Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 231615
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
915 AM PDT Thu Apr 23 2015

.Synopsis...
Unsettled weather through Saturday. Showers and thunderstorms are
expected again today and tonight in the high terrain. Maybe even
an evening valley thunderstorms. A good chance of rain then as a
stronger system moves across the area Friday night and Saturday
morning.

&&

.Discussion (Today through Sunday)...
Made a fairly large update to chance of moisture Friday night into
Saturday morning in the wetter direction.

Looks like more afternoon and evening convection today. We can`t
rule out some stronger cells like yesterday...but looks like
forcing will not be as strong today as it was yesterday. As
overnight shift noted...we do have some instability out into
valley and almost all short range high resolution models
suggesting a chance of the occurring. Would not be surprised at
all to see a few thunderstorms this evening in the Sacramento
area.

Good agreement in models that a wave will push down across the
Valley Friday night into Saturday morning. Position of the upper
low looks very favorable for nice large scale assent over the
valley as well as Sierra with also good moist upslope flow over
the Sierra. Have raised pops to "likely" category in valley and
higher in the Sierra. Rasch
&&

.Extended Discussion (Monday through Thursday)

Ridge of high pressure will strengthen on Monday and gradually
shift eastward on Tuesday. This will result in dry weather, mostly clear
skies, and above normal temperatures. Long range models still hint
at a weak trough trying to break down the ridge by midweek into
the end of next week. Most of the moisture will stay north of our CWA but
some light precipitation may impact the coastal range on Tuesday.
Temperatures will also gradually cool once the ridge weakens from
the trough. CEO/JBB


&&

.Aviation...

Moderate Delta Breeze impacting KSUU and KVCB early this morning
with onshore flow. Delta region may have a few hours of MVFR
conditions between 12-17z from marine stratus, otherwise, the TAF sites
should remain VFR this morning. Winds will generally be under 10
kts into this afternoon. However, onshore flow by late
afternoon/early evening could bring winds between 10-15 kts for
KSAC, KSMF, and KSCK starting around 00z.

Main aviation concern will be the development of thunderstorms and
showers later today. Development will begin over the mountains
this afternoon, especially the Sierra, then isolated
showers/thunderstorms could spread into the valley by later
afternoon/early evening. These storms could cause brief periods of
MVFR/IFR conditions. Valley precipitation will diminish by
tonight, but mountain showers could continue overnight into
Friday.  JBB

&&

.STO Watches/Warnings/Advisories...
None.
&&

$$






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