Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10
000
AGUS76 KRSA 231614
HMDRSA

DDHHMM
WRKHMD

HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
930 AM PDT THU OCT 23 2014

...PRECIP TO CONTINUE TODAY OVER NORTHERN CA...
...SHORT BREAK IN PRECIP ON FRIDAY BEFORE THE NEXT SYSTEM ARRIVES
SATURDAY MORNING...

.24 HOUR PRECIPITATION TOTALS (ENDING OCT 23 AT 500 AM PDT)...

A SLOW-MOVING COLD FRONT HAS SPREAD PRECIPITATION ACROSS PORTIONS OF
NRN CA AND SRN OREGON.  PRECIP AMOUNTS HAVE BEEN MAINLY LIGHT, BUT
HAVE GRADUALLY INCREASED TO BE MORE MODERATE OVER PORTIONS OF THE
NORTH COAST AND AROUND THE SHASTA DRAINAGE.  TOTALS WERE AROUND 0.9-
1.8" AND LOCALLY OVER 2" IN THE SMITH BASIN WITH AMOUNTS AROUND 0.5-
1.5" IN THE LOWER KLAMATH AND MAD RIVER BASINS.  TOTALS WERE 0.1-
0.4" IN THE EEL BASIN WITH MUCH HIGHER TOTALS OF 1.2-2.4" IN THE
KING RANGE NEAR CAPE MENDOCINO.  MOVING INLAND, TOTALS WERE 0.1" OR
LESS IN THE FAR NRN SACRAMENTO VALLEY AND 0.2-0.7" AND LOCALLY
HIGHER IN THE SHASTA DRAINAGE AND NEAR TRINITY LAKE.  UPPER KLAMATH
LOCATIONS RECEIVED AROUND 0.25" OR LESS EXCEPT LOCALLY UP TO 0.6" IN
THE SRN OREGON CASCADES.  NE CA AND EXTREME NW NV PICKED UP
GENERALLY 0.2" OR LESS, LOCALLY UP TO 0.4"


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

SATELLITE THIS MORNING SHOWS A STRONG UPPER LOW IN THE GULF OF
ALASKA WITH AN ASSOCIATED FRONTAL SYSTEM PUSHING THROUGH THE PACIFIC
NORTHWEST. THE SOUTHERN EDGE OF THE FRONT IS INTERACTING WITH A WELL
ORGANIZED MOISTURE PLUME AIMED AT THE NORTHERN CA COAST...WITH PWAT
AMOUNTS AROUND 1.3" BUTTING UP TO HUMBOLDT COUNTY. HEAVIEST PRECIP
IS CURRENTLY FALLING ALONG THE COAST FROM DEL NORTE SOUTH TO
MENDOCINO COUNTY...AND INLAND INTO THE TRINITY MTNS...UPPER
KLAMATH...AND SHASTA DRAINAGE. FAVORABLE UPSLOPE FLOW IS ALSO
BRINGING LOCALLY HEAVY PRECIP TO ELEVATED TERRAIN AROUND CAPE
MENDOCINO.

EXPECT PRECIP TO CONTINUE MOVING INLAND THROUGH THE MORNING HOURS...
AS WELL AS SAGGING A WEAKENING SOUTHERN EDGE INTO SONOMA AND MARIN
COUNTIES. WHILE THE STRONG UPPER JET SHOULD KEEP LIGHT TO MODERATE
PRECIP ACTIVITY GOING THROUGH THE LATE NIGHT HOURS OVER THE NORTHERN
THIRD OF THE STATE...EXPECT CONDITIONS TO DRY OUT ELSEWHERE. ON
FRIDAY...PRECIP WILL BE DRAWN NORTHWARD AS THE UPPER LOW DIVES SOUTH
AND THE JET TAKES A MORE S-N TRAJECTORY...MORE PARALLEL TO THE CA
COAST. THIS WILL PROVIDE A BRIEF BREAK FROM PRECIP UNTIL THE FRONTAL
SYSTEM AHEAD OF THE STRONG UPPER LOW MARCHES INLAND ON SATURDAY
MORNING.

FREEZING LEVELS WILL REMAIN RATHER HIGH DURING THE NEXT TWO DAYS...
FALLING AS LOW AS 7500-FT ON THE NORTH COAST TODAY...BUT GENERALLY
REMAINING AT OR ABOVE 9000-FT. AS A RESULT...THE MAJORITY OF WHAT
FALLS TODAY WILL REMAIN AS RAIN RATHER THAN SNOW.


.METEOROLOGICAL CONDITIONS (LONG TERM: SAT AM - WED AM)...

BY SAT MORNING, AN UPPER LOW IS FORECAST TO APPROACH THE OREGON
COAST FROM THE SW, WITH A COLD FRONT MOVING ACROSS NRN CA/SRN OREGON
AND A 120 KT+ JET ACROSS THE NORTH COAST.  MAINLY LIGHT PRECIP
SHOULD BE ONGOING ACROSS MUCH OF NRN CA/SRN OREGON BY THIS TIME.

A SECONDARY FRONT AND SHORTWAVE ARE EXPECTED TO MOVE ONTO THE NORTH
COAST BY SAT AFTERNOON.  THIS SHOULD BRING AN UPTICK IN PRECIP RATES
ON THE NORTH COAST FOR SAT AFTERNOON AND EVENING, WHILE PRECIP PICKS
UP A BIT IN THE NRN SIERRA AS WELL THANKS TO A SEMI-MOIST UPSLOPE
FLOW AND THE PASSAGE OF THE INITIAL SHORTWAVE.  SAT NIGHT, THE
TROUGH AXIS SHOULD MOVE ACROSS NRN CA, WITH PRECIP BEGINNING TO WIND
DOWN NEAR THE COAST WHILE PICKING UP A BIT IN THE NRN SIERRA AND
SPREADING INTO NRN NV.  PRECIP FINALLY WINDS DOWN ON SUN AS THE
TROUGH PUSHES EAST.  FREEZING LEVELS ARE FORECAST TO START OFF
AROUND 8500 FT OR ABOVE EARLY SAT AND LOWER TO 6000-7000 IN THE FAR
NORTH AND 7500-8500 FT IN THE NRN SIERRA FOLLOWING FRONTAL PASSAGE.

BRIEF RIDGING SHOULD BRING DRY CONDITIONS TO THE REGION ON MON.
MODELS INDICATE THE NEXT SYSTEM WILL BRING LIGHT PRECIP TO NW CA/SRN
OREGON/NRN NV MON EVENING THROUGH TUE NIGHT, WITH THE BULK OF THE
PRECIP STAYING NORTH OF THE CNRFC FORECAST AREA.  FREEZING LEVELS
ARE EXPECTED TO REMAIN AROUND 8500 FT OR ABOVE.


.HYDROLOGICAL CONDITIONS...

PRECIPITATION OVER NORTWEST CALIFORNIA FOR THE PAST 24 HOURS IS
PRODUCING MINOR RISES IN STAGE ON MANY AREA RIVERS.  NORTHWEST
CALIFORNIA RIVERS AND STREAMS ARE FORECAST TO FLUCTUATE NEAR CURRENT
LEVELS FROM PRECIPITATION FORECAST FOR THE NEXT 72 HOURS.

ALL RIVERS AND STREAMS IN THE CNRFC FORECAST AREA ARE CURRENTLY
BELOW...AND ARE FORECAST TO REMAIN BELOW MONITOR LEVELS THROUGH
MONDAY.

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

KL/JM/KL/SS

$$



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.