Marine Weather and Tide Forecast for Oroville, CA

FXUS66 KSTO 071003 AFDSTO

Area Forecast Discussion National Weather Service Sacramento CA 203 AM PST Sat Dec 7 2024

SYNOPSIS
Low elevation morning fog this morning, then a shift toward slightly cooler and breezier weather Sunday into early Tuesday morning. Dry weather continues through mid-week before unsettled weather potential returns late next week.

DISCUSSION
Areas of patchy dense fog are developing early this morning across the central and southern Sacramento Valley, the Delta, and the northern San Joaquin Valley. Sacramento Exec was reporting visibilities down to 1/2 mile at the time of this writing, as fog developed over/near the Yolo Bypass along I-80 and is moving into the Sacramento city area. We can expect to see fog continue to persist as we wake up and start college football Conference Championship Saturday, before burning off by mid-afternoon time.
Besides the persistent fog this morning, dry weather will continue today and into the next work week.

A shortwave trough is forecast to move through the PacNW this weekend, which will help flatten out the upper level ridging that has dominated our synoptic pattern for the past week. Resultant temperatures should cool slightly across NorCal today, with highs in the low 60s across the Valley. As the trough moves into the northern Plains late Sunday and into Monday, our heights will shift into a north-to-south component, as ridging deepens in the PacNW. The orientation of the heights and resulting PGF (pressure gradient force) gradients will usher in breezy to gusty northerly winds Sunday afternoon through early Tuesday AM. The National Blend of Models (NBM) current advertises around a 40-80% probability of wind gusts 30 mph or more Sunday and Monday, with the best chances presiding along the western Sacramento Valley (I-5 corridor) and in the mountain/foothills gaps and canyons.
Development of the gustier winds should help inhibit radiative fog development during this timeframe as well, and also help skies to clear the persistent haze and particulates.

.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)...

Ensembles guidance continues to indicate that by late next week, a trough originating in the Gulf of Alaska will strengthen and dig towards the south. The ECMWF and GEFS are coming into slightly better alignment regarding the potential rainfall/snowfall totals beginning Friday through Sunday, but there are still varying solutions on the track and strength. The NBM is showing a wet bias, and currently is projecting around a 30-70% probability of 1 inch of rainfall or more in the Valley, with the higher chances in the foothills/mountains, and northern Sacramento Valley. Not much change in the snowfall probabilities for the same time period, with the NBM showcasing around 40-70% chance for 12 inches of snowfall or more. Early snow level forecasts have snowfall down to around 5000 feet or so. As mentioned in the previous discussion, there is still uncertainty regarding the track, timing, and potential precipitation impacts so stay tuned to the forecast for updates as details become more clear. Temperatures in the extended period look to cool into the mid to upper 50s for the Valley.
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