Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 200452
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
952 PM PDT Sun Oct 19 2014

.Synopsis...
Frontal system will provide cooler temperatures and precipitation
chances Monday and Monday night. Another storm system will cause
shower chances mainly for northern areas late in the week.

&&

.Discussion...
Clear skies over Norcal this evening between trough approaching the
coast and high pressure over the Great Basin. Rain band with
frontal system will move into northwest California overnight...but
not reach the coastal range until early morning...Redding area
after 10 am and Sac metro during the afternoon. Current
temperatures are very similar to yesterday at this time. Current
forecast is on track and no evening update will be needed.

.Previous Discussion...
Ridge of high pressure will shift eastward overnight. A weak cold
front will move into the coastal range Monday morning and spread
through the interior during the day. The southern end of the front
will move through Sacramento during the afternoon hours. The front
this far south appears like it wont hold together but may bring
some showers this far south. Further north looks like the better
changes of rain. The central core of the low will move through the
interior Monday evening to keep a threat of showers in the
forecast. Once the low moves into the Great Basin more stable air
will filter in behind the system. Instability does not look that
great with this system but any thunderstorms would likely be
limited to the evening hours as the core of the low moves inland
and probably not that widespread.

Zonal flow aloft over the region for Tuesday with light northerly
winds. Cooler air will remain over the area to keep temperatures
in the lower to mid 70s for another day for the valley to the 50s
for the mountains. Some high cloudiness should be over the area
as well.

A large low will form in the Gulf of Alaska by Wednesday.
By Wednesday night some light rain may spread at times across the
far northern interior areas around Shasta county otherwise expect
dry conditions to prevail for most everyone.



.Extended Discussion (Thursday through Sunday)

A trough over the Eastern Pacific and onto the West Coast for the
later part of the week. There is still low confidence in the
extended forecast due to the models varying with the timing and
strength of waves and the trough moving onto the West Coast. The
GFS is still wetter and more progressive than the ECMWF and moves
the trough through on Saturday. The forecast leans more to the
GFS with the threat of precipitation mainly over the Northern
Sacramento valley and surrounding mountains as weak waves may
brush by the north and as the trough moves inland. Temperatures
are expected to remain near to a little above normal with highs in
the mid 70s to low 80s in the Valley and 50s and 60s in the
mountains on Thursday and Friday then a little cooling over the
weekend with the trough moving inland.


&&

.Aviation...

Generally VFR conditions tonight with increasing clouds and stronger
southerly winds aft 12z as front moves through the area Monday.
Clouds and precipitation may being local MVFR conditions in the
Valley and MVFR conditions with local IFR over the Mountains after
12z Monday. ISOLD TSRA possible Monday afternoon and evening.


&&

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

$$







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