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FXUS65 KREV 261006
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
306 AM PDT Wed Apr 26 2017

.SYNOPSIS...

Cool and windy conditions with light rain and high elevation snow
can be expected today in the northern Sierra and north of Highway
50 as low pressure moves by to the north. Temperatures will remain
on the cool side through the end of the week. High pressure returns
over the weekend for a warming and drying trend.

&&

.SHORT TERM...

No significant changes were made to the short term forecast.

An anomalous (3-4 standard deviations) moisture plume is sitting
just off the northern California coast this morning, with PWAT
values between 1.5 and 1.7 inches per satellite measurements
(AMSU/SSMI). However, while this is impressive from a magnitude
perspective, the plume is "more bark than bite" with forcing for
heavy precipitation weak over northern California and Nevada with
an upper disturbance far removed from the plume (near the Oregon and
Washington border).

Still, while forcing from a disturbance is lacking, warm air advection
lift combined with the already moist atmosphere will still serve to
bring a shield of light rain and high elevation snow to the region
this morning. Outside of the Sierra, this is simulated by the
GFS/NAM/HRRR to be mainly north of I-80 and east of Fernley. In
the northern Sierra, terrain forcing will aid lift and precipitation
there. With the warm air advection and rather light precipitation,
snow levels are slowly rising and are running between 7000 and 8000
feet in the Lassen/Plumas and Tahoe areas, respectively. Once the
warm air advection forcing moves past this morning, snow levels
are likely to rise a bit more. With the higher snow levels, only
the highest passes (above ~8,500 feet) appear to have any potential
for slickness due to snow this morning, with just wet roads expected
for the main Tahoe passes. As always, check with CALTRANS/NDOT for
the latest road conditions if you plan on traveling in the Sierra.


As far as winds today, they are still expected to increase substantially
by this afternoon with stout sustained winds between 20 and 35 mph
for many areas. The highest winds are expected out in the Basin and
Range east of Fernley/Dayton and over northern Washoe County, and
perhaps for southern Mono County near Highway 395 (which is susceptible
to northwest flow). Winds in those areas could reach 35-40 mph
sustained with gusts to 55 mph. With the wet conditions, dust is
not expected to be a major issue out in the Basin although with
such strong sustained winds there could be areas with minor visibility
reductions this afternoon and evening.

Tonight through Friday, northeast California and western Nevada will
see the end of shower chances but remain under northwest to north
flow aloft for below average afternoon temperatures. Afternoon
breezes could make it feel even cooler. As far as lows, near or
below freezing temperatures look to return by Thursday and Friday
nights in lower valley areas, especially outside of urbanized locations.
This is still not uncommon for this time of year. Snyder

.LONG TERM...Saturday through Wednesday...
Few changes to the long term with it expected to be dry for the
weekend and into the middle of next week. The East Pacific ridge is
expected to nose in for the weekend with temperatures warming to a
few degrees above average for Sunday and Monday. The ridge will then
retreat a bit as another short wave is expected to work down its
east side and push a backdoor cold front through the Great Basin.

While there are model differences for Tues/Wed next week with the EC
much stronger with the ridge, prefer the GFS solution at this time
given the pattern. Amplifying troughs near the dateline should keep
the ridge pinned off the coast with weaker waves dropping down the
east side. Granted, this is low confidence, and it appears the pattern
may be set for a change after that. Wallmann

&&

.AVIATION...
The main story today will be the gusty winds with sustained winds 20-
30 kts for area terminals, strongest near KHTH, KNFL and KLOL. Winds
will be WNW and strongest speeds between 20-02Z. There will be some
mtn wave turbulence as well, but LLWS will be limited due to good
mixing. Areas of LLWS will be confined to locations of terrain
channeling in the Sierra with crosswinds the result, KTVL being an
example.

Other concern will be MVFR CIGS in -RA through 19Z mainly north of
KTRK to Gerlach. Afterward, VFR conditions should prevail. Winds
will also diminish tonight from 02-06Z and become more NW. Gusty NW
winds are expected Thursday with winds 15-20 kts and gusts to 30 kts,
but mtn wave turbulence will be limited and no LLWS is expected.
Wallmann

&&

.REV Watches/Warnings/Advisories...
NV...Wind Advisory from 1 PM this afternoon to 8 PM PDT this evening
NVZ001-004.

Wind Advisory from 11 AM this morning to 8 PM PDT this evening
NVZ005.

Lake Wind Advisory from 11 AM this morning to 8 PM PDT this
evening for Lake Tahoe in NVZ002.

CA...Wind Advisory from 11 AM this morning to 8 PM PDT this evening
CAZ070.

Lake Wind Advisory from 11 AM this morning to 8 PM PDT this
evening for Lake Tahoe in CAZ072.

&&

$$

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http://weather.gov/reno
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