315
AGUS76 KRSA 091633
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
830 AM PST Sat Nov 9 2024

...MAINLY DRY WEEKEND EXCEPT CHANCE OF SHOWERS ALONG NRN CA COAST
AND INTO THE SRN OR CASCADES LATE THIS AFTERNOON INTO SUNDAY...

...PRECIP POSSIBLE OVER SRN OR AND NRN AND CENTRAL CA AND NRN NV
MONDAY AND MAINLY OVER SRN OR AND NRN CA ON WEDNESDAY AND SPREADING
INTO CENTRAL CA AND NRN NV ON THURSDAY AS SYSTEMS AFFECT THE
REGION...


.METEOROLOGICAL CONDITIONS (SAT AM - FRI AM)...

Ridge shifts east today as a weak shortwave trough approaches the
west coast.  The weak trough is expected to split with one area
moving into the Pac NW and the other off into the Eastern Pacific
off the CA coast tonight into Sunday.  Showers are possible along
the Nrn CA coast and along the west slope of the Srn OR Cascades
late this afternoon into Sunday with precip amounts generally less
than a third of an inch through Sunday evening with the highest
amounts expected in the Smith Basin and along the Srn end of Cape
Mendocino.

A stronger system approaches Sunday night with the associated cold
front and trough moving through on Monday.  This system will bring
cooler temperatures along with more widespread precipitation to Srn
OR and Nrn and Central CA and Nrn NV Monday.  Precip will increase
in intensity and coverage along the Nrn CA coast Sunday night and
spread south and east through Nrn CA Monday morning and into Central
CA and Nrn NV by Monday afternoon/night.  Precipitation amounts for
Sunday night into Monday night are generally 1-3 inches for the NW
CA coast (highest over Smith Basin and Southern end of Cape Mendo)
0.5-1.25 for the Shasta Mtns and Russian Basin and Nrn Sierra and
0.25-0.75 for the Santa Cruz Mountains and Big Sur Coast and the Sac
Valley and Central Sierra and a third of an inch or less for Nrn NV
and SJ Valley. Freezing levels around 8000ft and higher drop down to
around 5000 ft near the ORCA border and 7000-8000 ft for the Nrn
Sierra on Monday morning and down to around 4500ft near the ORCA
border and 5000-6000 ft for the Nrn Sierra and 6000-7000 ft for the
Central Sierra and 7000-8500 ft for the Srn Sierra and 5000-
7000 ft over Nrn NV Monday evening. Lingering showers possible
mainly over Srn OR and Nrn and Central CA and Nrn NV Tuesday as the
trough moves into the Rockies/ Great Basin on Tuesday leaving the
region in between systems. Freezing levels rise to around 8000 ft
and higher Tuesday night.

The next system approaches late Tuesday increasing precip along the
NW CA coast and spreading over Srn OR and Nrn CA on Wednesday. the
24 hr QPF 50th Percentile Clusters ending 00Z Thursday show precip
amounts as low as 1.25 inches for the Smith Basin and precip confined
to the NW CA and w slope of Srn OR Cascades in 11% of members
(canadian 25%, Gfs 20%, EC 6% to precip spread over Nrn CA to around
the I-80 corridor (12% of members) to amounts as high as 4 inches
for the Smith Basin and up to 1.5 inches for the Nrn Sierra. Low
confidence in precip amounts and how far south and east precip will
reach across Nrn Ca on Wednesday.  The current forecasts mainly uses
latest NBM and WPC with 2-3 inches for the Smith Basin and Srn Cape
Mendo and  0.5-1.25 inches for Shasta and 0.25-0.75 for the Nrn
Sierra and precip to around the I-80 corridor and possibly into the
Santa Cruz Mtns.  Freezing levels drop to around 5000-6000ft near the
ORCA border and 7000-8000ft over the Nrn Sierra Wednesday night. A
trough remains along the west coast and into the Eastern Pacific on
Thursday for a chance of precip over Srn OR and Nrn and Central CA
and possibly into Nrn NV.


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



Osborne

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