Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6
000
AGUS76 KRSA 241646
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
945 AM PDT Fri Mar 24 2017

...SYSTEMS MOVING THROUGH EVERY COUPLE DAYS INTO NEXT WEEK...

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

A trough moving out of the region brought light showers to inland
portions of srn CA as well as ern NV.  Amounts were mainly 0.1" or
less except local areas 0.2-0.4" in cntrl and NE NV.  A frontal
system moved into nrn CA/srn OR during the period as well, bringing
widespread precip from near the I-80 corridor northward.  Totals in
the Smith and lower Klamath basins were 0.6-1.6".  The Eel basin
picked up 0.2-0.8".  The Russian basin received around 0.1-0.5",
while the Napa basin and near San Francisco picked up 0.1" or less.
The nrn half of the Sacramento Valley received 0.25" or less, while
up around the Shasta drainage, totals were 0.3-1.1".  The upper
Klamath basin and far nrn Sierra received up to 0.2".


.METEOROLOGICAL CONDITIONS (SHORT TERM: FRI AM - MON AM)...

WV/IR imagery shows the next cold front moving toward the north
coast this morning with the upr trof crossing 130W. Blended TPW
imagery along with Trimble GPS-Met sensors indicate the moisture
plume associated with this system intersecting the coast near the SF
Bay Area with PW values hovering right around 1.00-inch. This
moisture source stretches back to the southwest to just north of the
Hawaiian Islands. 88-D indicates precip spreading across CA down to
about the I-80 corridor with precip gages since 24/12Z placing the
best amounts along coastal sections between the CA/OR border and the
Golden Gate. totals in this area are showing amounts generally from
0.25- to 0.50-inch...except for the Smith River basin where totals
are approaching 1.00-inch. Light amounts have been recorded
inland...but are expected to tick upward as the cold front moves
across the region today.

For the afternoon...as the cold front begins to move inland and
southward...precip will be heaviest over the northern/central Sierra
back through the Sacramento area and SF Bay Area. The moisture plume
will begin to narrow and continue to track south along the
coast...reaching the central coast during the late afternoon hours.
With the cold front clearing the north coast during the
period...precip will begin to taper off but remain with scattered
showers until the upr trof axis moves through the area.

During the evening...expect the cold front to move through central
CA and press across the western half of NV. Best totals will be on
the west slopes of the southern Sierra back toward the Big Sur
coast. Scattered showers will continue across northern CA with the
upr trof axis poised to move onshore during the overnight period.
Once this occurs...look for precip to be on the decrease for most
areas except for the eastern half of NV and back toward the far
southern Sierra.

Freezing levels generally between 7000- and 9000-feet for the Sierra
ahead of the cold front will drop to 5500- to 7500-feet behind the
boundary.

Saturday will be a generally dry day across the region in between
systems. The next round of precip will move in on Sunday. Timing the
precip across the area is a bit faster than the previous forecast
and slightly wetter for areas near and north of I-80. Freezing
levels in general will be from 5000- to 7000-feet.


.METEOROLOGICAL CONDITIONS (LONG TERM: MON AM - THU AM)...

An upper trough over the region Mon morning is expected to push east
through the day.  Expect widespread light showers for the Sierra,
far nrn CA, srn OR, and much of NV Mon morning into the afternoon
and quickly diminishing by the evening.  Models indicate additional
precip in the north by the middle of next week.  A blend of the
GFS/ECMWF was used with the GEm forecast an outlier.  Sierra
freezing levels are expected to be around 5000-7000 ft Mon and 9000-
11000 ft, falling to 6500-9000 ft, Wed afternoon into Wed night.


.HYDROLOGICAL CONDITIONS...

A series of storms will move across CA and NV over the next several
days and cause moderate rises to area streams. The largest rises
will occur on the coastal rivers, where most rivers are beginning to
rise this morning from the rainfall overnight. Moderate rises will
also be observed along the Sacramento and the tributaries. The
Tisdale and Fremont Weir are flowing and will continue for the next
5 days. The Colusa Weir is expected to begin flowing Saturday
afternoon. Stages will continue to rise on the Humboldt through the
weekend as flows from the tributaries continue to pour into the
mainstem.


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

KL/DRK/KL/MI

$$



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.