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Area Forecast Discussion (AFD)

Issued by Sacramento, CA (STO)

FXUS66 KSTO 181018

Area Forecast Discussion
National Weather Service Sacramento CA
318 AM PDT Sun Aug 18 2019

Near or below average temperatures expected through Monday. 
Gradual warming trend through next week with dry weather 


The Delta breeze influence is in full force as early morning 
temperatures in most Valley locations have dropped into upper 50s 
to low 60s. Forecast soundings and HREF ensemble probabilities 
also support marine stratus being advected into the Delta region 
the next couple of nights/mornings. Some of these probabilities 
extend eastward toward the Sacramento area. But will remain 
somewhat cautious with this output given previous instances of 
being too robust with the coverage of low clouds. Otherwise,
mostly clear skies should prevail across the region today with 
high temperatures roughly 4 to 7 degrees below average. This
equates to Valley highs in the mid to upper 80s.

To start the work week, a weak trough off the coast will enhance
the Delta breeze allowing for the potential for additional marine
stratus decks. 00Z NAM forecast soundings show this marine layer
being a bit deeper than Sunday with a greater eastward extension.
Monday will seemingly be a carbon copy of the previous day with
below average temperatures continuing. Gusty winds will continue
across the Delta with 20-30 mph speeds likely to be observed.

Moving beyond Monday, a gradual warming trend is anticipated as a
longwave trough over the eastern Pacific lifts up toward western
British Columbia. The ever persistent Four Corners ridge will
expand north and west by the middle of next week. Building
synoptic heights will raise Valley temperatures back into the
mid/upper 90s with a smattering of triple digits up toward Redding
and Red Bluff. The pattern also supports decreasing Delta
influences which allows overnight temperatures to sit above
average by mid-week. ~BRO


Ensemble guidance is in good agreement high pressure will remain 
in place through the extended forecast period. Warmest day is 
forecast to be Thursday with high temperatures right around the 
century mark across interior CA. A very slight cooling trend is 
then expected going into next weekend before heat builds again the
following week.


VFR conditions next 24 hours. Areas southwest wind gusts 25-30 
kts vicinity Carquinez Strait and west Delta. Local southerly wind
gusts 15-25 kts 22Z-02Z Monday elsewhere.