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[Printable]
036
FXUS66 KMFR 241750
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
950 AM PST MON NOV 24 2014

.DISCUSSION...CURRENT VISIBLE IMAGE SHOWS SCATTERED HIGH CLOUDS
OVER THE EASTERN PART OF THE REGION AND LOW CLOUDS IN THE VALLEYS.
MORE CLOUDS FROM AN APPROACHING WARM FRONT ARE OFFSHORE AND ARE
EXPECTED TO MOVE INLAND LATER THIS MORNING. THE NAM AND RAP ARE IN
GOOD AGREEMENT HOLDING OFF ANY WARM FRONTAL PRECIPITATION UNTIL
LATE IN THE AFTERNOON AND MOST CONFINED TO WEST OF THE CASCADES.
THUS HAVE TRIMMED BACK POPS FOR THIS MORNING AND AFTERNOON TO
BETTER REFLECT THE TIMING. QPF AMOUNTS TODAY SHOULD ALSO BE
LIGHT. EVEN THE COAST RANGE AND CASCADES WILL PROBABLY GET LESS
THAN A TENTH OF AN INCH BY THIS EVENING. THE WARM FRONT WILL MOVE
THROUGH THIS EVENING AND BRING A BETTER CHANCE OF LIGHT STEADY
PRECIPITATION MAINLY NORTH OF HIGHWAY 140 AND NORTH OF THE UMPQUA
DIVIDE. -PETRUCELLI


&&

.AVIATION...IFR CIGS/VIS REMAIN IN THE ILLINOIS, ROGUE AND
SISKIYOU COUNTY VALLEYS AND IT COULD REMAIN THAT WAY THROUGH EARLY
AFTERNOON BEFORE BREAKING OUT. EVEN THEN IT MAY ONLY BE FOR A
BRIEF TIME. ELSEWHERE VFR CONDITIONS ARE EXPECTED THROUGH THIS
AFTERNOON. MVFR AND LOCAL IFR CIGS RETURN WITH MOUNTAIN
OBSCUATIONS THIS EVENING AND TONIGHT AS A WARM FRONT MOVES INTO
THE AREA. EAST OF THE CASCADES...VFR CONDITIONS WILL CONTINUE
INTO TONIGHT, BUT THERE IS A CHANCE FOR LOW CLOUDS AND FOG TO
DEVELOP IN SOME OF THE BASINS, INCLUDING KLMT. -PETRUCELLI


&&

.MARINE...UPDATED 5 AM PST SUN NOV 23 2014...A WARM FRONT WILL MOVE
OVER THE WATERS THIS AFTERNOON INTO EARLY THIS EVENING. STEEP
MODERATE WEST SWELL WILL SLOWLY SUBSIDE TODAY...BUT THE FRONT WILL
BRING SMALL CRAFT WINDS TO THE AREA THIS AFTERNOON INTO EARLY THIS
EVENING.  SO...SEAS WILL REMAIN STEEP WITH CHOPPY SEAS DEVELOPING
TODAY.  WINDS AND SEAS WILL BOTH SUBSIDE TONIGHT. OFFSHORE HIGH
PRESSURE WILL REBUILD TUESDAY AND WEAKEN WEDNESDAY. A COLD FRONT
WILL MOVE ACROSS THE WATERS WEDNESDAY NIGHT INTO THURSDAY...FOLLOWED
BY ANOTHER ONE FRIDAY. /CC


&&

.PREV DISCUSSION... /ISSUED 333 AM PST MON NOV 24 2014/

DISCUSSION...
FOR THANKSGIVING TRAVELERS, WE EXPECT SOME LIGHT PRECIPITATION
TODAY THROUGH TUESDAY, WITH NO SNOWY ROADS EXCEPT POSSIBLY A
DUSTING IN THE DIAMOND AND CRATER LAKE AREAS THIS AFTERNOON.
AFTER A DRY BREAK WEDNESDAY, WE EXPECT WETTER WEATHER TO ARRIVE
BEGINNING THANKSGIVING DAY AND THEN PERSISTING THROUGH NEXT
WEEKEND INTO EARLY NEXT WEEK. SNOW LEVELS ARE LIKELY TO REMAIN
ABOVE MAJOR MOUNTAIN PASS ROADWAYS THROUGH EARLY NEXT SUNDAY, BUT
THEN MAY START COMING DOWN. SNOW IMPACTS LOOK POSSIBLE PER THE
LATEST NUMERICAL MODEL GUIDANCE NEXT SUNDAY NIGHT INTO EARLY NEXT
WEEK.

THE SNOW DEPTH AT CRATER LAKE NATIONAL PARK HEADQUARTERS
YESTERDAY MORNING WAS REPORTED TO BE 22 INCHES, WHICH IS 91.6% OF
THE 1931-2000 HISTORICAL AVERAGE. OVER THE NEXT WEEK WE ARE
EXPECTING A WARMING TREND THAT IS LIKELY TO CONSOLIDATE THE SNOW
ON THE GROUND ACROSS THE MOUNTAINS. A COOLER PERIOD IS EXPECTED
TO BEGIN AGAIN SOMETIME LATE NEXT WEEKEND TO EARLY NEXT WEEK TIME
FRAME WITH SNOW ACCUMULATION LIKELY.

TODAY THROUGH TUESDAY WARM AIR WILL OVERRUN THE COOLER AIR MASS IN
PLACE RESULTING IN PLENTY OF CLOUD COVER AND SOME LIGHT
PRECIPITATION. MODELS VARY QUITE A BIT ON AMOUNTS, EXTENT, AND
DURATION, BUT EXPECT MOST OF THE PRECIPITATION TO BE IN THE OREGON
CASCADES, COAST RANGE, COAST, AND UMPQUA BASIN. THESE AREAS MAY
GET A TENTH TO A QUARTER OF AN INCH OF WATER, BUT MOST AREAS WILL
SEE A FEW HUNDREDTHS TO A TRACE OF RAIN.

TUESDAY THROUGH THURSDAY WARM AIR ALOFT WILL DEVELOP AN INVERSION
OVER THE VALLEYS. HOW WARM IT WILL GET IN THE VALLEYS WILL DEPEND
ON HOW COOL IT GETS THE NIGHT BEFORE, WHICH WILL BE MODULATED BY
CLOUD COVER AND WIND. AS TIME GOES BY, THE NEXT STORM SYSTEM IN
THE PACIFIC WILL BEGIN TO DRAW AIR INTO IT RESULTING IN SOUTH AND
EAST WINDS ACROSS THE AREA THAT ARE LIKELY TO DISRUPT AND
EVENTUALLY MIX OUT VALLEY INVERSIONS. THIS SHOULD YIELD SOME
HIGHS IN THE 55-65F RANGE FOR MOST VALLEYS, WHICH IS 5-15F ABOVE
NORMAL.

THANKSGIVING DAY THROUGH THE WEEKEND WE EXPECT RAIN TO DEVELOP AS
A FRONTAL SYSTEM ARRIVES, SLOWS, STALLS, AND THEN PROGRESSES
THROUGH THE AREA. THIS WILL RESULT IN HIGH SNOW LEVELS WITH
INCREASINGLY WET WEATHER ACROSS THE REGION. THIS IS LIKELY TO
TRANSITION TO A COOLER AND WETTER PATTERN AROUND THE LATE SUNDAY-
MONDAY TIME FRAME, WHEN SNOW LEVELS MAY REACH DOWN TO SOME OF THE
PRIMARY MOUNTAIN PASSES AND POSSIBLY THE EAST SIDE, AT TIMES. BTL


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.

CA...NONE.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS UNTIL 7 PM PST THIS EVENING FOR
     PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST THIS
     EVENING FOR PZZ350-356-370-376.

$$




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