Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 281014

Area Forecast Discussion
National Weather Service Sacramento CA
314 AM PDT Fri Oct 28 2016

Wet and unsettled weather through the middle of next week
as several weather systems move across the area. Gusty south
winds on Sunday.


Light to moderate warm sector precipitation has been falling over
the southern three quarters of the CWA over night ahead of a low
pressure system now centered off the central CA coast. This low
and its associated cold front will move through central California
today bringing rain or showers to nearly all the forecast area.
Surface and upper level pressure gradients remain weak today so
winds should not be all that strong. Moderate precipitation will
continue over the northern Sierra but snow levels with this warm
system will remain well above pass levels so impacts will be
minimal. Norcal remains under moist southwest flow on Saturday.
Shortwave disturbances pivoting through this flow will bring a
threat of showers overnight and through the day but expected
precipitation amounts will be much less than today. Another colder
low pressure system now in the Gulf of Alaska will drop into the
eastern Pacific on Saturday night then push into Norcal on
Sunday bringing another round of heavier precipitation. The main
frontal band is forecast to move into the Sierra by Sunday
afternoon. This colder system will mean lower snow levels and it
is likely that significant snowfall will occur at the major
passes. Therefore...have left up the winter storm watch already in
place. Surface pressure gradients indicate breezy south winds on
Sunday. At this appears winds Sunday afternoon in the
valley will remain under advisory criteria but winds will be
somewhat stronger over the Sierra and will continue to mention
these winds in the Winter weather watch. The first part of Monday
will be another in between day with yet another Pacific storm
forecast to push onto the Norcal coast by Monday afternoon and


Models swing upper trough through Interior NorCal Tuesday. Dynamics
look fairly weak with this wave and thus POPs are slight to chance
category with best chances over the mountains. Weak upper riding
follows Tuesday night into Wednesday. Models diverge midweek with
ECMWF/GEM swinging another Pacific front through Wednesday
afternoon into night with associated QPF mainly over the Coastal
range and Northern mountains. GFS is significantly slower bringing
a more elongated wave inland Thursday. Forecast follows the
ECMWF/GEM during this period which advertises mainly dry forecast
Thursday into Friday under upper ridging.



For Intr Norcal, wdsprd MVFR with areas of IFR conds in pcpn
nxt 24 hrs with isold LIFR omtns. Lcl SWly sfc wnd gsts up to 25 kts
poss ovr hyr mtn trrn thru tngt.


Winter Storm Watch from late Saturday night through Sunday
evening for West Slope Northern Sierra Nevada-Western Plumas
County/Lassen Park.


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