Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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FXUS66 KHNX 171055

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
355 AM PDT Sun Sep 17 2017

Above normal temperatures today and Monday before a trough moves
through the region on Tuesday, with near normal temperatures and
dry conditions. A second and stronger trough is expected Thursday
with temps falling below normal later in the week. Breezy to gusty
winds will be possible at times, especially through the coastal
pass and the Kern County mountain pass areas.


The region has seen a change in the weather pattern as a
persistent now resides over the west. Temperatures which have
been running above normal across the San Joaquin Valley are now
struggling to reach those levels. Upper air analysis, along with
satellite IR imagery, show the passage of another trof across the
region as clouds stream through the Great Basin. At this point,
the trof will continue to push eastward as another upper level
disturbance moves into the Pacific Northwest by the start of the
work week. This transition between disturbance will allow for a
brief warm-up of temperatures. While temperatures will only reach
normal levels today, the passage of the next trof will allow for
additional cooling before major cooling occurs over the West

Model certainty, while not the best, is improving toward the later
part of this week. Models still attempting to resolve the
passage of a strong disturbance during the middle parts of the
week. While all models favor a trof solution, timing uncertainty
continues to be a big factor on exactly when to introduce the
passage of the deep trof across most of the state of California.
Based on the Weather Prediction Centers prognoses, will follow a
blend of the GFS/GEFS and ECMWF in the long term. This blend will
signal the arrival of the deep trof in the late Wednesday, early
Thursday time frame as temperatures drop some 10 to 15 degrees
below normal across the San Joaquin Valley. Therefore, will favor
the slow down the disturbance and expect its influence toward
latter part of the week. In addition, models continue to show a
more inside slider trajectory that will favor the Sierra Nevada
and Great Basin. Therefore, the precipitation potential over the
lower terrain may remain minimal during the passage of the

Model certainty remains on the lower side toward the latter parts
of the week. Yet, models do resolve some kind of digging of the
trof pattern during the latter half of the week, with as eastward
shift of the trof axis by the weekend. This trend will at least
allow for the continuation of cooler then normal temperatures
through the end of the week, followed by a warming trend during
the weekend. The trajectory of the trof pattern will only favor
the Sierra Nevada in its precipitation potential.


Areas of smoke from wildfires will continue to produce MVFR
visibility over the southern Sierra Nevada and adjacent foothills.
Otherwise, VFR conditions can be expected over the Central CA
interior during the next 24 hours.





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 for additional information
an/or to provide feedback.


.HNX Watches/Warnings/Advisories...



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