Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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FXUS66 KHNX 251108

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
408 AM PDT Wed Apr 25 2018

Warm temperatures and dry conditions will continue for the next
few days as high pressure dominates. There will be slight chances
for afternoon showers and thunderstorms for the higher elevations
of the Sierra Nevada Wednesday and will continue into the weekend
as a low pressure system moves into northern California. The main
system impacts will be increased winds and clouds for all other
areas as the system moves through the region.


Ridge axis extending from the desert SW into the PAC NW will hold
on today with dry conditions and continued above normal
temperatures across the Central CA interior. This feature will
hold in place one more day into Thursday before all eyes turn
west to the large scale closed upper low center currently becoming
more organized in the EPAC.

Model guidance has been having some trouble on where to track the
low over the past few days. Guidance is becoming more in agreement
now, even through day three. Deterministic runs of the GFS/ECM/NAM
are surprisingly in decent agreement tracking the low center
across NRN CA through Saturday evening. Initial impacts will be
breezy conditions developing along the west side of the valley on
Friday as a low level cool marine air intrusion into the SJV
pushes across Merced and gradually continues south into Kern
County due to increased gradients and a deepening marine layer
along the coast. H500 heights will remain high, so widespread
synoptic cooling will hold off until Saturday for the higher
elevations. Limited moisture in the higher levels will keep the
Sierra dry through Friday.

The upper low center will move into the great basin and remain
nearly stationary as it gets ripped in two. Strong westerlies
will take a piece of it into the midwest and another piece will
merge with a shortwave dropping south along the Sierra on Tuesday.
This low will dig into SRN NV by Wednesday.

Model guidance is indicating unstable conditions across the high
Sierra on Thursday afternoon with PWAT values around 0.75 to
nearly 1.0 inch. Some stronger storms are possible as SPC mentions
the Sierra, mainly north of Kings Canyon for the possibility of
strong storms. Hail and locally heavy rain is possible with these.
Frequent lightning is also possible. Campers and hikers are
encouraged to keep an eye to the sky Thursday afternoon.

With the low center crossing NRN CA on Saturday, we are
forecasting showers and isolated thunderstorms in the Sierra on
Saturday. Deep moisture is limited and PWAT`s are only around 0.50
inches. So whatever rain does fall will not be real heavy. With
continued PVA and increased upslope flow Saturday night into
Sunday with the associated trough moving through we will see a
chance of showers mainly north of the Kern County line. Gusty
winds will be a concern as the trough moves through the Kern
county mountains and will need to be concerned about gusty winds
through and below the passes as well as the Kern county desert

There will be a brief break in the action on Monday as the upper
level shortwave will dig a low center into SRN NV on Tuesday and
bring more unsettled weather to the Sierra Tuesday afternoon and
continue into Wednesday before the low center exits to the east
late Wednesday evening.

Snow levels will be about normal with the systems, with the first
one bringing snow levels down to around 5000 feet on Sunday
morning behind the trough. Snow showers are possible in the
Yosemite National Park, but not looking favorable for the YNP
valley. We will see snow levels rise to around 7000 feet by
Tuesday and then lower to around 6000 feet as the second trough
moves through tuesday evening with snow showers expected.
Moisture will limited and widespread heavy snow is not expected at
this time to warrant any statements.


VFR conditions will prevail across 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.


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