000
FXUS66 KSTO 202213
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
313 PM PDT Mon Aug 20 2018

.SYNOPSIS...
Gradual cooling with dry conditions expected through the week.
Areas of smoke and haze will continue, especially near wildfires.

&&

.DISCUSSION...
Temps trending a few degrees cooler at midday thanks to a Delta
Breeze, a little deeper marine layer and suppressed 5H heights from
the Pac NW trof. The cooling trend will continue Tue/Wed with the
passing trof, before leveling off Thu, followed by additional
cooling into the weekend.

Some of the higher resolution Model REF/QPF fields suggest at least
a small PoP is warranted over the Ern portion of Shasta Co Tue
afternoon/early evening as the upper level trof swings through the
region. Confidence is not high, thus the PoPs are low as moisture is
lacking. It is possible that the trof may kick up a little wind over
the Sierra/Srn Cascade ridges as it moves through the region.

Energy from SWrn Canada is forecast to slide SWwd across the Pac NW
and into Norcal on Tue. The continentality of this feature will mean
it will be devoid of moisture, thus the low PoPs and low confidence.
The synoptic forcing from the upper trof may elevate the well
developed marine layer to allow for some patchy stratus to form on
the east side of the Sac Vly Tue morning as onshore momentum should
continue overnite and on Tue. As the low pulls away to the E/NE on
Wed, the Delta Breeze should begin to weaken.

Some improvement in smoky conditions away from the fire origin is
expected over Norcal (given current status of WFs) this week as
upper level troughing over the region suppresses stagnant high
pressure over the Desert SW.   JHM

&&

.EXTENDED DISCUSSION (Friday THROUGH Monday)

Broad upper troughing remains over Interior NorCal through the
weekend keeping temperatures slightly below normal. Models show a
deeper short wave trough moving into the PacNW late Sunday into
Monday. Differences exist with depth of this system, but for now
forecast remains dry with additional cooling and increased onshore
flow day 7. Guidance puts max temperatures Monday upwards of 10
degrees below normal.


&&

.AVIATION...

Local MVFR/IFR conditions in HZ/FU near wildfires, otherwise VFR
continues over the area for the next 24 hours. Winds below 15
knots except local SW-W surface wind gusts 25-30 kts vicinity
Delta tonight and over higher mountain terrain this afternoon
into evening.

&&

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

&&

$$