Scientific Forecaster Discussion
fxus66 khnx 132225 aaa
Area forecast discussion...updated
National Weather Service Hanford California
225 PM PST Fri Dec 13 2019
Update...updated air quality section.
Synopsis...an upper level system will bring a chance of rain and
mountain snow through Saturday morning. A second system will
usher in cooler air, light precipitation, and gusty desert winds
Saturday afternoon through early Sunday. Ridging Monday and
Tuesday will keep weather quiet before another possible storm
system impacts central California during the middle of next week.
Discussion...WV imagery indicating a strong southwesterly
moisture fetch streaming from just west of Hawaii to norcal. Radar
composites are showing widespread precipitation from this feature
north of I-80 while further south just scattered mountain showers
southward to Yosemite National Park. The streaming mid/upper
moisture is pushing slowly southward across central California today with
visible imagery indicating mid/high clouds spreading southward.
This is also helping dissipate the fog and low clouds which were
present across portions of the San Joaquin Valley once again this
morning and hung around the Merced area until late morning.
Meanwhile, a mild airmass prevails over the area with
temperatures running well above seasonal normals. A noticable
change will taker place over the weekend as two upper level
systems push through central California. The first will spread increasing
precipitation southward through area by this evening and move out
by midday satruday. This will be followed by a secondary system
Saturday night and Sunday morning. The first system is expected to
produce between a half and an inch of liquid precipitation over
the Sierra Nevada north of Kings Canyon. The snow level will be
around 8000 feet this evening lowering to around 6000 feet by late
Saturday morning. A Winter Weather Advisory remains in effect for
elevations above 7000 feet for the central Sierra until 1000 PST
Saturday where between 4 and 8 inches of new snowfall are expected
with locally higher amounts near ridge tops. Between a quarter
and a half inch of rain are expected in the central Sierra
foothills with lesser amounts (generally a tenth of an inch or
less) in the San Joaquin Valley and further south. The second
system on Saturday night and Sunday does not have nearly as much
moisture with it, but it is colder. Up to a tenth of an inch of
liquid precipitation is expected in the Sierra Nevada and adjacent
foothills with the now level lowering to around 4000 feet by
Sunday morning when the precipitation ends.
A colder and drier airmass will build into our area early next
week behind the second system on Sunday night and provide for a
couple of days of dry conditions, slightly below normal
temperatures and frosty mornings in the San Joaquin Valley on
Monday and Tuesday.
The medium range models and ensemble means are now coming into
better agreement with a weak system bringing some light
precipitation to our area next Wednesday before another ridge
moves in for a drying trend and slightly warmer temperatures
Thursday and Friday. The extended progs are showing the potential
for a fairly strong storm to impact our area next Saturday and
Sunday. Stay tuned for updates.
Aviation...in the San Joaquin Valley and Sierra foothills, areas
of MVFR and local IFR in low clouds and rain. In the Sierra
Nevada, increasing areas of mountain obscuring IFR in low clouds
and precipitation becoming mainly IFR by 06z Sat. In the Tehachapi
Mountains, increasing areas of mountain obscuring IFR in low
clouds and precipitation after 06z Sat becoming mainly IFR by 12z
Sat. Otherwise, VFR conditions expected elsewhere across the
central California interior for the next 24 hours.
Air quality issues...on Saturday December 14 2019...
fireplace/wood stove burning status is: no burning unless
registered in Fresno... Kern and Madera counties. Further
information is available at valleyair.Org
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.Html for additional information
an/or to provide feedback.
Winter Weather Advisory until 10 am PST Saturday for caz192.