Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 081000
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
300 AM PDT Sat Aug 8 2020

.SYNOPSIS...
Warming trend into Sunday/Monday with moderate heat risk over
northern and central portions of the Sacramento Valley and
surrounding foothills. Afternoon thunderstorms possible over
higher mountain terrain, mainly Sierra Nevada, today into
Tuesday.

&&

.DISCUSSION...
EPAC ridging extends inland over NorCal as closed upper low
resides west of Point Conception. Moderate flow through the Delta
overnight, but slightly weaker than 24 hours earlier. Marine
layer about 1700 feet deep attm per Fort Ord profiler with some
coastal stratus extending into the Carquinez Strait. Increased
subsidence over interior NorCal today will result in slight
warming of the AMS. High temperatures forecast to be around 3 to 7
degrees above normal. 700-500 mb MU CAPE and modified TT`s
increase along the Sierra Nevada crest this afternoon under mid-
level southerly flow. This to suggest a threat of isolated
afternoon thunderstorms over the higher Sierra terrain from about
Lake Tahoe southward.

Only minor changes in synoptic pattern expected Sunday with a
continued upward trend in temperatures. Triple digit heat forecast
for much of the Northern and Central Sacramento Valley with
moderate heat risk. Upper 90s expected in the Southern Sacramento
and Northern San Joaquin Valleys. Closed upper low progged to
retrograde slightly offshore Sunday with elevated instability
limited to southern portions of our higher Sierra Nevada, south of
highway 50.

Above normal temperatures continue 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.

Heights/thicknesses begin to lower over interior NorCal Tuesday
with increased onshore flow as short wave trough progresses into
PacNW. Increasing mid-level westerly flow will shift thunderstorm
threat mainly east of the CWA Tuesday afternoon except for a
slight chance over higher elevations of our Sierra, south of
Highway 50.

PCH

&&

.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)...
Weak trough forecast to persist along the West Coast later next
week. Dry weather expected with temperatures close to average for
mid-August.

&&

.AVIATION...
VFR conditions next 24 hours. Southwesterly surface wind gusts
15-30 kts vicinity Carquinez Strait/W Delta, particularly after
02Z Sunday. Local southerly surface wind gusts 10-15 kts
Sacramento Valley 00Z-06Z Sunday.

&&

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

$$



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