Persistent smoky conditions thanks to inversion layer

November 12, 2018 – Dry weather continues with cool nights and near to above normal days through the week. Critical fire weather conditions expected to end this morning as winds diminish. Widespread smoke from the Camp Fire will continue to impact the area.

Discussion

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A persistent upper level ridge which has been over the Eastern Pacific moves inland today. A Red Flag Warning continues until 7 am this morning over the mountains and northern Sacramento Valley before gusty winds diminish. At 3 am, winds at Jarbo Gap were still gusting to 38 mph. Winds will decrease through the day today as the ridge axis moves across the area and the pressure gradient decreases. Humidity levels will remain quite low, though, with a gradual improvement this week.

Wildfire smoke continues to be an issue, with poor visibility for some spots, and bad air quality. Latest HRRR smoke forecast indicates smoke pushing north again later today and tonight as northerly winds decrease and shift to southerly. Strong inversions will keep smoke fairly confined to lower levels, with little wind to clear things out. Because of this, periods of dense smoke will be possible across the Valley at least for the next few days. Try to limit outdoor activity and check on sensitive groups. Go to to airnow.gov or you local air quality district for more information on air quality.

The region will remain under the influence of a persistent upper ridge, resulting in no change in the dry weather pattern. Smoke might help to keep temperatures cooler the next couple of days. High temperatures will be in the 60s to mid 70s for the Central Valley, with mostly 50s to 60s for the foothills and mountains. Cold overnight temperatures are expected mainly over the Central Sacramento Valley southward, with lows in the 30s and lower 40s. Lows will be in the teens to mid 20s across mountain basin locations.

Extended Discussion (Friday through Monday)

Broad upper ridge forecast to continue across the region later in the week maintaining dry weather with mild days and cool nights, and no strong wind events are expected. Forecast guidance is indicating the possibility of a pattern change as an upper trough approaches the area late next weekend into early next week. However, confidence in details remains low so have kept the area dry for now.