AGUS76 KRSA 181658
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
930 AM PST Sat Nov 18 2017

...PRECIP SHIFTS MAINLY NORTH OF I-80 THROUGH THE UPCOMING WEEK...

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

The synoptic feature of interest over the upcoming week is an upr 
ridge currently centered over central Mexico this morning. This high 
pressure will build westward over Baja California and expand 
northward early next week. At the same time...a deep upr trof will 
set up offshore mainly between 140W and 150W. In-between...a 
moisture plume will be directed north-northeast from the lower 
latitudes toward the Pacific Northwest and the far northern CA 
coast. 

The first opportunity for precip will be with a s/wv trof moving 
toward the BC and Washington coast later in the weekend. This system 
looks farther north and weaker on the 18/00Z models...and as a 
result...expected precip on Monday will have less southward 
progression with amounts trimmed from the previous forecast. Look 
for the majority of the precip to remain north of I-80. Freezing 
levels will be quite high with an upr ridge extending over the area 
and the s/wv trof crossing the coast well to the north. Early 
Monday...freezing levels will be near 8500-feet for the CA/OR border 
area and 10500-feet along I-80. Then through Monday as heights 
continue to build...freezing levels rise closer to 10000-feet along 
the CA/OR border and 11500-feet along I-80.

The for Tuesday through Thursday...with the moisture plume 
meandering along the Pacific Northwest and far northern CA 
coast...the opportunity for mainly light precip across the upper 
Klamath River basin and far northwest CA exists. However...without 
any significant forcing except for some weak isentropic lift...not 
expecting daily amounts to be anything impressive. Freezing levels 
will be greater than 10000-feet for the entire area Tuesday through 
early Thursday...eventually dropping across far northern areas as 
the upr ridge flattens somewhat with an approaching s/wv trof.


.HYDROLOGICAL CONDITIONS...

Thursday/Friday storm continues to move East and out of the CNRFC 
basins with moderate precipitation in the Southern Sierra and 
Humbolt basins, 1-2 inches on Friday morning. Temperatures are 
warming across California. Unregulated rivers from the North Coast 
to Southern Sierra are on their recession limbs. 


More information on the CNRFC website at http://www.cnrfc.noaa.gov

DRK/NB

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