772 
FXUS66 KSTO 031019
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
319 AM PDT Sat Apr 3 2021

.SYNOPSIS...
Dry weather with above normal temperatures trending cooler into next 
week. Chance of light precipitation over the higher elevations
next week. 

&&

.DISCUSSION...
Upper ridge axis has moved into the intermountain west with SW flow 
aloft prevailing over the Ern Pac (E of the closed low near 140W) 
and into CA. This has allowed onshore flow to increase steadily over 
night resulting in a 5 to 10 degree cooling trend in the areas 
influenced by the Delta Breeze. Nighttime fog product shows a 
healthy stratus deck along the coast and also making its way into 
the coastal valleys, and Wrn Solano Co areas. Ft Ord profiler 
indicates the stratus deck has deepened to over 2 kft in addition to 
good momentum through the Carquinez Strait. This is usually a good 
indicator of stratus making its way into the Valley and the HREF low 
cloud ceiling probability prog has increased its probabilities to 
over 50/50 this morning (over 70% in the Carquinez Strait) and 
higher probabilities for Sun morning, exceeding 80% if not 100%.
Forecast max temps today will be mainly in the 70s in the Valley 
(60s in the Strait) and some 5 to 12 degrees cooler than yesterday 
from Chico Swd in the Valley and surrounding foothills, but only a 
few degrees over the higher elevations. Additional cooling will 
occur Sun and Mon with above normal temps today and Sun falling to 0 
to 8 degrees below normal on Mon.  

Deterministic models trending similar for Mon with the trof off the 
B.C. coast dropping into the Pac NW and brushing Norcal, but 
differing on the details and chance of precip for a portion of our 
CWA, and the amount of cooling for the CWA. While the ECMWF has at 
least a few ensemble members with some light precip for the Sierra 
zones, the GFS has trended a little warmer with a few more ensemble 
members showing a wider range of QPF. We continue to "blend" the 
forecast to show some low PoPs over the Nrn mtns and Sierra while 
trending the temps cooler, but not as cool as the MAV and MET for 
Mon. 

As the trof moves Ewd on Tue short wave ridging builds back into 
Norcal with a warming trend.   JHM 

&&

.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)...

Dry with above normal high temperatures expected Wednesday under 
upper level ridging. Significant model differences exist beyond
mid week leading to forecast uncertainty. For now, forecast leans
toward EC/NBM solutions advertising a threat of showers over the 
mountains and Northern Sacramento Valley Thursday into Friday. 
Precipitation amounts look light. These solutions then point 
towards drier weather returning Saturday.
&&

.AVIATION...

VFR conds ovr intr NorCal nxt 24 hrs exc poss MVFR/IFR conds in 
ST vcnty of Delta and lcly in Srn Sac Vly til abt 18-20z. Sfc wnds
genly AOB 12 kts exc SWly wnd gsts to arnd 30 kts poss vcnty of 
Delta, mnly aft 00z Sun.

&&

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

$$