Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 190955
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
255 AM PDT Fri Oct 19 2018

.SYNOPSIS...
Warm and dry conditions through the weekend with daytime
temperatures a few to several degrees above normal. A cooling
trend starting Monday with a chance of precipitation northern
forecast area Tuesday through Thursday. High pressure rebuilding
with warming and drying at the end of next week.

.DISCUSSION...
A Rex Block type pattern is forecast to develop today with high
pressure over the Pacific Northwest and a weak low centered off
the Socal coast. Overall airmass warms a few to several degrees
today as the upper ridge portion of the block centers along the
coast. Surface high pressure digging into the great basin will
bring about a 4mb easterly surface gradient across the Sierra
tonight. This combined with upper east flow will bring breezy east
winds over the Sierra tonight through Saturday morning. West
facing wind prone canyons could see gusts up to about 25 mph.
As the upper ridge shifts inland on Saturday winds will decrease
with a slight cooling likely as the upper ridge axis shifts east
of the region. Even with the cooling, daytime highs Saturday will
still come in several degrees above normal.

By Sunday, the Socal upper low opens and moves inland over the
state. The effects of this will be minor but most areas will see
at least a little cooling. A bit more cooling occurs on Monday as
the upper low remains over the southwest U.S. but high
temperatures still remain slightly above normal.

&&
.EXTENDED DISCUSSION (Tuesday THROUGH Friday)

Pac frontal system approaches the West Coast Tuesday, shifting
inland Tue afternoon into night. Baroclinic zone weakens as it
moves inland under diffluent upper level flow. EC showing stronger
system and more widespread precip over CWA, while GFS indicating
little if any precip. EC has also trended drier from previous
run. Given synoptic pattern, forecast leans more towards drier
solution with low POPs mainly over the Coastal and Shasta
mountains Tue into Wed. Another disturbance moves into northern
portions of the forecast area Thursday. Lingering showers possible
over mainly the Shasta mountains Friday otherwise upper ridging
strengthens over Interior NorCal. Below normal high temps forecast
Tuesday through Thursday, warming to slightly above normal
Friday.

&&

.AVIATION...

VFR conds ovr Intr NorCal nxt 24 hrs with sfc wnds genly blo 12
kts.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$


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