Marine Weather and Tide Forecast for August, CA

DISCUSSION
Southerly flow and mid-level cloud deck observed this early afternoon across most of interior NorCal. Radar shows some light returns in the central Sacramento Valley and in portions of the Sierra south of 50, most likely light sprinkles or virga as latest 24-hour precipitation totals are very light or zero across most of the CWA Monsoonal moisture, along with some upper level support from an offshore trough will keep Valley light shower chances in the forecast for the rest of the day. Mountain thunderstorm chances will gradually increase as we move through the rest of the afternoon, with the best chances residing mainly south of I-80.

Thunderstorm risk will continue on Tuesday, with some nocturnal threat early Tuesday morning mainly in the Coastal Range. Chances then increase throughout Tuesday afternoon and evening across the higher elevations of the Sierra-Nevada, with better chances along and east of the crest. Cannot rule out a stray Valley/foothill shower tomorrow either, but latest CAMs looks to keep most activity confined within the higher elevations of the area. We will also see Valley high temperatures climb on Tuesday and Wednesday, with widespread Moderate HeatRisk. We currently have widespread triple-digit high temperatures on Tuesday and Wednesday across the Valley and foothill thermal belts.

By Thursday, onshore flow will increase in response to a weak closed low off the PacNW coast, which will help lower heights across the region. High temperatures will fall across most of the Valley, except in the northern Sacramento Valley where triple- digit highs will remain in the forecast until this weekend.
Further into the weekend, we may see additional monsoonal moisture surges into the area, with PWAT values approaching roughly 170% of normal by Saturday. With a ridge developing near the Four Corners region by the weekend, this setup will once again favor afternoon/evening mountain precipitation chances. For now, the NBM is suggesting roughly 30% chances of precipitation south of HWY-50 Saturday - Monday.

AVIATION

General VFR conditions prevail across interior NorCal next 24 hours. Surface wind gusts from south to southwest around 10 to 15 kts in the Sacramento Valley, Delta and Sierra Crest until 03Z Tuesday but lingering Delta Breeze up to 15 kts until 06Z Tuesday.

Mid to high level clouds continue periods of BKN to OVC conditions around 10-25 kft with isolated showers and mist with a slight chance (5-15%) of thunderstorms over the Sierra crest and eastward from 21Z Monday to 06Z Tuesday. Slight chance of showers returning after 12z Tuesday across the Sacramento Valley bringing isolated MVFR conditions if developed.



STO WATCHES/WARNINGS/ADVISORIES
None.