Low elevation morning fog potential persists through Saturday before a shift toward slightly cooler and breezier weather then arrives Sunday into Monday.
Discussion
Latest GOES-West visible satellite imagery illustrates mostly clear skies across interior northern California with just a few high cirrus clouds passing by from the north. The fog from earlier this morning has lifted, however areas of haze are still being observed across the area this afternoon. Current visibility observations are generally around 3 to 6 miles or greater, valid at 12 PM PST this afternoon.
Dry weather continues over the next several days, with daytime temperatures near to slightly above the climatological normal for this time of year. Daytime high temperatures are projected to be in the 60s for the Delta and Valley, with 40s to 60s in the foothills and mountains the next few days, with today being the warmest day. Another round of low elevation fog will be possible once again late tonight through Saturday morning. The HREF offers a 30 to 50 percent probability of visibilities of a quarter mile or less tonight through mid-morning on Saturday, mainly from Chico southward in the Valley. Motorists should slow down and use low- beam headlights if fog is encountered.
Ensemble guidance indicates a shortwave trough moving across the Pacific Northwest this weekend, bringing along slightly cooler (but still above normal) temperatures as the upper level ridge is flattened slightly. This trough will then progress eastward and drop down over the Four Corners region later this weekend and into early next week.
As high pressure rebuilds behind it, gusty north to east winds are expected to develop Sunday through Monday. The National Blend of Models (NBM) indicates a 40 to 80 percent probability of wind gusts of 25 mph or greater, mainly along and west of Interstate 5 in the Valley, and in the mountain/foothill gaps and canyons over the Sunday through Monday timeframe.
The gusty northerly winds in the Valley should be a limiting factor for overnight/morning fog development.
Extended Discussion (Tuesday through Friday)
Ensemble guidance is in good agreement that the breezy north to east winds will be diminishing by Tuesday as the trough continues to progress eastward. Near normal temperatures will prevail across the area for most of next week with highs in the 50s to low 60s for the Valley, Delta and lower foothills, and in the 40s to 50s in the upper foothills and mountains.
By late next week, there is decent agreement in the ensembles for a trough deepening from the Gulf of Alaska, bringing along the potential for unsettled weather to return to the region toward the end of the extended forecast period and beyond. Initial probabilities from the National Blend of Models (NBM) indicate a 35-75% probability of a half of an inch of rain from next Friday through Sunday, with a 30-70% probability of 12 inches of snow or more in the mountains over the same timeframe.
There is still some uncertainty in the cluster analysis so confidence is low on exact timing and details at the moment, so be sure to stay tuned for more information as we get closer!