High Wind in California, January 11, 2019

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
303 AM PST Fri Jan 11 2019

.SYNOPSIS...
High pressure over the district today will bring the second day
in a row of dry weather along with areas of dense fog in the San
Joaquin Valley. A series of Pacific storms will move through the
region starting late tonight through the entire work week bringing
a constant source of rain and mountain snow.

&&

.DISCUSSION...
Shortwave ridge of high pressure has been over Central California
for the last 24 hours, which is allowing for fairly light winds
and appreciable boundary layer moisture from the recent rainfall
to form dense fog. Many areas started to fog in last night and
have continued to see visibilities under 1/4th of a mile,
creating a high risk for transportation. For these reasons,
another Dense Fog Advisory was issued last night and is valid
through 11 AM PST today for the central portion of the San Joaquin
Valley.

As the area of high pressure aloft drifts eastward, a trough of
low pressure will propagate southeastward into Southern
California, which will bring multiple impacts for our CWA. The
first impact will be strong, south to southeast winds in primarily
the I-5 corridor through the Grapevine in southern Kern County,
especially towards Grapevine and Wheeler Ridge due to a strong off
shore pressure gradient. Strong wind gusts will start in the
early afternoon, and wind gusts in the Grapevine area may be as
high 50 mph starting around 4 PM today and lasting into the night.
We have issued a Wind Advisory for this area, and it will be
valid starting at 1 PM PST/21 UTC today through 4 AM PST/12 UTC
Saturday.

The second impact this system will have will be the precipitation
it produces starting tonight. The bulk of the moisture will be to
the south of our forecast area, but we are still expecting to see
precipitation in the western portion of the San Joaquin Valley,
as well the western portion of the Kern County Mountains. Areas in
the western portion of the valley are expected to get around 1/4"
to 6/10" of rainfall, while the Sierra Nevada will only see a few
hundredths of an inch of liquid. Snow levels are expected to be
around 4500 feet in Yosemite, and around 5500 feet in southern
Kern County. The Frazier Park area may need to be monitored for
winter weather impacts by the day shift as snow fall totals could
be in the 4-8" range. The precip from this event will be out of
the area around 4 PM PST tomorrow.

A break from the rain for the CWA will last for about 18-24 hours
until the next storm system enters the area on Sunday afternoon.
This will be the beginning of a series of moisture-laden waves
that impact the forecast area for nearly the entire work week.
Confidence in knowing exactly how much precip will fall with each
system is not clear at this time, but it would appear that the
intensity will increase with each subsequent system. By the end of
the work week on Friday, there could be as much as 4-6 feet of
snow in the Sierra Nevada, with some areas receiving as much as 8
feet of snow. Snow levels for the event will average around 6,000
feet for the duration of the week. In terms of rainfall, areas
below the snow line in the foothills could see 2-4 inches of rain,
with local 5" possible. In the northern portion of the San
Joaquin Valley, storm totals could be 1-2" range of rain with
local totals to 2.5" of rain. The southern portion of the valley
will likely see less, with totals in the .5" to 1" range.
Finally, the Mojave Desert can expect rainfall totals to also be
in the .5" to 1" range through Friday. Since there is the
possibility of localized heavy rainfall rates, burn scars will
also need to be closely monitored throughout the week. This would
appear to be the most significant precip event Central California
has seen since the beginning of the wet season this year. Be sure
to stay tuned as forecast details get refined as the event nears
with time since there are multiple weather-related impacts
possible next week.

&&

.AVIATION...
Areas of IFR and local LIFR in fog/mist in the San Joaquin Valley
through 19z Friday. Gusty south winds across the Kern County
mountains are expected after 21z Friday and will continue through
12z Saturday. Otherwise, VFR conditions will prevail for the next 24
hours across the Central California Interior.

&&

.AIR QUALITY ISSUES...
On Friday January 11 2019... Fireplace/Wood Stove Burning Status
is: No Burning Unless Registered in Fresno... Kings and Tulare
Counties.
Further information is available at Valleyair.org

&&

.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.html for additional information
an/or to provide feedback.

&&

.HNX Watches/Warnings/Advisories...
Wind Advisory from 1 PM this afternoon to 4 AM PST Saturday
CAZ092-095.

Dense Fog Advisory until 11 AM PST this morning CAZ089>092.

&&

public...Bollenbacher
avn/fw...JDB
synopsis...Bollenbacher

weather.gov/hanford