Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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AGUS76 KRSA 271815
HMDRSA

HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
930 AM PST FRI FEB 27 2015

...SHOWER REGIME NEXT FEW DAYS THEN TURNING DRIER MIDDLE OF NEXT
WEEK...

.24 HOUR PRECIPITATION TOTALS (ENDING FEB 27 AT 400 AM PST)...

A WEAK SYSTEM BROUGHT PRECIP TO THE NORTHERNMOST PORTIONS OF THE
REGION STARTING YESTERDAY MORNING. OVER THE W SLOPES OF THE SRN
OREGON CASCADES...UP TO A THIRD OF AN INCH OF PRECIP FELL...WHILE
LESS THAN A TENTH OF AN INCH WAS MEASURED EAST OF THE CREST. OVER
THE SMITH BASIN...1/3-2/3" WAS REPORTED...TRAILING OFF TO LESS THAN
A TENTH OF AN INCH AROUND CAPE MENDOCINO. THE NE CA PLATEAU RECEIVED
UP TO A TENTH OF AN INCH AS WELL.

NORTHEASTERN NEVADA ALSO REPORTED SHOWERS YESTERDAY...WITH AMOUNTS
RANGING FROM 0.05-0.25". HIGHEST AMOUNTS WERE REPORTED OVER HIGHER
TERRAIN NORTH OF I-80.


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

AN UPPER JET MOVING FROM THE NORTH AND ASSOCIATED SHORTWAVE ARE
BRINGING LIGHT SHOWERS TO PORTIONS OF NRN CA, SRN OREGON, AND NV
THIS MORNING.  EXPECT THIS SYSTEM TO EVENTUALLY FORM A CLOSED LOW
OVER CNTRL CA BY SAT, WITH LIGHT SHOWERS AFFECTING MOST OF THE
REGION FROM NORTH TO SOUTH BY TONIGHT.  AS THE UPPER LOW SLOWLY
DRIFTS SOUTH, EXPECT SHOWERS TO WIND DOWN IN THE NORTH AND INCREASE
IN SRN CA/NV, AFFECTING EVEN THE SE CA DESERTS ON SUN.  EXPECT
FREEZING LEVELS INITIALLY STARTING OFF 6000-8000 FT IN THE SIERRA
AND 8000-10,000 FT IN SRN CA, LOWERING TO 5000-7000 FT ACROSS THE
AREA THIS WEEKEND.


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

EXTENDED MODELS DO HAVE SOME DISAGREEMENTS WITH HANDLING THE NEXT
S/WV TROUGH TO MOVE THROUGH THE REGION DURING THE FIRST PART OF NEXT
WEEK. WHILE THE GFS HAS BEEN MORE POTENT WITH THIS INSIDE SLIDER
THROUGH THE PAST FEW DAYS...IT HAS BACKED OFF ON THE INTENSITY
RESULTING IN A MUCH DRIER FORECAST. THE EC IS HOLDING ONTO DEEPENING
THE TROUGH OVER CA AS IT MOVES THROUGH MONDAY AND TUESDAY...WHICH
RESULTS IN MORE PRECIP OVER THE REGION...ESPECIALLY SOUTHERN CA.
THIS EC SOLUTION BASICALLY CONSISTS OF AN UPPER TROUGH DIGGING INTO
CA ON MONDAY...TAKING ON A POSITIVE TILT OVER THE REGION. WITH THE
TROUGH AXIS SITTING OVER NRN CA MONDAY AFTERNOON...EXPECT SHOWERS TO
DEVELOP OVER THE SIERRA AS WELL AS OVER MUCH OF NEVADA. DURING THIS
TIME...ONSHORE FLOW DEVELOPS OVER SOUTHERN CA THAT DRAWS MOISTURE
INLAND AND PRODUCES LOCALLY MODERATE PRECIP OVER HIGHER TERRAIN...
THOUGH THE EC IS MORE EXUBERANT WITH THIS FEATURE THAN THE GFS.

BY TUESDAY MORNING...THE GFS PULLS THE TROUGH FULLY EAST OF THE
REGION AND KEEPS IT DRY THROUGH THE REST OF THE LONG TERM. THE EC
HOLDS THE TROUGH OVERHEAD THROUGH THE AFTERNOON...WHICH KEEPS PRECIP
GOING OVER THE SRN SIERRA AND SOUTHERN CA...FINALLY PUSHING EAST
OVERNIGHT. THE CURRENT FORECAST REFLECTS A BLEND OF THESE TWO
SOLUTIONS. HESITANT TO MOVE THE TROUGH THROUGH AS FAST AS THE GFS IS
TRENDING TOWARDS UNTIL THE EC STARTS TO LATCH ONTO THIS SOLUTION AS
WELL.


.HYDROLOGICAL CONDITIONS...

EXPECT LITTLE CHANGE IN RIVER CONDITIONS DURING THE NEXT FEW DAYS.
ONLY VERY SMALL RISES ARE EXPECTED ON SOME STREAMS AND RIVERS FROM
THE WEAK WEATHER SYSTEM EXPECTED OVER THE REGION DURING THE NEXT FEW
DAYS.  ALL STAGES ARE EXPECTED TO REMAIN WELL BELOW MONITOR LEVELS.


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

JM/KL/JM/AT

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