...COOLING THROUGHOUT THE WEEK AND INCREASING PRECIP CHANCES AS A
LOW MOVES THROUGH..

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

An upper low approaching from the northwest will bring unsettled
weather to the region throughout the week. The low is expected to to
travel down the west coast reaching the CA/OR border late this
afternoon generating a few showers over nw CA. The low will continue
its southerly journey tomorrow staying mainly offshore. Enough
moisture looks to rotate inland, however, for some showers and
possibly thunderstorms to fall over the Sierra and into NV tomorrow.
Models then have the low shifting closer to the coast early
Wednesday resulting in showers along the central and southern CA
coasts. The system will gradually continue to shift eastward
spreading showers inland the rest of Wednesday. Expect more
widespread chances of thunderstorms as well across CA and NV as
moisture and instability expand overhead. The center of the low will
head into srn CA around Point Conception on Thursday lifting
northeastward into NV later in the day. Shower activity will begin
to diminish Thursday evening shifting focus over NV before the
center of the system exits throughout the day Friday. Troughing will
remain overhead into the evening before ridging builds in behind it.
In addition to showers and thunderstorms, expect this system to
usher in cooler air resulting in widespread below normal
temperatures for most of this week.

There is some disagreement between the models on the pattern
Saturday into Sunday. The GFS builds a larger upper ridge stretched
across the entire west coast while the ECMWF has a more transitory
ridge ahead of another upper low approaching from the Gulf of
Alaska. Either way, both det models are dry for day 6. Kept precip
out of the forecast for Saturday.

Majority of the precip from this system is expected
Wednesday/Thursday. There is still some uncertainty on amounts.
Ensemble spread for 24 hr QPF over the nrn Sierra and coastal soCal
is about 0" to 2" for Wednesday into Thursday. QPF days 1-5: 0.50-
1.50" coastal srn CA and across the Sierra (up to 2" parts of the
Transverse), 0.25-1" NV (1-1.50"+ in the mountains), 0.10-0.75" Bay
Area/central coast, 0.10-0.25" down the valleys, and generally 0.10"
or less for nw CA.

Freezing levels starting at 10-13 kft this morning lowering to 8.5-
10.5 kft north of I-80 tomorrow morning. Away from se CA and far
eastern NV levels will lower further to about 8.5-11.5 kft by
Wednesday evening bottoming out 24 hrs later to 8.5-10.5 kft region
wide before gradually rising the rest of the period back up to 11-
13.5 kft.

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.