Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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AGUS76 KRSA 241626
HMDRSA

DDHHMM
WRKHMD

HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
930 AM PST WED DEC 24 2014

...QUICK-MOVING STORM TO BRING PRECIP TO THE REGION THROUGH
TONIGHT...
...DRYING FOR THU AND FRI WITH A WEAK SYSTEM IN THE FAR N EARLY NEXT
WEEK...

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

DRY CONDITIONS WERE OBSERVED ACROSS THE AREA AS HIGH PRESSURE MOVED
ACROSS THE REGION YESTERDAY.


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

SATELLITE IMAGERY SHOWS A SHARP SHORTWAVE RAPIDLY APPROACHING THE
NRN CA COAST.  PRECIP HAS FILLED IN OVER SRN OREGON AND FAR NW CA
OVER THE PAST HOUR OR TWO, AND HEAVIER PRECIP IS SEEN ON THE RADAR
OFF THE COAST.  PRECIP DRIVEN PRIMARILY BY STRONG DYNAMICS SHOULD
PROVIDE MORE UNIFORM COVERAGE OF PRECIP THAN WHAT CLIMATOLOGICAL
PATTERNS WOULD SUGGEST.  THE MAIN TREND FROM THE PREVIOUS FORECAST
WAS TO SPEED UP TIMING OF THE SYSTEM IN LINE WITH THE LATEST
GUIDANCE.

EXPECT PRECIP TO RAPIDLY SPREAD ACROSS ALL OF NRN CA AND INTO WRN NV
BY THIS AFTERNOON AND FINALLY REACH MOST OF NV BY THIS EVENING AND
SRN CA TONIGHT.  THE FRONT IS EXPECTED TO WEAKEN AS IT PROGRESS SWD
TONIGHT, AND AMOUNTS SHOULD BE LIGHTER ON THE COAST FROM AROUND THE
BAY AREA SWD AND IN THE SRN HALF OF THE SIERRA.  THE TROUGH IS
EXPECTED TO SLOW AS IT APPROACHES THE ROCKIES, LEAVING THE REGION
UNDER STRONG NLY FLOW ALOFT AND AN UPPER JET SLOWLY MOVING FROM W TO
E.  EXPECT SHOWERS TO WIND DOWN THU WITH A FEW LINGERING IN THE SRN
OREGON CASCADES AND NE NV IN THU NIGHT.  A BUILDING RIDGE SHOULD
BRING A RETURN TO DRY CONDITIONS FOR FRI.

FREEZING LEVELS ARE STARTING OFF NEAR OR ABOVE 10,000 FT AHEAD OF
THE FRONT AND ARE EXPECTED TO QUICKLY FALL BEHIND THE FRONT TO 3000-
5000 FT OVER ALL BUT SRN CA, WITH LEVELS DROPPING TO 6000-9000 FT
OVER SRN CA.


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

THE WEEKEND WILL FEATURE AN UPR RIDGE SITUATED JUST OFF THE WEST
COAST EXTENDING NNW TOWARD ALASKA. COOL NORTHERLY FLOW ACROSS CA AND
NEV WILL BE THE RULE. A SYSTEM DROPPING IN FROM THE PACNW WILL DIVE
TOWARD THE GREAT BASIN ON SUNDAY. THE S/WV TROF WILL BE FAIRLY
MOISTURE STARVED GIVEN ITS ORIGINS TO THE NORTH. LOOK FOR LIGHT
PRECIP TO DEVELOP OVER THE UPPER KLAMATH RIVER BASIN AND OTHER AREAS
NEAR THE CA/ORE BORDER...AS WELL AS LOCATIONS NORTH OF I-80 IN NEV.
LATER SUNDAY...THE S/WV TROF WILL MOVE TOWARD THE SE ACROSS EASTERN
NEV AND UTAH WITH PRECIP DISSIPATING LAST ACROSS NE NEV LATE SUNDAY.

DRY CONDITIONS WILL DEVELOP FOR MONDAY AHEAD OF THE NEXT S/WV TROF
EXPECTED TO DIVE IN FROM THE NORTH FOR TUESDAY INTO WEDNESDAY. A
PATTERN CHANGE DOES NOT LOOK LIKELY IN THE DAY 6-TO-10 (DEC 29 TO
JAN 2) PERIOD AS THE CPC OUTLOOK CONTINUES TO HOLD ONTO THE ABOVE
NORMAL HEIGHTS JUST OFF THE WEST COAST ASSOCIATED WITH THE UPR
RIDGE PRIMARILY ALONG 135W.


.HYDROLOGICAL CONDITIONS...

VERY MINOR RISES ARE EXPECTED THROUGHOUT MANY NORTHERN CALIFORNIA
RIVERS OVER THE NEXT COUPLE OF DAYS.  AFTER THAT, RIVERS WILL REMAIN
NEAR BASEFLOW CONDITIONS THROUGH THE FORECAST PERIOD.  NO RIVERS ARE
EXPECTED TO COME CLOSE TO MONITOR STAGE LEVELS.

THE ONLY WEIR STILL FLOWING ON THE SACRAMENTO SYSTEM IS TISDALE.  IT
IS EXPECTED TO STOP FLOWING TODAY.


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

DRK/KL/DRK/BW

$$



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