000
FXUS66 KSTO 091000
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
300 AM PDT Sun Aug 9 2020

.SYNOPSIS...
Moderate heat risk across mainly the northern and central portions
of the Sacramento Valley and surrounding foothills today into
Monday. Afternoon thunderstorms possible over higher mountain
terrain, mainly Sierra Nevada, through Tuesday. Near normal
temperatures midweek, then warming into Saturday.

&&

.DISCUSSION...
Upper ridging extends inland over NorCal as closed upper low
resides west of Point Conception. Moderate flow again through the
Delta overnight, however marine layer depth has decreased to
below 1000 feet at Fort Ord. Heights/thicknesses trend up today
resulting in AMS warming. Moderate heat risk expected across
mainly northern and central portions of the Sacramento Valley
today with triple digit heat. 700-500 mb MU CAPE and modified TT`s
per NAM12 increase again along the Sierra Nevada crest this
afternoon to support isolated thunderstorm development. Some TCU
likely over the Coastal Range this afternoon under increased
instability.

Above normal temperatures persist Monday with a continued
moderate heat risk for the foothills and Sacramento Valley, north
of the Sacramento area. Favorable modified TT values for deep
moist convection extend farther northward Monday afternoon through
the higher elevations of Western Plumas into Eastern Shasta
county. Isolated storms could also develop over the Coastal Range
late afternoon into early evening.

Heights lower over interior NorCal Monday night into Tuesday as
frontal system moves into the PacNW. Delta breeze strengthens
significantly tomorrow night with strong flow through the
Carquinez Strait Tuesday. Synoptic cooling and increased onshore
flow will return high temperatures to near normal Tuesday.
Increasing mid-level westerly flow will shift thunderstorm threat
mainly east of the CWA except for a slight chance over higher
elevations of our Sierra, south of Highway 50 during the
afternoon.

Little change in max temps on Wednesday as strong onshore flow
continues. Drier weather expected over the mountains Wednesday
under more stable SWly flow aloft.

PCH

&&


.EXTENDED DISCUSSION (Thursday THROUGH Sunday)...

A weak trough persists along the West Coast late in the week. Dry
weather expected with temps close to average for mid-August,
though a slight warming trend is expected next weekend as the
Southwest high expands northwestward.
&&

.AVIATION...

VFR conditions next 24 hours. Southwesterly surface wind gusts
20-30 kts vicinity Carquinez Strait/W Delta.
&&

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

$$