Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 101103

Area Forecast Discussion
National Weather Service Reno NV
303 AM PST Sun Dec 10 2017


High pressure will continue to bring dry conditions along with
valley inversions, cold nights, and light winds for the next
several days. Localized air quality issues are possible along the
Sierra Front due to the strong inversions. Inversions may ease
by the end of the week as a weak low pressure moves through the
west, but could return next weekend.



As many eastern and southern states experience snow all the way
down to Corpus Christi, TX...tranquil weather sticks around for
the Sierra and western Nevada as we enter into the new week. The
ridge of high pressure continues to park itself right over the
western half of the US causing clear skies, cold overnight lows,
and strong valley inversions. Kept haze in the forecast for the
urban valleys through much of this coming week due to those
strong, overnight inversions.

Winds will be generally light with an east to southeast flow due
to the pressure gradient extending from the surface high across
the northern and eastern Great Basin. This will also contribute
to the haze development in urbanized areas due to the lack of
mixing with the upper troposphere.

Afternoon high temperatures for this week will be slightly on the
warmer side for mid-December with most areas reaching up into the
upper 40s and lower 50s. -LaGuardia


The ongoing inversion-dominated pattern of afternoon highs near
seasonal average in valleys (and milder near the Sierra), chilly
overnight lows, light winds and areas of valley haze is expected
to continue through Thursday.

By Friday, the coastal ridge is expected to retreat offshore into
the eastern Pacific, allowing for a momentary shift in the storm
track. This shift will allow a weak low pressure to drop out of
the Pacific Northwest, possibly taking a slider-type track into
western NV. While confidence in precipitation chances are fairly
low, cloud cover will likely increase with this passing wave
especially from I-80 northward. Cooler mid level temperatures and
a shift to west winds on the ridges may help ease the inversion
and push temperatures a few degrees warmer in lower elevations.
In lower elevations, only a modest wind increase is anticipated,
so the haze may not clear out until late in the day.

By next weekend, depending on the eventual track of Friday`s
shortwave, the inversion may remain on the weaker side on
Saturday, although cooler air mass will lead to temperatures
dropping a few degrees compared to Friday. However by Sunday,
latest guidance indicates that high pressure will rebuild over
CA/NV, which would favor a return to inversions again.

Beyond next weekend, there remains a wide variety of scenarios for
the weather pattern over CA/NV. There is a small possibility of
weather systems arriving to the region on or after the 19th, but
several of the ensemble members keep the storm track too far east
to bring meaningful moisture to the Sierra or western NV.
Therefore, confidence remains low that the current dry period will
end by Christmas. MJD



VFR with light winds continue into next week with high pressure
overhead. Some haze around KRNO-KCXP is expected, but it should
not be a significant issue other than some minor reductions in
slantwise visibility. Patchy shallow ground fog may form in the
vicinity of KTRK each morning, but restrictions to visibility
should be minimal and brief if they occur at all. MJD


.REV Watches/Warnings/Advisories...


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