Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 201141 CCA
AFDMFR

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE MEDFORD OR
341 AM PST SAT DEC 20 2014

.DISCUSSION...A MAJOR PRECIPITATION EVENT IS UNDERWAY FOR PORTIONS
OF THE FORECAST AREA. AN EXTREMELY IMPRESSIVE FETCH OF DEEP
MOISTURE EXTENDS FROM THE COAST TO NEARLY 3000 MILES
OFFSHORE...POINTED AT THE OREGON COAST. THIS WILL MAINTAIN
MODERATE TO HEAVY RAINFALL OVER THE COAST...COAST RANGE...CASCADE
FOOTHILLS AND CASCADES THROUGH SUNDAY. SNOW LEVELS ARE CURRENTLY
ABOUT 5500 FEET AND ARE RISING...SO THIS WILL BE PRIMARILY A HEAVY
RAIN EVENT AND FLOODING WILL BE THE MAIN IMPACT. ADDITIONAL
IMPACTS WILL INCLUDE DANGEROUS SEAS...HIGH SURF AT THE COAST...AND
GUSTY TO STRONG WINDS AT THE COAST...SHASTA VALLEY...AND EAST
SIDE.

MODELS CONTINUE TO PAINT A FAIRLY CONSISTENT PICTURE...OVER THE PAST
4 RUNS AT LEAST...OF 48 HOUR PRECIPITATION TOTALS OF 5-7 INCHES OVER
THE CASCADES AND 4-5 INCHES AT THE COAST. WE HAVE ENSURED THAT THE
FORECAST REFLECTS THIS...WITH SOME ENHANCED RAINFALL IN THE MOST
OROGRAPHICALLY FAVORED LOCATIONS SUCH AS THE CURRY COUNTY COAST AND
THE HIGH CASCADES FROM CRATER LAKE NORTH.

SOME CONFIDENCE TOOLS CONTINUE TO SHOW IMPRESSIVE NUMBERS THIS
MORNING...WITH IVT VALUES OF 500 KG/M/S FOR 24 HOURS STRAIGHT ALONG
AND NORTH OF CAPE BLANCO. THESE IVT...OR INTEGRATED VAPOR
TRANSPORT...VALUES WHICH SUGGESTS HOW SIGNIFICANT THE MOISTURE IS
OVER THE REGION...ARE PEAKING AT VALUES THAT ONLY OCCUR ONCE EVERY 5-
10 YEARS OVER THE CASCADES...AND ONCE EVERY 2-5 YEARS AT THE COAST.
HOWEVER...THE SHEAR DURATION OF THESE HIGH VALUES MEANS THIS EVENT
COULD EVEN BE MORE SIGNIFICANT.

SO...WITH ALL THAT SAID...HAVE ADDED SOME AREAL FLOOD WATCHES TO
BOTH EASTERN CURRY AND JOSEPHINE COUNTIES...AS WELL AS THE CASCADE
FOOTHILLS AND CASCADES FROM CRATER LAKE NORTHWARD. THESE ARE IN
ADDITION TO AREAL FLOOD WATCHES THAT COVER THE COAST AND JUST INLAND
AT FFAMFR. THE CONCERNS HERE ARE NOT ONLY FOR
MUDSLIDES...ROCKSLIDES...AND LANDSLIDES...BUT ALSO FOR STREAMS
FLOODING AND URBAN FLOODING WITH PONDING OF WATER ON ROADWAYS
EXPECTED AT LEAST. TRAVELING TODAY INTO TOMORROW WILL BE DIFFICULT
WITH THE HEAVY RAIN...WHICH WILL REDUCE VISIBILITY. THE MAIN STEM
RIVER THAT IS FORECAST TO OVERFLOW ITS BANKS IS THE COQUILLE AT
COQUILLE...WHICH IS FORECAST TO REACH MINOR FLOOD STAGE BY SUNDAY
AFTERNOON. MORE RIVERS CERTAINLY WILL NEAR FLOOD STAGE WITH THIS
SIGNIFICANT EVENT.

VERY GUSTY WINDS WILL IMPACT THE COAST THIS MORNING...SHASTA
VALLEY...WITH A LONG-DURATION GUSTY WIND EVENT EAST OF THE CASCADES
DUE TO CONTINUAL 50KT+ H7 FLOW THROUGH SUNDAY EVENING.

THINGS DRY OUT MONDAY INTO TUESDAY AS RIDGING BUILDS SOME...LIKELY
BRINGING MORNING VALLEY FOG BACK TO THE REGION.  THE NEXT SYSTEM TO
MOVE IN WILL BE A COLD ONE FROM THE NORTHWEST...BRINGING SNOW LEVELS
DOWN TO 3000 FEET ON CHRISTMAS EVE...WITH AMOUNTS TO BE DETERMINED
GIVEN MODEL DIFFERENCES BETWEEN THE GFS AND ECMWF AT THIS TIME. WILL
NO DOUBT SHIFT FOCUS TO THAT ONCE HEAVY RAINS AND WIND BEGINS TO
DIMINISH ON SUNDAY.


&&

.AVIATION...FOR THE 20/06Z TAF CYCLE...EXPECT WIDESPREAD MVFR
CIGS/VIS WITH TERRAIN OBSCURED THROUGH TODAY. LOCAL IFR IS ALSO
POSSIBLE. PRECIPITATION WILL BE LIGHT TO MODERATE...EXCEPT AT THE
COAST AND IN THE MOUNTAINS WHERE IT WILL BE HEAVY AT TIMES.
FREEZING LEVELS AROUND 5000 FEET WILL RISE TO AROUND 9000 FEET
TODAY AND REMAIN THERE THROUGH MOST OF SUNDAY. LOW-LEVEL WIND
SHEAR WILL BE ENDING AT THE COAST AS WINDS BEGIN TO SURFACE, BUT
MAY CONTINUE AT KRBG THROUGH 15Z. SPILDE

&&

.MARINE...UPDATED 6 PM PST FRI DEC 19 2014...HEAVY WEST SWELL WILL
SLOWLY DIMINISH TODAY. HOWEVER, A STRONG WARM FRONT WILL BRING
SOUTH GALES TO THE WATERS WHICH WILL KEEP VERY STEEP COMBINED SEAS
GOING EVEN AS SWELL DIMINISHES. WINDS WILL DIMINISH SUNDAY AND
THEN REMAIN RELATIVELY LIGHT THROUGH EARLY NEXT WEEK, BUT MODERATE
SWELL IS LIKELY TO CONTINUE THROUGH MUCH OF NEXT WEEK. A STRONG
COLD FRONT MAY BRING MODERATE NORTH WINDS TO THE WATERS CHRISTMAS
EVE AND CHRISTMAS DAY WITH A CORRESPONDING INCREASE IN WIND WAVES.
-WRIGHT


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...WIND ADVISORY FROM 10 AM THIS MORNING TO 9 PM PST SUNDAY FOR
     ORZ030-031-624-625.
     FLOOD WATCH FROM THIS AFTERNOON THROUGH SUNDAY EVENING FOR
     ORZ025-027-617-623-624.
     FLOOD WATCH FROM 10 AM PST THIS MORNING THROUGH SUNDAY EVENING
     FOR ORZ024-618-621.
     HIGH SURF ADVISORY UNTIL 10 PM PST THIS EVENING FOR
     ORZ021-022-615-618.
     FLOOD WATCH FROM 10 AM PST THIS MORNING THROUGH SUNDAY EVENING
     FOR ORZ616-619-620.
     FLOOD WATCH FROM 10 AM PST THIS MORNING THROUGH SUNDAY EVENING
     FOR ORZ021-022-615.
     FLOOD WATCH FROM THIS AFTERNOON THROUGH SUNDAY EVENING FOR
     ORZ023.

CA...WIND ADVISORY FROM 10 AM THIS MORNING TO 9 PM PST SUNDAY FOR
     CAZ085-285.
     WIND ADVISORY FROM 7 AM THIS MORNING TO 1 AM PST SUNDAY FOR
     CAZ081-281.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS UNTIL 4 PM PST THIS AFTERNOON FOR
     PZZ350-356-370-376.
     GALE WARNING UNTIL 4 PM PST THIS AFTERNOON FOR
     PZZ350-356-370-376.
     HAZARDOUS SEAS WARNING UNTIL 10 PM PST THIS EVENING FOR
     PZZ350-356-370-376.

$$

NSK/NSK/MAS


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