935
FXUS66 KMFR 151154
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
354 AM PST MON DEC 15 2025
DISCUSSION (TODAY THROUGH SUNDAY)
KEY POINTS:
* A PERIOD OF ACTIVE WEATHER BEGINS TODAY
* TODAY THROUGH TOMORROW NIGHT: MINOR/MODERATE IMPACTS
- MODERATE TO ISOLATED HEAVY RAINFALL ALONG/NEAR THE COAST
- HIGH SNOW LEVEL: MON/TUES ABOVE 6000 FEET
- LIGHT SNOWFALL AMOUNTS WEDNESDAY FOR ELEVATIONS 4000+ FT
- STRONG WINDS: HIGH WIND WATCH FOR WEDNESDAY
* THURSDAY - FRIDAY NIGHT: MODERATE TO ISOLATED MAJOR IMPACTS
- SNOW: HEAVIEST FRIDAY/FRIDAY NIGHT
- CASCADES NORTH OF HIGHWAY 140
- SNOW LEVELS DROPPING TO AROUND 3500-4000FT
- ADVISORY/WARNING SNOWFALL AMOUNTS
- RAIN: MODERATE TO HEAVY RAINFALL FOR WESTSIDE AREAS
- HEAVIEST RAINFALL ALONG AND NEAR THE COAST
- WIND: STRONG WIND FOR EASTSIDE AREAS THURS/FRI
FURTHER DETAILS:
GENERALLY SPEAKING, THE OVERALL UPPER LEVEL PATTERN WILL BE NOTED BY
TROUGHING OVER THE GULF OF ALASKA WITH SMALLER PIECES OF ENERGY
KICKING OUT AHEAD OF THIS MAIN LOW PRESSURE AREA. THIS WILL RESULT
IN MULTIPLE ROUNDS OF PRECIPITATION THIS WEEK AS ENERGY ALOFT PASSES
THROUGH THE PACNW. INITIALLY, RAIN AND SNOWFALL AMOUNTS WILL BE
LOWER EARLY IN THE WEEK COMPARED TO LATER IN THE WEEK. AT THIS TIME,
WE ARE EXPECTING MINOR TO MODERATE IMPACTS TODAY AND TOMORROW FROM
PRECIPITATION, FOLLOWED BY POTENTIALLY STRONG WINDS ON WEDNESDAY.
THEN IMPACTS WILL BE HIGHER THURSDAY AND FRIDAY POTENTIALLY
LINGERING IN TO SATURDAY WITH MODERATE TO ISOLATED AREAS OF MAJOR
IMPACTS FROM PRECIPITATION (RAIN AND SNOW) AND WIND.
BOTH TODAY AND TUESDAY WILL HAVE A RISK FOR HEAVY RAINFALL FOR AREAS
MAINLY ALONG AND NEAR THE COAST. LATE THIS MORNING/EARLY AFTERNOON,
RAINFALL RATES ALONG/NEAR THE COAST MAY APPROACH 0.25"/HR,
ESPECIALLY ACROSS CURRY COUNTY (40% CHANCE), AND THIS MAY LAST
THROUGH THE AFTERNOON HOURS. EXPECTING A BREAK IN ACTIVITY TONIGHT
INTO EARLY TUESDAY MORNING. ACTIVITY PICKS UP AGAIN TUESDAY NIGHT
INTO WEDNESDAY MORNING WHEN 6HR RAINFALL COULD (30%-75%) APPROACH
0.50" OR GREATER FOR WESTSIDE AREAS AND CASCADES.
ON WEDNESDAY, SNOW LEVELS DO DROP LOW ENOUGH TO ALLOW ACCUMULATIONS
FOR AREAS AT 4000 FEET AND ABOVE. NOT EXPECTING ADVISORY LEVEL
SNOWFALL ACCUMULATIONS, BUT THIS SNOWFALL WILL BE A WELCOME TO A
VERY LOW-END START TO THE SEASON ACROSS OUR MOUNTAINS. THE BIGGER
IMPACT WILL LIKELY BE THE STRONG WIND SPEEDS FOR EASTSIDE AREAS
AND NORTHERN CALIFORNIA. A WIND ADVISORY IS LIKELY, BUT THERE MAY
BE SOME AREAS OF HIGH WIND WARNING AS WELL. WILL ALLOW THE WATCH
TO CONTINUE AS WE ANALYZE MORE DATA WITH UPGRADE ADJUSTMENTS
LIKELY WITHIN THE NEXT 12-24 HOURS.
PRECIPITATION THURSDAY THROUGH FRIDAY NIGHT WILL BE MOST IMPACTFUL
THIS WEEK AS ORTHOGONAL FLOW ALOFT SHOULD MAXIMIZE LIFT THROUGH
TOPOGRAPHY INFLUENCES AS WELL AS UPPER DYNAMICS. WHILE WIDESPREAD
FLOODING IS NOT ANTICIPATED, THERE MAY BE ISOLATED AREAS OF
NUISANCE TYPE FLOODING. WE WILL HAVE TO WAIT AND SEE HOW RAINFALL
EARLY THIS WEEK PANS OUT BECAUSE THIS MAY LEAD TO CHANGES IN
FLOODING POTENTIAL. HOWEVER, RIVERS ARE CURRENTLY RUNNING LOW
WHICH LIMITS THE THREAT OF RIVER FLOODING. THAT SAID, THERE WILL
LIKELY BE HAZARDOUS DRIVING CONDITIONS FOR SEVERAL DAYS THIS WEEK
AS ANY AMOUNT OF RAINFALL CAN LEAD TO AN INCREASED RISK FOR
DRIVING HAZARDS. THE HEAVIEST RAINFALL THROUGH THIS STRETCH WILL
BE FOR WESTSIDE AREAS, ESPECIALLY ALONG/NEAR THE COAST. CURRENTLY
THERE IS A 25%-50% CHANCE FOR AT LEAST 0.50"/6HR OF RAINFALL FOR
WESTSIDE AREAS. SNOWFALL AMOUNTS MAY END UP BEING THE HIGHEST WE
HAVE SEEN SO FAR THIS SEASON THURSDAY-FRIDAY NIGHT. SNOW RATIOS
MAY BE A LITTLE HIGH RIGHT NOW WHICH COULD BE LEADING TO INFLATED
AMOUNTS AS SNOW LEVELS DON'T DROP BELOW 5000 FEET UNTIL FRIDAY
AFTERNOON. IN OTHER WORDS, WE STILL HAVE SOME DETAILS TO REFINE,
BUT THE CURRENT FORECAST IS SHAPING UP TO BE THE HEAVIEST SNOWFALL
WE HAVE SEEN THIS SEASON.
-GUERRERO
AVIATION (12Z TAFS)
RAINFALL WILL SPREAD ACROSS THE REGION TODAY LIKELY IMPACTING ALL
THE TERMINALS AT SOME POINT THROUGH THIS CYCLE. LOW LEVEL
MOISTURE WILL LEAD TO LOW CLOUDS AND FOG WHICH WILL BRING
WIDESPREAD IFR TO MVFR CONDITIONS. IFR TO LIFR POTENTIAL EXISTS
EARLY THIS MORNING AND AGAIN OVERNIGHT TONIGHT FOR WESTSIDE
VALLEYS (KRBG AND KMFR). OVERALL, THIS CYCLE CAN BE SUMMED UP AS
UNFAVORABLE CONDITIONS AT THE TERMINALS GIVEN THE RAINFALL AND
INCREASED LOW LEVEL MOISTURE ANTICIPATED THROUGH THIS CYCLE.
-GUERRERO
MARINE...UPDATED 300 AM PST MONDAY, DECEMBER 15, 2025
SOUTH
WINDS INCREASE TO GALES NORTH OF CAPE BLANCO AND BEYOND 1-2 NM
FROM SHORE WITH SEAS BECOMING VERY STEEP AND HAZARDOUS FOR ALL
AREAS THROUGH THIS AFTERNOON. WINDS EASE LATE THIS 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.
MFR WATCHES/WARNINGS/ADVISORIES
OR...HIGH WIND WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON
FOR ORZ030-031.
CA...HIGH WIND WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON
FOR CAZ085.
PACIFIC COASTAL WATERS...HAZARDOUS SEAS WARNING UNTIL 4 PM PST THIS
AFTERNOON FOR PZZ350-356-370-376.
GALE WARNING UNTIL 4 PM PST THIS AFTERNOON FOR PZZ350-370.
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