Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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052
FXUS66 KHNX 191130
AFDHNX

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
430 AM PDT Sat May 19 2018

.SYNOPSIS...Scattered showers and a slight chance of afternoon
and early evening thunderstorms will continue over the higher
elevations of the Southern Sierra Nevada Sierra each day through
Wednesday with chances spreading into the foothills on Monday and
Tuesday. Otherwise, dry weather will prevail over the central
California interior through the middle of next week.

&&

.DISCUSSION...Elongated shortwave trough pushing through central
CA at this time. This system has been spreading mid/high clouds
into the area overnight, but no precipitation. This system has
displaced the ridge that prevailed over our area on Friday.
Meanwhile, moderate onshore p-grads continue to produce breezy
conditions across the Kern County Mountains and deserts. Once
again, scattered showers and isolated thunderstorms will be
possible over the higher elevations of the Southern Sierra
Nevada today as CAPE and instability are favorable for
thunderstorm development over the higher elevations this
afternoon.

The shortwave currently moving through our area is progged to
move east of our area by this afternoon only to be followed by a
stronger shortwave which is progged to push into Central CA by
Sunday night then cut off into a closed low over our area by
Monday. This system will bring a noticable cooling trend to our
area with temperatures lowering to near seasonal normals by
Sunday and to below seasonal normals by Monday. This system will
provide for enough instability and CAPE combined with ample
moisture over the Southern Sierra Nevada for showers and
thunderstorms to be more prevalent by Monday and even a chance of
showers and isolated thunderstorms over the Southern Sierra
Foothills and the eastern-most portion of the San Joaquin Valley
if the flow aloft turns offshore and allows for the deeper
moisture to reach the foothills. The low is progged to move slowly
east of the area on Tuesday and temperatures will recover as
heights and thicknesses rise, but a cyclonic flow aloft will keep
precipitation chances going over the Southern Sierra Nevada and
possibly the foothills depending on the timing of the departure
of the upper low.

The medium range models are not in good agreement toward the end
of next week and the RMOP is indicating low confidence for central
CA by next Friday. The GFS is indicating better run to run
continuity and has less ensemble spread than the ECMWF so it is
the preferred solution today. The GFS indicates the low continuing
to move east and slowly away from our area on Wednesday and
Thursday as a ridge slowly amplifies over CA which will result in
a drying trend and above normal temperatures across the area by
the end of next week. The ECMWF shows the ridge quickly breaking
down by next Thursday and an anomalously strong upper low moving
into central CA by the end of next week. If this idea were to pan
out our area will have the potential for widespread precipitation
and much cooler temepratures. However, this solution does not
appear to be reasonable based on the blocky upper longwave pattern
which has prevailed so far this spring.

&&

.AVIATION...Isolated thunderstorms with local MVFR/IFR conditions
will occur over the higher elevations of the Sierra between 20z
today and 03z Sunday. Otherwise...VFR conditions will prevail
across the Central CA Interior during the next 24 hours.

&&

.AIR QUALITY ISSUES...None.

&&

.CERTAINTY...

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.

&&

.HNX Watches/Warnings/Advisories...NONE.

&&

$$

public...DS
avn/fw...Durfee
synopsis...DS

weather.gov/hanford



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