Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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AGUS76 KRSA 222050 CCA
HMDRSA

HYDROMETEOROLOGICAL DISCUSSION...CORRECTED TYPO
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
930 AM PDT WED OCT 22 2014

...PRECIP EXPECTED OVER NORTHERN CA TODAY AND THURSDAY...
...SECOND SYSTEM TO MOVE INTO NORTHERN AND CENTRAL CA FRIDAY NIGHT
INTO SATURDAY...

.24 HOUR PRECIPITATION TOTALS (ENDING OCT 22 AT 500 AM PDT)...

A PAIR OF DISTURBANCES BROUGHT LIGHT SHOWERS TO PORTIONS OF NRN CA,
SRN OREGON, AND NRN NV.  AMOUNTS WERE 0.25" OR LESS ON THE FAR NORTH
COAST AND JUST A FEW HUNDREDTHS OR LESS ACROSS THE SHASTA DRAINAGE,
NRN SIERRA THROUGH SRN OREGON, AND IN NRN NV.


.METEOROLOGICAL CONDITIONS (SHORT TERM: WED AM - FRI PM)...

UPPER LOW SITTING OVER THE GULF OF ALASKA HAS BROUGHT A STRONG COLD
FRONT TO THE WASHINGTON AND OREGON COASTLINE THIS MORNING. THE UPPER
JET WILL GRADUALLY SLINK SOUTHWARD THROUGH THE DAY...BRINGING
INCREASING PRECIP TO THE NORTH COAST BY THE LATE AFTERNOON HOURS.
LONG FETCH MOISTURE PLUME CAN BE SEEN REACHING BACK TO NORTH OF
HAWAII...BRINGING NEARLY 1" PWAT VALUES TO THE NORTH COAST SO FAR
TODAY. MODELS ARE IN PRETTY GOOD AGREEMENT THIS MORNING...WITH THE
HEAVIEST PRECIP REMAINING TO THE NORTH OVER THE OREGON COAST. DO
STILL EXPECT A PERIOD OF MODERATE TO LOCALLY HEAVY PRECIP TO FALL
OVER THE SMITH BASIN LATE TONIGHT...BUT WEAKEN TO JUST MODERATE AS
THE SYSTEM SLIDES SOUTH INTO THURSDAY MORNING. THE 22/12Z NAM IS THE
OUTLIER WITH HOLDING THE FRONT TOGETHER STRONGLY AS IT MOVES INTO
THE RUSSIAN AND EEL R BASINS...AND INLAND INTO THE SHASTA DRAINAGE
THURSDAY AFTERNOON. FEEL THE GFS/ECMWF SOLUTION THAT BRINGS LIGHT TO
MODERATE PRECIP TO THOSE AREAS DURING THAT TIME FRAME IS MORE
REASONABLE.

EXPECT SOME CLEARING THURSDAY NIGHT AND FRIDAY AS THE GOA LOW
DEEPENS INTO A TROUGH. TROUGH AXIS IS EXPECTED TO CENTER AROUND 135W
BY FRIDAY AFTERNOON...WITH A STRONG UPPER JET JUST AHEAD PULLING A
1.1" PWAT PLUME ALONG WITH IT AS IT MOVES TOWARDS THE COASTLINE.
FRONTAL SYSTEM SHOULD BRING ANOTHER ROUND OF PRECIP TO THE NORTH
COAST BY SATURDAY MORNING.


.METEOROLOGICAL CONDITIONS (LONG TERM: FRI PM - TUE AM)...

MODELS HAVE TRENDED SLOWER WITH THE LATE-WEEK SYSTEM COMPARED TO
YESTERDAY MORNING`S RUNS.  MODELS ARE STILL STRUGGLING TO LOCK ONTO
THE DETAILS.  ECMWF/GEM SHOWED REASONABLE AGREEMENT, AND ECMWF
ENSEMBLES AND DETERMINISTIC SOLNS WERE REASONABLY SIMILAR, SO
UTILIZED A BLEND OF THE ECMWF AND GEM AS THE STARTING POINT IN THE
EXTENDED RANGE.  A DEEPENING LOW PRESSURE SYSTEM IS EXPECTED TO MOVE
NE TOWARD THE PAC NW FRI/SAT.  WITH A DECENT SHORTWAVE ALOFT, EXPECT
THE FRONTAL BAND OF PRECIP TO PUSH QUICKLY ONTO THE NORTH COAST FRI
NIGHT AND ACROSS NRN CA AND SRN OREGON ON SAT.  HEAVIEST AMOUNTS ARE
EXPECTED ON THE NORTH COAST NEAR CAPE MENDOCINO AND NWD WHERE
OROGRAPHIC EFFECTS WILL HELP ENHANCE TOTALS.  LIGHT SHOWERS ARE
EXPECTED TO MAKE IT INTO THE SRN SIERRA AND THE TRANSVERSE RANGES OF
SRN CA SAT NIGHT AS A VORT MAX SWINGS ACROSS CA.  SHOWERS CONTINUE
IN NRN CA/SRN OREGON AND MOVE INTO NRN NV SAT INTO SUN BEFORE THE
TROUGH EXITS AND DRYING RETURNS.  FREEZING LEVELS ARE FORECAST TO
START OFF AROUND 10,000 FT OR ABOVE ON FRI AHEAD OF THE COLD FRONT
AND LOWER TO 6000-7000 IN THE FAR NORTH AND 7500-8500 FT IN THE NRN
AND CNTRL SIERRA FOLLOWING FRONTAL PASSAGE.


.HYDROLOGICAL CONDITIONS...

RIVERS AND STREAMS IN NORTHWEST CALIFORNIA ARE RECEDING...OR REMAIN
STEADY THIS MORNING AFTER RISING IN STAGE YESTERDAY MORNING FROM
PRECIPIATION THAT FELL ON MONDAY.

PRECIPITATION FORECAST FOR THE NEXT 5 DAYS OVER NORTHERN CALIFORNIA
IS EXPECTED TO PRODUCE RENEWED...MINOR RISES IN STAGE ON MANY AREA
RIVERS BEGINNING THURSDAY MORNING.

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

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

KL/JM/KL/SS

$$



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