Area Forecast Discussion
Issued by NWS Reno, NV
FXUS65 KREV 231028
Area Forecast Discussion
National Weather Service Reno NV
328 AM PDT Sun Apr 23 2017
Weak low pressure will bring breezy conditions today with light
showers possible towards the Oregon border. Monday through
Wednesday, additional systems will keep breezy conditions going
with light shower chances spreading farther south. Drier weather
will return late in the week. Temperatures near average today
will fall to slightly below average this week.
Reduced POP late Monday night and Tuesday, otherwise no major changes
to the short term with this forecast package. The next two days
or so will feature a couple of weak upper disturbances, one today
and the next Monday, followed by a period of possible light
precipitation with warm air advection later on Tuesday and Tuesday
night. Total precipitation amounts look quite modest with around
0.10" to 0.25" possible north of Susanville and Gerlach and at the
northern Sierra crest, perhaps up to 0.10" in the Tahoe Basin,
with little or no measurable precipitation elsewhere.
Turning to today`s highlights, the axis of the first upper trough
is currently nearing the coast of far northern California. The
trough is expected to bring slight cooling, increased cloudiness
this morning, and breezy conditions by late morning/early afternoon
due to thermal gradients across the region. Winds aloft are expected
to be somewhat weaker than yesterday, with peak wind speeds driven
more by the thermal gradient (sustained winds elevated but overall
gusts less) than mixing down of stronger winds. Finally, there
could be a few light showers towards the Oregon border this morning.
Turning to Monday`s system, it will be a low amplitude and fast-
moving wave with the main forcing near or north of the California-
Oregon-Nevada-Idaho border. Once again, winds aloft will increase
with breezy conditions for Monday afternoon and evening, likely
prompting another lake wind advisory for Tahoe and Pyramid. As far
as precipitation, the system will push some moisture into the region
but forcing will be limited. Therefore, precipitation amounts in
the northern Sierra and out into northern/western Nevada are
expected to remain quite light...in fact, shadowing in the lee of
the Sierra may cause areas near and south of I-80 in the Basin to
get no measurable precipitation at all.
Late Monday night, snow levels are expected to fall enough to
bring light snow showers to northern Sierra passes. However,
current simulations show precipitation falling off then so any
accumulations should remain very light.
Late Monday night and Tuesday, POP was reduced substantially as
simulations show a break in systems. However, the next possible
light precipitation event is expected by later on Tuesday and
Tuesday night with a period of warm air advection. At this time,
the main shot at precipitation through Tuesday night looks to
remain north of I-80. Snyder
.LONG TERM...Wednesday through next weekend...
The active northwest flow will continue on Wednesday with a slow
transition to a ridge off the California coast for the weekend. One
more short wave is expected to move through during the day with
abundant moisture. As with the systems of earlier in the week, the
best forcing will remain to the north. Still, some light rain is
possible north of I-80 with some snow above 7000 feet or so.
Behind this wave, another one is progged to drop into eastern
Nevada for Thursday. Both the GFS and EC are in much better
agreement with this idea and their ensembles are also showing
support. The main impact from that wave will be to push a vigorous
cold front through. However, as it will be dropping from the north
and the best moisture is to the east, little rain or snow is expected.
It will be quite a bit colder behind the front into Friday with
brisk north winds making it feel colder. Highs only in the 50s to
low 60s are expected area wide Friday.
By Saturday, the flat ridge over the East Pacific is expected to
amplify and nudge into the West Coast for the weekend. North to
northeast surface winds will keep the warming slow at first, but
more warming is expected Sunday into early next week. Wallmann
VFR conditions through midnight tonight then some MVFR CIGS possible
north of I-80 after 08Z Monday in -SHRA. This first system will
continue through the day Monday.
The other concern is winds with peak gusts to 25 kts today at area
terminals from the west. An increase with gusts to 30-35 kts is
expected on Monday. Mtn wave turbulence will continue but large
areas of LLWS are not expected. The exception may be near KTVL
where terrain channeling of the low level wind may result in more
LLWS with a crosswind aloft. Wallmann
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