Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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AGUS76 KRSA 191554
HMDRSA

HYDROMETEOROLOGICAL DISCUSSION NATIONAL WEATHER SERVICE / CALIFORNIA
NEVADA RFC / SACRAMENTO CA 855 AM PDT SUN OCT 19 2014

...PRECIP MOVES ACROSS THE NORTH LATE SUN THRU EARLY TUE...
...STATIONARY BAND OF PRECIP NEAR THE CA/ORE BORDER WED AND THU...

.24 HOUR PRECIPITATION TOTALS (ENDING OCT 19 AT 500 AM PDT)...

A FEW LIGHT SHOWERS LINGERED ACROSS THE NORTH COAST EARLY YESTERDAY
WITH AMOUNTS NEAR A FEW HUNDREDTHS AT BEST.


.METEOROLOGICAL CONDITIONS (SHORT TERM: SUN AM - SAT AM)...

LATEST SYNOPTIC PATTERN SHOWS AN UPR RIDGE ALIGNED OVER THE
INTERMOUNTAIN WEST NORTHWARD INTO WEST-CENTRAL CANADA. OFFSHORE AN
UPR TROF IS NOW CROSSING 140W. ALSO...A WEAK UPR LOW FROM THE
SPLITTING SYSTEM A FEW DAYS AGO STILL RESIDES JUST SOUTH OF THE
US/MEXICO BORDER...DRIFTING TO THE EAST.

THE NEXT OPPORTUNITY FOR PRECIP ACROSS THE REGION IS WITH THE
OFFSHORE UPR TROF CROSSING 140W. THE ASSOCIATED COLD FRONT IS MOVING
WITHIN 130W THIS MORNING. BLENDED TPW IMAGERY SHOWS A NARROW
MOISTURE PLUME CONVERGING AHEAD OF THE FRONTAL BOUNDARY WITH VALUES
GENERALLY IN THE RANGE OF 1.00- TO 1.25-INCHES. OVERALL TIMING OF
THE PRECIP BRINGS LIGHT PRECIP TO THE IMMEDIATE NORTH COAST FROM
CAPE MENDOCINO NORTHWARD EITHER LATE SUNDAY OR EARLY MONDAY.

PRECIP SPREADS SOUTH AND INLAND THROUGH MONDAY WITH PRECIP REACHING
SOUTH TO A SF BAY AREA TO YOSEMITE LINE. THE UPR TROF AXIS WILL
CROSS THE COAST MONDAY AFTERNOON. THERE ARE SOME SLIGHT
DISCREPANCIES AMONGST THE LATEST MODELS IN TERMS OF HOW DEEP THE
S/WV TROF WILL BE AS IT MOVES ACROSS CA. THE 19/00Z EC IS THE
SHALLOWEST...WHILE THE OTHER CAMP OF THE 19/00Z GEM...19/06Z NAM...
AND 19/06Z GFS ARE A BIT DEEPER. FOR NOW...FOLLOWED THE MAJORITY OF
THE MODELS...AND THIS RESULTS IN SLIGHTLY HIGHER TOTALS FOR THE
NORTHERN SIERRA. IF THE EC VERIFIES...PRECIP TOTALS WILL BE ON THE
LOWER END. ALSO...THE DEPTH OF THE SYSTEM WILL AFFECT PRECIP
COVERAGE AND AMOUNTS OVER THE NORTHERN PORTION OF NEVADA. THE DEEPER
SOLUTIONS DO GENERATE WIDESPREAD LIGHT PRECIP ACROSS THE NORTHERN
HALF OF THE STATE.

AFTER THIS S/WV TROF EXITS THE REGION...THE CONFIDENCE IN THE LONGER
RANGE BEGINS TO LOWER. THERE ARE DEFINITE DIFFERENCES IN HOW STRONG
THE UPR RIDGE BUILDS OVER THE 4-CORNERS REGION AND THE ALIGNMENT OF
THE NEXT UPR TROF OVER THE EASTERN PACIFIC. FOR WEDNESDAY...THE
MOISTURE PLUME WILL INTERSECT THE PACNW COAST WITH THE SOUTHERN
FRINGE AFFECTING THE UPPER KLAMATH AND FAR NW CORNER OF CA (MAINLY
THE SMITH AND LOWER KLAMATH RIVER BASINS). AS A RESULT...THE
HEAVIEST PRECIP WILL REMAIN NORTH OF THE REGION WITH LIGHTER AMOUNTS
CLIPPING THE REGION. INTO THURSDAY...THE EC NARROWS AND ERODES SOME
OF THE MOISTURE PLUME AS IT FOCUSES ON THE CA/ORE BORDER AREA. THIS
WOULD CONTINUE LIGHT PRECIP OVER THE AFOREMENTIONED AREAS.
HOWEVER...THE GFS IS MORE BULLISH IN KEEPING THE PLUME TOGETHER WITH
SOME MODERATE TO LOCALLY HEAVY PRECIP DEPICTED OVER THE NORTH COAST
FROM NEAR CAPE MENDOCINO NORTHWARD. WITH THESE DRAMATIC
DIFFERENCES...FOR NOW HAVE STUCK WITH A MORE CONSERVATIVE APPROACH
IN TERMS OF PRECIP AMOUNTS OFFERED UP BY THE EC.

AS THE WEEKEND APPROACHES...THE EC AND GFS CONTINUE THEIR
DIFFERENCES. THE EC IS STRONGER WITH THE UPR RIDGE CENTERED NEAR THE
4-CORNERS REGION WITH THE UPR TROF DEVELOPING OUT BETWEEN 140W AND
150W. THE GFS SHOWS A MORE POSITIVELY TILTED UPR RIDGE EXTENDING
FROM NW MEXICO TOWARD THE CENTRAL PLAINS AND WESTERN GREAT LAKES
STATES. AS A RESULT...THE EASTERN PACIFIC UPR TROF IS FARTHER
DOWNSTREAM (BETWEEN 130W AND 140W) WHEN COMPARED TO THE EC. FOR
NOW...FOLLOWED THE EC AGAIN...WHICH IS THE FAVORED SOLUTION AT THIS
TIME.


.HYDROLOGICAL CONDITIONS...

PRECIPITATON FROM THE WEATHER SYSTEM ARRIVING LATE TONIGHT/EARLY
TOMORROW IS EXPECTED TO PRODUCE ONLY SMALL RISES TO RIVERS AND
STREAMS IN THE NORTH COAST REGION.

ALL RIVER FORECAST POINTS ARE EXPECTED TO REMAIN BELOW MONITOR
LEVELS DURING THE NEXT SEVERAL DAYS.


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

DRK/AT

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