AGUS76 KRSA 181520
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
830 AM PST Wed Feb 18 2026

...SERIES OF DISTURBANCES TO MOVE IN FROM THE NORTHWEST THROUGHOUT 
THE WEEK BRINGING PERIODS OF WIDESPREAD PRECIP, T-STORMS, AND 
MOUNTAIN SNOW...

.METEOROLOGICAL CONDITIONS (SHORT TERM: WED AM - SAT AM)...

Radar imagery shows shower activity across a large portion of 
California as a low pressure system tracks down the coast and a cold 
front/moisture plume with IVT ~400 units moves onshore over southern 
California. The Heaviest precipitation over southern CA will move 
out of the area over the next few hours with shower activity 
remaining across much of the State. An additional 1+ inches are 
currently forecast over the mountains of San Diego and Riverside 
Counties over the next 24 hours, most of which has already fallen or 
will fall in the next couple of hours. An additional .5 to 1 inch is 
forecast for coastal locations and the Sierra where showers and 
thunderstorms move onshore. Locally higher amounts are possible 
where thunderstorms form and track. 

An additional system is forecast to move in behind the current 
disturbance tonight and into Thursday morning bringing another round 
of precipitation to the forecast area. Similar to the current 
system, the low will track southeastward and push another moisture 
plume inland along the central and southern California Coast with 
shower and thunderstorm activity across the north in association with 
the low. The heaviest precipitation accumulations of >1 inch for 12Z 
Thursday to 12Z Friday currently target the central and southern 
Sierra, Big Sur Coast, and eastern Transverse and Peninsular Ranges 
where onshore moisture flux will be strongest. 

Precipitation will taper off on Friday into Saturday until another 
disturbance begins to move across the north. Models continue to 
struggle with the exact timing of this system with ensembles 
generally favoring an earlier onset while deterministic products 
are a bit later. 

Similar to the previous few days, freezing levels will be quite low 
in association with the next couple of systems into Friday morning. 
Levels across the north will generally sit below 3,000 feet 
throughout the 3-day window before rising early saturday under the 
WAA of the weekend storm. Freezing levels across the south will 
fluctuate between 4 and 6k feet, north-to-south. 

.METEOROLOGICAL CONDITIONS (LONG TERM: SAT AM - TUE AM)...

A large surface/upper low will approach the western U.S. on Saturday 
bringing widespread precipitation to northern and central CA through 
early next week. There remains uncertainty on the arrival timing of 
precip as the det models continue to show a later onset of showers 
compared to the ensembles. Ensembles have slowed down a bit since 
yesterday, but remain about 12-24 hrs ahead of the det GFS/ECMWF. 
The latest NAM is on the earlier side now as well, though not as 
early as the NBM. Looking at the 24 hr QPF clusters ending Saturday 
afternoon (00z Sunday), there is disagreement among the ensemble 
members on the arrival and spread of precip from the low. Cluster 1, 
comprising of 30% CMC 50% GEFS and 48% ECMWF is the slowest with 
showers confined mostly to the immediate nrn CA coast north of Point 
Reyes. The other 2 clusters push precip further inland to varying 
degrees at either Shasta (cluster 2: 30% CMC, 33% GEFS, 24% ECMWF) 
or into the northern Sierra and past the Golden Gate (cluster 3: 40% 
CMC, 17% GEFS, 28% ECMWF). The official forecast is on the slower 
side of the ensembles but quicker than the det models with lighter 
showers along the coast north of Point Reyes and into Shasta 
Saturday morning. The low will continue to rotate offshore of the 
PacNW throughout the weekend sending bands of precipitation into nrn 
and cntrl CA. The system will draw in additional warmer moisture on 
Monday into central/southern CA. Some uncertainty as to when or even 
if that precip will arrive. For the current period, nearly all of 
the precip is expected north of Point Conception with a few lighter 
showers over Santa Barbara/Ventura counties.

There is good agreement that the bulk of the impacts from this 
larger system will be across nrn coastal CA into Shasta and the 
northern Sierra, but uncertainty as to how far south of these areas 
higher totals may travel. The official forecast for Saturday was a 
blend of the 50% NBM and the det NBM to slow down some of the 
precip. The rest of the period made use of the latest det NBM. QPF 
12z Sat-12z Tues: 3-6" nrn CA coast north of Point Reyes (up to 
8.50" King Range), 5-7" Shasta, 3-7.25" northern Sierra, 1-2.50" 
central Sierra, 0.25-1.25" southern Sierra, 1-3" central coast 
mountains, 0.50-1.75" rest of Bay ARea/central coast, 1-3.50" Sac 
Valley, 0.10-1" SJ valley, and 0.10-0.50" around Point Conception.

This low will be drawing in a warmer moist airmass raising freezing 
levels this weekend from sw to ne. On Saturday, the Sierra will 
start at around 3-6 kft rising to 5-9 kft by the evening. This 
increase will continue Sunday reaching 7-10.5 kft in the evening. 
Levels will lower a bit into Tuesday down to 5.5-10 kft as troughing 
from the main low descends a little into nrn CA, but the core of the 
main system will still be offshore of the PacNW.



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/AS

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