Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 272213
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
213 PM PST TUE JAN 27 2015

.DISCUSSION...HIGH AND MID LEVEL CLOUDS ARE BLANKETING MOST OF THE
CWA AND THIS WILL PERSIST INTO TONIGHT. LOW CLOUDS ARE STILL IN
ROSEBURG AND IT MAY NOT BREAK OUT AT ALL THROUGH EARLY THIS
EVENING. A WEAK FRONT WILL MOVE INTO THE NORTHWEST PART OF THE
FORECAST AREA THIS EVENING, THEN DISSIPATE TONIGHT. THIS FRONT
WILL HAVE LITTLE OR NO IMPACT ON THE CURRENT AIR STAGNATION
ADVISORY FOR THE WESTSIDE VALLEYS AND VALLEYS EAST OF THE
CASCADES. THERE IS A CHANCE THE ATMOSPHERE WILL MIX OUT ENOUGH
EAST OF THE CASCADES THIS AFTERNOON, BUT THE INVERSION WILL
STRENGTHEN TONIGHT AND PERSIST THROUGH AT LEAST FRIDAY MORNING,
IF NOT LONGER. THUS HAVE EXTENDED THE AIR STAGNATION ADVISORY
UNTIL FRIDAY MORNING, BUT IT COULD EASILY CONTINUE THROUGH
SATURDAY.

OVERALL THE PATTERN IS NOT GOING TO CHANCE MUCH WHICH MEANS MUCH
OF THE SAME WITH LOW CLOUDS AND FOG DEVELOPING IN THE EVENINGS AND
LASTING THROUGH THE MORNING HOURS FOR THE WESTSIDE VALLEYS. IT`S
POSSIBLE WE COULD HAVE SUFFICIENT CLOUD COVER TONIGHT TO DELAY OR
LIMIT THE EXTENT OF THE FOG AND LOW CLOUDS TONIGHT INTO WEDNESDAY
MORNING, BUT WE`LL LET THE NIGHT SHIFT TAKE ANOTHER LOOK AT THIS.
-PETRUCELLI

MEDIUM RANGE FORECAST...SATURDAY THROUGH TUESDAY.

THE EXTENDED FORECAST PERIOD WILL START OFF RELATIVELY WARM AND DRY
WITH A STRONG LONG WAVE RIDGE OFF THE WEST COAST.

THE RIDGE WILL WEAKEN AND THE AXIS WILL MOVE ONSHORE SATURDAY NIGHT
INTO SUNDAY. THIS USUALLY OPENS UP THE STORM DOOR BUT THE UPSTREAM
SYSTEMS ARE WEAK.  THOSE SYSTEMS WILL RIDE OVER THE RIDGE AND
FLATTEN IT...AND FLOW ALOFT WILL BECOME ZONAL SUNDAY INTO MONDAY.

BOTH THE EC AND GFS SOLUTIONS MOVE A FRONT ONSHORE THIS WEEKEND FOR
THE NEXT CHANCE OF PRECIPITATION OVER THE AREA. THE EC MOVES THE
FRONT ONSHORE LATE SATURDAY NIGHT INTO SUNDAY MORNING WHILE THE GFS
MOVE A WETTER FRONT ONSHORE SUNDAY EVENING. BOTH MODELS STALL THE
FRONT OVER THE AREA AS IT BECOMES PARALLEL TO THE UPPER LEVEL
FLOW...BUT THE EC DOES IT OVER DOUGLAS COUNTY WHILE THE GFS STALLS
IT OVER NORTHERN CALIFORNIA.

THE MODEL SOLUTIONS DIVERGE EVEN MORE EARLY NEXT WEEK.  THE GFS
SOLUTION HOLD ON TO A WEAK LONG WAVE RIDGE OVER THE WESTERN U.S.
WHILE THE EC REDEVELOPS THE OFFSHORE LONG WAVE RIDGE.  THE DGEX
SOLUTION IS IN BETWEEN...STARTING WITH THE GFS SOLUTION...THEN
MOVING TOWARD THE EC SOLUTION TUESDAY.  OVERALL IT LOOKS LIKE THE
FRONTAL ZONE WILL OSCILLATE BACK AND FORTH OVER THE CWA MONDAY INTO
TUESDAY AS WAVES DEVELOP AND PROPAGATE ALONG THE BOUNDARY.  THIS
WILL MAKE FOR GENERALLY UNSETTLED WEATHER WITH LIGHT TO MODERATE
INTERMITTENT PRECIPITATION.

EVENTUALLY THE OFFSHORE RIDGING WILL DRY THE AREA OUT AND WEDNESDAY
LOOKS TO BE DRY. -JRS

&&

.AVIATION...BASED ON THE 27/18Z TAF CYCLE...ALONG THE COAST...AREAS
OF MVFR CIGS/VSBYS WILL CLEAR TO VFR THIS AFTERNOON. THE LOWER
CONDITIONS WILL RETURN TO THE SAME AREAS THIS EVENING.
INLAND...AREAS OF IFR/LIFR CIGS/VSBYS IN THE WEST SIDE VALLEYS WILL
CLEAR TO VFR BY THIS AFTERNOON. THE LOWER CONDITIONS WILL RETURN TO
THE SAME AREAS LATE TONIGHT THROUGH WEDNESDAY MORNING...BUT COVERAGE
WILL BE A BIT LESS THAN THIS MORNING. THE REMAINDER OF THE AREA WILL
REMAIN VFR THROUGH WEDNESDAY. /FB


&&

.MARINE...UPDATED AT 115 PM TUESDAY 27 JANUARY 2015...WEST SWELL
WILL GRADUALLY SUBSIDE WITH LIGHT SOUTH WINDS THROUGH WEDNESDAY. A
WEAK FRONT WILL MOVE THROUGH THE COASTAL WATERS THIS EVENING THEN
DISSIPATE WEDNESDAY. MODERATE NORTHERLY WINDS WILL DEVELOP
THURSDAY INTO FRIDAY AS OFFSHORE HIGH PRESSURE BUILDS...RESULTING
IN INCREASED CHOP. THE HIGH PRESSURE WILL WEAKEN SATURDAY NIGHT
INTO SUNDAY. /FB


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...AIR STAGNATION ADVISORY UNTIL 1 PM PST FRIDAY FOR
     ORZ023-024-026-616-620-622.
     AIR STAGNATION ADVISORY UNTIL 1 PM PST FRIDAY FOR
     ORZ029>031-623>625.

CA...NONE.

PACIFIC COASTAL WATERS...NONE.

$$



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