Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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AGUS76 KRSA 151630
HMDRSA

HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
930 AM PDT TUE APR 15 2014

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  PLEASE NOTE...THIS WILL REPRESENT THE LAST HYDROMETEOROLOGICAL
  DISCUSSION FOR THE 2013-2014 WINTER OPERATIONS SEASON.  IF
  CONDITIONS WARRANT...A SPECIAL ISSUANCE OF THIS PRODUCT MAY OCCUR
  DURING THE DRY SEASON.  THE NEXT SCHEDULED ISSUANCE OF THIS
  PRODUCT WILL TAKE PLACE ON OCTOBER 15 2014 WHEN THE 2014-2015
  WINTER OPERATIONS SEASON BEGINS.

********************************************************************


...LIGHT SHOWERS EXPECTED OVER NORTHERN AREAS THURS NIGHT AND FRI...

.24 HOUR PRECIPITATION TOTALS (ENDING APR 15 AT 500 AM PDT)...

WEAK RIDGING OVER THE AREA PROVIDED DRY CONDITIONS THROUGH THE
PERIOD.


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

BENIGN PATTERN OVER THE AREA TODAY WITH THE REGION SANDWICHED
BETWEEN A DEEP TROUGH SITUATED OVER THE EAST COAST AND A BUILDING
RIDGE OVER THE EASTERN PACIFIC. THE RIDGE IS EXPECTED TO BUILD OVER
THE WEST COAST TODAY AND TOMORROW BEFORE BEING EDGED OUT BY A UPPER
TROUGH DROPPING IN FROM THE PACIFIC NORTHWEST.

WHILE NOT PARTICULARLY STRONG...THIS UPPER TROUGH DOES DRAW FROM A
DECENT MOISTURE PLUME...PULLING AROUND 0.8" PWAT TOWARDS THE
NORTHERN CA COAST AS IT APPROACHES THURSDAY AFTERNOON. THE 06Z GFS
BRINGS IN THE STRONGEST WAVE OF PRECIP TO THE NORTH COAST...UPPER
KLAMATH...AND NE CA PLATEAU THURS NIGHT INTO EARLY FRIDAY...THOUGH
THE LATEST NAM-WRF AND EC RUNS ARE NOT TO FAR OUT OF LINE EITHER.
PRETTY GOOD CONFIDENCE IN A QUICK SHOT OF LIGHT TO LOCALLY MODERATE
PRECIP DURING THE END OF THE SHORT TERM.


.METEOROLOGICAL CONDITIONS (LONG TERM: FRI AM - MON AM)...

TIMING DIFFERENCES PLAGUE THE EARLY PORTION OF THE EXTENDED-RANGE
FORECAST ON FRI REGARDING THE TIMING OF A TROUGH PASSAGE MOVING
ACROSS NRN CA/SRN OREGON AND THEN WEAKENING AS IT MOVES ACROSS NV.
AS FAR AS MODEL PREFERENCE IS CONCERNED, THE ECMWF WAS A BIT SLOWER
AND STRONGER WITH THE WAVE COMPARED TO ITS PREVIOUS RUN AND THE GEM
WAS A BIT FASTER.  THE 06 UTC GFS WAS MORE CONSISTENT WITH ITS
PREVIOUS RUN THAN OTHER GUIDANCE AND WAS A GOOD COMPROMISE BETWEEN
THE FASTER GEM AND SLOWER ECMWF SOLNS.

EXPECT A BAND OF SHOWERS TO PUSH ACROSS NRN NV AND TRAILING DOWN
INTO THE HIGHER TERRAIN OF THE SIERRA ON FRI NEAR AND AHEAD OF THE
TROUGH AXIS.  A WEAK DISTURBANCE IS FORECAST TO MOVE INTO SRN CA
AROUND THE SAME TIME, BUT LITTLE IN THE WAY OF PRECIPITATION IS
EXPECTED.  BY FRI EVENING AND OVERNIGHT, PRECIP SHOULD PUSH INTO
CNTRL AND THEN ERN NV ASSOCIATED WITH THE MOVEMENT OF THE TROUGH
AXIS.  FREEZING LEVELS 9000 FT AND ABOVE ARE EXPECTED.

EXPECT ENOUGH LEFTOVER MOISTURE/INSTABILITY FOR SOME CONVECTIVE
SHOWERS TO FORM OVER THE SIERRA AND PARTS OF CNTRL NV FOR SAT
AFTERNOON AND EVENING.  BY SUN, MODELS DIVERGE EVEN MORE, WITH THE
GFS SHOWING A TROUGH OVER THE REGION AND THE ECMWF AND GEM
DEVELOPING A RIDGE.  HAVE SIDED WITH THE BETTER AGREEMENT IN THE
RIDGE SOLN, AND HAVE LEFT THE FORECAST MAINLY DRY FOR SUN EXCEPT FOR
MAYBE A STRAY SHOWER IN THE HIGHER TERRAIN OF THE SIERRA.


.HYDROLOGICAL CONDITIONS...

LIGHT PRECIPITATION FORECAST FOR DAY 3 AND DAY 4 IS EXPECTED TO HAVE
LITLE EFFECT ON BASIN INFLOWS AND RIVER STAGE RISE FOR AFFECTED
WATERSHEDS IN NRN CA...THE UPPER KLAMATH BASIN AND NRN NV.  FLOWS
IN THE RIVERS WILL REMAIN LOW GIVEN THE MUCH BELOW NORMAL SNOWPACKS
AND/OR DRY SOIL CONDITIONS.  ALL RIVERS AND STREAMS ARE CURRENTLY
BELOW...AND ARE EXPECTED TO REMAIN BELOW MONITOR LEVELS FOR THE NEXT
SEVERAL DAYS.


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

KL/JM/KL/AT

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