...DRY CONDITIONS TODAY AND MOST OF TOMORROW BEFORE CHANCES OF
SCATTERED SHOWERS LATE THURS/FRI AS MOISTURE MOVES THROUGH CENTRAL
CA/NV...
...CHANCES OF MORE WIDESPREAD PRECIP THIS WEEKEND, PARTICULARLY OVER
SOUTHERN CA, BUT CONFIDENCE IS LOW ON AMOUNTS...

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

Troughing remains overhead as an upper low sits over BC. This trough
is ushering in drier air over the region keeping conditions dry
through at least tomorrow morning. At that time, another weaker
trough from offshore will begin to carry moisture into central CA
before moving into NV later in the day. This may generate some
showers over coastal srn CA, the Sierra, and parts of NV late
Thursday through Friday. Amounts look generally 0.10" or less but
locally higher over the Ruby Mountains.

Beyond Friday, uncertainty in the forecast remains high as models
continue to disagree on the path/timing of the next system and
ensemble spread of QPF is wide. There is agreement on an upper low
shifting off of the BC coast at the end of the week and heading
south along the PacNW coast as another system forms offshore west of
CA. Both also split the core of the main upper low in two sending
one into Canada and the other towards the PacNW. The GFS takes this
trough directly into WA/OR throughout the day Saturday with the
southern edge of the system dipping into the northern regional
boarder. It also forms a surface/upper low offshore of southern CA.
The ECMWF has the PacNW system moving southeastward positioning it
over nrn CA and OR as it travels inland while a similar system to
the one the GFS develops forms offshore west of srn CA. Early Sunday
morning, the GFS has an upper trough entering ID and a system just
offshore of soCal/Baja. The ECMWF has an upper low stretched across
OR/nrn CA and a system offshore of srn CA. The ECMWF solution
carries the surface feature already into coastal srn CA at that time
while the GFS does not. It also generates more precip over NV as the
upper low passes directly through it vs the GFS where it is further
north. In terms of QPF, this translates to the ECMWF predicting 0.75-
1.25" over San Diego county from 06z-12z Sunday and the GFS showing
0.10" or less. For all of Sunday the ECMWF has about twice the QPF
overall than the GFS. Ensembles don't give a much clearer picture
either. The ECMWF ensembles are overall wetter as well. Looking at
the 24 hr QPF spread over San Diego, every single member for Sunday
shows at least some precip and up to 2.50". At LAX, that upper value
stretches to over 4". The GEFS has several entirely dry members and
only one going above 1" in both locations. All this to say, there is
a great deal of uncertainty in the weekend forecast.

The one area of agreement is on a ridge building in over the eastern
Pacific behind this next system and drifting overhead early next
week. Given the uncertainty, the official forecast was mainly WPC
guidance. These amounts could change significantly over the coming
days. Highest totals are expected over srn CA. QPF 12z Sat-12z Mon:
0.25-1" coastal srn CA (locally over 1" over the San Diego
mountains), 0.10-0.50" Sierra, 0.10-0.75" NV/se CA, and generally
0.10" or less across the rest of CA.

Freezing levels will lower from about 8.5-13.5 kft across the region
today to 5.5-12.5 kft by early Friday. Should remain about that
range over the weekend before increasing again from west to east into
Monday as high pressure arrives. Expecting CA back up to 12-14.5 kft
by Monday morning.

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.