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
000
AGUS76 KRSA 261609
HMDRSA

HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
930 AM PST THU FEB 26 2015

...LIGHT TO MODERATE RAIN/SNOW EXPECTED OVER CA/NV TODAY THROUGH
EARLY SUNDAY...
...SECOND WAVE TO AFFECT THE REGION MONDAY AND TUESDAY...

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

THE REGION REMAINED UNDER NW FLOW ALOFT WITH A RIDGE OFF THE COAST
AND A TROUGH OVER THE ERN U.S.  AN UPPER JET MOVED INTO THE REGION
FROM THE NORTH LATE IN THE PERIOD, BRINGING LIGHT PRECIP TO EXTREME
NE NV, BUT ONLY TRACE AMOUNTS WERE NOTED WITHIN THE CNRFC FORECAST
AREA.


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

SATELLITE THIS MORNING SHOWS A WEAK S/WV MOVING THROUGH NORTHEASTERN
NEVADA...WHICH HAS BROUGHT SOME LIGHT SHOWERS TO AREAS N OF I-80 SO
FAR. WITH PRECIPITABLE WATER A MERE THIRD OF AN INCH AS MEASURED BY
THE KLKN 12Z SOUNDING THIS AM...DO NOT EXPECT MUCH QPF TO ACCUMULATE
TODAY...BUT UP TO A QUARTER OF AN INCH IS POSSIBLE OVER FAVORED
AREAS OF THE RUBY MTNS.

THE NEXT SYSTEM BEGINS TO MOVE INTO THE NORTH COAST THIS EVENING AS
THE UPPER JET NOSES INTO SOUTHERN OREGON AND NRN CA. THIS WILL
DIRECT A 1" MOISTURE PLUME AT NORTHERN CA STARTING THIS
EVENING...AND MOIST NORTHWESTERLY FLOW WILL BRING THE FIRST BURST OF
SHOWERS TO THE REGION. OVERNIGHT INTO FRIDAY...AN UPPER LOW IS
EXPECTED TO DROP OUT OF THE PACIFIC NORTHWEST...THOUGH WILL TAKE
MORE OF AN INSIDE TRACK SOUTHWARD. THIS SYSTEM SHOULD DOMINATE THE
PATTERN THROUGH THE WEEKEND. AS THE CENTER OF THE UPPER LOW MOVES
THROUGH OREGON FRIDAY AFTERNOON...PRECIP IS EXPECTED TO MOVE INTO
NORTHERN CA AND NEVADA...AND POSSIBLY INTO THE NORTHERN SIERRA.
FAIRLY MOISTURE-STARVED FROM THE PLUME OUTRUNNING IT...THIS SYSTEM
IS NOT EXPECTED TO PRODUCE MORE THAN LIGHT TO OCCASIONALLY MODERATE
SHOWERS.

BY SATURDAY MORNING...THE UPPER LOW SHOULD BE CENTERED OVER NORTHERN
CA...AND SCATTERED PRECIP ACTIVITY IS EXPECTED ACROSS MUCH OF THE
REGION. SOUTHERN CA SHOULD START TO SEE PRECIP INCREASE THROUGH THE
DAY AS MOIST ONSHORE FLOW AROUND THE LOW MOVES THROUGH. WITH THE LOW
OVERHEAD AND MOVING THROUGH NRN AND CENTRAL CA DURING THE DAY...
PRECIP ACTIVITY IS EXPECTED TO REMAIN SHOWERY WITH A CHANCE OF SOME
TSTM DEVELOPMENT AS WELL. THE MOST ORGANIZED AREA OF PRECIP WILL
REMAIN OVER SRN CA WITH THAT MOIST ONSHORE FLOW...AS WELL AS OVER
THE CENTRAL AND SOUTHERN SIERRA ESPECIALLY DURING THE AFTERNOON AND
EARLY EVENING HOURS. PRECIP WILL CONTINUE BUT BEGIN TO WIND DOWN
OVERNIGHT SAT INTO EARLY SUNDAY AS THE UPPER LOW CONTINUES TO MOVE
SOUTH THROUGH THE STATE AND THE BEST FORCING MOVES OUT OF THE
REGION.

THIS SYSTEM IS EXPECTED TO BE A BIT COLDER THAN THE ONE THAT MOVED
THROUGH IN EARLY FEB. AS SUCH...FREEZING LEVELS ARE EXPECTED TO
START OUT AROUND 6000-7000 FT TONIGHT INTO EARLY FRIDAY...THEN
QUICKLY LOWER TO AROUND 5000-FT LATER FRIDAY AND SATURDAY AS THE
UPPER LOW IS OVERHEAD. THIS COLDER TEMPS SHOULD BRING SNOW TO PASS
LEVELS AND BELOW OVER MUCH OF THE SIERRA FRIDAY THROUGH SUNDAY.


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

AN UPPER LOW OVER CNTRL CA/NV SUN MORNING IS EXPECTED TO WEAKEN AND
MOVE EAST BY MON MORNING.  EXPECT LIGHT SHOWERS DURING THIS PERIOD
OVER PORTIONS OF CNTRL/SRN CA/NV.  THIS SYSTEM IS EXPECTED TO BE
QUICKLY FOLLOWED BY ANOTHER SYSTEM DROPPING IN FROM THE NORTH MON,
BRINGING AN ADDITIONAL ROUND OF LIGHT PRECIPITATION TO MUCH OF THE
REGION INTO TUE.  FOR THE MOST PART, GENERALLY FOLLOWED A BLEND OF
THE FASTER 00 UTC ECMWF AND SOMEWHAT SLOWER 06 UTC GFS.  EXPECT
FREEZING LEVELS GENERALLY AROUND 5000-6000 FT, EXCEPT LOWERING TO
3000-4000 FT TUE AND EVENTUALLY 2000 FT OR LESS TUE NIGHT OVER SRN
OREGON, NERN CA AND NRN SIERRA, AND NRN/CNTRL NV.


.HYDROLOGICAL CONDITIONS...

OTHER THAN SOME VERY SMALL RISES OVER THE WEEKEND LITTLE CHANGE IN
RIVER CONDITIONS ACROSS CALIFORNIA AND NEVADA IS EXPECTED THROUGH
MID WEEK NEXT WEEK.

ALL STAGES ARE EXPECTED TO REMAIN WELL BELOW MONITOR LEVELS FOR THE
NEXT 5 DAYS.


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

KL/JM/KL/AM

$$



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