Area Forecast Discussion
Issued by NWS Reno, NV

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955
FXUS65 KREV 231014
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
314 AM PDT Tue Jul 23 2019

.SYNOPSIS...

Mid-summer heat will persist across the Sierra and western Nevada
for the upcoming week. The threat for mainly afternoon and evening
showers and thunderstorms continues for the next few days. A
few strong storms are possible with frequent lightning, locally
heavy rainfall, gusty winds and small hail.

&&

.SHORT TERM...

Thunderstorm activity yesterday was limited to west central NV.
While none of the storms showed the supercell signatures as was
the case on Sunday, the strongest cell produced peak outflow gusts
of 45-55 mph along I-80 between Fernley and Lovelock, with
visibility briefly reduced to 1/2 mile in blowing dust at
Lovelock airport around 7 pm. A few more lightning fires were
also ignited in Pershing and Churchill counties yesterday.

Currently, isolated weak radar echoes have occurred across parts
of western NV and also around Tahoe, but none have produced
lightning or measurable rain so far. Latest satellite loops aren`t
indicating much shortwave energy or disturbances, just some
elongated bands of mid-upper level moisture moving across western
NV. We`ll keep a slight chance for lightning which may occur
after sunrise this morning, but overall potential isn`t looking
that favorable.

For this afternoon and evening, another round of isolated-
scattered showers and thunderstorms is expected, with the best
chances again over west central NV. A few cells may develop as far
west as Gerlach-Reno-Carson City and eastern Tahoe shores, before
an enhanced zephyr breeze (a bit stronger than yesterday due to a
shortwave passage across the Pacific Northwest) pushes activity
farther east. Strong outflow gusts of 45+ mph, brief heavy
rainfall and frequent lightning will be the primary concerns.
After sunset, outflow interactions may keep a few cells going near
and east of US-95, but overall activity should wind down prior to
midnight as upper level support doesn`t appear to be favorable
for sustaining nocturnal storms.

For Wednesday-Thursday, the best chance for afternoon-evening
thunderstorms shifts to areas south of US-50 as the upper ridge
axis also drifts farther south. Another wave of moisture on
Thursday night may bring a small potential for overnight
convection back to the eastern Sierra and western NV, but there
remains some uncertainty on this track. For now we only have a
slight mention of showers for parts of Mineral-Mono counties, with
increasing cloud cover along the Sierra and western NV south of
I-80.

Above average temperatures will continue for the next few days
with highs generally in the mid-upper 90s for lower elevations
and lower-mid 80s near the Sierra. MJD

.LONG TERM...Friday onward...

Very few changes to the ongoing forecast. A trough moving into the
Pacific Northwest Friday will flatten the ridge, with a jet max
setting up between the two features. This will aid in thunderstorm
development farther north as compared to the storms midweek.
However, with the afternoon winds, storms are likely to be rapidly
pushed eastward. Lingering moisture and instability will lead to
additional thunderstorm chances Saturday, however, most likely
storms will be south of US-50 as drier and more stable southwest
flow sets up across northern CA/NV.

There is still good ensemble agreement in the ridge strengthening
across the region Sunday into Monday, likely bringing the warmest
daytime highs we have seen so far this year. Triple digits are
possible across most western Nevada valleys, with potential heat
concerns for vulnerable populations. The good news is that a
rather dry air mass will be in place, so this should allow decent
cooling overnight, bringing some relief.

Looking a bit farther ahead, moisture does start to creep
northward again around Tuesday. However, true to form, there is a
trough nudging into the Pacific Northwest once again, so this may
shift storm chances more into central Nevada and bring an
increase in afternoon winds to the region. -Dawn

&&

.AVIATION...

Seasonably hot temperatures will continue to bring density
altitude concerns during the day. Typical afternoon winds can be
expected each day, with gusts in the 15-25 kt range. The strongest
winds are likely to be along the northern Sierra front into
northern Washoe County today, where gusts may briefly reach 30
kts.

Latest high resolution guidance suggests thunderstorm activity
may start earlier today, around 18z, along the Sierra, shifting
eastward into the afternoon. The greatest coverage is likely to be
south and east of a KBAN-KWMC line. Storms may bring gusty and
erratic outflow winds, kick up dust, and bring localized heavy
rainfall with reductions to CIGS/VIS and terrain obscuration.

Chances for a thunderstorm to directly impact any terminal site:

KRNO/KCXP/KMEV: 15%
KTVL/KTRK: 10%
KMMH/KHTH/KNFL: 30%

Additional thunderstorms are possible this week, but chances will
shift south of US-50 and east of US-95. -Dawn

&&

.FIRE WEATHER...

Two main concerns today: First, additional thunderstorms are
possible through the afternoon and evening. Second, increasing
westerly afternoon winds, especially along the northern Sierra
Front into northern Washoe County where gusts could reach 30 mph
this afternoon. These winds could help spread any new fires that
were sparked from lightning the past two days.

Thunderstorms today will be wetter than previous days due to
increasing moisture and slower storm motions. However, this
doesn`t mean a lightning strike can`t happen outside of the wet
thunderstorm core and ignite a new fire. Thunderstorms also can
produce gusty and erratic outflow winds, bringing a dangerous wind
shift for any ongoing fire fighting efforts.

Latest high resolution guidance suggests thunderstorm activity may
start earlier today, around 11 am, along the Sierra, shifting
eastward into the afternoon. The greatest coverage is likely to be
south and east of a Bridgeport, CA to Winnemucca, NV line. Storms
will shift mainly south of US-50 by midweek and should mainly be
wet. -Dawn

&&

.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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