Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
FXUS66 KHNX 171300
Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
500 AM PST Tue Jan 17 2017
High pressure will maintain dry weather across the area today with
some patchy dense fog in the morning. Active weather will return
on Wednesday as the first in a series of Pacific storm systems
brings rain and mountain snow that will continue into the weekend.
Positively tilted upper ridge will continue to dominate the region
today with dry conditions. The low stratus deck cleared from the
San Joaquin Valley late yesterday afternoon into the evening with
mainly clear skies still prevailing now. The clearing resulted in
rapid radiation cooling with temps falling into the 30s throughout
the valley. Some patchy freezing fog has developed around Hanford
& Lemoore as well. Expect skies to remain mostly clear today which
will allow temps to climb several degrees warmer than the last few
were due to the persistent low overcast.
Things are definitely changing beginning Wednesday as the first in
a series of Pacific storm systems approaches the coast. Precip is
expected to move in from the north around midday Wednesday and
spread south into the evening. Heaviest rain and mountain snow is
expected late Wednesday night and early Thursday morning. Latest
QPF for the San Joaquin Valley is one to three quarters of an inch,
highest around Merced County and lowest in Kern County. The southern
Sierra and foothills could see up to 2" rainfall, with up to 1" in
the Kern County mountains and maybe a quarter inch in the desert.
Snow levels will start out high, around 8000 feet at the onset, but
lower overnight to around 5000 feet late Wednesday night. A Winter
Storm Warning has been issued for the Southern Sierra Nevada from
Yosemite NP down to the Tulare/Kern County line from 2pm Wednesday
through 2pm Thursday. 6-12 inches of snow is possible above 5000
feet with up to 18 inches above 7000 feet.
There will not be much of a break as the next system quickly moves
in early Friday for another round of rain/snow. This storm will be
colder with snow levels down to around 3000 feet. Some showers may
continue into Saturday in a cool air mass, then another storm is
set to arrive on Sunday and looks to continue through Monday. This
storm is also likely to bring some snow down into the foothills.
The Relative Measure of Predictability is rather high for these
two systems and the modTrend shows negative linear regression with
both, especially the Sun-Mon trough. Hydrologic concerns may be
raised again with these storms and the lower snow levels may bring
hazardous travel conditions to heavily traveled mountain passes.
Areas of MVFR in haze and mist will persist across the San Joaquin
Valley for the next 24 hours, with local IFR/LIFR through 18Z today
and again after 06Z Wednesday. VFR conditions will otherwise prevail
over the central California interior.
.AIR QUALITY ISSUES...
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.
Winter Storm Warning from 2 PM Wednesday to 2 PM PST Thursday
ABOVE 5000 FEET FOR THE CAZ096-097.