...DRY CONDITIONS THROUGH THURSDAY EVENING AS THE REGION SITS
UNDER HIGH PRESSURE...
...CHANCES FOR HEAVIER MORE WIDESPREAD PRECIP FRIDAY AND OVER THE
WEEKEND AS THE STORM TRACK SHIFTS FURTHER SOUTH...

.METEOROLOGICAL CONDITIONS (SHORT TERM: TUE AM - MON AM)...

High pressure over the eastern Pacific and across CA/NV is steering
all the storm activity into the PacNW for the next couple of days.
This will keep conditions dry through Thursday. After that, an upper
low approaching from the Gulf of Alaska will send the southern end
of a cold front towards northern CA for Friday. There are timing
differences between the GFS and ECMWF with the ECMWF being a bit
ahead in general from this point forward. The front and troughing
from the parent system will sweep through northern and into central
CA on Friday weakening into more scattered showers on Saturday.
There is uncertainty on the QPF for the Friday/Saturday system as
ensembles show a wide spread. The 48 hr QPF clusters ending 00z Sun
show three different progressions. Cluster 1, containing 41% of the
overall ensemble members, spreads 1.50+" across the entire CA coast
and over 3" along the nrn CA coast, Shasta, and across the Sierra.
Cluster 2, which contains 25% of ensemble members barely shows any
precip south of I-80. Cluster 3, containing the remaining 24% of
members, is in between focusing heavier precip over the north coast,
Shasta, and the northern/central Sierra. The official forecast is
somewhere in between clusters 1 and 3 for now.

A brief transitional ridge in between systems then for the rest of
Saturday as another low approaches from the Gulf of Alaska. The
ECMWF remains the quicker model, more in agreement with the CMC and
other ensembles on the next front moving through nrn CA on Sunday
while the GFS is about 18 hrs behind. Timing seems to be the main
point of disagreement for the end of the forecast window as
ensembles are in relatively good agreement on the main focus of
precip being across the north coast, Shasta, and the
northern/central Sierra with much less spread on the amounts
compared to Friday/Saturday.

The official QPF started with a blend of WPC and the NBM, but added
in some of the west WRF over the Sierra as well as the ECMWF
elsewhere. Went more in line with the timing of the ECMWF for the
Sunday system as well trimming back the spread of lighter showers
from the NBM. Expect values to change in the coming days as
hopefully models come into better agreement and ensemble spread
narrows. Highest totals are forecast over the nrn CA coast north of
Sonoma County, over Shasta, and the northern Sierra. All but about
0.10" is expected in the extended. QPF through 12z Mon: 1.50-4.50"
Sonoma County northward along the coast (4-5.50" Smith Basin), 2.50-
3.75" Shasta, 1-2.75" Sierra, 0.50-1" Bay Area, 0.25-0.75" central
coast (up to 1" Santa Cruz mountains, up to 1.25" Big Sur coast),
0.10-0.75" down the valleys (up to 1" closer to the foothills), and
0.10-0.25" over coastal srn CA.

Freezing levels coming down Friday down to 8-10.5 kft lowering
further in the evening to 5.5-8 kft north of I-80. Levels to rebound
later Saturday from sw to ne up to 8.5-13.5 kft over CA by the
evening before lowering again with the next system on Sunday or
Monday.

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.