Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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FXUS66 KHNX 230050 AAA

Area Forecast Discussion...Updated
National Weather Service San Joaquin Valley - Hanford CA
450 PM PST Tue Jan 22 2019

...Updated Air Quality Issues section...

.SYNOPSIS...High pressure along the West coast will bring
dry weather a day to day warming trend through the weekend.
Areas of night and morning fog will occur in the San Joaquin
Valley through the period.


.DISCUSSION...A long and well deserved respite from stormy
weather is in the offing for the central California interior.
If the long range models are right, the rest of this month
will be storm-free across the entire Golden State. As simple
as that sounds, our weather pattern still won`t be free of
mesoscale issues during the next 7 days which will be addressed
later in this discussion. In the broader overview, a high
amplitude ridge of high pressure aloft anchored off the West
coast will remain largely in control for at least the next 7
days. During this time, dry weather will be the rule.

The models keep the high pressure ridge centered over the Eastern
Pacific through Friday. As long as California remains on the
east side of this ridge, the prevailing flow aloft will be
northerly over the state. This also allows room for short wave
troughs to drop out of western Canada and track as inside sliders
into the Great Basin. Although none of them will carry much
moisture with them, these clipper-like systems will produce
strong and gusty winds in their wake along the Sierra crest. The
next one is slated to brush the eastern slopes of the Sierra
Thursday afternoon into Thursday evening and will be followed by a
second somewhat stronger short wave trough Friday afternoon into
Friday night. During these periods, brisk northeasterly winds will
buffet the Sierra crest. This will be an impact for any hikers
over the Sierra summits later this week. Otherwise, from tonight
through Friday, we can expect little more than cirrus clouds on
occasion along with relatively light, terrain driven winds over
much of the CWA.

The development of low clouds and fog each night in the San
Joaquin Valley and its rate of dissipation during the daylight
hours will be the most problematic part of the forecast this
week. Fog may not become all that widespread in the valley until
perhaps this weekend...a time when the Eastern Pacific ridge
finally moves inland. One thing about valley fog is that it
erodes form the outer edges inward during the midday hours. In
locations where fog is slowest to burn off, afternoon temperatures
might not get any higher than the lower 50s this week. In the
sunniest locales, thermometer readings will rise into the 60s. The
potentially warmest parts of our CWA this week will be just above
the inversion. Some foothill communities could experience high
temperatures of 70 degrees or warmer later this week, especially
this weekend. In contrast, the nights will be relatively cool to
chilly through the period. Tonight will be our coldest night this
week. Minimum temperatures will be in the lower to mid 20s in the
Kern county desert. The normally colder locations of the San
Joaquin Valley may get nipped by frost early Wednesday morning.
Successive nights this week should not be as cold.

The Eastern Pacific ridge might get nudged westward over the
Pacific again early next week as another short wave trough drops
out of western Canada. If so, temperatures will trend cooler
over the higher terrain by next Tuesday and the Sierra crest
could be dealing with another episode of gusty winds. Otherwise,
little change is expected in the overall pattern early next week.
That means, you guessed it, the possibility of more night and
morning fog woes in the San Joaquin Valley.


Areas of MVFR with local IFR/LIFR in mist/fog in the San Joaquin
Valley after 12Z Wed. Otherwise, VFR conditions will prevail
over the central CA interior during the next 24 hours.


On Wednesday, January 23rd, 2019, fireplace/wood stove burning
status is: no burning unless registered in Fresno, Kings, and Merced
Counties. Further information is available at



The level of certainty for days 1 and 2 is high.
The level of certainty for days 3 through 7 is high.

Certainty levels include low...medium...and high. Please visit for additional information
an/or to provide feedback.


.HNX Watches/Warnings/Advisories...


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