Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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HYDROMETEOROLOGICAL DISCUSSION NATIONAL WEATHER SERVICE / CALIFORNIA
NEVADA RFC / SACRAMENTO CA 930 AM PST FRI DEC 19 2014

...SYSTEM MOVING THROUGH  NORTHERN CA TODAY FOLLOWED BY ANOTHER OVER
THE WEEKEND...
...DRY CONDITIONS EARLY IN THE WEEK THEN A POSSIBLE STORM FOR
CHRISTMAS EVE AND DAY...


.24 HOUR PRECIPITATION TOTALS (ENDING DEC 19 AT 400 AM PST)...

LINGERING PRECIP WITH A DISSIPATING SYSTEM BROUGHT LIGHT PRECIP
(GENERALLY AT OR LESS THAN 0.10-INCH) TO COASTAL SECTIONS OF CENTRAL
AND SOUTHERN CA...AS WELL AS EXTREME SOUTHERN NEV.

THE NEXT COLD FRONT BEGAN MOVING ACROSS NORTHERN CA DURING THE
SECOND HALF OF THE PERIOD. GREATEST AMOUNTS FELL OVER THE NW PORTION
OF CA. THE SMITH RIVER BASIN SOUTH TO CAPE MENDOCINO ALONG THE COAST
AND THE WESTERN PORTION OF THE SHASTA LAKE DRAINAGE SAW TOTALS
GENERALLY BETWEEN 0.75- AND 1.50-INCHES (LOCAL TOTALS BETWEEN 2.00-
AND 2.50-INCHES WERE OBSERVED UNDER HEAVIER CELLS). LESSER TOTALS
WERE OBSERVED FOR THE RUSSIAN RIVER BASIN NE TOWARD THE EASTERN
PORTION OF THE SHASTA DRAINAGE AND FEATHER RIVER BASIN. TOTALS IN
THIS AREA WERE FROM 0.25- TO 0.50-INCH. FOR THE SACRAMENTO
VALLEY...TOTALS WERE CONFINED TO THE NORTHERN HALF. REDDING AIRPORT
SAW 0.50-INCH AND RED BLUFF RECORDED 0.30-INCH. OROVILLE WAS JUST
SHY OF 0.10-INCH.


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

WET MORNING IN STORE FOR MUCH OF NORTHERN CA TODAY...AS RADAR SHOWS
A FRONTAL BAND MOVING THROUGH THE REGION FROM THE NORTH BAY EAST
THROUGH SACRAMENTO AND INTO THE NORTHERN SIERRA. MODERATE TO LOCALLY
HEAVY SHOWERS HAVE BEEN REPORTED AS THIS BAND MOVED THROUGH AREAS
FURTHER NORTH THIS AM...THOUGH IT IS MOVING QUICKLY ENOUGH TO
PREVENT ANY PARTICULARLY HIGH TOTALS FROM ACCUMULATING. EXPECT
PRECIP TO CONTINUE DIPPING SOUTHWARD THROUGH THE AFTERNOON...BUT
WEAKENING AS IT DOES. ALL MODELS INDICATE MOISTURE STALLING OUT OVER
THE SIERRA FROM JUST SOUTH OF THE FEATHER R BASIN TOWARDS
YOSEMITE...SO LOCALLY HIGHER TOTALS MAY COME UP THERE BY EARLY
EVENING. FAIRLY DECENT PWAT PLUME IS FEEDING THIS SYSTEM...WITH
AMOUNTS AROUND 1" MEASURED BY THE BLENDED TPW PRODUCT JUST OFFSHORE
NEAR THE SF BAY. EXPECT THIS SYSTEM TO FIZZLE OUT AS IT DROPS SOUTH
OF THE SANTA CRUZ MTNS DURING THE EVENING HOURS.

THE NEXT SHOT OF PRECIP QUICKLY MOVES IN BEHIND THIS ONE`S HEELS...
IN THE FORM OF A WARM FRONTAL PATTERN SETTING UP OVER THE PACIFIC
NORTHWEST. STRONG WESTERLY FLOW WITH THE JET WILL DRIVE THE MAJORITY
OF THE MOISTURE AND ENERGY INTO THE PACIFIC NORTHWEST...BUT THE
SOUTHERN EDGE IS EXPECTED TO MOVE INTO NORTHERN CA LATE TONIGHT.
MODELS INDICATE HEAVIEST PRECIP TO FOCUS OVER THE SMITH BASIN AND
SOUTH TO AROUND CAPE MENDOCINO...WITH ADDITIONAL HIGHER
ACCUMULATIONS EXPECTED OVER THE W SLOPES OF THE SRN OREGON CASCADES
WHERE FAVORABLE MOIST WESTERLY FLOW WILL SET UP FOR AN EXTENDED
PERIOD OF TIME. PRECIP IS EXPECTED TO MOVE SOUTH OF CAPE MENDOCINO
AND INLAND TOWARDS SHASTA BY SAT MORNING. ADDITIONAL ENERGY MAY MAKE
IT INTO THE NORTHERN SIERRA...THOUGH NOT EFFICIENTLY AND ONLY EXPECT
LIGHT PRECIP AS FAR S AS THE AMERICAN R BASIN. EXPECT PRECIP TO
CONTINUE THROUGH THE AFTERNOON AND EVENING HOURS...THEN THE WARM
FRONT WILL WEAKEN AND LIFT NORTHWARD OVERNIGHT SAT INTO SUNDAY
MORNING.

LIGHT PRECIP IS EXPECTED TO CONTINUE THROUGH MUCH OF SUNDAY AS THIS
WARM AIR ADVECTIVE PATTERN SITS IN PLACE...SLOWLY LIGHTENING UP...
AND REALLY ONLY FOCUSED ALONG THE SMITH BASIN AND W SLOPES OF THE
SRN OREGON CASCADES. EXPECT CLEARING BY MONDAY MORNING AS RIDGING
OVER THE EASTERN PACIFIC STRENGTHENS.


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

A FEW SHOWERS EARLY IN THE PERIOD OVER THE FAR NORTH WILL DISSIPATE
THROUGH MONDAY AS AN UPR RIDGE CENTERED NEAR 30N/130W STRENGTHENS
OVER THE AREA. THIS WILL BRING DRY CONDITIONS ON TUESDAY INTO EARLY
WEDNESDAY.

NEXT SYSTEM WILL APPROACH FROM THE NW AS THE UPR RIDGE GETS
DISPLACED TO THE EAST. THE 19/00Z EC AND GFS NOW SHOW A SLIGHTLY
MORE WESTERLY TRACK OF THE S/WV TROF ACROSS THE AREA...WHICH BRINGS
A BIT MORE PRECIP TO NORTHERN CA ON LATER WED INTO EARLY THU. LOOK
FOR WIDESPREAD PRECIP OVER THE NORTHERN HALF OF THE REGION WITH
SCATTERED LIGHTER PRECIP FOR THE SOUTHERN SIERRA.


.HYDROLOGICAL CONDITIONS...

RENEWED MINOR RISES ARE EXPECTED INTO THE WEEKEND FOR MOST STREAMS
AND RIVERS IN NORTHERN CALIFORNIA.

OVERFLOW AT COLUSA WEIR STOPPED EARLY THIS MORNING...RENEWED
OVERFLOW IS FORECAST TO BEGIN AGAIN TOMORROW MORNING.

OVERFLOW AT TISDALE WEIR IS EXPECTED TO CONTINUE FOR THE NEXT
FIVE DAYS.

HIGH TIDE IS EXPECTED TO EXCEED MONITOR STAGE AT RIO VISTA BRIDGE
DURING THE NEXT 3 DAYS.

ALL OTHER RIVER FORECAST POINTS ARE EXPECTED TO REMAIN BELOW MONITOR
LEVELS THROUGH THE WEEKEND.


MORE INFORMATION ON THE CNRFC WEBSITE AT HTTP://WWW.CNRFC.NOAA.GOV

DRK/JM/DRK/AT

$$



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