Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 292228
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
228 PM PST THU JAN 29 2015

.SHORT TERM...A VERY WEAK UPPER SYSTEM WILL CONTINUE TO SLIDE BY
LARGELY UNNOTICED THIS AFTERNOON, AND THEN THE UPPER RIDGE
REBUILDS STRONGLY AND RULES OUR WEATHER FRIDAY THROUGH SATURDAY.
LOW LEVEL OFFSHORE FLOW HAS ALREADY RESUMED AT THE COAST, AND
THEY`VE CLEARED OUT NICELY. INLAND, STRATUS HAS BURNED OFF WITH
THE EXCEPTION OF PORTIONS OF THE UMPQUA VALLEY. IT IS ALSO SLOWLY
ERODING IN THE UMPQUA, BUT IT MAY NOT FULLY BURN OFF BEFORE IT
BEGINS TO FILL IN AGAIN THIS EVENING. THERE HAS BEEN LITTLE
CHANGE, SYNOPTICALLY, SO LOW LEVEL INVERSIONS WILL LEAD TO ANOTHER
ROUND OF FOG IN WEST SIDE VALLEYS TONIGHT. IN FACT, INVERSIONS
WILL CONTINUE THROUGH THE WEEKEND, AND THUS I`VE EXTENDED THE AIR
STAGNATION ADVISORY ONE MORE DAY (UNTIL SUNDAY AFTERNOON). SINCE
THE PATTERN IS SO PERSISTENT, FEW CHANGES WERE MADE TO THE
FORECAST FOR THE SHORT TERM.

ONE NOTE ABOUT THE COAST: OFFSHORE FLOW CONTINUES THROUGH SATURDAY
AND THIS WILL KEEP MOST OF THE COAST (ESPECIALLY THE CURRY COAST)
CLEAR AND MILD. THE OFFSHORE FLOW PEAKS FRIDAY NIGHT INTO
SATURDAY, AND I`VE RAISED TEMPERATURES FOR THE CURRY COAST AND
ADJACENT MOUNTAINS FOR FRIDAY THROUGH SATURDAY.

THE RIDGE WEAKENS AND SHIFTS EAST ON SUNDAY. THIS WILL MEAN AN
INCREASE IN CLOUD FOR SUNDAY AND ALSO THE CHANCE FOR SOME RAIN
LATE. RAIN USUALLY HAS A HARD TIME MAKING MUCH PROGRESS INLAND IN
THE WAKE OF A STRONG RIDGE, SO THE HIGHEST POPS HAVE BEEN CONFINED
TO THE WATERS AND NORTH COAST SUNDAY INTO SUNDAY NIGHT. HOWEVER,
EVENTUALLY SOME RAIN WILL PROBABLY MAKE IT INLAND, SO I HAVE
RAISED POPS FURTHER INLAND AS WELL. -WRIGHT

.LONG TERM...MONDAY THROUGH THURSDAY.

THROUGH THE FIRST HALF OF NEXT WEEK..THE UPPER LEVEL FLOW TURNS MORE
TOWARD ZONAL WESTERLY ACROSS THE EASTERN PACIFIC. THIS WILL ALLOW A
SERIES OF FRONTS TO MOVE INLAND. HOWEVER THE STORM TRACK REMAINS
EITHER NORTH OF OR STAYING IN THE NORTHERN THIRD OF OUR FORECAST
AREA. AS A RESULT RAINFALL AMOUNTS WILL BE LIGHT WITH VERY LITTLE
RAIN SOUTH OF THE SISKIYOU MOUNTAINS INTO NORTHERN CALIFORNIA.

THE LONG WAVE RIDGE WILL REDEVELOP OFFSHORE TUESDAY AND MOVE BACK
ONSHORE WEDNESDAY. THIS IS IN RESPONSE TO A DEEPENING LOW PRESSURE
AND TROUGH IN THE GULF OF ALASKA. BOTH OF THE MEDIUM-RANGE MODEL
SOLUTIONS SUPPORT THIS SCENARIO...BUT THE EC IS WEAKER AND A BIT
MORE PROGRESSIVE WITH THE RIDGE. BOTH MODELS BRING A WARM FRONT INTO
THE COASTAL WATERS TOWARD THE END OF NEXT WEEK. WE HAVE INTRODUCED
RAIN CHANCE FOR SW OREGON IN THE SECOND HALF OF NEXT WEEK ALTHOUGH
CONFIDENCE IS NOT VERY HIGH ON WHEN THE MID WEEK RIDGE WILL WEAKEN.
HOWEVER WITH BOTH MODELS SHOWING WETTING RAIN BY DAY 10..CONFIDENCE
APPROACHES MODERATE THAT WE WILL SEE RAIN DURING THE FIRST WEEKEND
OF FEBRUARY. /FB

&&

.AVIATION...BASED ON THE 29/18Z TAF CYCLE...IFR CIGS/VIS WILL
RETURN TO THE COAST AND MOST OF SW OREGON VALLEYS TONIGHT WITH LIFR
POSSIBLE AT KRBG AND KMFR AROUND DAYBREAK. OTHERWISE CONDITIONS WILL
REMAIN VFR FOR THE REMAINDER OF THIS AFTERNOON AND EVENING. /FB

&&

.MARINE...UPDATED AT 200 PM THURSDAY 29 JANUARY 2015...HIGH PRESSURE
OFFSHORE WILL BUILD TONIGHT THROUGH FRIDAY...MODERATE NORTHERLY
WINDS ARE EXPECTED...RESULTING IN INCREASED WIND CHOP...ESPECIALLY
SOUTH OF CAPE BLANCO. THE HIGH PRESSURE WILL WEAKEN SATURDAY NIGHT
AS THE NEXT FRONT APPROACHES. THE FRONT WILL PRODUCE WEAK SOUTH
WINDS AND MODERATE WEST SWELL ON SUNDAY THEN MOVE ONSHORE SUNDAY
NIGHT. SPILDE

&&

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

CA...NONE.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST FRIDAY
     FOR PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR WINDS UNTIL 4 AM PST SATURDAY FOR
     PZZ376.

$$


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