Dense Fog in California, December 2, 2018

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
455 AM PST Sun Dec 2 2018

.SYNOPSIS...Clouds will linger in upslope regions today
in the wake of a cold front. Otherwise, dry weather will
prevail over the central California interior into Tuesday
with night and morning fog in the San Joaquin Valley.
A storm system will bring a return of wet weather to the
district by late Tuesday.

&&

.DISCUSSION...The cold front that swept southward through the
central California interior Saturday afternoon and evening
brought precipitation into all areas except the Kern county
desert. Amounts were relatively light compared to the storm
earlier this week. Generally less than a quarter of an inch
fell in the San Joaquin Valley and in the Kern county mountains.
Up to six tenths of an inch of precipitation fell in the
foothills and higher elevations of the Sierra. Very light
precipitation is still occurring in the upslope regions of the
CWA but even in these regions, there will be little more than
a few hundredths falling this morning. Snow levels range from
3000 feet in the Sierra to about 4000 feet in the Tehachapi
mountains, so roads will be slick at and above these elevations
this morning where precipitation is falling. This includes the
mountain passes of Kern County. In the meantime, a few patches
of dense fog have formed in the San Joaquin Valley. As of this
writing, the worst of it appears to be in the valley portion
of Tulare county and the fog extends westward into Kings county.

In the broader picture, a northwesterly flow aloft resides over
the central California interior in the wake of our most recent
cold front. The northwest flow will ensure that clouds remain
banked up along the west slopes of the Sierra and the north
facing slopes of the Tehachapi mountains today long after
precip ends this morning. Brisk winds will continue through and
below the mountain passes of Kern county today. Despite a cloudy
start on the east side and south end, the San Joaquin Valley
will become mostly sunny today and skies will be brilliantly
sunny over the high Sierra under a fresh blanket of snow.
Sunshine will rule the desert as well. Despite sunshine, high
temperatures today will be a few to several degrees cooler than
normal.

A short wave ridge of high pressure offshore will build inland
tonight and Monday. Residual stratocumulus in the upslope
regions should finally clear out. The San Joaquin Valley will
be setting up for a very foggy night under clear skies and
nearly calm wind. In fact, dense fog should be more widespread
later tonight into Monday morning and will likely make travel
potentially hazardous for valley motorists during the morning
commute period. Otherwise, dry weather will prevail Monday
with plenty of sunshine. High temperatures will still run
slightly cooler than normal.  Meanwhile, the next storm system
will be organizing over the Eastern Pacific. The models forecast
this storm system to remain off the central California coast
through Wednesday before finally moving it inland Thursday.
Beforehand, Monday night will remain dry even though the ridge
axis moves eastward into the Great Basin. Although Some high
clouds could move into the CWA Monday night, fog could reform
in the San Joaquin Valley before those clouds thicken up
Tuesday morning. If dense fog becomes a problem Monday night,
it will most likely be in the south valley where cirrus remains
relatively thin.

A southwesterly flow aloft will become established over the
Golden State Tuesday which, in turn, will transport deeper
moisture, at least in the mid levels, northward over much of
our CWA. We're thinking that the Eastern Pacific storm will
remain far enough offshore Tuesday that the best chance of
measurable rain will be west of I-5. Inevitably, precipitation
will spread inland as the offshore storm nears the central
California coast Tuesday night and Wednesday.  While this
system remains offshore, we can expect a rather cool and
unsettled weather pattern over the CWA during midweek. The
atmosphere might become more unstable Thursday as this storm
finally moves inland. In additon to showers, this cold core
storm could trigger isolated thunderstorms over the San Joaquin
Valley and foothills Thursday afternoon.

Showers may linger through Thursday night, especially in the
upslope regions, as this storm exits into the Great Basin.
Short wave ridging aloft will bring dry weather back into the
CWA Friday. The ECM tries to bring another storm system into
central California Friday night while the other models keep
ridging over the state through next weekend. We're favoring
model consensus for now and keep the pattern dry in the
extended periods. If skies are clear in the San Joaquin
Valley any of these nights, then fog will surely be a problem
for morning commuters next weekend. Otherwise, temperatures in
the 4 to 7 day period will average pretty close to normal.

&&

.AVIATION...
In the SJV, expect widespread MVFR conditions due to mist and low
cigs, along with areas of IFR/LIFR in fog through 19z Sun and
developing again after 03z Mon. Upslope cloudiness will cause
terrain obscuration across the Tehachapi Mountains until 20z Sunday.
Strong wind gusts over the Kern County mountains and desert areas
will diminish after 15z Sunday. Otherwise mainly VFR conditions will
prevail across the central California interior for the next 24 hrs.

&&

.AIR QUALITY ISSUES...
On Sunday December 2 2018... Fireplace/Wood Stove Burning Status
is: No Burning Unless Registered in Tulare County.
Further information is available at Valleyair.org

&&

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

&&

.HNX Watches/Warnings/Advisories...
Winter Weather Advisory until 9 AM PST this morning CAZ095.

Dense Fog Advisory until 9 AM PST this morning CAZ089>092.

&&

public...Durfee
avn/fw...JEB
synopsis...Durfee

weather.gov/hanford