Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
840 AM PST FRI DEC 26 2014

...COOL NORTHERLY FLOW WITH A COUPLE SYSTEMS DROPPING INTO AREA...

.24 HOUR PRECIPITATION TOTALS (ENDING DEC 26 AT 400 AM PST)...

NORTHERLY FLOW WITH A S/WV TROF DIVING THROUGH EASTERN NEV BROUGHT
SOME SCATTERED LIGHT TO LOCALLY MODERATE PRECIP TO THE AREA.
HEAVIEST AMOUNTS WERE OBSERVED OVER NE NEV WITH LOWER ELEVATIONS AT
0.10-INCH OR LESS BUT NW FACING SLOPES PICKING UP THE
MOST...ESPECIALLY THE RUBY MOUNTAINS WITH 0.25- TO 0.75-INCH (LOCAL
TO 1.00-INCH).

A FEW REMAINING SHOWERS OVER SAN DIEGO COUNTY BROUGHT AMOUNTS NEAR
OR LESS THAN 0.10-INCH MAINLY TO THE HIGHER TERRAIN.

SOME LIGHT SHOWERS ALSO AFFECTED AREAS NEAR THE CA/ORE BORDER AS
THEY DRIFTED FROM N-TO-S IN THE FLOW WITH TOTALS 0.10-INCH OR LESS.

FINALLY...A FEW UPSLOPE SHOWERS DEVELOPED NEAR LAKE TAHOE AND SOUTH
TOWARD KIRKWOOD WITH A FEW HUNDREDTHS AT BEST.


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

LATEST WV/IR IMAGERY SHOWS AN UPR RIDGE SITUATED OFFSHORE BETWEEN
130W AND 140W. THIS IS SANDWICHED BETWEEN A SLOW MOVING DOWNSTREAM
UPR TROF CENTERED NEAR THE 4-CORNERS REGION...WHILE UPSTREAM AN UPR
LOW IS SPINNING NORTH OF THE HAWAIIAN ISLANDS. ALSO...A S/WV TROF IS
RIDING UP AND OVER THE UPR RIDGE FROM NEAR THE ALEUTIAN ISLANDS
TOWARD THE GULF OF ALASKA. THIS SYSTEM WILL IMPACT THE REGION ON
SUNDAY. UNTIL THEN...LOOK FOR MAINLY DRY CONDITIONS WITH COOL
NORTHERLY FLOW OVER THE REGION. ACCORDING TO THE 26/12Z RAOBS ACROSS
THE AREA...PW VALUES RANGE FROM 0.13-INCH AT KLKN TO 0.36-INCH AT
KMFR. THE ENTIRE AREA IS CURRENTLY SITTING BELOW SEASONAL NORMALS
WHEN IT COMES TO AVAILABLE MOISTURE...GENERALLY 50- TO 80-PERCENT OF
AVERAGE.

OVERALL...THE MODELS ARE IN REASONABLE AGREEMENT WITH THE FIRST S/WV
TROF DIVING INTO THE REGION FROM THE NORTH ON SUNDAY. PRECIP WILL BE
LIGHT AND LIMITED TO AREAS NEAR THE CA/ORE BORDER AND FAR NORTHERN
NEV. THERE APPEARS TO BE A SLIGHT UPTICK IN AVAILABLE MOISTURE WITH
THIS FEATURE...BUT NOT A LOT GIVEN ITS ORIGIN FROM THE NORTH. AS A
RESULT...PRECIP AMOUNTS ARE NOT OVERLY IMPRESSIVE WITH 0.25-INCH OR
LESS WITH AN EMPHASIS ON LESS.

THE OVERALL PATTERN BECOMES A BIT MOTTLED INTO NEXT WEEK WITH THE
ARRIVAL OF A STRONGER SYSTEM FROM THE NORTH THAT WILL ALSO LACK ANY
SIGNIFICANT MOISTURE. IN FACT...THIS SYSTEM LOOKS TO HAVE AN ORIGIN
WITH A LONGER TRAJECTORY OVER WESTERN CANADA THAN THE FIRST...AND
REALLY DOESN/T INJECT ANY PACIFIC MOISTURE AS IT DROPS NORTH THROUGH
THE PACNW TOWARD CA AND NEV.

A VERY GENERAL IDEA OF THIS COLD SYSTEM DROPPING INTO THE AREA FROM
THE NORTH LOOKS TO BE A GOOD BET WITH ALL THE MODELS INDICATING THIS
OCCURRING NEXT WEEK...BUT THE DETAILS ARE NOTHING CLOSE TO SIMILAR
AT THIS POINT. DIFFERENCES AMONGST THE MODELS AND EVEN RUN-TO-RUN
INFIGHTING IS VERY APPARENT. THE GFS HAS TRENDED TO THE EAST AND
FASTER...WHILE THE EC HAS GONE THE OPPOSITE DIRECTION WITH A FARTHER
WEST AND SLOWER SOLUTION. A FARTHER WEST SOLUTION EVENTUALLY DRAWS
IN MORE MOISTURE FOR PRECIP ACROSS THE SOUTHERN HALF OF THE
REGION...WHILE THE GFS SOLUTION KEEPS PRECIP VERY SCATTERED AND
LIGHT. THE GEM...WHICH WAS RATHER FAR TO THE EAST WITH ITS 25/12Z
RUN IS NOW TO THE WEST (CLOSER TO THE EC)...AND SLOWER. IT IS
INTERESTING TO NOTE THAT THE 26/00Z GEFS IS SOMEWHERE INBETWEEN THE
OPERATIONAL GFS AND EC (SIMILAR TO THE NAEFS)...WHILE THE 26/00Z
ECENS IS FAIRLY CLOSE TO ITS OPERATIONAL RUN. WHAT THIS ALL
SAYS...RATHER LOW CONFIDENCE WITH THE TRACK AND TIMING OF THIS
INCOMING SYSTEM NEXT WEEK. FEEL SLOWER AND JUST A TAD TO THE WEST IS
THE WAY TO GO RIGHT NOW...SO LEANED MORE TOWARD THE EC SOLUTION BUT
WITH LOW CONFIDENCE. MOST LIKELY THINGS WILL CHANGE AS THE 26/12Z
MODELS GET RUN.


.HYDROLOGICAL CONDITIONS...

WITH COOLER AND DRIER WEATHER EXPECTED MOST AREA RIVERS ARE RECEDING
AND ARE EXPECTED TO CONTINUE TO RECEDE THROUGH THE COMING WEEK.

ALL RIVERS ARE FORECAST TO STAY WELL BELOW MONITOR STAGES THROUGH
THE NEXT FIVE DAYS.


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

DRK/PF

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