Seasonably warm, dry, and breezy weather continues today. A brief cool down is then expected on Friday and Saturday before temperatures warm back up from Sunday into next week. A few isolated showers or thunderstorms will also be possible from Friday afternoon through early Saturday morning across the northern Sacramento Valley and northern Sierra.
Discussion
As of early this morning, mostly clear skies remain evident across interior NorCal via latest GOES-West satellite imagery. A bit of a stout northerly breeze, occasionally gusting to 30 mph, is expected to work through the northern and central Sacramento Valley through this morning, but winds are generally expected to lighten through the afternoon. Otherwise, with northerly winds peaking this morning, afternoon high temperatures look to reach closer to seasonal normals and around 2 to 4 degrees cooler than yesterday.
An upper level, shortwave trough is then expected to dig southward from the Pacific Northwest on Friday, then rapidly transition toward the intermountain West throughout the day on Saturday. There remains some ensemble uncertainty on exactly how the shortwave will evolve, but overall impacts for interior NorCal look to remain minor at most. Regardless, as this shortwave moves within the vicinity of interior NorCal late day Friday into early Saturday, a few isolated showers and thunderstorms may pop up (10% to 25% chance) across the northern Sacramento Valley and northern Sierra. Otherwise, the region looks to trade northerly winds for south to west winds in onshore flow from Friday into the weekend.
Additionally, a somewhat pronounced cool down is anticipated, with Valley high temperatures in the 70s to low 80s and 50s to 60s at higher elevations. This cooldown looks to remain short lived, however, as heights aloft begin to rise on Sunday and temperatures return to near normal by Sunday afternoon.
Extended Discussion (Monday through Thursday)
Ensemble guidance continues to trend toward rising heights and upper level ridging building in across the western CONUS moving into next week. Some troughing perturbations over the Pacific Northwest may result in enough lift for isolated late day thunderstorm activity along the Sierra, but confidence is limited at this time.
Rather, a return to seasonably warm (Valley high temperatures: upper 80s/low 90s, Higher Elevation high temperatures: 70s to 80s) and dry weather and periodically breezy conditions looks to be the overarching theme across the extended forecast period.