High Wind and Dense Fog in California, December 28, 2018

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
215 PM PST Thu Dec 27 2018

.SYNOPSIS...
A cold front will continue pushing through the area on Today,
bringing a period of increased winds as well as a few showers to
the mountains. Dry weather will prevail for Friday through the
middle of next week with below normal temperatures.

&&

.DISCUSSION...
Cold front pushing through the region today as clouds and light
mountain showers persisted for most of the day. After the front
passed through parts of Central California, surface winds were
able to increase as gusty winds have been reported over the West-
side of the valley and areas over Merced County. A wind advisory
is in place for the strong winds today that are expected to
continue beyond sunset and into the evening hours. As the winds
increase, fog, which lingered over the valley this morning has
dissipated with only low clouds hugging the mountains still
lingering. In addition, mixing of the lower atmosphere by the wind
has allowed for slight warming of the lower levels. Most surface
observing sites around the valley has shown a 24 hour trend on the
plus-size. While the 24 change in temperatures have ranged from 1
to 4 degrees, the region is responding to the strong winds
currently aloft. As a strong 100 knot jet across the region,
strong northerly winds followed by cold air will affect the
district.

Model upper-air analysis places a 100 knot jet just to the east of
the district with +90 knots crossing the area this evening and
overnight. Downward transfer may allow for breezy conditions
through the evening and possibly into the early hours of Friday.
While the orientation of the jet will lean more toward a “Mono-
type” wind direction, strong overnight winds may exist over
Central California with limited moisture. Therefore, winds will be
more of an issue going into Friday than the potential for
precipitation. Evenmore, the northerly winds may dry-out the
atmosphere slightly and allow for the lowering to dew-points.
Response time may be 24 hours which supports the possible Freeze
on Saturday morning. Yet, during the period of strong northerly
winds, enough downward motion may hinder the development of fog
across the San Joaquin Valley. With this, will not mention fog
overnight and maintain the wording of a freeze watch going into
Saturday morning. Based on the amount of drying, will see
widespread temperatures near and below 32 degrees with isolated
locations reaching the 27 degree mark. With a weak short-wave
ridge crossing the area on Sunday, could see similar conditions
before yet another disturbance enters the region.

Models indicating the passage of an inside-slider crossing the
Great Basin later on Sunday which may allow for another round of
stronger surface winds. Therefore, after two days of near freezing
conditions across the San Joaquin Valley, enough mixing may
prevent a third very cold morning. Yet, the trajectory of the
inside-slider may not support precipitation across the district
(except for possibly Yosemite) as conditions remain dry going into
the New Year. While model uncertainty is growing toward the middle
of next week, the trend is for possible ridge across the West
Coast. Therefore, will keep at least the next seven days dry for
now as the general trend is leaning toward the ridge pattern.

&&

.AVIATION...
Across the San Joaquin Valley, local MVFR in low clouds along the
east side and south end until 03Z Fri. Areas of MVFR and local IFR
in mist between 09Z Fri and 18Z Fri. In the southern Sierra
foothills and north facing slopes of Tehachapi Mountains, areas of
MVFR and local IFR in low clouds until 06Z Fri. Surface wind gusts
of 35 knots or greater will occur through and below the eastern
slopes of the Kern County Mountain passes until 12Z Fri. Otherwise,
VFR conditions will prevail over the Central CA Interior during the
next 24 hours.

&&

.AIR QUALITY ISSUES...
On Thursday December 27 2018...Fireplace/Wood Stove Burning
Status is: No Burning Unless Registered in Fresno and Kings
Counties. 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...
Wind Advisory until 7 PM PST this evening for the Kern County
Mountains and Deserts /CAZ095-098-099/.

Hard Freeze Watch from late Friday night through Saturday
morning for the San Joaquin Valley /CAZ089>092/.

Wind Advisory until 11 PM PST this evening for the San Joaquin
Valley. /CAZ089>091/.

&&

public/synopsis...Molina
avn/fw...DS

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