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Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
107 PM PDT Mon Apr 13 2026

...SCATTERED SHOWERS AND T-STORM ACTIVITY OVER CENTRAL AND SOUTHERN 
CA/NV REST OF TODAY...
...LIGHT PRECIPITATION ON WEDNESDAY OVER NRN CA WITH PASSING FRONT...
...POTENTIAL FOR MORE PRECIPITATION LATE WEEKEND WITH SYSTEM OUT OF 
GULF OF ALASKA...

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

Forecast overall remains on track, only minor changes to the QPF 
compared to this morning. An upper trough currently sits over srn CA 
this afternoon with some light scattered showers showing up over 
central and srn CA on radar. Lightning detection has picked up a few 
flashes as well but nowhere near the activity we saw this weekend. 
Observations over the past 5 hours show some orographically enhanced 
precip over the Sierra with gages reporting anywhere from 0.10-
0.75". The San Diego area also has gages reporting from a few 
hundredths to nearly 0.25". Convective showers and thunderstorms 
remain a possibility the rest of today, particularly over 
central/southern interior CA and into central/srn NV as the trough 
gradually exits into the Four Corners. 

Some brief ridging for Tuesday into Wednesday will dry conditions 
back out over the region before a low and front descending into the 
PacNW from BC sends additional shower activity into nrn CA for mid 
week. Expecting precip to stay north of I-80 through Wednesday 
evening. The system then digs into the region throughout the day 
Thursday. There is some disagreement as to how deeply into CA the 
trough will go, but either way this one does not look to generate 
any significant precip. Official forecast has less than 0.10" across 
the Sierra and up to 0.25" for parts of NV for Thursday. The low 
will exit again into the Four Corners Friday as a brief ridge builds 
back in over the eastern Pacific returning dry conditions ahead of 
yet another low from the Gulf of Alaska late in the weekend. With 
all this troughing, temperatures will remain near to about 10 or so 
deg F below seasonal normals fluctuating a bit between systems.

The afternoon forecast used some of the 18z HRRR for the next 6-12 
hours to capture convective showers then leaned on WPC guidance and 
occasionally the 12z GFS/ECMWF to slow down the late weekend system 
(det models and latest ensembles are trending a bit slower with the 
initial onset of showers). All in all changes from the morning were 
on the order of 0.10-0.25" in either direction for the 6 day window. 
Majority of the precip is still anticipated over the Smith Basin at 
1-1.75".