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HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
900 AM PDT FRI OCT 24 2014

...LIGHT RAIN EXPECTED ACROSS FAR NRN CA/SRN OREGON THIS MORNING...
...PRECIP EXPECTED ACROSS NRN CA/SRN OREGON TONIGHT THROUGH SUN...
...ADDITIONAL PRECIP EXPECTED ACROSS FAR NRN CA/SRN OREGON MON NIGHT
THROUGH WED NIGHT

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

A STATIONARY FRONT ALIGNED THROUGH FAR NORTHERN CA...ALONG WITH
PERSISTENT MOIST ONSHORE FLOW WAS THE FOCUSING MECHANISM FOR
MODERATE TO LOCALLY HEAVY PRECIP ACROSS NW CA INTO THE UPPER KLAMATH
RIVER BASIN. THE GREATEST TOTALS WERE OBSERVED FROM CAPE MENDOCINO
NE INTO THE TRINITY AND LOWER KLAMATH RIVER BASINS WITH 1.00- TO
3.00-INCHES. ELSEWHERE IN THIS BAND OF PRECIP TOTALS WERE GENERALLY
FROM 0.50- TO 1.00-INCH. THE SOUTHERN EXTENT OF THE PRECIP REACHED
FROM NORTHERN SONOMA COUNTY NE ACROSS THE FEATHER RIVER BASIN AND
FAR NWRN NEVADA.


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

SATELLITE IMAGERY SHOWS A DEEPENING BAROCLINIC SYSTEM SEVERAL
HUNDRED MILES WEST OF CNTRL CA THIS MORNING.  THE WARM FRONTAL
PORTION OF THE SYSTEM IS LIFTING NORTH ACROSS FAR NRN CA/SRN OREGON
THIS MORNING AND BRINGING LIGHT SHOWERS TO THOSE AREAS.  AS THE
FRONT CONTINUES TO LIFT NWD, EXPECT SHOWERS TO END BY LATE THIS
AFTERNOON WITH DRY CONDITIONS THROUGH THIS EVENING.

A FAIRLY STRONG SHORTWAVE ALOFT IS EXPECTED TO HELP PUSH THE COLD
FRONT QUICKLY ACROSS THE NORTH COAST TONIGHT WITH ACCOMPANYING PW
VALUES AROUND 1 INCH.  H85 WINDS FROM AROUND CAPE MENDOCINO NWD ARE
EXPECTED TO PEAK AROUND 50-65 KTS BY LATE TONIGHT, BUT THE SLY
DIRECTION IS NOT IDEAL FOR OROGRAPHICS NORTH OF THE CAPE.  LIGHT
PRECIP IS EXPECTED TO SPREAD ACROSS THE NORTH COAST TONIGHT AND
SPREAD ACROSS NRN CA AND SRN OREGON SAT MORNING.  SLY WINDS IN THE
NRN SACRAMENTO VALLEY ARE EXPECTED TO PEAK AROUND 30-50 KTS SAT
MORNING, LEADING TO SOME ENHANCED TOTALS AROUND LAKE SHASTA.

A SECONDARY BOUNDARY IS EXPECTED TO MOVE ONTO THE NORTH COAST SAT
AFTERNOON AS A WEAKER VORT MAX APPROACHES.  THIS SHOULD LEAD TO
ENHANCED PRECIP RATES FOR PARTS OF THE NORTH COAST MAINLY NORTH OF
CAPE MENDOCINO, WITH CONTINUED MODERATE AMOUNTS IN THE LAKE SHASTA
DRAINAGE AND INCREASING AMOUNTS IN THE NRN SIERRA AS MOIST,
OROGRAPHIC FLOW IMPROVES AND THE WAVE ALOFT APPROACHES.  EXPECT
PRECIP TO TAPER OFF SAT NIGHT AND SUN AS THE TROUGH AXIS SHIFTS TO
THE EAST.  FAR NRN NV SHOULD SEE SOME LIGHT AMOUNTS LATE SAT
NIGHT/SUN AS THE TROUGH MOVES ACROSS THE AREA.

FREEZING LEVELS ARE EXPECTED TO START OFF AROUND 10,000 OR ABOVE
PRIOR TO THE ARRIVAL OF THE COLD FRONT.  EXPECT FREEZING LEVELS TO
FALL TO 6000-7500 FT IN THE NORTH AND 7500-9000 FT IN THE NRN SIERRA
BY LATE SAT NIGHT.


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

THE PERIOD BEGINS WITH RELATIVELY GOOD AGREEMENT WITH A POSITIVELY
TILTED UPR RIDGE EXTENDING FROM NEAR THE HAWAIIAN ISLANDS NE TO JUST
OFF THE CA COAST AND THEN INLAND OVER THE PACNW. A COUPLE
DISTURBANCES WILL BE LOCATED WEST OF THE PACNW BETWEEN 130W AND
150W. IN THE SW FLOW BETWEEN THE UPR RIDGE AND S/WV TROFS WILL BE A
CHANNEL OF MOISTURE WORKING ITS WAY NE FROM WEST OF HAWAII.

AS THE S/WV TROFS MAKE THEIR WAY TOWARD THE PACNW...EXPECT A WARM
FRONT TO MOVE ACROSS THE NORTH COAST AND UPPER KLAMATH RIVER BASIN
LATER MONDAY. WARM SECTOR PRECIP WILL AFFECT THESE AREAS THROUGH
TUESDAY BEFORE THE COLD FRONT BEGINS TO SAG SOUTH TOWARD THE REGION
ON WEDNESDAY.

DIFFERENCES IN THE MODELS REALLY SHOW UP LATER WEDNESDAY INTO
THURSDAY. AS THE FLOW BUCKLES AND BECOMES MORE AMPLIFIED...THE
24/00Z EC DEVELOPS AN UPR RIDGE ALIGNED SLIGHTLY FARTHER WEST THAN
THE 24/06Z GFS OVER THE INTERIOR. THE UPSTREAM UPR TROF ON THE EC
DIGS OUT BETWEEN 140W AND 150W...WHILE THE GFS IS CLOSER TO THE
COAST WITH THE SYSTEM. AS A RESULT...THE GFS WANTS TO DRAG PRECIP
THROUGH NORTHERN CA ON THU WHILE THE FRONTAL BAND REMAINS OFFSHORE
ON THE EC. THERE HASN/T BEEN TOO MUCH RUN-TO-RUN CONSISTENCY WITHIN
THE MODEL...OR BETWEEN THE MODELS. STILL SOME TIME TO IRON OUT THE
DETAILS AS THIS FALLS AT THE END OF THE 6-DAY FORECAST PERIOD AND
OUTSIDE THE WINDOW.


.HYDROLOGICAL CONDITIONS...

PRECIPITATION OVER NORTHWEST CALIFORNIA FOR THE PAST 24 HOURS
PRODUCED SOME MINOR RISES IN STAGE MAINLY ALONG THE NORTH COAST OF
CALIFORNIA. RAINFALL FORECAST FOR THE NEXT 48 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

DRK/KL/DRK/PF

$$




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