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248
FXUS66 KHNX 261016
AFDHNX

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
316 AM PDT Thu Apr 26 2018

.SYNOPSIS...
Mainly dry and warm conditions will continue today, except for a
chance of afternoon showers and thunderstorms in the Sierra
Nevada due to an approaching low pressure system. Expect cooler
and breezy conditions on Friday and into the weekend, and then
another chance for mainly mountain showers and thunderstorms
during early next week.

&&

.DISCUSSION...The approaching low pressure system that is off the
coast of northern California will bring increasing onshore flow
later today into this evening, mainly towards Merced County and
along parts of the west side of the San Joaquin Valley. Otherwise,
temperatures will remain above average today at most locations,
although with slight cooling. There is a chance of thunderstorms
in the southern Sierra Nevada today due to the approaching low
that will bring mid-level moisture and instability. With any
thunderstorms that develop, brief heavy rain, frequent lightning,
and small hail are possible at times this afternoon through the
early evening. In addition, SPC (Storm Prediction Center)
continues to show a chance for thunderstorms in the Sierra for
this afternoon into the evening.

Cooler air will spread over much of Central California on Friday
as the closed low pressure system moves inland over N CA. Average
to slightly below average temperatures will continue through the
weekend as the trough associated with this low remains over the
region. Showers and isolated thunderstorms cannot be ruled out
over the Sierra high country over the weekend; however, most of
the moisture and dynamics will shift into northern California.
Gusty winds will occur through the favored passes and canyons in
the Kern County mountain/desert areas during Friday afternoon
through late Saturday night, so a Wind Advisory has been issued.
Decent forecast model agreement continues through the weekend, so
confidence has been increasing for this period as we get closer.

A low pressure system will arrive Monday and bring yet another
chance for showers and thunderstorms over the Sierra Nevada and
adjacent foothills. This upper-level low will move eastward by
late Tuesday; however there is uncertainty regarding chances of
mountain convection to continue beyond this time due to notable
differences in model solutions (as typical at lead times beyond
the next five days during this time of year). The Euro continues
to show precipitation for Wednesday through next Thursday over the
Sierra, while the GFS shows high pressure building from the East
Pacific, or a dry scenario with warming for this period. So,
blended with WPC (Weather Prediction Center) guidance and kept
mainly a dry forecast for the middle part of next week, including
beyond Tuesday night. Also trended temperatures back upward, or
closer to average for this period (early May).


&&

.AVIATION...
MVFR and occasional IFR in showers and thunderstorms along the
Sierra mainly north of Kings Canyon after 18z today through 03z
Friday. 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 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.

&&

.HNX Watches/Warnings/Advisories...
Wind Advisory from 2 PM Friday to 5 AM PDT Sunday CAZ095-098-099.

&&

$$

public...BSO
avn/fw...JDB
synopsis...BSO

weather.gov/hanford