178
FXUS66 KMFR 121046
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
246 AM PST FRI DEC 12 2025
DISCUSSION
SATELLITE IMAGERY EARLY THIS MORNING SHOWS SOME
SPOTTY MID TO HIGH LEVEL CLOUDS PASSING OVER THE AREA, WHILE
NEARLY ALL OF THE VALLEYS WEST OF THE CASCADES REMAIN FILLED WITH
EITHER FOG OR LOW STRATUS CLOUDS AS STRONG INVERSIONS PERSIST.
THE OVERALL PATTERN IS NOT GOING TO CHANGE MUCH THROUGH SATURDAY
WITH STRONG UPPER RIDGING KEEPING THE STORM TRACK WELL NORTH OF THE
FORECAST AREA. THIS MEANS CONTINUED DRY AND MILD WEATHER (WHERE LOW
CLOUDS AND FOG ARE ABSENT). THE LOW CLOUDS AND FOG FOR THE AREAS
MENTIONED ABOVE WILL KEEP AFTERNOON TEMPERATURES IN CHECK FRIDAY AND
SATURDAY. IT'S NOT OUT OF THE QUESTION LOW CLOUDS IN THE ROGUE
AND ILLINOIS VALLEY WILL PERSIST THROUGH FRIDAY AFTERNOON AS WELL.
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. THE NBM IS BRINGING RAIN INTO THE COAST AS
EARLY AS SATURDAY NIGHT. THIS IS TOO SOON, ESPECIALLY CONSIDERING
THAT ALL ENSEMBLE MEMBERS ARE DRY THROUGH SUNDAY NIGHT, SO HAVE
BACKED OFF ON THE RAIN FORECAST UNTIL A MORE ROBUST FRONT ARRIVES
LATE SUNDAY INTO MONDAY.
BASICALLY SUNDAY IS LIKELY TO END UP BEING THE LAST QUIET DAY OF THE
FORECAST PERIOD. THE OPERATIONAL MODELS AND ENSEMBLES HAVE BEEN
SHOWING FOR THE PAST FEW DAYS A MORE ACTIVE PATTERN SETTING UP BY
THE START OF NEXT WEEK. IN A RELATIVE SENSE, IT WILL SEEM LIKE A
SIGNIFICANT CHANGE WITH BOUTS OF MODERATE TO HEAVY RAIN AND MOUNTAIN
SNOW ALONG WITH MODERATE TO STRONG WINDS POSSIBLE AT THE COAST, AND
EAST OF THE CASCADES ON MONDAY. HOWEVER, IT'S NOT ALL THAT UNUSUAL
TO HAVE ACTIVE WEATHER OF THIS MAGNITUDE THIS TIME OF THE YEAR.
THE CHANGE IN THE PATTERN IS ONE WHERE WE'LL SEE A PARADE OF
FRONTS MOVING THROUGH THE AREA FROM MONDAY-FRIDAY NEXT WEEK
BRINGING MORE RAIN, MOUNTAIN SNOW, AND MODERATE TO OCCASIONALLY
STRONG WINDS.
THE MAIN ISSUE WILL BE THE TIMING OF EACH INDIVIDUAL SYSTEM WHICH IS
LIKELY TO VARY IN THE DAYS TO COME.
LOOKING BEYOND NEXT WEEK LEADING UP TO CHRISTMAS HOLIDAY, THERE'S
INCREASING 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.
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
THE LAST COUPLE OF WEEKS. IN OTHER WORDS, THE SWITCH BASICALLY
GETS FLIPPED NEXT WEEK AS THE OVERALL PATTERN CHANGES.
-BPN/PETRUCELLI
AVIATION...12/12Z TAFS
MUCH LIKE YESTERDAY, STRONG HIGH PRESSURE
IS IN CONTROL AND LOW LEVEL MOISTURE IS PERSISTING IN VALLEYS. AREAS
OF LOW STRATUS AND FOG ARE PRESENT IN VALLEYS WEST OF THE CASCADES,
INCLUDING IFR IN THE ROGUE VALLEY AT MEDFORD AND GRANTS PASS AND
LIFR IN FOG IN THE SHASTA VALLEY AS WELL AS PATCHY FOG IN THE UMPQUA
AND COQUILLE VALLEYS. THESE CONDITIONS WILL PERSIST THROUGH FRIDAY
MORNING AND SOME AREAS, SUCH AS MEDFORD, ARE EXPECTED TO SEE
MVFR/IFR LOW CLOUDS INTO THE AFTERNOON ON FRIDAY. ALONG THE COAST,
AREAS OF FOG WITH IFR/LIFR ARE PRESENT (INCLUDING AT NORTH BEND).
THESE CONDITIONS WILL PERSIST INTO FRIDAY MORNING, BEFORE LIFTING TO
VFR. LOW FLIGHT CONDITIONS ARE LIKELY TO RETURN, OR WILL PERSIST,
FOR THESE AREAS TONIGHT. EAST OF THE CASCADES, EXPECT MAINLY VFR
THROUGH THE TAF PERIOD. -BPN
MARINE...UPDATED 200 AM PST FRIDAY, DECEMBER 12, 2025
LIGHT TO
MODERATE NORTH WINDS AND MODERATE WEST SWELL WILL PERSIST THROUGH
FRIDAY NIGHT. GRADUALLY, WINDS SHIFT TO SOUTHERLY SATURDAY AND
INCREASE INTO SUNDAY, BUT STILL PROBABLY REMAIN BELOW SMALL CRAFT
ADVISORY LEVELS.
LOW PRESSURE THEN DEEPENS OVER THE NORTH PACIFIC AND A COLD FRONT
WILL SWING THROUGH THE WATERS SUNDAY NIGHT INTO MONDAY. THIS WILL
BRING A HIGH PROBABILITY OF GALES (>70%) AND A PERIOD OF STEEP TO
VERY STEEP HAZARDOUS SEAS. A SERIES OF FRONTAL SYSTEMS IS LIKELY TO
KEEP THE WEATHER ACTIVE WITH ELEVATED WINDS AND SEAS MUCH OF NEXT
WEEK. -SPILDE/BPN
MFR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
CA...DENSE FOG ADVISORY UNTIL 9 AM PST THIS MORNING FOR CAZ081.
PACIFIC COASTAL WATERS...NONE.
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