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Hydrometeorological Discussion
National Weather Service / California-Nevada RFC / Sacramento CA
800 AM PDT Thu Sep 3 2026

...COLD FRONT CONTINUES TO SLOWLY DROP SOUTH OVER NORTHERN CA...
...SHOWERS POSSIBLE FOR SOUTHERN CA AND SOUTHERN NV THIS WEEKEND...

.METEOROLOGICAL CONDITIONS (THU AM - WED AM)...

An upr low continues to spin just west of the mouth of the Columbia 
River this morning...while a sfc cold front extends from the 
interior of the Pacific Northwest back southwest across northern CA 
before reaching offshore just north of the SF Bay Area. The moisture 
plume entrained ahead of the frontal boundary continues to show a 
healthy amount of moisture aimed at the SF Bay Area with peak values 
just shy of 1.50-inches offshore...while the 03/12Z KOAK RAOB 
indicates 1.21-inches of PW. For the most part...radar imagery along 
with automated gauge reports show mainly light precip impacting the 
higher terrain of northern CA. Best precip today is anticipated to 
be in the vicinity of the now slow moving cold front...especially 
upslope locations of the northern Sierra where 700-mb winds are 
expected to be from the southwest anywhere from 30- to 40-kt.

By Friday morning...the moisture plume will continue to erode as it 
slowly makes its way near Point Conception ahead of the sfc cold 
front. Precip is expected to dissipate before reaching central CA 
with some lingering light amounts over the central Sierra up into 
northwest NV early on in the period.

For the upcoming weekend...attention shifts toward southern CA. As 
now Hurricane Marie makes its way toward the west-northwest south of 
25N...moisture entrained into this system will advect northward 
toward southern CA and the lower Colorado River basin. Each 
successive model run appears to be less aggressive in precip 
development across southern CA with the latest forecast showing 
light amounts between Los Angeles and San Diego stretching inland 
over the southeast CA deserts and extreme southern NV. Totals are 
currently looking to run anywhere from a few hundredths of an inch 
up to about 0.33-inch over the southern CA coastal mountains. 

Also...the persistent upr low off the Pacific Northwest coast will 
finally rotate inland and shift off toward the northeast and reach 
the northern Rockies on Monday into Tuesday. This will weaken the 
overall cyclonic flow over the west coast. There is disagreement 
with how close to the coast the next system diving toward the region 
from the northwest will get with the GFS basically right along the 
coast and the EC more offshore. This will determine how cool the 
region remains...or if temperatures finally start to rebound closer 
to normal for this time of year. 


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.