Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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AGUS76 KRSA 031915
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
930 AM PST Sat Dec 3 2016

...PRECIPITATION EXPECTED OVER NORTHERN AREAS SUNDAY THROUGH TUES...


.24 HOUR PRECIPITATION TOTALS (ENDING DEC 3 AT 400 AM PST)...

Ridging over the area kept most of the region dry over the last 24-
hrs. The exception was a few light showers over the Upper Klamath
and W slopes of the Srn OR Cascades overnight.


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

Ridging will continue over the Eastern Pacific today with cool and
breezy conditions expected for the forecast area. By Sunday, a
shallow upper trough will move into the Pac NW, drawing a moisture
plume towards the Oregon and Nrn CA coastline with around 1"
amounts. Light precip is expected over the Smith and Upper Klamath
basins, along w the Srn OR Cascades by late Sunday morning, with a
few light showers possible over the Shasta area by afternoon. Precip
should quickly move into Nrn NV by Sunday night. Freezing levels are
expected to start out around 6000-ft, quickly lowering to around
3000-ft by Monday morning.

After the initial wave on Sunday, a second round of precip is
expected on Monday night as the upper trough moves southeast towards
the CA/OR border. Models differ on how far south this gets, with the
GFS shallower than the EC. Overall the trend has been towards the
shallower solution, and edged that way with the QPF forecast. Precip
is expected to move in late Monday afternoon, and continue
overnight. By Tuesday morning, precip should be focused on the NE
corner of CA and into Nevada, with some lingering showers along the
E slopes of the Nrn Sierra Wednesday afternoon. Freezing levels for
this system are expected to be around 3000-ft near the OR/CA border,
and around 5000-ft over the Nrn Sierra if precip reaches that far
south.

A ridge develops over the west on Wednesday as the trough moves into
the Great Basin, but this feature should be short lived. By Thursday
morning, another frontal system is expected to push into the Pacific
NW, fueled by a heartier PW plume with amounts around 1.3-1.4", and
driven by a 140-kt jet. While the EC is more exuberant with precip
amounts than the GFS, relatively good consensus on timing exists.
Expect precip to spread into much of Northern CA and possibly
Central CA by Friday morning.


.HYDROLOGICAL CONDITIONS...

Rivers across the area will slowly recede towards baseflow over the
next few days. All forecast points are expected to remain well below
monitor levels.


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

JM/MI

$$



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