Forecast Discussion For Your Phone - Sacramento and the Northern Sierra Nevada Mountains

Northern CA Forecast Discussion

FXUS66 KSTO 192107 AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
207 PM PDT Fri Aug 19 2022

SYNOPSIS...
Hot temperatures continue into the weekend, with slight cooling and increased onshore flow Sunday and Monday. Temperatures gradually warm back up to above normal by mid-week.

.DISCUSSION

... Current visible satellite imagery shows abundant sunshine across much of interior northern California, with some mountain cumulus clouds developing over the Sierra. The monsoonal moisture has retreated southward, and any threat of showers and thunderstorms has been eliminated from interior NorCal.

Areas of haze and smoke may continue to trickle down into the northern Sacramento Valley the next few days from the wildfires to the north and west. Temperatures are trending a few degrees cooler than this time yesterday for areas in the vicinity of the Delta as locally breezy conditions slowed the warming early this morning. However, with plenty of solar heating and high pressure returning, another day of widespread moderate heat risk with areas of high heat risk is expected over the area. There will be minimal relief in temperatures overnight in the foothills and northern Sacramento Valley. Even higher daytime temperatures are forecast for tomorrow. With the little overnight relief, and hot temperatures continuing through tomorrow evening, the Heat Advisory remains in effect through 7 pm PDT Saturday. An upper level trough will approach the PacNW coast on Sunday, assisting in the breakdown of the ridge over the area. Counterclockwise flow from the area of low pressure will contribute to enhanced onshore flow. The combination of lowering heights and an increased Delta breeze will allow for cooler temperatures to return to the area Sunday and Monday. Even though temperatures will be substantially cooler going into early next week than what has been observed the past few days, the northern Sacramento Valley will still see the low triple digits for the daytime high. The cooler temperatures and elevated Delta breeze will be short lived early next week, as the ridge looks to build back in over the area.

.EXTENDED DISCUSSION

(Tuesday THROUGH Friday)... Cluster analysis indicates high pressure will build back in over the extended forecast period, although it will setup south of the area due to the influence of an upper level trough moving across the PacNW. Ensembles are in good agreement for the trough to shift eastward later in the week, allowing the ridge to expand over interior northern California, and for above normal temperatures to return. The signature on the Extreme Forecast Index (EFI) highlights some areas with above normal temperatures for the extended, however it does not look nearly as impressive as the past few days. Some guidance suggests the return of monsoonal moisture to the area late-week which will be something to monitor the next few days.

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