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AGUS76 KRSA 071442
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
640 AM PST Sun Dec 7 2025

...DRY CONDITIONS CONTINUE FOR MOST OF THE REGION THROUGH THE
PERIOD AS THE AREA REMAINS UNDER STRONG HIGH PRESSURE...
...OCCASIONAL SHOWERS ALONG THE N COAST THROUGH MID WEEK AS SYSTEMS
SLIDE DOWN THE RIDGE INTO THE PACNW...

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

Little has changed since yesterday as a strong area of high pressure
remains over the eastern Pacific steering any moisture/precip north
of CA. Fog remains stubbornly entrenched down the central valleys as
well. Models continue to show systems rotating around the ridge into
the PacNW on and off over the next several days resulting in shower
chances along the north coast and the srn OR Cascades. What has
changed is that things are trending a bit drier as both det models
and their ensembles have these systems a bit further northward than
in previous runs. The result is lower QPF for the period than in
previous forecasts. Amounts over the Smith have gone down by 0.10-
0.50" and over the srn OR Cascades by 0.50-1". The forecast was a
blend mainly of WPC guidance and the NBM. Forecasting about 0.25-
0.50" over the Smith Basin, 0.10-0.25" immediately to the south
along the coast, then little to nothing towards Cape Mendocino.
Expecting 0.75-1.25" over the srn OR Cascades over the next 6 days.

Looking out further into the future, ensembles have the ridge
sticking around for at least another week, then about mid month the
500 mb height clusters show some potential for a low in the Gulf of
Alaska to break down the ridge. This solution is shown in one form
or another by about 33% of the ensemble members. The others at least
predict some weakening of the ridge compared to what we`ve been
experiencing. Also finally seeing some signs of moisture making it
to and a bit past 40N mid to late December, but this is far from
certain.

Freezing levels 8 to 13.5 kft from the OR border to soCal today.
Levels rising early next week back up to 10.5-14 kft for most of the
rest of the week rising a bit further up north to 11-13 kft.


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



AS

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