Area Forecast Discussion
Issued by NWS Elko, NV

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FXUS65 KLKN 272224

Area Forecast Discussion
National Weather Service Elko NV
324 PM PDT Thu Oct 27 2016

.SYNOPSIS...Anomalous moist Pacific storm system moves across
Nevada late tonight and Friday. Significant rainfall will occur
with the heaviest rain across Humboldt and northern Elko county
where local flooding is possible. Fast moving Pacific waves bring
additional showers on Sunday, Monday, and Tuesday.


.SHORT TERM...Today through Saturday.
Anomalously moist upper level low off the California coast has
tapped into hurricane Seymours moisture. This weather system is
interacting with the Pacific front that has reached the northern
intermountain region with the trailing portion over extreme
northwest Nevada corner. The combination of these features results
with moisture wrapping up around the upper low as it reaches the
Lake Tahoe basin Friday morning and will be over Elko by mid
afternoon. The highest QPF amounts are expect to cut across
Humboldt county, the Independence range and as far east as
Jarbidge wilderness. Rainfall amounts in this area could approach
1 inch across the valleys with upwards to 2 inches for the Santa
Rosas and Independence range. Widespread rain is expected after
midnight and continues into Friday afternoon, then gradually
diminishes as showers late in the day. Although not a classic
flash flood scenario, went ahead and issued a watch with the main
concern being mud and debris flows, potential for rock slides,
and ponding of water for some of the valley floors that could make
travel difficult on back roads.

A pocket of mid level cold advection accompanies the upper low as
it tracks into northeast Nevada on Friday afternoon. Would expect
some thunderstorms (and possibly small hail) with embedded cells
that produce heavy showers. The area most favorable for this type
of activity favors northern Nye county up towards the Elko area.
The 12Z NAM12 showed a band of significant QPF (1+ inches), but
pulled back on this possibility in the latest 18Z run that showed
maximum amounts below 0.50 inches. This is a possible scenario
that a band of heavy showers develop, but confidence is not high
that this will occur.

For White Pine and northeast Nye county, the best chance of
showers occurs on Friday as the front moves across the region.
Rainfall amounts will be the lowest, but still respectable with
0.25 to 0.50 possible at some locations (but valleys closer to the
Utah border will not be as wet).

Extensive cloud cover across the region will keep temps on the
cool side. Given the moist but mild air, snow levels will be high
and no appreciable snow accumulations are expected.

Aside from isolated showers across northwest Nevada on Saturday,
most areas will be dry but breezy. The next Pacific weather system
will be encroaching from the west, and some showers will be
developing northwest of Winnemucca. Southwest flow prevails and
daytime temps stay above normal with 60s in the valleys (upper 50s
near the Idaho border).

.LONG TERM...Saturday night through next Thursday.
The upper level pattern will continue to be progressive and there
is a very moist pattern ahead that could result in more significant
rain totals.

A strong low pressure trough situated about 400 miles west of
Eureka California will begin its eastward movement towards the
CONUS Saturday night. The movement of the low center will serve
to bring the trough axis out of the positive-tilt formation and
the southwest flow across the Sierras will likely scrape off some
of the moisture content. Model agreement is much better showing
that the system will eject as an open wave across northern
California and Nevada on Sunday. This will be a grand scenario
for more heavy precipitation, at least across northwest Nevada,
where snow levels will dip to around 6000 feet. Another system
may follow the same track through the state on Tuesday however
there is still some model inconsistencies on the depth of the
trough and whether it will focus on the northern section of the
state, or central Nevada instead. High temperatures will generally
be in the 50s. Low temperatures will be in the 40s Saturday night,
then generally fall into the 30s each night afterwards with a few
20s popping up.


.AVIATION...CIGS will be lowering overnight. VFR conditions will
hold until after midnight at KWMC KEKO KELY and KTPH. Then KWMC
and KEKO could experience intermittent MVFR CIGS before daybreak
Friday. There is a possibility of MVFR VIS at KWMC as well during
heavy rain showers before daybreak.


.FIRE WEATHER...Significant rainfall is expected across zones 467,
468, and 469 late tonight and Friday. Widespread showers with
embedded thunderstorms will be possible across northeast Nevada,
central and east central Nevada. Dry on Saturday except for
isolated showers in zone 467, but the chance for more showers
occur on Sunday and Monday.


Flash Flood Watch from midnight PDT tonight through Friday
evening for Humboldt County-Northern Elko County.



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