Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 242303
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
403 PM PDT FRI OCT 24 2014

.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT.

A WARM FRONT HAS LIFTED NORTH WITH A DECREASE IN CLOUDS AND
INCREASE IN SOUTHERLY WINDS IN ITS WAKE. A DEEP SURFACE LOW AND
ITS ASSOCIATED COLD FRONT IS CENTERED OFFSHORE FROM NORTHERN
CALIFORNIA AROUND 40N 132W AND WILL TRACK NORTHEAST TO THE COAST
OF WASHINGTON DURING THE NEXT 24 HOURS.

THE MAIN IMPACT WILL BE FROM STRONG SOUTHERLY WINDS (STRONGEST IN
THE LATE MORNING AND AFTERNOON HOURS). BUT, IT WILL ALSO PRODUCE
MODERATE TO HEAVY RAIN FOR MUCH OF THE AREA WEST OF THE CASCADES
(AND LIGHT RAIN ELSEWHERE), ISOLATED THUNDERSTORMS (WITH THE
HIGHEST PROBABILITY NEAR THE COAST), AND UP TO 6 INCHES OF MOUNTAIN
SNOW WITH THE SNOW LEVEL AROUND 7000 FEET ON SATURDAY FALLING TO
AROUND 5000 FEET WITH POST-FRONTAL SHOWERS ON SATURDAY NIGHT.

THE MOST NOTABLE ADJUSTMENTS TO THE FORECAST WERE TO ADD A HIGH
WIND WARNING FOR THE COAST LATE SATURDAY MORNING INTO SATURDAY
AFTERNOON, AND ADD A WIND ADVISORY FOR THE SHASTA VALLEY THAT IS IN
EFFECT NOW THROUGH THIS EVENING. THEREAFTER, WINDS INCREASE TO
HIGH WIND WARNING CRITERIA WITH GUSTS OF 55 TO 70 MPH IN THAT
LOCALE AND MANY OTHERS...INCLUDING THE MOUNTAINS AND MUCH OF THE
EAST SIDE. THERE IS AN OFFSHORE COMPONENT TO THE NEAR SHORE WINDS
THIS EVENING THAT WILL RESULT IN THE STRONGER WINDS DEVELOPING
INLAND BEFORE ARRIVING AT THE COAST. FOR INSTANCE, THE CAPE BLANCO
BUOY OVER THE COASTAL WATERS HAS HAD A PEAK GUST THIS AFTERNOON OF
30 MPH BUT WINDS HAVE ALREADY GUSTED TO 45 MPH AT WEED.

THE FORECAST PRECIPITATION AMOUNTS WERE ADJUSTED SLIGHTLY HIGHER
FOR CURRY, JOSEPHINE, AND WESTERN AND SOUTHERN PORTIONS OF
SISKIYOU COUNTY. MODERATE TO HEAVY RAIN WITH ISOLATED THUNDERSTORMS WILL
REACH THE COAST AROUND MIDNIGHT THEN SPREAD INLAND SATURDAY WITH
THE HEAVIEST PRECIPITATION OCCURRING WEST OF THE CASCADE CREST.
STORM TOTAL AMOUNTS LATE TONIGHT INTO SUNDAY MORNING ARE FORECAST
TO BE UP TO 4 INCHES IN THE COASTAL RANGE OF CURRY COUNTY WITH UP
TO 2 INCHES ELSEWHERE IN CURRY, COOS, JOSEPHINE, AND WESTERN AND
SOUTHERN SISKIYOU COUNTY. UP TO AN INCH ELSEWHERE ON THE WEST SIDE
AND GENEARLLY UP TO A HALF INCH ON THE EAST SIDE.

THE PRECIPITATION WILL BE HEAVIEST AND WIND SPEEDS STRONGEST
AROUND THE TIME OF FRONTAL PASSAGE...FROM SATURDAY MORNING INTO
SATURDAY EVENING. WIND SPEEDS AND RAINFALL AMOUNTS WILL DIMINISH
SATURDAY NIGHT BUT A SHOWERY AIR MASS WILL PERSIST INTO SUNDAY.
WEAK RIDGING IS EXPECTED SUNDAY NIGHT INTO MONDAY WITH A DECREASE
OF CLOUDS AND NORTHWESTERLY FLOW ON THE BACK SIDE OF THE TROUGH
LEADING TO A CHILLY START TO MONDAY. THIS COOLING WILL LIKELY BE
MODERATED BY THE DEVELOPMENT OF VALLEY LOW CLOUDS.

MONDAY WILL BE A DRY DAY WITH THE POSSIBLE EXCEPTION OF VERY LIGHT
SHOWERS AT THE COAST NORTH OF NORTH BEND. BUT, HIGH CLOUDS WILL
ALREADY BE ARRIVING AHEAD OF ANOTHER STRONG FRONT, MODELS ARE IN
VERY GOOD AGREEMENT THAT IT WILL REACH THE COAST MONDAY NIGHT.

.LONG TERM...FROM TUESDAY MORNING THOUGH FRIDAY.
MODELS ARE IN VERY GOOD AGREEMENT STARTING TUESDAY WITH ANOTHER
WET SYSTEM IMPACTING THE AREA TUESDAY INTO WEDNESDAY. ALTHOUGH THE
JET AXIS IS NORTH OF THE REGION LOW LEVEL CONVERGENCE COMBINING
WITH OROGRAPHIC LIFT BRINGS HEAVY PRECIPITATION TO THE WEST SIDE
WITH A WETTING RAIN POSSIBLE EAST OF THE CASCADES IN A NEAR ZONAL
FLOW PATTERN.

THE UPPER LEVEL RIDGE BUILDS AND SHIFTS EAST AS THE UPPER
LEVEL TROUGH DEEPENS OFFSHORE INTO FRIDAY MORNING WITH SHOWERS
WEAKENING OVER THE REGION THROUGH FRIDAY MORNING. FROM FRIDAY THE
ECMWF AND THE GFS VARY IN THE THE DEPTH AND LOCATION OF A CUTOFF
LOW BEYOND 130W...WITH THE ECMWF PUTTING THE LOW OFF OF THE
SOUTHERN CALIFORNIA COAST AND THE GFS LOCATING IT OFF OF THE
NORTHERN CALIFORNIA COAST. CONFIDENCE IS MUCH HIGHER ON THE
FORECAST UP TO FRIDAY...AND LOWER NEXT WEEKEND. /SVEN


&&

.AVIATION...FOR THE 24/18Z TAF CYCLE...A WARM FRONT IS MOVING NORTH
OF THE REGION WITH THE RAIN ACCOMPANYING IT. CONDITIONS ARE SLOWLY
BECOMING VFR AT ALL TERMINALS WITH KRBG BEING THE STRAGGLER. AS THE
RAIN ENDS, GUSTY SOUTH TO SOUTHEAST WINDS ARE EXPECTED TO DEVELOP,
ESPECIALLY EAST OF THE CASCADES. THESE VERY STRONG WINDS REMAIN OVER
MOST OF THE REGION INTO THE MORNING AS THE FRONT APPROACHES THE
COAST. -SVEN

&&

.MARINE...UPDATED 230 PM PDT FRI 24 OCT 2014...STRONG LOW PRESSURE
WILL MOVE THROUGH THE COASTAL WATERS OVER THE NEXT 48 HOURS.
SOUTHERLY WINDS WILL INCREASE THROUGH THIS EVENING AND TONIGHT AS
GRADIENTS TIGHTEN AHEAD OF THE LOW AND ITS ASSOCIATED COLD FRONT.
WINDS WILL REMAIN STRONG THROUGH MUCH OF SATURDAY.

THERE IS SOME QUESTION AS TO HOW STRONG WINDS WILL BECOME, AND HOW
LONG THEY WILL PERSIST. WHILE PRESSURE GRADIENT FORECASTS BETWEEN
EUREKA AND NORTH BEND WOULD SUGGEST STORM FORCE WINDS UNDER USUAL
CIRCUMSTANCES, THE FRONT WILL BE ORIENTED ROUGHLY PARALLEL TO THE
COAST, AND THIS WILL KEEP WINDS SLIGHTLY WEAKER THAN WE WOULD
TYPICALLY SEE WITH THIS STRONG OF A SYSTEM. WINDS WILL SHIFT WEST
AND BEGIN TO EASE IN THE LATE SATURDAY AFTERNOON. THIS IS SUBJECT TO
CHANGE DEPENDING ON THE TRACK OF THE LOW, BUT AT LEAST 12-18 HOURS
OF STRONG GALES TO LOW END STORM FORCE WINDS ARE NEARLY CERTAIN OVER
MUCH OF OUR WATERS. VERY STEEP AND CHAOTIC SEAS WILL ALSO ACCOMPANY
THE HIGH WINDS, COMPOSED OF MODERATE WEST SWELL AND VERY STRONG
SOUTHERLY CHOP.

CONDITIONS WILL IMPROVE SUNDAY, BUT ANOTHER FRONT WILL AFFECT THE
WATERS LATE MONDAY INTO TUESDAY. -BPN/WRIGHT

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WARNING FROM 11 PM THIS EVENING TO 11 PM PDT SATURDAY
     FOR ORZ029>031.
     HIGH WIND WARNING FROM 11 AM TO 5 PM PDT SATURDAY FOR
     ORZ021-022.
     HIGH WIND WARNING FROM 11 PM THIS EVENING TO 5 PM PDT SATURDAY
     FOR ORZ028.
     WIND ADVISORY FROM 5 AM TO 5 PM PDT SATURDAY FOR ORZ026.

CA...HIGH WIND WARNING FROM 11 PM THIS EVENING TO 5 PM PDT SATURDAY
     FOR CAZ082.
     HIGH WIND WARNING FROM 11 PM THIS EVENING TO 5 PM PDT SATURDAY
     FOR CAZ081.
     WIND ADVISORY UNTIL 11 PM PDT THIS EVENING FOR CAZ081.
     HIGH WIND WARNING FROM 11 PM THIS EVENING TO 11 PM PDT SATURDAY
     FOR CAZ083-085.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS UNTIL 2 AM PDT
     SATURDAY FOR PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 PM PDT THIS
     EVENING FOR PZZ350-356-370-376.
     GALE WARNING FROM 2 AM TO 2 PM PDT SATURDAY FOR PZZ350-356.
     HAZARDOUS SEAS WARNING UNTIL 8 PM PDT SATURDAY FOR
     PZZ350-356-370-376.
     HIGH WIND WARNING FROM 11 AM TO 5 PM PDT SATURDAY FOR PZZ310.
     GALE WARNING UNTIL 2 PM PDT SATURDAY FOR PZZ370-376.

$$

DW/SVEN/BPN






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