Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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FXUS66 KHNX 142245
AFDHNX

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
245 PM PST Thu Dec 14 2017

.SYNOPSIS...An area of high pressure off the West coast
will dominate the weather pattern across central California
for several more days. A cold frontal passage early Saturday
morning could bring a few snow showers to the Sierra crest.
Otherwise, dry weather will prevail over the district through
at least Tuesday night.

&&

.DISCUSSION...Some changes in the overall weather pattern are
finally foreseen in the days ahead, but it`s not a favorable
change for precipitation-starved California. For another 24
to 36 hours, our mundane pattern will continue with a
continuation of very low humidities and red flag conditions
above 4,000 feet while a murky haze and patchy late night and
morning fog reside in the San Joaquin Valley.

The resilient monster high pressure ridge that has barricaded the
Golden State from Pacific storms the past several days will begin
to retrograde Friday and allow enough room for a cold front to
drop southward out of western Canada toward the end of this week.
Although this front will be greatly limited on moisture, it could
brush the higher elevations of Yosemite National Park and the
Sierra crest with a few snow showers late Friday night or first
thing Saturday morning. Otherwise, the cold front will herald the
arrival of a freshly cold air mass out of Canada this weekend.
High temperatures in its wake will run a good 5 to as much as 15
degrees lower across the central California interior, especially
above the valley floor. The cold front will also finally break the
inversion and allow for better nightly humidity recoveries over
the higher terrain this weekend. Enough atmospheric mixing should
occur to disperse particulate matter out of the San Joaquin
Valley. In the post frontal environment Saturday, northerly winds
will be gusty in Merced county and over the western half of the
San Joaquin Valley where blowing dust is possible.

A modest offshore flow will become established across the Golden
State by Sunday and continue into early next week as the Eastern
Pacific ridge builds back over central and southern California.
The models forecast a somewhat stronger upper level trough to
move into the Pacific Northwest Tuesday night then track as an
inside slider into the Great Basin on days 6 and 7. The trajectory
of these types of troughs usually do not bring much if any
precipitation into the central California interior. However, the
GFS does track this system a bit farther west, so if this were to
happen, showers could occur over the mountains by next Thursday.
A more important highlight will be the colder air mass that this
storm system will probably bring into the CWA during the latter
part of next week. Minimum temperatures Friday morning, December
22nd could range from the upper teens to mid 20s in the Kern
county desert and in the mid 20s to around 30 in the San Joaquin
Valley. Otherwise, the overall pattern still looks dry for the
next 7 days.

&&

.AVIATION...
Widespread MVFR visibility in haze and mist will persist in the San
Joaquin Valley, with areas of IFR and local LIFR/VLIFR in fog
developing around 06Z until 18Z Friday. Otherwise, VFR conditions
will prevail over the central CA interior during the next 24 hours.

&&

.AIR QUALITY ISSUES...
On Thursday December 14 2017... Unhealthy for sensitive groups in
Fresno... Kern... Kings and Tulare Counties.  Firepalce/Wood Stove
Burning Status is: No Burning Unless Registered in Fresno...
Kern... Kings... Madera... Merced and Tulare 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 low.

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...
Red Flag Warning until 8 PM PST Friday CAZ295>297.

&&

$$

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

weather.gov/hanford



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