Seasonably warm air temperatures continue, cold water temperatures persist too

July 16, 2019 – Dry weather with seasonably hot temperatures continue. Breezy winds through the Delta and over the Sierra crest at times.

Discussion

Clear skies cover the rengion early this morning other than a few high clouds across the far northern portion of the state associated with a short-wave moving through the PacNW.

Current temperatures are slightly cooler compared to 24 hours ago and range from the 40s in the mountain valleys to the mid 70s across milder portions of the Central Valley and foothill thermal belts.

Little change is expected the next several days as a weak trough lingers along the West Coast. Dry and seasonably hot weather will continue.

Extended Discussion (Saturday through Tuesday)

Extended period starts out Saturday under high pressure over most of the southern U.S and near zonal upper level flow. Daytime highs are forecast to come in right around season normal and any type of precipitation should remain well east of the forecast area. A weak trough development over the eastern Pacific is forecast to bring upper flow to more southerly on Sunday.

Although humidity values may come a bit, especially over the Sierra, with this transition, models keep significant moister out of the region so forecast will remain dry. GFS does hint at some moist convection Sunday evening but GEFs ensemble members are quite varied over the eastern Pacific during this time period so uncertainty is high.

Upper flow remains mainly southerly on Monday as weak trough digs in off the coast but moisture stays mainly east of the state. Daytime highs are expected to remain right around normal.

Only minor changes are expected going into the middle of next week as offshore upper trough starts lifting northward over the southwestern U.S. high pressure ridge. Initially the synoptic pattern will be quasi-zonal in nature while an upper trough grazes the region on Friday.

The height gradient stays well to the north suggesting little to no impacts across northern California. As this system exits toward the north-central U.S., modest height rises take place along the West Coast over the weekend.

By early next week, ensemble solutions show a stout Four Corners ridge extending westward suggesting an increase in temperatures. Until then, highs are forecast to remain around, or slightly below climatology. The lower Sacramento and upper San Joaquin Valleys should see temperatures in the upper 80s to lower 90s while mid to upper 90s are likely in the upper Sacramento Valley.