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Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
730 AM PST Thu Feb 25 2021

...SCATTERED LIGHT PRECIP OVER FAR NORTHERN AREAS THROUGH SAT...
...POTENTIAL FOR PRECIP EARLY NEXT WEEK AGAIN OVER THE NORTH...

.METEOROLOGICAL CONDITIONS (SHORT TERM: THU AM - SUN AM)...

Weak ridging overhead as a s/wv moves through AZ to the SE, and a 
frontal system develops over the Pac NW this morning. Over the next 
24-hrs, expect the latter system to develop and move southeastward, 
bringing the threat of light showers to the Srn OR Cascades, Upper 
Klamath, and Northern NV. Biggest threat looks to be Friday and 
Friday night, as the system opens into a deep trough over Idaho, but 
even then the system doesn't have a lot of moisture to work with. 
Expect 0.5-0.75" total over the W slopes of the Srn OR Cascades, and 
up to 0.3" over Nrn NV by Saturday morning. Light showers may 
continue through the day on Saturday over Nrn NV as the trough 
narrows and digs through NV, but are expected to wrap up by Sunday 
morning. 

Airmass to the north is on the colder side, so freezing levels today 
are expected around 2000-4000-ft over far Northern areas, dropping 
to 1000-3000-ft late Friday into Saturday.


.METEOROLOGICAL CONDITIONS (LONG TERM: SUN AM - WED AM)...

Expect dry conditions Sun as an upper low moves south into western 
AZ and ridging builds into the western U.S.  Guidance diverges 
significantly regarding a potential upper trough moving into the Pac 
NW Mon and potentially moving across the CNRFC forecast area through 
around Tue.  Looking at deterministic and ensemble guidance, ECMWF 
and CMC guidance show mainly light showers (potentially a bit 
heavier in the Sierra) across mainly north coast and higher terrain 
areas of the region, while GFS is mainly dry until Tue-Wed with some 
precip over southern CA.  WPC guidance seemed a bit dry considering 
how many ensemble members showed precip, and blended in some NBM 
through Mon 00 UTC and then blended in some deterministic guidance 
through Tue to incorporate the potential for a bit more widespread 
precip.  Expect freezing levels generally 3000-6000 ft except 5000-
7000 ft in southern CA.  Most guidance indicates a drying trend by 
later Tue.