AGUS76 KRSA 071959
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
100 PM PDT Tue Apr 7 2026

...ANTICIPATED A SHIFT TO COOLER AND WETTER LATER WED THROUGH SUN...

.METEOROLOGICAL CONDITIONS (TUE PM - MON AM)...

Dry conditions continue this afternoon as an upr ridge along the 
west coast slides inland. An area of low pressure has moved within 
140W as it slowly tracks toward the CA coast basically along 38N. 
Ahead of this feature...a convergent area of moisture has advected 
northward and become entrained into the circulation with a broad 
area of PW values near 1.00-inch. 

For Wednesday...the higher moisture content air will reach the CA 
coast while the upr low remains just outside 130W. With increasing 
diffluent flow over portions of northern CA...scattered precip will 
begin to develop during the afternoon hours in a line from Cape 
Mendocino over to Oroville and Susanville along with points north. 
SPC continues to paint an area of general thunderstorms over the 
interior of northern CA during this period.

The upr low continues to slowly track to the east on 
Thursday...moving within 130W. With better forcing over northern 
CA...precip is expected to increase with the best totals along 
coastal sections from the Eel River basin northward...and then 
inland over the Shasta Lake drainage down through the 
northern/central Sierra. Overall totals will range from 0.25- to 
0.50-inch.

Finally by Friday and Saturday...a secondary disturbance dropping 
southeast from the Gulf of Alaska will kick the initial upr low 
parallel to the central and southern CA coast before swinging inland 
(slightly farther north in the 07/12Z GFS and EC...more south closer 
to the CA/MX border in the 07/12Z CMC). This will bring the best 
precip to central and southern CA. Also...as the secondary 
disturbance is moving closer to the northern CA coast...precip 
should continue across northern CA. It should be said...at this time 
there continues to be a lower confidence with the secondary system 
as the trajectory of the system varies quite a bit with the most 
recent models. As a result...the Sunday (Day 6) forecast trends 
closer to the latest WPC QPF and NBM.

Freezing levels will start elevated on Wednesday...9000-feet 
northwest to 13000-feet southeast. Then as each of the systems move 
toward the region...freezing levels will drop to 4000-feet 
northwest...about 5000-feet along I-80...and 5500- to 7000-feet over 
central sections...and 7500- to 9000-feet south.

Afternoon update changes resulted in increases for northern CA in 
the range of 0.10- to 0.33-inch on average...relatively unchanged in 
central CA (except southern Sierra increases 0.10- to 0.33-inch) and 
similar to slightly down for coastal southern CA. Over 
NV...northwest portions of the state remained similar...with an area 
of plus 0.10-inch for south-central NV.


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



DRK

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