Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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AGUS76 KRSA 251656
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HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
955 AM PDT SAT OCT 25 2014

...PRECIP CONTINUES OVER NRN CA/SRN OREGON TODAY AND TONIGHT...
...NEXT STORM EXPECTED TO BRING PRECIP TO FAR NW CA/SRN OREGON TUE-
WED...

.24 HOUR PRECIPITATION TOTALS (ENDING OCT 25 AT 500 AM PDT)...

A WARM FRONT LIFTED NORTH ACROSS FAR NRN AND NW CA AS WELL AS SRN
OREGON FRI MORNING, BRINGING LIGHT RAIN TO THOSE AREAS.  A COLD
FRONT THEN SPREAD LIGHT TO MODERATE PRECIPITATION ACROSS NW CA AND
DOWN THE COAST TO NEAR MONTEREY BAY DURING THE OVERNIGHT PERIOD.  24-
HOUR PRECIPITATION TOTALS WERE AROUND 0.2-0.6" NEAR THE SMITH BASIN
SWD TO THE EEL BASIN, ALTHOUGH GAUGES IN THE KING RANGE PICKED UP
1.3-1.8" WITH A GOOD SLY OROGRAPHIC FLOW INTO THE RANGE.  RUSSIAN/
NAPA BASIN GAUGES PICKED UP ABOUT 0.1-0.4", WHILE JUST A FEW
HUNDREDTHS OF AN INCH MADE IT AS FAR SOUTH AS THE SANTA CRUZ MTNS BY
5 AM.  A COUPLE OF GAUGES ON THE WEST SIDE OF THE SACRAMENTO VALLEY
MANAGED TO PICK UP 0.01" BY THE 5 AM CUTOFF AT THE END OF THE
PERIOD, WITH UP TO AROUND 0.1" AND LOCALLY HIGHER IN THE HILLS JUST
WEST OF THE VALLEY.  TOTALS WERE AROUND 0.1" OR LESS IN THE VICINITY
OF LAKE SHASTA AND UPPER KLAMATH BASIN, EXCEPT 0.2-0.3" IN THE SRN
OREGON CASCADES AND FAR NRN PORTION OF THE UPPER KLAMATH.  FINALLY,
NE CA PICKED UP AROUND 0.01", WITH A COUPLE OF GAUGES PICKING UP
0.01" ALSO DOWN TOWARD LASSEN NP.


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

FIRST COLD FRONTAL BAND IS CURRENTLY BRINGING PRECIPITATION IN A
LINE STRETCHING FROM THE UPPER KLAMATH BASIN SWD INTO THE SACRAMENTO
VALLEY AND DOWN TO MONTEREY BAY.  OVERALL, PRECIP AMOUNTS HAVE BEEN
HIGHER AND TIMING A BIT FASTER THAN PREVIOUSLY EXPECTED.  PRECIP
RATES HAVE BEEN MODERATE ALONG THE FRONTAL BOUNDARY, AND PRECIP
SHOULD FILL IN ACROSS PORTIONS OF THE CNTRL COAST AND ACROSS INTO
THE NRN SIERRA THROUGH THE MORNING HOURS.  AFTER A BRIEF BREAK ON
THE NORTH COAST, SHOWERS HAVE BEGUN TO DEVELOP RAPIDLY AND MOVE TO
THE NNE FROM AROUND SHELTER COVE NWD.

THIS AFTERNOON, EXPECT LIGHT PRECIP FROM THE INITIAL FRONT TO SPREAD
INTO THE CNTRL SIERRA AND CONTINUE ACROSS PORTIONS OF THE CNTRL
VALLEY OVER TO THE CNTRL COAST.  ANOTHER BOUNDARY IS EXPECTED TO
MOVE INTO THE NORTH COAST ALONG WITH THE APPROACH OF A WAVE ALOFT.
BEHIND THE BOUNDARY, EXPECT WINDS TO FINALLY SHIFT FROM SLY TO WLY
ALONG THE NORTH COAST, THUS PROVIDING A PERIOD OF BETTER OROGRAPHIC
FLOW FOR AREAS NORTH OF CAPE MENDOCINO.  AS A RESULT, EXPECT PRECIP
RATES TO ENHANCE THIS AFTERNOON ACROSS THE NORTH COAST, ESPECIALLY
TOWARD THE LOWER KLAMATH AND SMITH BASINS.  SHOWERS WILL CONTINUE TO
BE A THREAT ACROSS ALL OF NRN CA THIS AFTERNOON WITH THE FORCING
ALOFT AND SOME MODEST INSTABILITY ACROSS THE REGION.

THE TROUGH AXIS IS EXPECTED TO PUSH INLAND ACROSS NRN CA/NV THIS
EVENING AND TONIGHT, WITH PRECIP EXPECTED TO BEGIN TO WIND DOWN AND
LIFT TO THE NORTH.  AS THE TROUGH CONTINUES TO PUSH TO THE EAST ON
SUN, EXPECT A FEW SHOWERS TO DRIFT ACROSS FAR NRN NV, WHILE PARTS OF
NW CA/SRN OREGON SEE THE TYPICAL SHOWERS IN THE POST-FRONTAL NWLY
FLOW.

AS FAR AS FREEZING LEVELS ARE CONCERNED WITH THE SYSTEM TODAY AND
SUN, FREEZING LEVELS ARE GENERALLY 8500 FT ON THE NORTH COAST AND
ABOVE 10,000 FT ELSEWHERE.  TEMPS HAVE BEGUN TO FALL A BIT BEHIND
THE FRONT IN NW CA AND SRN OREGON.  FREEZING LEVELS SHOULD BOTTOM
OUT AROUND 5500-7000 FT IN THE NORTH AND 7500-9000 FT IN THE NRN
PORTION OF THE SIERRA BY LATE TONIGHT.

DRY CONDITIONS ARE EXPECTED SUN NIGHT THROUGH MON NIGHT AS WEAK
RIDGING SHIFTS EAST ACROSS THE REGION BETWEEN SYSTEMS.  LATEST
GFS/ECMWF AGREE REASONABLY WELL REGARDING THE NEXT SYSTEM EXPECTED
TO IMPACT THE FAR NORTH TUE-WED.  THE MAIN FORCING REMAINS WELL TO
THE NORTH OF THE REGION, AND JUST THE FAR NW PORTION OF CA AND SRN
OREGON ARE EXPECTED TO SEE LIGHT TO OCCASIONALLY MODERATE AMOUNTS AS
THE SRN END OF THE FRONT CLIPS THE REGION.  FREEZING LEVELS ARE
EXPECTED TO REMAIN ABOVE 10,000 FT ACROSS THE AREA WITH THE REGION
REMAINING ON THE WARM SIDE OF THE FRONT.

MODELS DRIFT APART BEYOND MIDWEEK, WITH ALL SHOWING ANOTHER FRONT
MOVING INTO NW CA BUT WITH PLENTY OF SPREAD REGARDING TIMING.  FOR
NOW, WENT WITH A COMPROMISE BETWEEN THE FASTER GFS/GEM AND MUCH
SLOWER ECMWF.  THIS COMPROMISE KEEPS MOST OF THE PRECIP WITH THIS
SYSTEM BEYOND THE END OF THE 6-DAY FORECAST WINDOW.


.HYDROLOGICAL CONDITIONS...

PRECIPITATION OVER NORTHWEST CALIFORNIA FOR THE PAST 24 HOURS HAS
BEEN FARILY LIGHT AND HAS NOT HAD MUCH EFFECT ON AREA RIVERS.

RAINFALL FORECAST FOR THE NEXT 24 HOURS IS EXPECTED TO BRING RENEWED
RISES ALONG THE NORTH COAST.  ELSEWHERE SOILS REMIAN RELATIVELY DRY
AND ONLY SLIGHT RISES ARE EXPECTED.

ALL RIVERS AND STREAMS IN THE CNRFC FORECAST AREA ARE CURRENTLY
BELOW...AND ARE FORECAST TO REMAIN BELOW MONITOR LEVELS THROUGH
MONDAY.



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

KL/PF

$$



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