Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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AGUS76 KRSA 281621
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HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
820 AM PST SUN DEC 28 2014

...LIGHT PRECIP FAR NORTH TODAY...
...COLDER SYSTEM DROPS TOWARD THE REGION LATER MONDAY...

.24 HOUR PRECIPITATION TOTALS (ENDING DEC 28 AT 400 AM PST)...

A S/WV TROF MOVING FROM THE PACNW TOWARD THE NORTHERN/CENTRAL
ROCKIES...ALONG WITH A COLD FRONT MOVING THROUGH THE UPPER KLAMATH
AND FAR NORTHERN NEV BROUGHT LIGHT PRECIP TO THESE AREAS. AMOUNTS
WERE GENERALLY NEAR 0.10-INCH OR LESS WITH A FEW WETTER AREAS
REACHING 0.25-INCH.


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

S/WV TROF MOVING TOWARD THE NORTHERN/CENTRAL ROCKIES THIS
MORNING...WHILE THE ASSOCIATED COLD FRONT IS HUNG UP ALONG THE
CA/ORE BORDER INLAND TO FAR NORTHERN NEV. THERE HAS BEEN A SLIGHT
UPTICK IN AVAILABLE MOISTURE AHEAD OF THE FRONTAL BOUNDARY WITH PW
VALUES ALONG THE COAST JUST ABOVE 0.50-INCH AND INLAND CLOSER TO
0.33-INCH...ACCORDING TO LATEST BLENDED TPW IMAGERY. SOME LIGHT
PRECIP IS FALLING IN THE VICINITY OF THE COLD FRONT...BUT AMOUNTS
ARE LIGHT WITH GAGES INDICATING APPROX 0.10-INCH OR LESS SINCE
28/12Z.

THE COLD FRONT WILL BECOME FAIRLY STATIONARY OVER THE NEXT 24 HOURS
WITH LIGHT PRECIP CONTINUING FOR THE FAR NORTHERN TIER OF THE
REGION. WILL HAVE TO WAIT UNTIL THE STRONGER SYSTEM FROM THE NORTH
ARRIVES LATER MONDAY TO PUSH THE BOUNDARY SOUTHWARD. THE NEXT S/WV
TROF IS CURRENTLY DROPPING SOUTH THROUGH WESTERN CANADA AND IS NOW
SHIFTING ACROSS NORTHERN BC. GIVEN ITS CONTINENTAL POLAR
AIRMASS...THERE IS VERY LITTLE IN THE WAY OF MOISTURE AVAILABLE FOR
THIS SYSTEM.

MODELS HAVE IMPROVED WITH THEIR TRAJECTORY FOR THIS SYSTEM AS IT
CONTINUES TO MOVE SOUTH ACROSS CA AND NEV BEFORE SWINGING TO THE
EAST TOWARD ARIZ. TIMING IS STILL A BIT IN QUESTION AS THE 28/00Z EC
IS JUST A TAD BIT SLOWER THAN THE 28/00Z AND 28/06Z GFS. THE GFS IS
APPROX 6 HOURS FASTER UNTIL THE MODELS BECOME BETTER IN SYNC ONCE
THE SYSTEM CROSSES THE LOWER COLORADO RIVER EARLY THU.

AS THE SYSTEM MOVES SOUTH ACROSS NORTHERN AND CENTRAL CA...MUCH OF
THE PRECIP WILL BE FOCUSED ON THE CASCADE/SIERRA CREST AND POINTS
EAST OVER NEV. ONCE THE CORE OF THE SYSTEM MOVES TOWARD CENTRAL
CA...IT LOOKS AS IF THERE WILL BE AN INCREASE IN MOISTURE ACROSS
SOUTHERN CA AS THE WESTERN FLOW WILL DRAW PW VALUES BETWEEN 0.33-
AND 0.50-INCH TOWARD THE COAST...AND THEN INLAND OVER THE SE CA
DESERTS AND FAR SOUTHERN NEV. MORE WIDESPREAD PRECIP WILL FALL IN
THIS AREA MAINLY ON WED AHEAD OF THE UPR LOW...BUT SINCE MOISTURE IS
NOT OVERLY IMPRESSIVE AMOUNTS WILL BE LIMITED. UPSLOPE AREAS FACING
SW AND W BETWEEN SAN BERNARDINO COUNTY SOUTH THROUGH SAN DIEGO
COUNTY WILL SEE THE BEST AMOUNTS.

AS THIS SYSTEM EXITS EARLY THU ACROSS ARIZ...LOOK FOR DRY NORTHERLY
FLOW TO ONCE AGAIN DOMINATE THE AREA WITH AN UPR RIDGE RESIDING JUST
OFF THE COAST.


.HYDROLOGICAL CONDITIONS...

WITH COOLER AND DRIER WEATHER EXPECTED DURING THE COMING WEEK, MOST
AREA RIVERS ARE RECEDING AND ARE EXPECTED TO CONTINUE TO RECEDE.
THE ONLY EXCEPTION IS SOUTHERN CALIFORNIA WHERE SOME RIVERS MAY SEE
MINOR RISES IN FLOW TUESDAY AND WEDNESDAY WITH ANTICIPATED RAINFALL.

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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