000
FXUS66 KSTO 232223
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
323 PM PDT Tue Jul 23 2019


.SYNOPSIS...
Hot temperatures this week with widespread Valley temperatures
near 100 degrees. There is a slight chance of thunderstorms over
the Central Sierra late this week, though they will likely remain
east and south of our forecast area.

&&

.DISCUSSION...
The forecast area is currently situated between an
upper level trough approaching the West Coast and the monsoon
high pressure centered over the desert SW. Monsoon moisture was
funneled into the forecast area overnight, and impulses along the
trough created enough lift for showers and thunderstorms to form
in the northern San Joaquin Valley and Motherlode area early this
morning. Lightning strikes ignited multiple fires in Calaveras
County, though most have been contained at this time as winds are
generally light enough to prevent significant fire growth. The
showers moved out of the forecast area by late morning. The low
has allowed temperatures to cool a few degrees from yesterday,
though Valley highs will still peak in the mid 90s to near 100
degrees.

After the trough moves onshore and passes through the area
tonight, the monsoon high will build north and west through the
rest of the week and into the weekend. Ensemble models do not have
the best grasp on exactly how the high pressure will propagate as
run to run consistency is fairly low on the extent the expansion
west. Current runs show the ridge building mainly north through
Friday, which will bring more monsoon moisture into the forecast
area. There is a slight chance of thunderstorms over the Sierra
each afternoon this week, though they will likely remain east and
west of the forecast area.

Breezy winds are expected this evening as the trough passes. Winds
will be southerly in the Sacramento Valley and northerly in the
northern San Joaquin Valley. The Delta Breeze will continue
through this week, which will keep overnight Valley low
temperatures mainly in the 60s. HEC

&&

.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...
Long range and ensemble model guidance are in good agreement a
ridge of high pressure originating from the desert southwest will
continue to build into our region through the weekend.
Temperatures are forecast to break the century mark for most
valley locations both Saturday and Sunday. At the start of next
week, the high pressure that is forecast to warm up temperatures
for the weekend is expected to weaken as troughing off the West
Coast starts to influence our region. Southwest flow is expected
to strengthen as this pattern change occurs and will likely mean a
somewhat stronger Delta Breeze and slightly cooler temperatures
especially for Delta influenced areas. Temperatures are forecast
to be near normal at the end of the extended period.

&&

.AVIATION...
VFR conditions continue over the next 24 hours. Local southwest
wind gusts 25-30 kts near KSUU. Gusts to 20 kt possible for the
northern Sacramento Valley through 06z. Otherwise, sustained winds
less than 15 kts.

&&

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

$$