Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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AGUS76 KRSA 261811
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Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
930 AM PST Sun Feb 26 2017

...ONE COOL SYSTEM EXITING SOUTHERN CA TODAY...
...NEXT SYSTEM ARRIVES LATER TODAY INTO TOMORROW...

.24 HOUR PRECIPITATION TOTALS (ENDING FEB 26 AT 400 AM PST)...

Scattered light precip fell with a cool system moving in from the
north yesterday. Amounts along the north coast...and inland toward
the upper Klamath River basin...Shasta Lake drainage...and
northern/central Sierra were generally from a few hundredths of an
inch to 0.10-inch.

Also...light precip fell from the Monterey Bay area south along the
coast to the Los Angeles area with amounts ranging from a few
hundredths of an inch to 0.25-inch.


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

WV/IR imagery shows a s/wv trof moving across southern CA this
morning...bringing an area of light to locally moderate precip to
the area. Overall...available moisture is not too impressive with
the 26/12Z RAOBs at KVBG and KNKX indicating PW values 0.54- and
0.71-inch respectively. This matches the more dense Trimble GPS-Met
IWV sensors. As this s/wv trof moves inland later this morning and
crosses the CA/AZ border...look for precip to taper off across the
area.

Attention will next turn to another system dropping in from the
north...currently located just west of the WA coast. Radar imagery
already shows some scattered light precip along the immediate coast
from Cape Mendocino to the CA/OR border. As the day progresses into
Monday the precip will spread south across the area. Also of
interest is how this system from the north phases with a disturbance
currently west of southern CA near 32N/140W. As this occurs...a
plume of higher moisture content air will stretch from the lower
latitudes east of Hawaii to the coast near the US/Mexico border.
Peak PW values within this plume are right around 1.00-inch...but
the latest EC and GFS are slightly different on where the axis of
the best moisture intersects the coast. The EC is to the
north...right around the US/Mexico border while the GFS is over far
northern Baja. As a result...the EC brings a bit more precip to
extreme southern CA...mainly San Diego county. The GFS would only
have light amounts over San Diego county with the bulk of the precip
falling south of the border. The GEM is somewhere in-between the
two. For now...did spread precip over extreme southern CA closer to
the EC solution. Will need to see how the models trend with the
26/12Z cycle to see what...if any...changes are needed.

A transition to an upr ridge across the eastern Pacific and coast of
CA will be the rule for the latter half of the week. However...a
system moving toward the Pacific Northwest on Saturday will bring
light precip down to the CA/OR border area.


.HYDROLOGICAL CONDITIONS...

Most rivers and streams in the CNRFC forecast area are expected to
continue receding slowly or fluctuate near present levels through
Friday with little or no precipitation in the forecast.
Precipitation forecast for southern California may cause a moderate
rise in stage on the San Diego River on Monday.

On the Sacramento River, Tehama Bridge and Ord Ferry are currently
above flood stage.  Clear Lake and the Yolo Bypass at Lisbon are
also above flood stage at this time.  Overflow at Moulton, Colusa,
Tisdale, and Fremont weirs is forecast to continue for several more
days.

On the San Joaquin River system, the Merced at Stevinson and the
Tuolumne River at Modesto are above flood stage, and the San Joaquin
River at Vernalis is at danger stage.

On the Humboldt River, Battle Mountain and Comus remain above flood
stage.

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

DRK/SS

$$



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