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AGUS76 KRSA 011529
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
830 AM PST Mon Dec 1 2025

...EASTERN PACIFIC RIDGING WILL KEEP MOST OF THE REGION DRY
THROUGHOUT THE WEEK...
...LOW CONFIDENCE IN PRECIPITATION ACCUMULATIONS ACROSS THE NORTH
BEGINNING FRIDAY AND INTO SATURDAY...

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

Broad and persistent ridging over the eastern Pacific is forecast to
keep conditions relatively dry over the course of the next six days.
Shortwave activity embedded in the downstream portion of the ridge
has trended towards inside slider activity which will increase
precipitation chances over northeast Nevada on Tuesday/Wednesday.
Model trends have pushed the track of the low further east into the
Great Basin, decreasing precipitation accumulations across central
and southern California. Accumulations in NE NV from 12Z Tuesday to
12Z Wednesday are relatively modest with up to 0.25 inches over the
Ruby Mountains, which may result in a few inches of accumulating
snow. While precipitation accumulations have decreased across
southern California on Wednesday/Thursday due to the eastward shift
in the low track, the region may still see light drizzle and trace
to a couple hundredths in accumulating precipitation.

The eastern Pacific ridge begins to flatten out on Friday, which may
open the door for unsettled weather into the far North Coast into
the weekend. Model guidance is quite uncertain on how much the ridge
flattens out and whether or not the system impacting the Pacific
Northwest shifts far enough south to reach the forecast region.
Morning forecasts generally followed the guidance of the NBM and
WPC, spreading precipitation accumulations as far south as northern
Mendocino county and the Shasta Basin with the highest accumulations
(up to half an inch) over the Smith Basin. Given the uncertainty
associated with the weekend`s forecast, accumulations will be
updated as new guidance permits.

Freezing levels are forecast to start the period above 13k feet over
the west under the ridge and decrease to 5k feet over the east under
troughing. Forecasts suggest freezing levels to decrease across the
north under the flattening ridge to ~8k feet  while remaining
relatively high (>13k feet across the south) into the weekend.

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.

QPF graphics are available at www.cnrfc.noaa.gov/qpf.php



CH

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