Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 190402
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
902 PM PDT Tue Apr 18 2017

.SYNOPSIS...
Stormy weather into Thursday, then dry and warmer Friday through
early Monday.

&&

.DISCUSSION...
A few showers are lingering over the Sierra Nevada and Western
Shasta County this evening. Most area should be ending in the next
couple of hours but models are trying to indicate some showers
lingering overnight for Western Shasta County.

Models this evening are in better agreement on the timing of when
the next round of precipitation will occur. Late in the day
precipitation should be spreading along the coastal range. It
should spread over the Northern part of the valley in the evening
hours. Further south it looks like precipitation may start for
Sacramento towards midnight.

.PREVIOUS DISCUSSION...
Long wave trough continues in the EPAC with series of short waves
moving through across CA in moist SW flow aloft. Satellite
imagery showing current wave tracking across Central CA this
afternoon and radar indicating bulk of associated precip is south
of the forecast area. HRRR suggesting potential for some
scattered light evening showers possible over the mountains of
Shasta and Sierra Nevada, otherwise clouds should be decreasing
most areas tonight.

Model spread leading edge of precip with next system across NW
portions of the Interior NorCal by tomorrow afternoon. Mainly
light precip expected across most of the forecast area tomorrow
night as system moves through. Moderate precip possible across
the west slopes of the Sierra Nevada due to orographic
enhancement. Snow levels lower overnight to 5000 to 6000 feet with
some accumulation at pass levels possibly impacting travel.
Showers Thursday morning gives way to mainly dry conditions by
the afternoon as increasing subsidence spreads in from the west.

Dry weather expected Friday into the weekend as large scale upper
ridging from the EPAC progresses over California. Around 10
degrees of warming expected Friday with highs in the upper 70s for
the Central Valley with 50s to lower 70s for the mountains and
foothills.

PCH

$$
.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)


A ridge will be pushing off to the east of us to start the
extended forecast with nice weather continuing on Saturday. A
short wave trough will push in from the west Saturday night and
move over the northern CWA. Overall this should just bring an
increase in clouds to northern parts for the overnight and early
Sunday but maybe an isolated light shower will be possible. Mostly
sunny skies will settle back in by the afternoon Sunday with mild
highs.

Overall quiet weather expected for Monday but a short wave could
bring a few light showers to northern areas after 21z. A bit
stronger wave of energy looks to move over the area on Tuesday but
there is disagreement on the placement of this. For now the best
chances for showers will be in the higher elevations north and
east of SAC. Snow levels look to be quite high with little to no
snow expected.


&&

.AVIATION...


VFR conditions for the next 24 hours. Isolated showers possible
through 9Z. Light winds less than 10 kt. Changing conditions after
22Z from the west will spread rain east late Tuesday and Tuesday
night.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$



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