Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 190532
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
932 PM PST THU DEC 18 2014

.DISCUSSION...A FAST MOVING COLD FRONT WILL MOVE ACROSS OUR AREA
THROUGH EARLY FRIDAY MORNING. THE FORECAST WAS UPDATED EARLIER
THIS EVENING TO ISSUE A WIND ADVISORY FOR THE SOUTHERN PORTION OF
THE SHASTA VALLEY NEAR WEED THROUGH 1 AM. THE PEAK GUST SO FAR AT
WEED OF 46 MPH OCCURRED AT 748 PM. ALSO, ANOTHER UPDATE IS
IMMINENT TO ADD A SLIGHT CHANCE OF COASTAL THUNDERSTORMS NORTH OF
CAPE BLANCO OVERNIGHT AS WELL AS BOOST EXPECTED RAINFALL AMOUNTS
OVERNIGHT. THIS INCREASE IS MAINLY FOR THE NEXT 6 HOURS IN CURRY
COUNTY AND EASTERN DOUGLAS COUNTY AND TO A LESSER BUT STILL
NOTEWORTHY EXTENT FOR JOSEPHINE AND WESTERN SISKIYOU COUNTIES.
AMOUNTS IN THOSE AREAS WILL BE MODERATE TO HEAVY AT AROUND
TWO/THIRDS OF AN INCH TO AN INCH. AMOUNTS WILL BE LIGHT TO
MODERATE ELSEWHERE WITH THE MAJORITY OF PRECIPITATION OCCURRING
OVERNIGHT. THE SNOW LEVEL NOW AROUND 6500 TO 7000 FEET IS FORECAST
TO FALL TO AROUND 4500 FEET BY THE END OF THE NIGHT THEN BOTTOM
OUT AROUND 4000 FEET AROUND THE TIME OF THE FRIDAY MORNING
COMMUTE WITH NUMEROUS LINGERING POST FRONTAL SHOWERS AND SNOW
SHOWERS. THE SNOW LEVEL WILL REBOUND TO AROUND 5000 FEET DURING
THE DAY WITH DIMINISHING SHOWERS. SNOW AMOUNTS AT PASS LEVELS OVER
THE CASCADES, SISKIYOUS, AND THE EAST SIDE PASSES ARE LIKELY TO
AMOUNT TO AROUND 1 TO 3 INCHES DURING FRIDAY MORNING.

THE BREAK BETWEEN SYSTEMS WILL BE SHORT WITH DANGEROUS HIGH SURF
AT THE BEACHES OF SOUTHERN OREGON BUILDING TO PEAK BREAKER HEIGHTS
OF AROUND 25 FEET ON FRIDAY EVENING. SURF WILL REMAIN HIGH ON
SATURDAY. THE SNOW LEVEL IS FORECAST TO BE AROUND 4500 FEET AS
PRECIPITATION BEGINS AHEAD OF A STRONG WARM FRONT LATE FRIDAY
NIGHT INTO SATURDAY MORNING. THE SNOW LEVEL WILL RISE QUICKLY AND
SUBSTANTIALLY...TO AROUND 9000 FEET ON SATURDAY. SOUTHERLY WINDS
WILL BE GUSTY, STRONGEST AT THE COAST IN THE MORNING INTO EARLY
AFTERNOON WITH THE POSSIBILITY OF REACHING ADVISORY LEVELS NEAR
WEED AND NEAR SILVER LAKE IN THE AFTERNOON INTO EARLY EVENING.
RAIN WILL BE HEAVY IN CURRY COUNTY AND LIGHT TO MODERATE
ELSEWHERE. THE WARM FRONT WILL LIFT NORTHWARD WITH THE WIDESPREAD
PRECIPITATION OF SATURDAY AND SATURDAY NIGHT TRANSITIONING TO A
FOCUS NORTH OF HIGHWAY 140 ON SUNDAY (WHICH INCLUDES EASTERN
DOUGLAS AND NORTHERN KLAMATH COUNTY). THE SNOW LEVEL ON SUNDAY
WILL REMAIN AROUND 9000 FEET WITH THE NEAREST IMPACT ON TRAVEL
LIKELY TO BE NORTH OF OUR AREA...HEAVY RAIN INTO MONDAY ACROSS
WILLAMETTE PASS IN EASTERN LANE COUNTY. RIDGING IS LIKELY TO
RESULT IN DIMINISHING SHOWERS MONDAY THEN A WEAK FRONT MAY ARRIVE
TUESDAY.

MODEL SOLUTIONS DIVERGE BEYOND TUESDAY. AS IT NEARS, A CLOSE EYE
WILL BE GIVEN TO THE DETAILS OF A FRONT THAT MAY TRACK ACROSS OUR
AREA DURING WEDNESDAY. THE 00Z GFS IS DEEPER/COLDER WITH THE
ASSOCIATED UPPER TROUGH THAN THE 12Z ECMWF. BUT, BOTH INDICATE
SNOW LEVELS INITIALLY ABOVE THE MAIN PASSES THEN FALLING AND
PROVIDING UP TO A FEW INCHES OVER THE PASSES DURING THE DAY.

&&

.AVIATION...BASED ON THE 19/00Z TAF CYCLE...VFR WILL PREVAIL FOR
MOST AREAS THIS EVENING...BUT A POTENT FRONT WILL MOVE ONSHORE
BRINGING AREAS OF MVFR CIGS/VIS TO THE COAST ALONG WITH A PERIOD OF
MODERATE TO HEAVY RAINFALL. LOWER CIGS AND VIS WILL SPREAD INLAND
LATER THIS EVENING AND OVERNIGHT WITH HIGHER TERRAIN BECOMING
OBSCURED. LOCAL IFR CIGS/VIS WILL DEVELOP LATE TONIGHT. THE LOWER
CONDITIONS WILL PERSIST INTO FRIDAY...BUT CLEAR TO VFR BY FRIDAY
AFTERNOON. SPILDE

&&

.MARINE...UPDATED 415 PM PST THU DEC 18 2014...GALES AND
VERY STEEP HAZARDOUS SEAS ARE EXPECTED ACROSS NEARLY ALL OF THE
COASTAL WATERS THROUGH THIS EVENING AS A COLD FRONT MOVES ONSHORE.
HEAVY WEST SWELL WILL BUILD FRIDAY...PEAKING AROUND 20 FEET AT 18
SECONDS LATE FRIDAY AFTERNOON AND EVENING. THE LONG PERIOD SWELL
WILL REMAIN HEAVY THROUGH SATURDAY AS ANOTHER ROUND OF GALE FORCE
WINDS ARRIVES WITH A STRONG WARM FRONT. SUNDAY INTO MONDAY THIS
WARM FRONT WILL LINGER ALONG THE COAST NORTH OF CAPE BLANCO AS
SEAS SUBSIDE AND WINDS GRADUALLY DIMINISH. SPILDE

&&


.MFR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH SURF ADVISORY FROM 11 AM FRIDAY TO 10 PM PST SATURDAY FOR
     ORZ021-022-615-618.

CA...WIND ADVISORY UNTIL 1 AM PST FRIDAY FOR CAZ081-281.

PACIFIC COASTAL WATERS...GALE WATCH FROM LATE FRIDAY NIGHT THROUGH
  SATURDAY EVENING FOR PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR WINDS UNTIL 10 PM PST THIS EVENING
     FOR PZZ350-356-376.
  HAZARDOUS SEAS WATCH FROM FRIDAY MORNING THROUGH LATE SATURDAY
  NIGHT FOR PZZ350-356-370-376.
  GALE WARNING UNTIL 10 PM PST THIS EVENING FOR
  PZZ350-356-370-376.
     HAZARDOUS SEAS WARNING UNTIL 1 AM PST FRIDAY FOR
     PZZ350-356-370-376.

$$

DW/DW/MAS


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