AGUS76 KRSA 151636
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
930 AM PDT Sat Apr 15 2017

...WET PATTERN NRN TWO THIRDS OF THE REGION SUN-THU...

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Special Note: This will be the last HMD of the 2016-2017 winter
operational season. The next issuance of this product will be
October 15, 2017 unless conditions warrant a special issuance.
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.24 HOUR PRECIPITATION TOTALS (ENDING APR 15 AT 500 AM PDT)...

An upper-level trough exiting the region brought light showers to 
portions of NW and far nrn CA, srn OR, and the nrn half of NV. 
Totals across these areas were 0.25" or less.  NW flow brought 
perhaps a stray shower with about 0.01" near the Grapevine area of 
CA as well.


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

Weak ridging over the region today in between systems is providing 
dry conditions across the forecast area, which should last through 
tonight.  Beginning Sun morning, expect a wet pattern to return to 
mainly the nrn two thirds of the region.  Three systems are expected 
to impact the area, around Sun, Mon-Tue, and Wed-Thu.  Each system 
is expected to spread mainly light precip across the region, with 
the best chance of moderate precip in the Sierra and at times the 
north coast.  Some of the guidance suggests convergence lines with 
locally heavier precip will be possible in the Shasta drainage early 
next week as shortwaves move across the region.  Expect Sierra 
freezing levels roughly 7000-10000 ft, except lowering to 5500-7500 
ft by late Wed night.  Models then indicate dry conditions with a 
warming trend by the end of next week into the beginning of the 
following week.


.HYDROLOGICAL CONDITIONS...

In the Upper Sacramento system, expect Colusa and Tisdale weirs to 
remain flowing as long as current releases are maintained out of 
Keswick.  In the Lower Sacramento, Fremont weir is expected to 
remain flowing throughout the forecast period due to elevated 
releases from Oroville and Shasta.

The Mon/Tues system will bring minor rises on many Northern/Central 
California streams.  Michigan Bar on the Cosumnes is expected to 
rise just above its monitor level.

The Truckee river at Truckee is above monitor, and expected to 
remain above monitor as long as the elevated releases out of Tahoe 
are maintained.  Reno could reach monitor stage next week due to the 
Mon/Tues storm.

In the San Joaquin system, the lower Merced and Tuolumne are 
expected to see stages above monitor levels as along as current 
releases from upstream reservoirs are maintained.  On the mainstem, 
Newman is expected to fall below monitor due to cutback in releases 
from Friant.  However, the lower end of the system at Vernalis is 
expected to stay above monitor level for the foreseeable future.

The lower Humbolt is expected to remain above flood stage for quite 
a while through the snowmelt season.


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

KL/BW

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