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Area forecast discussion
National Weather Service San Joaquin Valley - Hanford California
310 PM PST Thu Feb 23 2017

Synopsis...
some lingering showers across the Sierra foothills will diminish
this evening. Temperatures will drop to freezing levels over much
of the San Joaquin Valley tonight. Dry conditions will prevail on
Friday then a couple of weak disturbances will move through this
weekend into early next week with generally light precipitation.

&&

Discussion...
broad upper trough still covers much of the western Continental U.S. With a
few light showers over the southern Sierra foothills. Hi-res models
agree this activity will gradually diminish after sunset with dry
conditions expected later this evening. Visible satellite imagery
shows lots of flat cumulus over the San Joaquin Valley, but this
too should dissipate with clearing skies forecast. A good onshore
surface flow continues with the sfo-las pressure gradient around
10 mb; producing gusts up to 45 mph in the Kern County mountains
and desert. Winds in the sjv are lighter but still breezy in some
areas. The gradient will relax through the night and winds will
trend lower.

The combination of clearing skies and diminishing winds will set
the stage for good radiation cooling conditions tonight. Freezing
temperatures are forecast across much of the San Joaquin Valley,
thus a freeze warning has been issued. 3-6 hours of freezing temps
are forecast with some rural areas dropping to around 28 degrees.
Temps should nudge up a bit Friday night but some areas are still
likely to reach the freezing mark.

Dry conditions will prevail on Friday then precipitation chances
return this weekend into early next week. There a couple short
wave troughs progged to swing through from the north, thus they
will have lower snow levels, generally around 3-4k feet. Also,
precipitation amounts are expected to be fairly light compared to
previous systems as there is no rich moisture tap. The GFS remains
faster with the initial wave arriving by Saturday evening, while
the European model (ecmwf) holds it off until early Sunday morning. The second
wave drops down Sunday night through Monday. Combined rainfall
from the 2 waves may reach a quarter of an inch in parts of the
sjv, with many areas likely seeing less than a tenth of an inch.
Quantitative precipitation forecast in the mountains is from a quarter to one half an inch, with
a couple of inches possible down to around 3000 feet. Winds will
become breezy to locally gusty again this weekend.

Medium range models show dry conditions Tuesday through the end of
next week as an epac upper ridge gradually builds in over the West
Coast. Temperatures will remain several degrees below normal early
next week, then trend warmer to near normal by later in the week.

&&

Aviation...areas of MVFR and local IFR conditions along the valley
facing slopes and over the southern Sierra Nevada and Tehachapi
Mountains in low clouds thru 06z Fri. Areas of MVFR visibilities in
mist over the San Joaquin Valley between 09z Fri and 18z Fri.
Otherwise, VFR conditions will prevail across the central California
interior during the next 24 hours.

&&

Air quality issues...
none.

&&

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

&&

Hnx watches/warnings/advisories...
freeze warning from 2 am to 8 am PST Friday caz089>092.

&&

$$

Public...dch

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