Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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ZCZC RNOWRKHMD 311747
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HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
955 AM PST SAT JAN 31 2015

...PRECIP WRAPPING UP OVER SRN CA/NV THIS AFTERNOON...
...SYSTEM TO BRING PRECIP TO FAR NRN CA/SRN OREGON SUNDAY NIGHT
THROUGH TUESDAY...
...POTENTIAL HEAVY RAIN SYSTEM AS EARLY AS THURSDAY EVENING...

.24 HOUR PRECIPITATION TOTALS (ENDING JAN 31 AT 400 AM PST)...

AN UPPER LOW BROUGHT PRECIP TO SRN CA AND NV STARTING YESTERDAY. THE
SRN SIERRA AND TEHACHAPI MTNS PICKED UP LESS THAN 0.1"...WHILE SOME
LOCATIONS ON THE EAST SIDE MEASURED UP TO 0.2". THE SAN GABRIEL AND
SAN BERNADINO MNTNS PICKED UP 0.05-0.2" PRECIP...WITH SIMILAR
AMOUNTS STRETCHING DOWN THE MNTNS OF RIVERSIDE AND SAN DIEGO
COUNTIES. COASTAL AND VALLEY LOCATIONS PICKED UP JUST A FEW
HUNDREDTHS. THE DESERTS SAW UP TO 0.2" PRECIP...WHILE THE LAS VEGAS
METRO AREA SAW ANYWHERE FROM 0.1" TO UPWARDS OF 0.5". EASTERN NEVADA
GENERALLY RECEIVED UNDER 0.1" AS WELL.


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

SATELLITE THIS MORNING SHOWS A POSITIVELY TILTED RIDGE EDGING INTO
NRN CA WITH A VERY DRY AIRMASS...WHILE AN UPPER LOW CONTINUES TO
SPIN NEAR THE CA/NV/AZ BORDER. LIGHT SHOWERS CONTINUE OVER SRN
NEVADA AND THE DESERTS IN EASTERN SAN BERNADINO COUNTY...THOUGH
THINGS ARE WRAPPING UP AS AVAILABLE MOISTURE WANES. AFTER A FEW
SHOWERS OVER THE SRN CA MTNS FROM BIG BEAR SOUTHWARD THROUGH THE
AFTERNOON...EXPECT DRY CONDITIONS TO TAKE OVER YET AGAIN.

ANOTHER SYSTEM IS EXPECTED TO ARRIVE OVER FAR NRN CA SUNDAY
EVENING...WITH LIGHT SHOWERS ASSOCIATED WITH A WARM FRONTAL PATTERN
HITTING THE SMITH BASIN THROUGH THE OVERNIGHT HOURS SUNDAY INTO
MONDAY. MODELS EXPECT PRECIP TO INCREASE IN INTENSITY AND BECOME
MODERATE BY MONDAY MORNING...AND EXTEND DOWN TO CAPE MENDOCINO AND
POSSIBLY EVEN PT ARENA. PRECIP SHOULD CONTINUE THROUGH THE AFTERNOON
AND EVENING HOURS AS MOIST ONSHORE FLOW CONTINUES OVER THE REGION.
THE GFS HOLDS ONTO MODERATE PRECIP CONTINUING LONGER THAN THE EC
DOES. THE EC LIFTS THE PRECIP BAND NORTHWARD BY TUES AM...WHILE THE
GFS HANGS ON THROUGH TUES AFTERNOON. TOOK A MORE GFS-CENTRIC STAB AT
THE FORECAST THIS MORNING AND WRAPPED UP PRECIP TUESDAY NIGHT.

RIDGING WILL DOMINATE THE PATTERN THROUGH MID-WEEK...THEN EXPECT A
BIG PATTERN SHIFT AS THE FIRST SIGNIFICANT RAIN-MAKER IN OVER A
MONTH APPROACHES THE NORTHERN CA COAST THURSDAY. BOTH THE EC AND GFS
HAVE BEEN HONING IN ON THIS SYSTEM FOR A FEW DAYS NOW...AND
CONFIDENCE IS INCREASING IN A MODERATE TO HEAVY RAINFALL EVENT FOR
NORTHERN CA THURSDAY NIGHT THROUGH SATURDAY. FOR NOW...IT LOOKS LIKE
PRECIP WILL BEGIN ALONG THE NORTH COAST LATE THURSDAY AFTERNOON...
INCREASING IN INTENSITY BY FRIDAY MORNING BUT NOT MAKING TREMENDOUS
INLAND PROGRESS YET. THE GFS HAS BEEN MORE AGGRESSIVE IN TERMS OF
SPEED AND QPF OUTPUT FOR THIS SYSTEM...THOUGH BOTH AGREE THAT IT
WILL BE A VERY WARM ONE WITH HIGH SNOW LEVELS (9000-FT OR ABOVE).


.HYDROLOGICAL CONDITIONS...

PRECIPITATION FORECAST FOR THE NEXT FIVE DAYS WILL HAVE MINIMAL
IMPACTS ON AREA RIVERS.  SOME MINOR RISES ARE FORECAST FOR
WATERSHEDS ALONG THE FAR NORTH COAST OF CALIFORNIA AND INTO SOUTHERN
OREGON.

SOME MINOR SNOWMELT IS OCCURING IN HIGH ELEVATION BASINS.  THE
SNOWMELT IS CAUSING SOME VERY MINOR RISES IN THE SIERRA NEVADA
WATERSHEDS.  MOST AREA RIVERS ARE EITHER FLAT OR RECEDING.

ALL RIVER STAGES ARE EXPECTED TO REMAIN WELL BELOW MONITOR LEVELS
THROUGH THE NEXT FIVE DAYS.


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

JM/PF

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