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877
AGUS76 KRSA 251701
HMDRSA

HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
900 AM PST SUN JAN 25 2015

...PRECIP MOVING UP FROM THE SOUTH MONDAY THRU WEDNESDAY...

.24 HOUR PRECIPITATION TOTALS (ENDING JAN 25 AT 400 AM PST)...

DRY CONDITIONS WERE OBSERVED YESTERDAY AS A DRY REX BLOCK PATTERN
EXISTED ALONG THE WEST COAST.


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

CLASSIC REX BLOCK PATTERN IN PLACE ACROSS THE WEST COAST THIS
MORNING AS WV/IR IMAGERY SHOWS THE UPR RIDGE CENTERED OVER NORTHERN
CA...WHILE THE UPR LOW TO THE SOUTH IS WEST OF CENTRAL BAJA NEAR
25N/130W. THE PATTERN OVER THE NEXT FEW DAYS WILL SHOW THE UPR RIDGE
SLIDING OFF TOWARD THE EAST ACROSS THE ROCKY MOUNTAINS...WHILE THE
UPR LOW BEGINS TO DRIFT NORTHWARD ON THE UPSTREAM SIDE OF THE UPR
RIDGE. FOR THE MOST PART THE UPR LOW WILL MOVE NORTH ALONG 120W AND
THEN OPEN UP AS IT APPROACHES SOUTHERN CA AND THEN MOVE INLAND
TOWARD THE NNE ACROSS NEV.

LOOKING AT THE BLENDED TPW IMAGERY FROM THIS MORNING...THERE ALREADY
IS EVIDENCE OF HIGHER MOISTURE CONTENT AIR ADVECTING NNW THROUGH THE
GULF OF CALIFORNIA. PW VALUES IN THIS AREA ARE GENERALLY BETWEEN
1.00- AND 1.25-INCHES. AS THE SYSTEM MOVES NORTHWARD...LOOK FOR
MOISTURE TO INCREASE ACROSS SOUTHERN CA WITH PW VALUES FROM 0.75- TO
1.00-INCH...WHILE SLIGHTLY LESSER PW VALUES OVER THE NORTHERN TWO-
THIRDS OF THE REGION (0.50- TO 0.75-INCH).

OVERALL...MODELS ARE IN RELATIVELY GOOD AGREEMENT WITH PRECIP MOVING
TOWARDS SOUTHERN CA EARLY ON MONDAY AND THEN PUSHING NORTH ACROSS
MUCH OF CENTRAL CA AND SOUTHERN NEV THROUGHOUT THE DAY. THEN INTO
TUESDAY...PRECIP WILL MOVE MAINLY ACROSS THE EASTERN HALF OF
NORTHERN CA AND ALL OF NORTHERN NEV. BY WEDNESDAY...THE SYSTEM WILL
HAVE PUSHED OFF TOWARD THE EAST ACROSS THE CENTRAL ROCKIES...WHICH
WILL RESULT IN PRECIP DECREASING OVER THE AREA.

THE TREND OF THE FORECAST WAS TO BOOST EXPECTED AMOUNTS FOR MOST
AREAS...BUT IN PARTICULAR THE SOUTHERN CA HIGHER TERRAIN AND MUCH OF
THE SIERRA FROM I-80 SOUTHWARD. ALSO...WITH THE 25/12Z NAM AND
25/09Z SREF BOTH DRAGGING SOME LIGHT PRECIP OVER THE SACRAMENTO
VALLEY...DECIDED TO INCLUDE A FEW HUNDREDTHS OF AN INCH AS THE
SYSTEM PASSES ON TUESDAY.

FREEZING LEVELS WITH THE SYSTEM WILL GENERALLY BE IN THE RANGE OF
7500- TO 8500-FEET.

AN ELONGATED UPR TROF THAT WILL FORM A CUTOFF LOW NEAR NORTHERN BAJA
WILL AFFECT THE REGION LATER IN THE WEEK. THE POTENTIAL EXISTS FOR
SOME LIGHT PRECIP ACROSS SOUTHERN CA...NEAR THE CREST OF THE
SOUTHERN SIERRA AND THE SOUTHERN HALF OF NEV FROM THURSDAY INTO
EARLY SATURDAY.


.HYDROLOGICAL CONDITIONS...

FORECAST PRECIPITATION FOR MONDAY AND TUESDAY IS EXPECTED TO PRODUCE
VERY SMALL RISES IN STAGE ON MANY RIVERS AND STREAMS IN SOUTHERN CA
AND THE SIERRA NEVADA.  ALL STAGES ARE EXPECTED TO REMAIN WELL BELOW
MONITOR LEVELS THROUGH THE NEXT SEVERAL DAYS.


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

DRK/AT

$$




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