High Wind in California, February 22, 2018

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
456 AM PST Thu Feb 22 2018

.SYNOPSIS...At least two cold storm systems will track
southward out of western Canada during the next 5 days and
bring precipitation to much of the central California interior.
The storms could bring accumulating snow to the foothills and
over the Grapevine tonight and again Monday night. In the
interim, this weekend will be dry with high temperatures near
seasonal normals.

&&

.DISCUSSION...Mother Nature is paying us back for bringing us
balmy, dry weather during the first two weeks of February. In
most cases, the payback is welcome, but it is certainly having
its drawbacks. For starters, the change to much colder weather
has had a negative impact on agriculture. Unfortunately, the
Golden State will remain locked in this cooler than normal
pattern for a while longer and not without the threat of more
frosty overnight temperatures in the San Joaquin Valley. On
the bright side, the storms that visit the Golden State during
the next week will bring us badly needed precipitation. It
won't be enough to end the drought, but it will at least put a
dent in it.

In the broader view, the upper level pattern across the lower
48 states will be in a jam.  A strong and persistent upper level
ridge of high pressure will remain anchored off the Eastern
seaboard for the next several days and it will slow the normal
eastward progression of storm systems across the country. An
upper level trough of low pressure that has been centered over
the Great Basin since President's Day weekend will sit nearly
idle for much of the next 7 days. Storm systems venturing out
of the Gulf of Alaska will have nowhere to go but southward
down the western side of this trough.  Considering their origins,
these storms will bring cold air with them, but not a whole lot
of moisture.

The next storm is currently poised over the Pacific Northwest.
As it approaches from the north, it will bring an increase in
cloudiness to much of the central California interior today.
Precipitation will first develop over the higher elevations of
the Sierra by this afternoon while westerly winds ramp up over
the Kern county mountains and desert. By dusk, precipitation
will spread into the lower elevations such as the foothills
as well as the east side of the San Joaquin Valley. And by
late this evening, precipitation will move into the Kern county
mountains. Colder air accompanying this storm will bring snow
levels down as low as 1500 feet by this evening, so any precip
that falls down to this elevation will be in the frozen form.
Although precip will be rather light, it will be in the form
of snow, and because it will fall at elevations that normally
don't get snow, it certainly will pose a potential travel
hazard for motorists. In general, snow accumulations of a
dusting to a couple of inches may occur in the foothills by
Friday morning. Higher elevations of the Sierra could pick up
3 to 6 inches by the time this storm exits into the Great
Basin Friday afternoon. Westerly winds in the Kern county
mountains and desert should diminish accordingly during the
second half of tonight. Otherwise, Friday will be an unseasonably
chilly day across the entire CWA.  Afternoon temperatures could
struggle to climb above 50 degrees in parts of the San Joaquin
Valley.

Skies should clear out pretty rapidly Friday evening as colder,
drier air advects southward into the district in the wake of this
exiting storm. Before daybreak Saturday, temperatures in many
San Joaquin Valley locations will again fall below freezing and
possibly as low as the mid 20s in the normally coldest locations.
Meanwhile, in the Kern county desert, thermometer readings could
bottom out in the teens Friday night.

The weather this weekend will be relatively pleasant with light
winds, mostly clear skies, and seasonable afternoon temperatures,
thanks to weak short wave ridging aloft.  During this time, the
next storm will be brewing in western Canada. The models bring
this storm southward, but put it on a slightly westward trajectory
than our current storm which means it could pick up more moisture
as it moves through central California early next week. Precip
with this second storm will spread southward over the district
Monday afternoon and evening and linger into Tuesday before the
storm finally exits east of the state later Tuesday. Colder air
behind this storm may again lower snow levels to 2k feet or lower
by Tuesday and bring a renewed threat of accumulating snow into
the foothills and over the mountain passes of Kern county.

Tuesday night through Wednesday should bring us a break in wet
weather as another weak upper level ridge moves in over central
California. Another cold storm will approach from the northwest
Wednesday night and bring precipitation back into much of the
central California interior next Thursday. This late week storm
looks like it might be the wettest storm of them all, but it's
not something to hang our hats on yet. The models love to excite
us with QPF, then back off with each model run as the storm's
get closer, so stay tuned. One thing we can be fairly confident
of is that temperatures will generally average below normal for
most of the next 7 days.

&&

.AVIATION...
Mountain obscurations over the Southern Sierra Nevada and Kern
County Mountains in low clouds and showers after 18z Thu.  Otherwise
VFR conditions expected across the remainder of the Central CA
Interior during the next 24 hours.

&&

.AIR QUALITY ISSUES...
None.

&&

.CERTAINTY...

The level of certainty for days 1 and 2 is medium.
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...
Winter Weather Advisory from 10 PM this evening to 10 AM PST
Friday CAZ095.

Wind Advisory from 10 AM this morning to 10 PM PST this evening
CAZ095-098-099.

Winter Weather Advisory from 6 PM this evening to 6 AM PST
Friday CAZ093-094.

&&

public...Durfee
avn/fw...Andersen
synopsis...Durfee

weather.gov/hanford