Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
FXUS66 KHNX 271017
Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
317 AM PDT THU OCT 27 2016
A strong Pacific weather system moves into the region later today
and Friday bringing widespread rain and high elevation snow. This
system will move east of the area on Saturday before another storm
system arrives on Sunday.
.DISCUSSION...Regional radars show rain moving northeastward into
the Bay Area this morning along the frontal boundary that
stretches from Northwest California well back to the southwest.
Lots of weather phenomena offshore this morning with an incoming
low pressure area now near 30N/130W showing quite a bit of
dynamics as it moves steadily east. To the south is Seymour with
its moisture plume streaming towards Southern California. Lots of
potential for the above mentioned low and Seymour`s moisture to
combine over California for some potentially meaningful and much
For today, it appears the threat of precipitation in Central
California will arrive later than sooner as the flow off the coast
is nearly south to north ahead of the incoming low. Models now
bring the onset later this afternoon and especially overnight as
the main baroclinic zone and lift arrive after midnight. I have
trimmed back pops for this morning and trended for tonight and
early Friday as the main time period of precipitation. Expected
rainfall amounts will be heavily dependent on just how much
moisture from Seymour gets entrained and how fast the frontal band
moves through. Latest estimates indicate that locations near
Yosemite could see 2-2.5" of rain by late Friday and around 1.5 to
2 inches in Sequoia Park. Lower elevations such as the San Joaquin
Valley could receive up to an inch from Fresno north. Snow levels
will be very high due to the southern source area of both the low
and the tropical feed. Current temperature at White Mountain
Summit at 14246 feet is 30 degrees and this bodes well for only
the Sierra crest to receive snow as freezing levels start out at
around 12000 feet or higher this afternoon and fall overnight.
By late Friday models move the system to the east of the area
however showers are possible through the evening. Saturday will be
mainly dry before another weaker storm system pushes into Central
California on Sunday. Monday looks dry however Tuesday`s forecast
has low confidence of a third system bringing precipitation as
models vary considerably as to the development and track of
another low pressure area.
All in all, a welcome rain event for sure.
VFR conditions can be expected for the central California interior
during the next 24 hours.
.AIR QUALITY ISSUES...
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.