Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 150513
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1010 PM PDT Fri Jul 14 2017


.SYNOPSIS...
Heating up through the weekend. Slight chance of thunderstorms
along the Sierra crest this weekend. Temperatures cool to near
average early next week.

&&

.DISCUSSION...
Only addition to previous discussion will be the apparent increase
in some high level cloudiness from the SW Sat afternoon/evening as
moisture works around the Wrn periphery of the Desert SW high and
ahead of the weak trof around 25N/125W. This moisture should skirt
across the Srn portion of the CWA Sat nite into Sun as an upper trof
moves through the Pac NW and suppresses this moisture to the Srn
zones. SWly flow aloft should quickly disperse this moisture Ewd on
Sun.  JHM

Temperatures Fri afternoon ran a couple of degrees warmer compared
to Thu`s. This warming trend will continue into the weekend as an
upper level ridge builds westward.

Weak onshore flow and a suppressed marine layer will lead to
widespread triple digits across the Sacramento and northern San
Joaquin valleys. Daytime highs will hover between 102-108 degrees
this weekend across the valley, with peak heat on Sunday.
Northerly winds will keep overnight lows on the warm side Saturday
evening, generally on the mid 60s to mid 70s. Have nudged
guidance overnight temperatures up a few degrees Saturday night
into Sunday morning. Thus, a heat advisory is in effect from 1 pm
Saturday to 8 pm Sunday given the increased risk of heat related
illness, especially for sensitive groups.

Hot temperatures combined with a period of northerly winds
Saturday night-Sunday morning may increase fire concerns.

Daytime highs will cool down early next week as ridging shifts
eastward and an upper level trough moves across the forecast area.
Isolated afternoon thunderstorms will be possible again in the
Sierra south of Lake Tahoe, although confidence is low. Any
storms that develop should move quickly to the east of our
forecast area. Stable southwest flow will keep the area dry next
week.

&&

.EXTENDED DISCUSSION (Tuesday THROUGH Friday)

An upper level trough will stall just offshore through the
extended period with high pressure centered over the west central
US, allowing temperatures to remain within a few degrees of
normal through Wednesday. Models depict the high pressure
beginning to build slightly farther west Thursday and Friday.
Expect temperatures to climb a few degrees through Friday with
northern valley locations reaching the low 100s and the rest of
the valley near the century mark. Monsoonal moisture will continue
to remain south of the area so have kept precipitation out of the
forecast.

HEC

&&

.AVIATION...

VFR conditions over NorCal next 24 hours. Winds generally less
than 10 kts for TAF sites, gusts up to 25 kts in the vicinity of
the Delta.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 1 PM Saturday to 8 PM PDT Sunday for
Carquinez Strait and Delta-Central Sacramento Valley-Clear
Lake/Southern Lake County-Motherlode-Mountains Southwestern
Shasta County to Northern Lake County-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Northern
San Joaquin Valley-Southern Sacramento Valley-Western Plumas
County/Lassen Park.

&&

$$



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