Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 151621

Area Forecast Discussion
National Weather Service Sacramento CA
921 AM PDT Fri Sep 15 2017

Dry with seasonal temperatures through the weekend. Cooler weather
with a chance of showers next week.


Upper level trough has shifted east into the Great Basin as
northerly winds have begun to develop across Northern California.
Remarkably, a few stratus clouds that developed across the
Sacramento Valley yesterday have lingered into this morning. With
a bit of cold advection, temperatures are running a few degrees
cooler than 24 hours ago.

With mainly clear skies today, warmer temperatures are expected
across the region by this afternoon. Expect high temperatures to
reach the mid 80s across the Valley today, with 60s and 70s over
the mountains. Similar temperatures are expected through the
weekend. These forecast highs are within a few degrees of normal
for this time of year.

Cooler weather will begin to settle into the region on Monday as a
deep upper trough drops out of the Gulf of Alaska. This trough has
trended slightly weaker with recent computer model runs, and
precipitation looks more likely to remain north of our forecast
area. Breezy south to west winds look possible on Monday,
particularly over higher elevations.



The extended forecast begins next Tuesday which should be the
coolest day with valley highs in the mid 70s and highs over the
mountains and foothills ranging 50s to low 70s (40s near the
Sierra Crest). This much cooler pattern is thanks to a trough
swinging through the Pacific Northwest and extending southward
into CA next week. Latest GFS and ECMWF models indicate that the
bulk of precipitation will stay north of us, but we could still
see a chance of showers through the end of the week. Showers will
likely be over higher terrain, but there`s a slight chance that
some shower activity could occur in the northern Sacramento
valley. As stated in the previous extended discussion...these
cooler temperatures are likely to catch travelers and outdoor
recreationalists off guard! This will also serve to lower snow
levels, perhaps significantly enough to cause a dusting of snow
across the highest crests. Something to prepare for if you plan to
be in higher terrain during the first half of next week. The
trough will gradually track eastward which will cause a warming
trend after Tuesday. JBB/CEO



VFR conditions next 24 hours. Breezy north winds developing
today, with gusts to 18 kts across northern Sacramento Valley
after 18z impacting the KRDD and KRBL TAF sites. Winds lighten by
00z Saturday except for the delta region where wind gusts could
be up to 20 kts overnight. JBB



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