High Wind in California, September 18 to 19, 2017

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
333 PM PDT Mon Sep 18 2017

.SYNOPSIS...
After seasonable conditions today, temperatures will lower to
several degrees below normal the next couple of days then even
cooler later in the week. Breezy conditions will develop tonight
and continue through Thursday with gusty winds through and below
mountain passes. A few light showers are possible over the Sierra
Wednesday night through Friday with snow showers above 8000 feet.
A warming trend is expected next weekend with mostly clear skies.

&&

.DISCUSSION...
Sunny skies prevail across central California today but satellite
imagery shows lots of clouds to the north in association with an
upper trough over the Pacific Northwest. Temperatures are running
at to slightly below readings from this time yesterday and highs
will top out near climatological norms.

The aformentioned trough will move down over the Great Basin and
northern Rockies tonight through Tuesday. An increasing onshore
surface flow will develop and a cooler air mass will settle in.
Temperatures will lower to several degrees below normal on both
Tuesday and Wednesday. A short wave trough from the Gulf of Alaska
is then expected to dig all the way down to southern CA later this
week and bring in an even cooler air mass. Highs on Thursday and
Friday are forecast to be around 15 degrees below normal with mid
70s in the San Joaquin Valley and Kern County Desert.

The SFO-LAS surface pressure gradient is beginning to rise and
westerly winds around the Bay area are up substantially from this
time yesterday. Gusty winds have already developed through and
below the Kern County mountain passes and will across the coastal
ranges this evening with breezy condtiions into the San Joaquin
Valley. Expect these conditions to persist through the week as
models show the onshore pressure gradient remaining tight. A turn
to a NNE offshore surface flow is expected to develop next weekend.

Moisture progs are limited this far south but a few showers are
possible over the Sierra Nevada beginning Wednesday night. Snow
levels will lower to around 8000 feet with some light snowfall
possible at times through Friday.

The amplified long wave trough will gradaully shift east over the
Rockies during the weekend as a high pressure ridge over the East
Pacific begins to nudge inland. Temperatures will trend warmer but
are still forecast to remain a little below normal by Sunday.

&&

.AVIATION...
Areas of smoke from wildfires will continue to produce MVFR
visibility over the southern Sierra Nevada and adjacent foothills.
Otherwise, VFR conditions can be expected over the Central CA
interior during the next 24 hours.

&&

.AIR QUALITY ISSUES...
None.

&&

.CERTAINTY...

The level of certainty for days 1 and 2 is high.
The level of certainty for days 3 through 7 is medium.

Certainty levels include low...medium...and high. Please visit
www.weather.gov/hnx/certainty.php for additional information
an/or to provide feedback.

&&

.HNX Watches/Warnings/Advisories...
NONE.
&&

public...DCH
avn/fw...Andersen
synopsis...DCH

weather.gov/hanford