Area Forecast Discussion
Issued by NWS Medford, OR

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060
FXUS66 KMFR 081754
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
954 AM PST MON FEB 8 2016

UPDATED AVIATION AND MARINE SECTIONS

.DISCUSSION...LEAVING THE CURRENT FORECAST AS-IS THIS MORNING.
STRONG OFFSHORE FLOW IS IN SWING OVER THE REGION WITH SOME
CASCADE AND SOUTH COAST LOCATIONS GUSTING FROM THE EAST TO AROUND
30 MPH. CURRY COUNTY COASTAL TEMPERATURES ARE IN THE LOWER 70S.
LATEST HRRR FORECASTS INDICATE A WEAK ONSHORE FLOW SHOULD TAKE
OVER ON THE SOUTH COAST BEACHES THROUGH THE NEXT FEW HOURS SO DO
NOT ANTICIPATE TEMPERATURES THERE WILL GET TO MUCH HIGHER.

MORNING SATELLITE PICTURES SHOWED THE UMPQUA...ILLINOIS AND SCOTT
VALLEYS IN A LOW STRATUS WITH SOME FOG BEING REPORTED BUT NOT
WIDESPREAD. DOESN`T LOOK LIKE THE LOW CLOUDS ARE TOO THICK SO WE
EXPECT MOSTLY SUNNY SKIES PREVAILING BY EARLY AFTERNOON AREA-
WIDE. HIGH TEMPERATURES SHOULD REACH TO 10-15 DEGREES ABOVE
NORMAL TODAY...WITH MORE OF THE SAME THROUGH MID WEEK. STAVISH


&&

.AVIATION...FOR THE 08/18Z TAF CYCLE...LOW LEVEL WIND SHEAR WILL BE
AN AVIATION HAZARD AT WEST SIDE TERMINALS IN THE NEXT FEW HOURS AS
SURFACE WINDS REMAIN LIGHT AND WINDS ABOUT 1500 FEET OFF THE GROUND
ARE SOUTHEASTERLY AT 30-40KT. LIFR CONDITIONS WILL PERSIST AT
ROSEBURG FOR THE NEXT FEW HOURS BUT SHOULD CLEAR TO VFR BY EARLY
AFTERNOON. VFR WILL PREVAIL ELSEWHERE. LIFR CONDITIONS WILL RETURN TO
THE UMPQUA VALLEY AND PERHAPS THE SCOTT, ILLINOIS AND WESTERN
PORTIONS OF THE ROGUE VALLEYS OVERNIGHT INTO TUESDAY MORNING. THE
REMAINDER OF THE AREA WILL BE VFR. SPILDE


&&

.MARINE...UPDATED 1000 AM PST MON FEB 8 2016...STEEP SEAS
DOMINATED BY A LONG PERIOD WEST SWELL WILL BUILD INTO THE WATERS
TODAY. A THERMAL TROUGH ALONG THE COAST WILL MOVE NORTH AND PUSH
INLAND BY THIS EVENING. WINDS WILL REMAIN LIGHT BUT BECOME
SOUTHERLY THIS EVENING AS LOW PRESSURE DEEPENS BEYOND 130W. A WEAK
FRONT WILL DISSIPATE OVER THE WATERS WEDNESDAY...THEN ANOTHER
STRONGER FRONT WILL ARRIVE THURSDAY INTO FRIDAY WITH HIGHER WINDS
AND SEAS.

A FRONT MAY NEAR THE COASTAL WATERS WEDNESDAY. MODELS ARE
SHOWING THIS FRONT WEAKENING AS IT MOVES INTO THE WATERS
BUT THERE MAY BE A SLIGHT INCREASE IN SOUTH WINDS AND SEAS. A
STRONGER FRONT WILL MOVE IN THURSDAY INTO FRIDAY WITH THE POTENTIAL
FOR SMALL CRAFT ADVISORY WINDS AND STEEP SEAS.  ANOTHER STEEP LONG
PERIOD SWELL IS EXPECTED TO MOVE INTO THE WATERS THURSDAY NIGHT AND
FRIDAY. SPILDE

&&

.PREV DISCUSSION... /ISSUED 355 AM PST MON FEB 8 2016/ THE
NORTHERN HEMISPHERIC PATTERN CONTINUES TO SHOW A FIVE WAVE PATTERN
AROUND THE GLOBE WITH MODERATE AMPLITUDES. THIS PATTERN WILL
CONTINUE BUT LONGITUDINAL FLOW WILL INCREASE...CREATING A MORE
BLOCKY PATTERN AROUND THE GLOBE. THE PATTERN WILL REMAIN
PROGRESSIVE...BUT WILL SLOW DOWN OVER THE NEXT SEVERAL DAYS AS A
STRONG RIDGE BUILDS OVER THE EASTERN PACIFIC AND WESTERN NORTH
AMERICA.

THE RIDGE WILL MOVE VERY SLOWLY EAST...AMPLIFYING THROUGH TODAY.
IT WILL BE DIRECTLY OVER THE MEDFORD CWA LATER THIS MORNING. DRY
CONDITIONS...LOW LEVEL OFFSHORE FLOW...AND ABOVE NORMAL
TEMPERATURES WILL PERSIST INTO TUESDAY. THE WARMEST TEMPERATURES
WILL BE ALONG THE SOUTH COAST AND OVER THE RIDGES. MOSTLY CLEAR
SKIES WILL PREVAIL OVER MOST OF THE AREA. THE EXCEPTION WILL BE
THE WEST SIDE VALLEYS...WHERE WARM AIR ALOFT WILL STRENGTHEN
INVERSIONS...WHICH WILL ALLOW NIGHT THROUGH MORNING LOW CLOUDS AND
FOG TO DEVELOP IN SOME LOCATIONS. SINCE THIS IS LATE IN THE
SEASON FOR SUCH PATTERNS...THE LOW CLOUDS AND FOG WILL BURN OFF
IN THE AFTERNOONS AND EVENINGS.

USUALLY AIR STAGNATION IS A CONCERN IN A PATTERN LIKE THIS...BUT
GIVEN THE EXPECTED AFTERNOON MIXING...WILL NOT ISSUE ANY
ADVISORIES AT THIS TIME.

THE RIDGE WILL CONTINUE TO DRIFT EAST...AND WEAK SHORT WAVES
EJECTING FROM THE UPSTREAM TROUGH WILL START TO MOVE OVER THE
AREA WEDNESDAY. TYPICALLY THE FIRST SHORT WAVE AFTER A RIDGE HAS
LITTLE EFFECT OTHER THAN HERALDING THE END OF OFFSHORE LOW LEVEL
FLOW...AND THESE LOOK TOO WEAK TO DO MUCH OF ANYTHING. THE SHORT
WAVES THAT FOLLOW WILL ALSO BE WEAK AND MOST OF THE ENERGY WILL BE
DIRECTED TO THE NORTH OF THE AREA. THE 08/00Z GFS SOLUTION
LIMITS PRECIPITATION TO THE COASTAL WATERS UNTIL FRIDAY NIGHT WHEN
A WEAK FRONT BRINGS SOME LIGHT PRECIPITATION TO THE COAST.
MEANWHILE THE 08/00Z EC SOLUTION KEEPS IT DRY INTO THURSDAY NIGHT
EXCEPT FOR SOME VERY LIGHT PRECIPITATION NEAR THE COAST WEDNESDAY
NIGHT. IT THEN PUSHES A WETTER COLD FRONT ONSHORE FRIDAY MORNING.
TYPICALLY THE MODELS TEND TO BREAK DOWN A STRONG RIDGE TOO
QUICKLY...AND KEEP PUSHING THE ONSET OF PRECIPITATION BACK WITH
EACH SUCCESSIVE RUN. THAT APPEARS TO BE THE CASE HERE...BUT THE
DRY EVENT HAS TO END AT SOME POINT. SO...WILL BRING SOME CHANCE
POPS ONSHORE LATE THURSDAY NIGHT.

&&

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

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

$$

MAS/MTS/JRS



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