Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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AGUS76 KRSA 011722
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
920 AM PST Wed Mar 1 2017

...DRY CONDITIONS EXPECTED THROUGH FRIDAY...
...NEXT SYSTEM TO MOVE INTO NORTHERN CA LATER FRIDAY...

.24 HOUR PRECIPITATION TOTALS (ENDING MAR 1 AT 400 AM PST)...

A few lingering showers brought a few hundredths of an inch to SW
CA.  A vort max and a NW flow brought light showers to far nrn
CA/srn OR and NE NV.  Amounts were generally 0.1" or less except
locally up to 0.2" in the Smith basin and 0.1-0.5" in the srn OR
Cascades.


.METEOROLOGICAL CONDITIONS (SHORT TERM: WED AM - SAT AM)...

Ridge of high pressure over the region into early Friday bringing
dry conditions. A weak shortwave trough moving south offshore of the
Central and Southern CA coast does not have much moisture with it
and should not affect CA on Thursday.

Ridge shifts to the east on Friday as an upper level trough deepens
over the eastern Pacific.  Moisture plume (about 0.8 inches) drops
south off the NW CA coast on Friday and Friday night.  The moisture
and onshore flow along with a front will bring precipitation to the
far NW Coast and Southern Oregon by Friday night. Increased amounts
a tad over Smith Basin and around Crater Lake Friday evening and a
little over the NW CA Coast and Upper Klamath Basin late
Friday night into early Saturday morning.

.METEOROLOGICAL CONDITIONS (LONG TERM: SAT AM - TUE AM)...

Expect precip to continue to spread across nrn CA and srn OR on Sat
as the system drops south across the area.  Moisture values are not
that impressive and flow is moderate at best, although the GFS shows
brief, strong H7 flow into the nrn Sierra Sat night.  Some of the
heavier precip rates in the Sierra look to hold off until later Sat
night into Sun morning as dynamics increase near a vort max aloft
and upper jet.  Precip should become lighter later Sun and make its
way down into srn CA.  The forecast for Mon is uncertain.  For now
we show some light precip in the north early decreasing through the
period.  This is most like the 00 UTC GFS; however, more recent runs
of the GFS are showing less precip.  ECMWF shows precip, but it
brings in another system Mon night, which is inconsistent with other
guidance.  Expect Sierra freezing levels to start off 6500-9500 ft
early Sat and fall to 3500-6500 ft by early Sun.  Expect levels 2500-
5000 ft early Mon and then rising to 4500-6500 ft in the nrn Sierra
with diminishing precip Mon afternoon.


.HYDROLOGICAL CONDITIONS...

The Upper Sacrametno River is slowly receding.  Recession is slower
than what would naturally occur due to sustained releases out of
Keswick.

The Lower San Joaquin River is receding as well.  Reduction of flows
coming down the Tuolumne River are producing a steady decrease in
flow in the San Joaquin River at Vernalis.  Stages at Vernalis are
forecast to recede about one foot over the next few days.

The Humboldt River remains high. Following a crest at Comus yesteday
of 1.6 feet above flood stage, the river is expected to slowly
recede.


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

KL/HSO/KL/PF

$$



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