Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 142232 CCA

Area Forecast Discussion
National Weather Service Reno NV
148 PM PST Wed Feb 14 2018


A weak weather system could bring light snow showers tonight,
mainly in northeast California and northwest Nevada. A few showers
will linger over Mono County Thursday morning. Dry conditions
will then prevail for the next few days, below average
temperatures Thursday becoming warmer through Saturday. A
stronger storm may bring snow showers early next week along with
much colder temperatures.



Some adjustments were made to the first 12 hours tonight, but
little change was made otherwise. The changes were to increase the
threat of snow for northern areas tonight and cool Friday morning

The next slider is making its way down this afternoon with a
decent band of precipitation across Southern Oregon into Southwest
Idaho. As this band progresses south, the forcing with the wave
gradually weakens. Still, there is enough moisture and forcing for
the band to hold together well enough through Susanville, Gerlach
and Grass Valley (south of Winnemucca) with around an inch of
snow. As it moves south of there, the band is expected to break up
and become more isolated by the time it hits Tahoe and the Sierra
Front. The morning commute will be slick for northern areas, but
Reno-Tahoe are not expected to see a repeat of Monday morning.

Behind the front Thursday, northeast winds and cold advection will
cool temps back a few degrees below average. This will be followed
by another cold night Thursday night. Gradual warming is expected
Saturday under the northwest flow aloft. The next wave on Friday
afternoon will stay well to the north and east.

Saturday will be the warmest day of the forecast (and possibly the
rest of the month) with winds aloft becoming more west and a
little better mixing for temps rising a few degrees above average.
Then, the next cold front approaches Saturday night with
increasing winds. Winds will be spotty in the lower valleys, but
winds prone areas and ridges are likely to be quite gusty
overnight. This is another slider system with the moisture post-
frontal and thus it will remain confined to areas near the Oregon
Border Saturday night. X

.LONG TERM...Sunday through Wednesday...

There were a few adjustments made to the long term forecast based on
reasonable continuity of deterministic solutions. Precipitation
chances, QPF, and winds were all increased as a strong front moves
through the region Sunday into Monday. Both EC and GFS have
consistently shown the strong front for several runs, and the
character of the system is taking shape with a reasonable amount of
forecaster confidence.

The current forecast has more widespread chances of snow and snow
showers than previous ones based largely on the expected forcing
associated with this system. QPF values remain low, but are likely
to increase over the next few days if forcing remains as strong as
currently depicted. While not expected to be a large snow producer,
chances are increasing for more widespread light accumulations. Some
analogs to previous systems of this nature have produced higher
snowfalls, but the system trajectories were slightly farther west
than this system is currently projected to be. Gradients are being
depicted as being quite strong, so an increase in winds ahead,
along, and behind the front was warranted. Current gust estimates
for Sunday are in the 30-45 mph range with 20-30 mph for Monday.

One thing that can be said with a higher degree of certainty is that
temperatures will trend much colder. 700 mb temperatures have been
-15 to -20C and would yield the coldest surface temperatures of the
season if the current solutions verify. These temperatures would
correlate to highs in the low 30s with some locations struggling to
reach the upper 20s by Monday. There are still some timing issues
between the GFS and EC, so there is room for temperature adjustment
over the next couple of days.

After this system passes, another weak, migratory ridge will pass
the region for Tuesday. Another wave will be approaching next
Wednesday; it`s current trajectory is off-shore, but uncertainty is
too high to determine details at this time. Boyd



VFR conditions near and south of I-80 for the next 48 hours. Some
gusty W-SW winds at the terminals through 06Z this evening with
peak gusts to 30 kts and some mtn wave turbulence. IFR conditions
for 1-2 hours north of KSVE-KLOL as a band of -SN moves south,
with timing best between 02-06Z. This band will break up before
it reaches KTRK-KRNO. Winds on Thursday to be more NE, but
generally light except over the Sierra ridges. X


.REV Watches/Warnings/Advisories...
NV...Lake Wind Advisory until 10 PM PST this evening for Lake Tahoe
     in NVZ002.

CA...Lake Wind Advisory until 10 PM PST this evening for Lake Tahoe
     in CAZ072.



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