Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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AGUS76 KRSA 251617
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
915 AM PDT Sat Mar 25 2017

...STORM EXITS EAST TODAY...
...NEXT ROUND OF PRECIP MOVES IN SUNDAY INTO MONDAY...

.24 HOUR PRECIPITATION TOTALS (ENDING MAR 25 AT 500 AM PDT)...

A cold front swept across the region on Friday into early Saturday
bringing widespread precip to the northern 2/3 to 3/4 of the region.
Best amounts were observed across the higher terrain of northern CA
with precip gages ranging generally from 1.00- to 2.00-inches with
local amounts at the wettest locations reaching 3.00-inches.

For the higher terrain of central CA the totals generally ranged
from 0.50- to 1.25-inches with slightly higher amounts closer to
1.75-inches over portions of the Santa Cruz Mountains and Big Sur
coast. Central Valley locations showed a north-to-south gradient
with the heaviest north near Redding...around 1.00-inch with the
lightest down around a few hundredths of an inch. In between some
totals were closer to 0.25-inch around Sacramento...Stockton and
Merced. Slightly higher amounts close to 0.50-inch were observed
around Fresno.

For Nevada...the highest totals were observed across the central
portion of the state with 0.25- to 0.50-inch for the higher terrain.
Similar amounts were seen across the Ruby Mountains. Elsewhere in
the state totals were for the most part near or less than 0.10-inch.


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

Upr trof axis is moving inland this morning...aligned from N-to-S
from the northern Sierra south toward near Point Conception. The
associated cold front is clearing the eastern portion of the
area...shifting toward the Colorado River basin. Precip this morning
is fairly scattered with the best totals since 25/12Z across the
southern Sierra and back southwest toward the coast near Point
Conception with amounts near or just above 0.10-inch. The overall
trend through today will be for drying conditions except from some
lingering afternoon showers across the the higher terrain from the
southern Sierra down through portions of southern CA and far eastern
NV. Otherwise...look for transitory weak anti-cyclonic flow to move
across the area late Saturday into Sunday ahead of the next s/wv
trof moving toward the area.

Trend of the forecast was slightly slower and a bit weaker as the
system begins to split as it reaches the coast and eventually forms
a cutoff low downstream near the 4-Corners region early next week.
Look for precip to spread from northwest to southeast across the
area Sunday into early Monday with the best amounts over the higher
terrain of CA from near I-80 and points northward...and then the
northeast quadrant of NV. Moisture is also not overly impressive
with this system with PW values peaking near or just over 0.75-inch
ahead of the cold front without much inland advection.

An upr ridge then builds across the area on Tuesday with the
southern extent of the next system moving toward the Pacific
Northwest dragging across the northern 1/4 to 1/3 of the region. The
GFS is much slower with this system as compared to the GEM and
EC...which was followed for the latter portion of the forecast.


.HYDROLOGICAL CONDITIONS...

Runoff from the precip that moved across the area yesterday was less
than expected across many basins. Snow lines across much of the area
where lower than expected, which contributed to the reduced runoff.
Most of the headwater rivers have peaked and are receding this
morning.

The next storm system will move across the region on Monday which
will bring some small renewed rises to a few of the coastal rivers.
Many of the rivers in the Sierra will see very little renewed
rises, if any at all.

The Colusa Weir is expected to spill later today as the floodwave
moves down the Sacramento. Expect flows to come down a bit on the
San Joaquin River through next week as outflows have been reduced
from several reservoirs in the system. Flood stages remain on the
Humboldt and will do so for the next 5 days.


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

DRK/MI

$$



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