November 16, 2021 – Areas of patchy Valley fog this morning. Breezy north to northeast winds Tuesday into Wednesday morning. Chance of more widespread light showers late Thursday into Friday.
Discussion
A quick moving, weak trough is passing through the area early this morning. Only very light rainfall amounts have occurred with this system with amounts less than 0.10 inches over the southern Cascades and northern Shasta county. The system will quickly move into the Great Basin region today with breezy north winds developing behind it over the Central Sacramento Valley with a few gusts to 30 mph during the afternoon.
A brief period of patchy fog will be possible this morning as skies clear and before north winds begin to increase by mid morning. The winds will help mix and dry the atmosphere, diminishing the fog threat Tuesday and Wednesday.
Brief high pressure ridge will build in Wednesday, before another quick moving trough approaches late Thursday. Ensembles have been trending weaker with this system with the GEFS depicting a much flatter trough versus early model runs.
Precip with this system is still expected to be a bit farther south and more widespread for areas north of interstate 80 versus yesterdays system. Current forecast indicates rainfall amounts trending lower and now ranging from 0.10 to 0.25 inches. It should be a warm system with little snow expected, as snow levels likely remain above 7500 feet.
Extended Discussion (Saturday through Tuesday)
Weak upper trough moves through Saturday with little impact as NBM keeps the forecast dry. Models show a positively tilted closed upper low off the CA coast next weekend but differ on position and depth of feature. Oper GFS brings the low close enough to the coast to bring a threat of showers over the higher Sierra Nevada early next week. Ensembles/NBM support a drier forecast for now.