Hydrometeorological Discussion National Weather Service / California-Nevada RFC / Sacramento CA 645 AM PDT Mon Aug 31 2026 ...COOLER WITH PRECIP CHANCES INCREASING OVER NORTHERN CA... .METEOROLOGICAL CONDITIONS (MON AM - SUN AM)... A weak disturbance is moving through the southwest flow aloft from a location along the southern CA coast toward southern NV this morning. This is expected to touch off scattered showers and thunderstorms primarily over eastern NV during the afternoon and early evening hours...before this s/wv trof exits the area over northern UT. At the same time...general troffing is developing over the northeast Pacific and is expected to dig southward along the west coast. An initial s/wv trof rotating through this flow will move across northern CA on Tuesday...reaching the coast during the afternoon hours and exiting the area over eastern OR early Wednesday. There isn/t a lot of moisture entrained into this system...resulting in relatively light precip over portions of northwest CA up toward the upper Klamath River basin. A deeper low spinning over the northeast Pacific...just off the Pacific Northwest coast along 130W will shove a more potent moisture plume southward toward the northern CA coast on Wednesday. Max PW values within this feature are looking to be close to 1.50-inches. This looks more promising for precip production for Wednesday afternoon into Thursday with the best amounts located over the Smith River basin with 1.00- to 2.50-inches...tapering off to 0.25- to 0.75-inch across the rest of the northern CA higher terrain...and very little over the Sacramento Valley. For the end of the week into the upcoming weekend...models are hinting at tropical/monsoon moisture advecting northward from near Baja toward southern CA. There is very low confidence in exact placement of this elevated moisture...which may bring an increasing chance of at least some light precip for southern CA. Please Note: This product may NOT be routinely updated. Please refer to the following product issued by the CNRFC www.cnrfc.noaa.gov/Daily-Briefing for a graphical summary of weather and hydrologic conditions. |