Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 201026

Area Forecast Discussion
National Weather Service Sacramento CA
326 AM PDT Thu Apr 20 2017

Shower chances will diminish by this afternoon. Dry and warmer
weather for Friday and into the weekend. The next chances for
precipitation return for the start of next week.


.DISCUSSION (Today through Sunday)...

Model height analysis showed an upper level trough of low
pressure continuing to move across northern California overnight
as water vapor imagery indicated dry air behind the trough moving
onshore. Radar trends showed scattered rain and snow showers
across the forecast area with intensity starting to diminish.

Latest short term model forecasts show precipitation trends
diminishing this morning and eventually ceasing by the early
afternoon hours. Some isolated light rain or snow cannot be ruled
out for the higher terrain this afternoon, but chances are
unlikely as an upper level ridge is forecast to build into the
region this evening.

Temperatures will warm to near to slightly above normal for Friday
under stable conditions provided by the ridge. Another weather
disturbance will approach the west coast and head towards the
Pacific northwest on Saturday. Main portions of jet stream and
associated instability will remain to the north of the forecast
area, however some precipitation is possible for the northern
mountains and extreme northern Sacramento valley for Saturday
night. Any developing precipitation will be light with small
accumulations. Sunday should remain dry, but a small chance for an
isolated shower is possible for the northern mountains.


.EXTENDED DISCUSSION (Monday through Thursday)

Extended forecast will be controlled mainly by flat upper ridging
over the eastern Pacific and west coast. Unfortunately, model
agreement in timing of shortwave troughs passing over this ridge
is quite poor. In general, areas north of about Chico will see a
continued threat of showers through the extended period. This
threat may extend farther southward Tuesday or Tuesday night as
models show a bit more consistency in tracking a bit deeper of a
shortwave through Norcal. Overall, QPF still on the light side
during this time as with the remainder of the extended period so
impacts should remain minimal. May see breezy south winds at times
as shortwaves pass through but again winds are not expected to
have major impacts during the extended period.



IFR/MVFR ceilings Sacramento valley and over mountains as weak
weather system passes through becoming mainly VFR after 18z all
areas. Generally south winds to 15 knots becoming northerly after



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