Snow Advisory 7, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
250 PM PST SAT DEC 17 2005

.DISCUSSION...THE FIRST IN A SERIES OF LOW PRESSURE SYSTEMS WAS VERY
WEAK AS IT MOVED INLAND TODAY. IT HAS DONE LITTLE EXCEPT INCREASE
HIGH CLOUDS WITH A FEW MOUNTAIN FLURRIES.  THE NEXT LOW IS NEAR 37N
132W AND MUCH STRONGER. IT WILL MOVE NORTHEAST AND MOVE INTO
NORTHERN CALIFORNIA ON SUNDAY. SNOW WILL DEVELOP IN THE VICINITY OF
MOUNT SHASTA TONIGHT WITH HEAVY SNOW...ACCUMULATIONS OF 6 TO 12
INCHES DURING THE DAY ON SUNDAY. UP TO 6 INCHES IS POSSIBLE
ELSEWHERE IN THE MOUNTAINS ACROSS OUR REGION WITH UP TO 3 INCHES IN
THE EAST SIDE VALLEYS. THE SNOW LEVEL WILL START AT VALLEY FLOORS
AND RISE TO 4500 TO 5000 FEET IN THE AFTERNOON WITH WARMER AIR
ADVECTED. PRECIPITATION RATES SHOULD BE HEAVIEST IN THE AFTERNOON.
MEANTIME...SOUTHERLY FLOW WILL BE DOWNSLOPE INTO MUCH OF THE
SHASTA...ROGUE AND UMPQUA VALLEYS WITH ONLY LIGHT AFTERNOON RAIN
LIKELY. IT WILL BE WINDY AT THE COAST AND IN THE SHASTA VALLEY AND
AT RIDGE TOPS WITH SOUTH WINDS OF 25 TO 40 MPH.

PRECIPIATION WILL DIMINISH IN INTENSITY AND COVERAGE SUNDAY NIGHT
BUT LIGHT PRECIPITATION WILL CONTINUE NEAR MOUNT SHASTA THROUGH THE
NIGHT WITH AN ADDITIONAL FEW INCHES OF SNOW POSSIBLE.

MODELS ARE COMING INTO CLOSER AGREEMENT WITH A FASTER AND STRONGER
SOLUTION FOR THE THIRD TROUGH. IT IS FORECAST TO ALSO MOVE NORTHEAST
AND LIKELY DELIVER ANOTHER ROUND OF RAIN AND SNOW MONDAY THROUGH
MONDAY...AGAIN HEAVIEST IN NORTHERN CALIFORNIA.

ANOTHER TROUGH WILL MOVE INTO THE OREGON OFFSHORE WATERS TUESDAY
WHILE A SHORTWAVE PROVIDES A SLIGHT CHANCE TO CHANCE OF LIGHT RAIN
AND MOUNTAIN SNOW. THE PERSISTENT SOUTHERLY FLOW WILL RAISE SNOW
LEVELS ABOVE PASS LEVELS.

LONG TERM...CONFIDENCE IS LOW ON THE DETAILS OF THE LONG TERM.
MODELS HAVE BEEN FLIP FLOPPING ON THE STRENGTH OF THE OFFSHORE LOW
WITH THE LATEST GFS RUN MUCH STRONGER THAN PREVIOUSLY INDICATED. BUT
THE LOW IS LIKELY TO CONTINUE THE ACTIVE PATTERN AS IT ARRIVES
WEDNESDAY INTO THURSDAY. RIDGING BEHIND THE TROUGH WITH LIGHT
OVERRUNNING PRECIPITATION...MAINLY ON THE WEST SIDE FRIDAY INTO
SATURDAY FOLLOWED BY ANOTHER SYSTEM OFFSHORE SATURDAY NIGHT.

&&

.AVIATION..VFR CONDITIONS UNDER HIGH LEVEL CLOUDINESS THIS EVENING.
A STRONG STORM WILL MOVE INTO NORTHERN CALIFORNIA LATE TONIGHT
THROUGH SUNDAY WITH MOUNTAINS OBSCURED AND STRONG SOUTHERLY WINDS.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...GALE WARNING FLORENCE TO CA BORDER 0-60 NM.
     SNOW ADVISORY 6AM TO 4PM SUNDAY ZONE 30.
CA...GALE WARNING OR BORDER TO PT ST GEORGE 0-60 NM.
     WINTER STORM WARNING 6AM TO 4PM SUNDAY ZONE 82>83.
     SNOW ADVISORY 6AM TO 4 PM SUNDAY ZONE 80,85.
&&

DW
ALSO VISIT THE NWS ON THE WEB AT WWW.WEATHER.GOV/MEDFORD

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
1221 PM PST SAT DEC 17 2005

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1219 PM     SNOW             6 SSW DUNSMUIR          41.15N 122.32W
12/17/2005  0.0 INCH         SHASTA             CA   TRAINED SPOTTER

            VERY LIGHT SNOW - 31 DEGREES AT 2020 Z

&&

SPENCER