Dry, mild and breezy today, stronger winds expected Wednesday

November 16, 2019 – Dry and mild conditions this weekend through early next week. Very warm over the weekend and Monday with record highs possible in the north Sacramento Valley. Pattern change still on track around mid week with breezy winds, cooler temperatures and maybe some rain/snow mainly in the Sierra Nevada.

Discussion

Clear skies and cooler temperatures are seen early this morning, with satellite beginning to pick up on some areas of patchy fog mainly in the southern Sac/northern San Joaquin Valleys. Ridging will continue to build into northern California today, as a closed low sits off the coast of SoCal and another system digs into the Central Rockies and moves east. Some breezy winds are expected to develop later this morning mainly in the northern Sacramento Valley and foothills, with winds peaking in the afternoon. Sustained north winds from 15-20 mph will be seen, with gusts up to around 25 mph. Winds will decrease in the evening. Of note, fuels continue to be extremely dry and elevated fire weather conditions are expected today.

Ridging continues to influence NorCal through Monday with the main impact being much warmer than normal temperatures. Afternoon highs will be anywhere from 10 to 20 degrees above average, and some temperature records may be tied or broken.

A trough begins to move over the PacNW late Monday night and Tuesday, cooling temperatures back down for Tuesday (although most highs will still be 5-8 degrees above normal). Some small chances for precipitation are seen mainly in the northern mountains in Shasta County and in the higher elevations of the Sierra Nevada Tuesday evening and overnight. North winds return Tuesday afternoon with winds increasing overnight and Wednesday.

Extended discussion (Wednesday through Saturday)

While model uncertainty is still evident, main concern in the extended is the potential for gusty north to northeast winds by the middle of next week. Upper level energy will approach the West Coast early next week, and drop into a closed low over NorCal by mid week. ECMWF ensemble means continue to indicate elevated probabilities of wind gusts exceeding 35 mph for the Valley and the Sierra foothills Wednesday into early Thursday. Latest guidance indicates wind gusts in the 30 to 40 mph range (locally higher) could be possible Wednesday into early Thursday; strongest winds will be on Wednesday. Despite not expecting excessively low humidity levels, fuels remain at critically dry levels for this time of year. Therefore, these gusty winds could bring fire weather concerns. The main areas of concern could be along the west side of the Sacramento Valley into Lake County, the northeast Sierra foothills, and portions of the Coastal Range. Lighter winds are expected Thursday afternoon as pressure gradient relaxes.

In terms of precipitation, this system could bring some mountain rain or snow showers mainly for areas along and/or south of I-80 per latest deterministic and ensemble output. ECMWF ensemble means suggest modest probabilities of 24-hour QPF > 0.1″ for those areas.

Regarding temperatures, highs will be above average through the period, with Valley highs in the mid 60s to low 70s.