.

Temperatures will feel quite different on Saturday as well with
highs forecast to be 5-8 degrees below normal. A change in the
pattern indeed. -LaGuardia

LONG TERM...Sunday through next week...

Broad trough should hang around the west coast Sunday into Monday
leaving the area on the cool side, but still unstable enough for a
low chance of showers and thunderstorms. Ensembles continue to
point to persistent troughing along the CA coast through most of
next week. However the troughing may take the form of a detached
low near the central or southern CA coast which would allow for a
warming trend and at least a low chance of showers and thunderstorms
across the region. Difficult to pick out which day may have the
best chance at this time, but with the early June sun angle and
slightly unstable conditions daily afternoon and evening
convection is not out of the question. Brong


VFR conditions expected for the remainder of the day as high
pressure is in control. West winds are forecast to increase this
afternoon dropping off before midnight. Typical zephyr winds of
15-25 kt gusts are likely during this time. Some patchy FG is
possible for KTRK from 10-14Z tonight under the clear and calm

Isolated thunderstorms are possible by early Friday afternoon for
terminals KMMH, KTVL, and KTRK as conditions become more unstable.
Chances extend into portions of western Nevada and northeast
California later in the day on Friday possibly impacting KRNO,
KCXP, and KMEV. Nocturnal thunderstorms are forecast overnight
into early Saturday morning with showers thereafter during the day
for the Tahoe Basin, northeast California, and portions of western
Nevada. Strong outflow gusts, small hail, brief downpours, and
lightning are possible with any storms. Any storms that due form
near any area terminals could see IFR/MVFR conditions at times.

Southwest winds on Saturday are expected to be moderately strong
with gusts in the 25-35 kt range for all area terminals. Moderate
turbulence, especially if traveling over the Sierra, is
anticipated for much of Saturday afternoon. Winds look to ease by
midnight on Sunday. -LaGuardia


Issued Fire Weather Watch for southern Mono County for Saturday
for gusty winds and low humidity after a few days of abnormally
warm temperatures.

Low pressure will approach the California coast Friday then swing
inland Saturday. This will increase the threat for thunderstorms
Friday afternoon along the Sierra Front and Tahoe Basin, outflow
winds to 50 mph and lightning away from rain cores are possible.
As the trough swings inland Friday Night the threat for
thunderstorms will continue into Saturday morning, however
increasing moisture will likely bring wetting rains especially for
the Tahoe Basin and the Tahoe, Plumas and Lassen Forests.

Winds should also remain gusty Friday and Saturday. For Friday,
winds will be more southerly and strongest across Mono-Mineral
Counties, gusts up near 30 mph, as the low approaches the coast.
Saturday winds look strongest for Mono-Mineral-Churchill-Pershing
counties as a dry air moves in behind the trough and maintains
low afternoon RH. Gusts Saturday could reach 30-40 mph, with some
localized gusts up near 45 mph across southern Mono and Mineral
Counties. Brong


.REV Watches/Warnings/Advisories...
NV...Fire Weather Watch from Saturday morning through Saturday
evening NVZ423-429.

Fire Weather Watch from Saturday morning through Saturday
evening NVZ420.

Fire Weather Watch from Saturday morning through Saturday
evening below 7000 feet in NVZ421.

CA...Fire Weather Watch from Saturday morning through Saturday
evening below 7000 feet in CAZ274.



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