Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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AGUS76 KRSA 171505
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
705 AM PST Sun Dec 17 2017

...NEXT SYSTEM ARRIVES TUESDAY...

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

Cutoff low spinning just to the south of the Arizona border this
morning...generating an area of showers and t-storms over the desert
southwest. This was all part of the system that dove through the
area yesterday...leaving dry northerly flow in its wake with an upr
ridge once again rebuilding over the far eastern Pacific and the
storm track aimed at southern BC and the state of Washington.

The next system expected to flatten the upr ridge will arrive from
the WNW on Tuesday and then dive southeast across the area into
Wednesday. Moisture entrained into this system is not overly
impressive with PW values near 1.00-inch concentrated in a narrow
channel just ahead of the cold front. There are some slight timing
differences with the overnight models as the EC is a bit faster.
Also...it is ever so slightly deeper than the GFS...bringing light
precip a bit farther south.  For now...took a general compromise
between the two...expecting agreement to improve as the system gets
closer in time. Overall...freezing levels will start fairly high
with 8000-feet near the CA/OR border and 10000-feet near the I-80
corridor. This will drop considerably as the cold front passes with
3000-feet near the CA/OR border and 4000-feet near the I-80
corridor.

After this system moves off toward the east...look for the upr ridge
to rebuild again just off the west coast with general northwesterly
flow across CA and NV for dry conditions. Still not much hope for a
good widespread system through the end of the calendar year.


.HYDROLOGICAL CONDITIONS...

Flows will remain steady on the rivers for the next 5 days as no
significant precipitation is expected.


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

DRK/MI

$$



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