Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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620
FXUS66 KHNX 201220
AFDHNX

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
420 AM PST Sat Jan 20 2018

.SYNOPSIS...Scattered showers will continue over the Kern County
Mountains today, with snow accumulations still possible over the
major passes. A weak ridge will bring a dry period top the area
tonight and Sunday then a weak system will bring a chance of light
precipitation to areas from Fresno County north on Sunday night
and Monday. A stronger system will bring chances of precipitation
to the area on Wednesday Night and Thursday.

&&

.DISCUSSION...IR imagery indicating an upper trough is currently
pushing through Central CA. Some instability showers are being
indicated by radar in Kern County. Mesowest indicating snow levels
are around 3500 feet in Kern County, and law enforcement and Cal-
Trans have indicated light snow falling over Tejon Pass on I-5.
While only light accumulations are expected today, disruption to
travel over the major passes is possible today so will continue
the Winter Weather Advisory for the Kern County Mountains above
3000 feet through this afternoon. Meanwhile, the precipitation
has all, but ended over the southern Sierra Nevada north of Kings
Canyon so have expired the Winter Weather Advisory for that area.
Other than the instability showers mainly over the Kern County
Mountains today, a clearing trend will take place with a
northerly flow prevailing and a chilly airmass pushing southward
into our area.

WRF indicating shortwave ridging will prevail over the area
tonight and Sunday With mainly clear skies, decreasing winds, a
dry airmass and cool air aloft which will inhibit fog formation,
temperatures in the San Joaquin Valley will drop below the
freezing mark for a few hours late tonight and Sunday morning
although a hard freeze is not anticipated. Temperatures will
recover a bit by Sunday afternoon under mostly sunny skies.

The next low pressure system is progged to push through the PAC
NW Sunday Night and Monday. The WRF had been trending northward
with each run with the southern extent of the precipitation and
keep most of it confined to Fresno County northward. Snow levels
over the southern Sierra Nevada are expected to range between 4000
and 5000 feet with only an inch or two of new snow expected above
the snow line as the more significant precipitation remains to
the north of our CWFA.

Medium range models are showing shortwave energy to our north
might clip our northern most areas with light precipitation
Tuesday Night and Wednesday then a more significant upper trough
will push through the region Wednesday Night and Thursday. This
system has the potential to produce widespread precipitation
across our area Wednesday night and early Thursday. QPF progs are
showing a quarter to half an inch of rain for the San Joaquin
Valley and 1 to 2 inches of liquid precipitation for the higher
elevations of the southern Sierra Nevada. Winter Weather
highlights will likely be necessary for the mountains for
Wednesday Night and Thursday as the time approaches.

The medium range models are also coming into good agreement with
an upper ridge building into CA behind this system toward the end
of next week. This would bring a return to dry conditions and a
warming trend for our area. Areas of dense fog will likely return
to the San Joaquin Valley by next weekend of this projected
pattern pans out.

&&

.AVIATION...Areas of mountain obscuring IFR conditions over the
southern Sierra Nevada, adjacent foothills, and the Tehachapi
Mountains thru 21Z Saturday. Areas of MVFR visibilities in mist
developing in the San Joaquin Valley after 03Z Sunday. Otherwise,
VFR conditions will prevail across the central California interior
for the next 24 hours.

&&

.AIR QUALITY ISSUES...None.

&&

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

&&

.HNX Watches/Warnings/Advisories...

Winter Weather Advisory until 4 PM PST this afternoon ABOVE 3000
FEET CAZ095.

&&

$$

public...DS
avn/fw...JEB
synopsis...DS

weather.gov/hanford



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