748
FXUS66 KMFR 140510
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
910 PM PST SAT DEC 13 2025
UPDATE
AVIATION DISCUSSION UPDATED.
AVIATION...14/06Z TAFS
AREAS OF LOW STRATUS AND FOG ARE PRESENT
IN VALLEYS WEST OF THE CASCADES, RESULTING IN IFR/LIFR CONDITIONS AT
MEDFORD, GRANTS PASS AND MONTAGUE. OVERNIGHT, IFR/LIFR IS ALSO
EXPECTED TO DEVELOP IN OTHER VALLEYS WEST OF THE CASCADES AS WELL IN
THE KLAMATH BASIN, INCLUDING KLAMATH FALLS. THESE CONDITIONS WILL
PERSIST THROUGH 18-20Z SATURDAY. SOME AREAS, SUCH AS MEDFORD AND
GRANTS PASS MAY SEE LITTLE OR NO CLEARING, AND JUST SEE CEILINGS
LIFT HIGHER LATE IN THE AFTERNOON TO IFR/MVFR AND PERSIST INTO THE
EVENING.
ALONG THE COAST AND JUST OFFSHORE, SATELLITE IMAGE SHOWS A MARINE
STRATUS SURGE MOVING UP ALONG THE COAST. THIS IS EXPECTED TO BRING
IFR/LIFR FROM GOLD BEACH SOUTH TONIGHT AND SUNDAY. MEANWHILE, A
WEAK FRONT COULD RESULT IN LOW STRATUS NORTH OF CAPE BLANCO WITH
MAINLY IFR/MVFR BUT LOCAL LIFR. THESE CEILINGS ARE EXPECTED TO
PERSIST INTO LATE SUNDAY MORNING. SUNDAY NIGHT, ANOTHER FRONT
APPROACHES THE COAST. THIS IS EXPECTED TO BRING CHANCES FOR MVFR AT
NORTH BEND AFTER 06Z 12/15.
PREV DISCUSSION
/ISSUED 208 PM PST SAT DEC 13 2025/
DISCUSSION...MUCH LIKE THE LAST FEW DAYS, SATELLITE IMAGE
SHOWS LOW CLOUDS PERSISTING IN THE ROGUE, ILLINOIS, AND SHASTA
VALLEYS. ELSEWHERE IT'S CLEAR AND WILL REMAIN CLEAR THROUGH THIS
EVENING. IT'S LIKELY THE LOW CLOUDS WILL PERSIST ROGUE AND ILLINOIS
VALLEY THROUGH THE AFTERNOON AND TONIGHT. HOWEVER, LOW CLOUDS AND
FOG ARE LIKELY AGAIN IN THE VALLEYS IN DOUGLAS COUNTY, SCOTT,
KLAMATH RIVER, AND SHASTA VALLEY LATE THIS EVENING THROUGH SUNDAY
MORNING.
MEANWHILE, LOW CLOUDS AND FOG SHOULD BURN OFF LATE THIS AFTERNOON IN
THE SHASTA VALLEY, ONLY TO RE-FORM AGAIN LATE THIS EVENING AND
LASTING THROUGH AT LEAST EARLY SUNDAY AFTERNOON.
THE UPPER RIDGE WILL WEAKEN SLIGHTLY AS A WEAK FRONT MOVES IN FROM
THE WEST SUNDAY. GIVEN THE WEAK SHORTWAVE AND SURFACE FRONT WILL BE
RUNNING INTO THE STRONGER UPPER RIDGING, THE MOST LIKELY SCENARIO IS
THE FRONT WILL WEAKEN AND DISSIPATE AS IT REACHES THE COAST SUNDAY
AFTERNOON. PER THE USUAL THE NBM SOLUTION IS TOO BULLISH (MEANING
POPS ARE TOO HIGH AND TOO FAR INLAND) WHICH DOES NOT ADD UP GIVEN
THE ABOVE MENTIONED. TO FURTHER SUPPORT THIS THINKING, THE MAJORITY
OF THE INDIVIDUAL ENSEMBLE MEMBERS, AND THE OPERATIONAL MODELS ALSO
SHOW THE FRONT WEAKENING AND DISSIPATING AS IT REACHES THE COAST AND
INLAND, AND HAS BEEN SHOWING THIS SOLUTION THE PAST FEW DAYS.
SUNDAY WILL BE THE LAST QUIET DAY OF THE FORECAST PERIOD. THE
PATTERN WILL BECOME MORE ACTIVE STARTING MONDAY AND IS LIKELY TO
LAST FOR THE NEXT7-10 DAYS. IN A RELATIVE SENSE, IT WILL SEEM LIKE A
SIGNIFICANT CHANGE WITH BOUTS OF MODERATE TO HEAVY RAIN HIGH
ELEVATION MOUNTAINS SNOW. HOWEVER, IT'S NOT ALL THAT UNUSUAL TO HAVE
ACTIVE WEATHER OF THIS MAGNITUDE THIS TIME OF THE YEAR.
THE FIRST FRONT WILL ARRIVE AT THE COAST EARLY MONDAY MORNING
BRINGING RAIN AND GUSTY WINDS TO THE COAST, NORTH OF CAPE BLANCO.
PRECIPITATION WILL MOVE INLAND DURING THE DAY MONDAY, WITH WINDS
INCREASING EAST OF THE CASCADES. THE BULK OF THE PRECIPITATION
MONDAY WILL BE ALONG THE COAST, COASTAL MOUNTAINS AND CASCADES, MOST
OF THE ROGUE VALLEY COULD END UP DRY DURING THE DAY MONDAY WITH NOT
MUCH MORE THAN A FEW LIGHT RAIN SHOWERS DUE TO THE NON-FAVORABLE
SOUTHWEST FLOW. ALSO AREAS EAST OF THE CASCADES WILL LIKELY GET
LITTLE TO NOTHING, BUT IT WILL BE WINDY IN THE AFTERNOON.
FOR THE REMAINDER OF WEEK, WE'LL HAVE A SERIES OF FRONTS MOVING
THROUGH THE AREA BRINGING MORE RAIN, MOUNTAIN SNOW. MODERATE TO
OCCASIONALLY STRONG WINDS ARE ALSO POSSIBLE TUESDAY NIGHT INTO
WEDNESDAY MORNING EAST OF THE CASCADES, WITH THE HIGHER TERRAIN AT
HIGHEST RISK FOR STRONG WINDS. IT LOOKS LIKE WE'LL CATCH A RELATIVE
BREAK IN THE ACTION WEDNESDAY WHEN SNOW LEVELS LOWER, BUT THAT MEANS
ROAD SNOW CONCERNS WILL BE LIMITED.
A STRONGER STORM WILL ARRIVE THURSDAY BRINGING ANOTHER ROUND OF
MODERATE TO HEAVY PRECIPITATION. STRONG WINDS WILL BE A CONCERN
THURSDAY, ESPECIALLY EAST OF THE CASCADES WHERE SOME OF THE GUIDANCE
SHOWS 700 MB WINDS BETWEEN 60-70 KTS OVER A LARGE CHUNK OF REAL
ESTATE EAST OF THE CASCADES.
THE MAIN ISSUE WILL BE THE TIMING AND EXACT TRACK OF OF EACH
INDIVIDUAL SYSTEM WHICH IS LIKELY TO VARY FROM DAY TO DAY.
LOOKING BEYOND NEXT WEEK LEADING UP TO CHRISTMAS HOLIDAY, THERE'S
STRONG EVIDENCE THAT'S BEING SUPPORTED BY THE ECMWF, GEFS ENSEMBLE
MEANS AND CLUSTERS, WE'LL BE HEADING INTO A COLDER AND WET PATTERN
WITH STORMS ORIGINATING FROM THE GULF OF ALASKA AS WE GET TOWARDS
THE FOLLOWING WEEKEND THROUGH AT LEAST CHRISTMAS DAY.
THESE TYPICALLY RESULT IN COLDER TEMPERATURES, AND PRECIPITATION
WITH LOWER SNOW LEVELS. THE PATTERN SHOWS BELOW NORMAL 500 MB
ANOMALIES WITH A STRONGER UPPER TROUGHING IN THE WESTERN U.S. WITH
RIDGING AND ABOVE NORMAL 500 MB ANOMALIES IN THE NORTHEASTERN PART
OF THE U.S. THE ANOMALIES BEING SHOWN ARE PRETTY SIGNIFICANT THIS
FAR OUT WHICH IS UNUSUAL SINCE THEY TEND TO "WASH OUT" AND LEAN MORE
TOWARDS CLIMATOLOGY.
THIS IS A ALMOST THE OPPOSITE OF THE PATTERN WE HAVE EXPERIENCED FOR
ALMOST THE LAST THREE WEEKS, WITH STRONGER RIDGING IN THE WESTERN
PART OF THE U.S. AND DEEP UPPER TROUGHING IN THE NORTHEASTERN PART
OF THE U.S. IN OTHER WORDS, THE SWITCH BASICALLY GETS FLIPPED AS THE
OVERALL PATTERN CHANGES. -PETRUCELLI
MARINE...UPDATED 1200 PM PST SATURDAY, DECEMBER 13, 2025...RELATIVELY
CALM CONDITIONS WILL PERSIST THROUGH EARLY SUNDAY WITH BREEZY
SOUTH WINDS AND SUB-ADVISORY SEAS EXPECTED. WINDS INCREASE THROUGH
SUNDAY AS A FRONTAL SYSTEM APPROACHES THE AREA. CONDITIONS ARE
LIKELY TO REMAIN BELOW ADVISORY CRITERIA UNTIL SUNDAY AFTERNOON,
BUT WINDS WILL APPROACH ADVISORY CRITERIA NORTH OF CAPE BLANCO
SUNDAY MORNING. THIS COULD LEAD TO A BRIEF PERIOD OF STEEP SEAS
NORTH OF CAPE ARAGO BEFORE MORE WIDESPREAD STEEP SEAS DEVELOP
ACROSS ALL AREAS SUNDAY AFTERNOON.
WORSENING CONDITIONS ARE EXPECTED SUNDAY EVENING INTO MONDAY AS LOW
PRESSURE DEEPENS OVER THE NORTH PACIFIC AND A COLD FRONT SWINGS
THROUGH THE WATERS SUNDAY NIGHT INTO MONDAY. THIS FRONT IS EXPECTED
TO BRING SOUTHERLY GALES TO AREAS NORTH OF CAPE BLANCO AND BEYOND 5
NM FROM SHORE LATE SUNDAY NIGHT THROUGH MONDAY AFTERNOON WITH VERY
STEEP AND HAZARDOUS SEAS EXPECTED FOR ALL OTHER AREAS. WINDS EASE
MONDAY AFTERNOON, BUT WESTERLY SWELL BUILDS (10-12 FT @ 12 SECONDS)
BEHIND THE FRONT WHICH WILL MAINTAIN STEEP SEAS INTO MID-WEEK.
ADDITIONAL FRONTAL SYSTEMS WILL MAINTAIN ACTIVE WEATHER THROUGH THE
WEEK WITH GALES POSSIBLE AGAIN ON TUESDAY AND THURSDAY, ALONG WITH
CONTINUED STEEP TO, AT TIMES, VERY STEEP AND HAZARDOUS SEAS. /BR-Y
MFR WATCHES/WARNINGS/ADVISORIES
OR...CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FROM 1 PM SUNDAY TO 1
AM PST MONDAY FOR PZZ350-356-370-376.
HAZARDOUS SEAS WARNING FROM 1 AM TO 4 PM PST MONDAY FOR PZZ350-
356-370-376.
GALE WARNING FROM 1 AM TO 4 PM PST MONDAY FOR PZZ350-370.
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