026 
FXUS66 KSTO 191640
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
940 AM PDT TUE MAR 19 2013

.SHORT TERM DISCUSSION...

NO MAJOR UPDATES THIS MORNING. THE CENTER OF THE LOW PRESSURE
STORM IS OFFSHORE NEAR 40N 138W AND IS TAPPING INTO A MOISTURE
PLUME TO THE SOUTH. A SW-NE ORIENTED MOISTURE PLUME STARTING NEAR THE
HAWAIIAN ISLANDS EXTENDS NORTHEASTWARD TO ABOUT 40N 130W AND IS
MEASURING AN INCH TO JUST OVER AN INCH AND A HALF OF PRECIPITABLE
WATER. THOUGH LIGHT PRECIPITATION COULD BEGIN LATER TODAY...THE
HEAVIEST PRECIPITATION WILL IMPACT OUR ENTIRE CWA TONIGHT THROUGH
WEDNESDAY MORNING WITH THE MAIN FRONTAL BAND. SHOWERS WILL
CONTINUE WEDNESDAY AFTERNOON INTO EVENING. RAIN SHOULD DIMINISH IN
THE VALLEY WHILE MOST OF THE LINGERING PRECIPITATION WILL BE ACROSS
HIGHER TERRAIN.

HAVE TAKEN A LOOK AT THE LATEST CNRFC FORECAST FOR AMOUNTS OF
RAIN/SNOW AND GENERAL ESTIMATES DON'T APPEAR TO HAVE CHANGED MUCH.
RAIN ACROSS THE VALLEY SHOULD VARY 0.15" UP TO 0.75" FROM THE
NORTHERN SAN JOAQUIN VALLEY UP TO THE FAR NORTHERN SACRAMENTO
VALLEY, RESPECTIVELY. HOWEVER...IT LOOKS LIKE MOST VALLEY SITES
WILL BE IN THE 0.25-0.5" RANGE.

SNOW LEVELS INITIALLY STARTING OUT HIGH TODAY...ABOVE 7000 FEET
AND WILL LOWER DOWN TO AROUND 6000 FEET ON WEDNESDAY. SNOW
ACCUMULATION AMOUNTS STILL ESTIMATED TO BE 3 TO 6 INCHES NEAR
SIERRA PASS LEVELS WHILE AREAS ABOVE 8000 FEET ALONG THE SIERRA
COULD PEAK AROUND 8-10 INCHES OR MORE FOR SNOW ACCUMULATION.

NORTHERLY WINDS WILL DEVELOP BEHIND THE SYSTEM FOR THURSDAY AND
FRIDAY. VALLEY WILL HAVE BREEZY CONDITIONS ON FRIDAY WITH
SUSTAINED WINDS UP TO 20 MPH WITH GUSTS AROUND 25 MPH.  JBB

&&

.EXTENDED DISCUSSION (SATURDAY THROUGH TUESDAY)

WITH ALL MODELS SHOWING VARIOUS FORMS OF UPPER LEVEL RIDGING OVER
THE WEST COAST GOING INTO THE WEEKEND...HAVE REMOVED ANY PRECIP
THREAT FROM THE THE ENTIRE CWA SATURDAY. FAIR AND DRY CONDITIONS
ARE EXPECTED SATURDAY WITH MAINLY LIGHT NORTHERLY WINDS AND
DAYTIME HIGHS EXPECTED TO COME IN A FEW TO UP TO 10 DEGREES ABOVE
NORMAL. LATEST ECMWF DROPS AN INSIDE SLIDER TYPE SHORTWAVE ACROSS
FAR NORTHERN CALIFORNIA ON SUNDAY. THIS WAS A CHANGE FROM PREVIOUS
RUNS WHICH KEPT A RIDGE FIRMLY IMPLANTED OVER THE WEST COAST. GEM
HAS HINT OF THIS SHORTWAVE WHILE GFS HAS BEEN MORE CONSISTENT
WITH THE RIDGE SCENARIO. FOR NOW...HAVE KEPT SECOND HALF OF
WEEKEND DRY GOING WITH MORE CONSISTENT GFS. MONDAY STAYS DRY UNDER
THE UPPER RIDGE BUT NEED TO KEEP AN EYE ON SUBSEQUENT ECMWF RUNS
WHICH MAY KEEP TROUGHING OVER THE ROCKIES AND BRING A THREAT OF
MINOR SIERRA SHOWERS. MODEL TO MODEL CONSISTENCY REMAIN POOR ON
TUESDAY WITH GFS AND GEM BRINGING A PACIFIC TROUGH AND A THREAT OF
PRECIP INTO THE COAST NEXT TUESDAY WHILE ECMWF BRINGS AN UPPER
RIDGE AXIS RIGHT OVER THE WEST COAST FOR A DRIER SOLUTION. FOR NOW
HAVE STAYED WITH THE GFS/GEM SOLUTIONS DUE TO BETTER RUN TO RUN
AGREEMENT BUT CONFIDENCE IN MUCH OF EXTENDED IS NOT HIGH DUE TO
SIGNIFICANT MODEL DIFFERENCES.


&&

.AVIATION...

GENERALLY VFR CONDITIONS TODAY OVER INTERIOR NORCAL TODAY
FOLLOWED BY OVERNIGHT LOCAL MVFR IN THE CENTRAL VALLEY AND IFR IN
THE MOUNTAINS AS A LOW PRESSURE SYSTEM MOVES THROUGH. CEILINGS
WILL BECOME OVERCAST AND LOWER THIS AFTERNOON AS THE SYSTEM
APPROACHES. LIGHT RAIN WITH LOCAL MVFR CIGS/VSBYS SHOULD REACH
THE KRDD-KRBL AREA BY 00Z...SLOWLY SPREADING SOUTHEASTWARD
OVERNIGHT AND REACHING THE SAC METRO AREA AROUND 6-9Z.

OVER THE SIERRA...EXPECT IFR CIGS/VSBYS IN RAIN AND SNOW AFTER
ABOUT 00Z WITH SNOW LEVELS MOSTLY ABOVE 6500 FEET. SOUTHERLY
WINDS 10 TO 15 KNOTS IN THE VALLEY...WITH 20-30G45 KTS OVER
SIERRA RIDGES TONIGHT. -DVC

&&

.STO WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$