Discussion
Satellite this morning shows some a line of cumulus and high clouds over Northern CA, ahead of the weather system moving down from the Pacific NW. Radar returns showed some virga over the northern half of the CWA, evident of the increasing moisture moving into the area.

Chances for showers and thunderstorms are projected to begin over the northwestern portions of the CWA near the Coastal Range and adjacent are this evening before another push of rain over the Sierra late Monday morning through Monday evening. Showers will be scattered in nature with best chances for thunderstorms across the Coastal Range and the western portions of Shasta, Tehama, and Glenn counties from this evening to Monday morning (15-30% chance of thunderstorms). The 12z HRRR run shows showers tapering off by early Tuesday morning. For total rain amounts from this evening to Monday night, NBM probability shows a 40-75% chance of amounts greater than 0.25", highest over the Southern Cascades.

With this, there is also the potential for some snowfall at the higher elevations of the Sierra above 7000 feet. Warm roads may mitigate any significant accumulations and is not expected to impact major roadways.

After Tuesday morning, things quieten with a brief reprieve from active weather before another weather system moves in from the northwest Tuesday evening through Wednesday night. This will bring another round of scattered showers and isolated thunderstorms with breezy winds near storms. NBM forecasts 0.50-1.00" over the Sierra and 0.10-0.50" elsewhere with a 15-25% chance of thunderstorms over the Sierra. There is a 40-70% chance of amounts over 0.50" across the Sierra north of I-80 on Wednesday.

Temperature highs will continue its cool trend with highs in the upper 70s to low 80s through Wednesday before temperature begin to warm back to normal.

.EXTENDED DISCUSSION (Thursday THROUGH Sunday)...
Ensembles continue to vary slightly on the timing and movement of an upper level low as it progresses through interior NorCal. The NBM still favors the slower EC ensemble, which will keep shower chances in the Sierra Nevada throughout the day on Thursday. The best chances will be along and south of I-80, with the NBM advertising around a 10-40% chance of rainfall totals greater than 0.25" inches on Thursday. Locally breezy to gusty northerly winds may develop Thursday as well as the trough continues to slide off towards the east and ridging builds in the eastern Pacific.
Friday, ridging continues to move inland and as a result high temperatures will climb into the low to mid 80s and continue to warm as we move into the weekend. Ridging may also inhibit the Delta breeze from cooling Delta breeze influenced areas over the weekend as well, with high temperatures climbing into the low 90s.
As we warm, the area should also be free from any precipitation chances Friday through Sunday.

AVIATION
MVFR/IFR conditions spreading across interior NorCal through the forecast period . Isolated tstms possible N of I-80 aft 21z. In Central Vly, areas of Sly sfc wind up to 15 kts. Vcnty of Delta, SWly sfc wind 15-25 kts with local gusts to 35 kts. Over hyr trrn, areas of SWly sfc wind gusts 30-40 kts.

STO WATCHES/WARNINGS/ADVISORIES
None.