High Wind in California, April 10 to 11, 2018

Area Forecast Discussion
National Weather Service Reno NV
311 PM PDT Mon Apr 9 2018

.SYNOPSIS...
A couple of fast-moving systems will produce gusty winds and
lighter amounts of rain and snow at times Tuesday through
Thursday. Much colder temperatures are expected Thursday, then dry
weather with a warming trend returns for the weekend. Another
storm system may bring cooler and wetter conditions early next
week.

&&

.SHORT TERM...

Main changes to the short term forecast were to drop the wind
advisory for much of northeast California and northern Washoe
County after Tuesday evening and to increase precipitation
chances in northeast California and the Sierra Wednesday night.

A more progressive spring-like pattern with a few fast-moving
waves develops starting Tuesday afternoon and evening. The first
wave has a limited moisture so any precipitation will remain
very light and mostly limited to northeast California and the
Sierra north of Highway 50.

The bigger impact will come from increased winds Tuesday afternoon
and evening. A ~100 kt jet aloft and 700 mb/ridge winds to around
50 kts will result in ridge winds 80-100 mph and valley winds
from 15-30 mph with gusts 45-55 mph. Wind advisories are in effect
for all but the Tahoe Basin (where a lake wind advisory is in
effect). There will be a break in the winds behind this first
system Tuesday night into Wednesday morning; however, the advisory
remains stretched through Wednesday evening to cover the next
wind increase on Wednesday.

The second system has a 120-140 kt jet and mid level winds just
as strong for Wednesday afternoon. The only change in thinking
with today's simulations is that winds may be reduced some north
of a Pyramid Lake to Susanville line and for the western Sierra
Valley. This is due to significant moistening and some cooling,
with a shifting south of the best thermal gradient by Wednesday
afternoon and evening. It will still remain breezy, but the main
impact from wind may move to the Highway 395 corridor south of
Susanville.

Light precipitation should develop in northeast California and
the northern Sierra by late Wednesday afternoon, but most of the
precipitation will hold off until the evening or later with the
main trough.

A quick burst of snow looks likely in the moist, unstable air
just behind the front. A few inches are possible in northeast
California above 5000 feet, including the Tahoe Basin while Mono
County sees lighter amounts. A bit of snow will fall down to the
valley floors near the 395 corridor, but any accumulation would
likely be above 5000 feet.

Thursday continues to look cold and brisk with highs only in the
30s and 40s. The brisk wind will make it feel even colder. Some
snow/pellet showers are possible north of Highway 50 under the
cold pool aloft. A quick and brief-lived inch or two of snow may
occur in the heaviest showers, with a few thunderstorms also
likely. Snyder

.LONG TERM...Friday morning through next Tuesday

Not much change to the long term as a ridge starts to build in from
the west contributing to a warmer and drier trend for Friday and
Saturday. Calm winds, clear skies, and above average temperatures
can be expected.

The pattern starts to change on Sunday afternoon with an increase in
southwest winds and a drop in temperatures ahead of a system from
the northwest. As of now, the system looks to move through the
region Sunday night into Tuesday, but there is some disagreement
between the models. The GFS has a shallower, but faster trough
moving out of the region by Monday night yielding to lower QPF and
stronger winds compared to the EC. The EC has a deeper, closed low
that sets up along the Pacific NW coast making its way through
northeast CA and the Sierra for Monday morning lasting until Tuesday
afternoon. Due to its slower progression according to the EC, more
QPF is possible with the bulk of the precipitation setting up for
the Tahoe Basin down into Mono County.

New model runs have the system coming in slightly colder and wetter
than compared to previous runs, but as far as the details of how
cold, wet, and windy it will be still need to be ironed out. As
previously stated in this morning's discussion, we are still leaning
towards the EC due to the climatology for this time of year
supporting slower and closed low systems.

While both global models are in a disagreement with next week's
system, it can be agreed that the spring storm door remains open.
-LaGuardia

&&

.AVIATION...

VFR conditions will remain through the rest of the afternoon into
the evening hours today. Cloud cover will increase tonight along
with a pick up in southwest winds by Tuesday morning ahead of a fast
moving shortwave. Expect gusts over the Sierra in the 80-90 kt range
with 40-50 kt gusts in the valleys. Due to these strong winds,
turbulence and the possibility of low level wind shear will exist.

Precipitation will not be a major issue as this quick system has a
lack of moisture. Light showers are possible for KTRK and KTVL
Tuesday evening lowering flight conditions to MVFR at times.
Precipitation moves out by early Wednesday morning.

Right behind this system is a second one moving through Wednesday
evening into Thursday. Stronger winds with a better chance for
precipitation is expected at all area terminals. -LaGuardia

&&

.REV Watches/Warnings/Advisories...
NV...Wind Advisory from 11 AM to 11 PM PDT Tuesday NVZ005.

     Wind Advisory from 2 PM Tuesday to 11 PM PDT Wednesday NVZ001.

     Lake Wind Advisory from 11 AM Tuesday to 5 AM PDT Thursday for
     Lake Tahoe in NVZ002.

     Wind Advisory from 11 AM Tuesday to 11 PM PDT Wednesday
     NVZ003-004.

CA...Wind Advisory from 11 AM Tuesday to 11 PM PDT Wednesday CAZ071.

     Wind Advisory from 11 AM to 11 PM PDT Tuesday CAZ070.

     Wind Advisory from 2 PM Tuesday to 11 PM PDT Wednesday CAZ073.

     Lake Wind Advisory from 11 AM Tuesday to 5 AM PDT Thursday for
     Lake Tahoe in CAZ072.

&&

For more information from the National Weather Service visit...
http://weather.gov/reno