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Hydrometeorological Discussion
National Weather Service / California-Nevada RFC / Sacramento CA
630 AM PDT Sun Sep 13 2026

...LIGHT LINGERING SHOWERS AS A LOW PASSES TODAY ALONG WITH BELOW 
NORMAL TEMPERATURES...
...POSSIBLE ADDITIONAL LIGHT SHOWERS OVER NRN CA WEDS WITH OTHERWISE 
DRY CONDITIONS THE REST OF THE PERIOD...

.METEOROLOGICAL CONDITIONS (SUN AM - SAT AM)...

An upper low is making its way through the PacNW this morning with 
the southern edge of the system scraping northern CA. Not much to 
show on radar with just a few light echos along the border. 
Overnight observations showed about 0.10" over those locations with 
higher totals on the OR side. The low will head northeastward 
lifting into ID later today while troughing from the low remains 
overhead. Some lingering showers possible along the CA/OR border 
into tonight as the low passes. Otherwise, dry conditions and more 
widespread below normal temperatures expected for the rest of today. 
Models then still show drier air moving in over CA/NV behind the low 
tomorrow preventing additional chances for precip. 

One thing that has changed from yesterday, now the GFS and the ECMWF 
show a low forming over the PacNW on Tuesday rather than just some 
broader weak troughing. This low also carries some moisture with it 
breaking up the drier airmass that was expected to remain overhead 
basically the rest of next week. Both the GFS and the ECMWF then 
show the low digging into nrn CA some time Wednesday, disagreements 
on exactly when, and dropping some light precip as it arrives. 
Models then lift the low back northeastward into OR/ID at the end of 
the week with some ridging building in behind it. Don't have a lot 
of confidence on this development but if it sticks around the next 
few model runs we'll see. For now, blended in the ECMWF/GFS into WPC 
morning guidance to generate some showers over nrn CA/srn OR on 
Wednesday. Amounts look minimal at less than 0.10". Should this low 
manifest, it would also act to keep cooler temperatures overhead and 
delay a bit of warming from that next ridge.


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.