817
FXUS66 KMFR 031223
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
423 AM PST WED DEC 3 2025
UPDATE
AVIATION DISCUSSION UPDATED.
AVIATION...03/12Z TAFS
ALONG THE COAST, CONDITIONS ARE MAINLY VFR
BUT LOCALIZED IFR IS POSSIBLE THROUGH MID MORNING. INLAND, AREAS OF
VALLEY FOG AND LOW CLOUDS ARE PRESENT WEST OF THE CASCADES WITH
AREAS OF MVFR EAST OF THE CASCADES. FOG AND LOW CLOUDS HAVE
DEVELOPED IN THE UMPQUA VALLEY, ILLINOIS VALLEY AND GRANTS PASS
AREAS. HAVE ALSO KEPT LIFR IN THE TAF FOR MEDFORD, WITH GUIDANCE
SHOWING FOG DEVELOPING EARLY IN THE MORNING. EAST OF THE CASCADES,
MVFR IN LOW CLOUDS HAS DEVELOPED IN SOUTHERN AND EASTERN LAKE
COUNTY, INCLUDING LAKEVIEW. LOW CLOUDS AND FOG WILL LIFT TO VFR IN
THE LATE MORNING OR EARLY AFTERNOON. THEN, EXPECT LOW CLOUDS AND FOG
TO RETURN TO THE UMPQUA VALLEY AND OTHER VALLEYS WEST OF THE
CASCADES WEDNESDAY NIGHT AND EARLY THURSDAY MORNING.
PREV DISCUSSION
/ISSUED 306 AM PST WED DEC 3 2025/
DISCUSSION...
KEY POINTS:
* VALLEY FOG IS PRESENT THIS MORNING. AREAS OF FOG MAY OCCUR
AGAIN TONIGHT AND THURSDAY MORNING.
* CHANCES FOR LIGHT RAIN FOR SOUTHWEST OREGON BEGIN ON THURSDAY,
THEN EXPECT INCREASING CHANCES FOR PRECIPITATION FRIDAY INTO
SATURDAY ACROSS THE AREA.
- PRECIPITATION WILL BE MAINLY LIGHT, WITH A POTENTIAL FOR
LOCALLY MODERATE RAIN ALONG PORTIONS OF THE COAST AND
NORTHERN/NORTHEASTERN DOUGLAS COUNTY.
- SNOW LEVELS WILL BE HIGH, AROUND 6500 FEET OR HIGHER.
* KING TIDES ARE THIS WEEKEND, BUT NOT EXPECTING SIGNIFICANT
IMPACTS/HAZARDS
* SIGNS POINTING TOWARDS ACTIVE WEATHER AROUND DEC 9TH-12TH
- MODERATE TO HEAVY RAIN (WEST OF CASCADES) AND MODERATE TO HEAVY
SNOW (CASCADES)
FURTHER DETAILS:
TODAY, CONDITIONS WILL BE DRY WITH A HIGH PRESSURE RIDGE REMAINING
IN PLACE. MORNING FOG AND LOW CLOUDS ARE LIKELY IN VALLEYS WEST
OF THE CASCADES, LIFTING AND CLEARING IN THE LATE MORNING AND
EARLY AFTERNOON. DAYTIME TEMPERATURES TODAY WILL BE SIMILAR TO
YESTERDAY FOR AREAS WEST OF THE CASCADES, AND WILL BE COOLER THAN
YESTERDAY ACROSS EAST SIDE AREAS.
SATELLITE IMAGERY SHOWS A LOW CENTERED OVER THE ALEUTIAN ISLANDS.
THIS LOW WILL ALLOW SHORTWAVE TROUGHS, ASSOCIATED FRONTS AND
MOISTURE TO MOVE OVER THE RIDGE AND INTO THE PACIFIC NORTHWEST
LATER THIS WEEK AND INTO THE WEEKEND.
ON THURSDAY, DETERMINISTIC MODELS AND ENSEMBLES SHOW A WEAK FRONT
WILL MOVING OVER THE RIDGE AND INTO THE REGION. PRECIPITATION
WITH THIS FRONT IS EXPECTED TO BE MAINLY FOCUSED NORTH OF THE
AREA. HOWEVER, MODELS SUPPORT CHANCES FOR LIGHT PRECIPITATION ON
THURSDAY, ACROSS NORTHERN PORTIONS OF THE CWA IN SOUTHWEST
OREGON. THE NATIONAL BLEND OF MODELS SHOWS HIGHEST CHANCES
(30-60%) FOR LIGHT RAIN WILL BE OVER COOS, DOUGLAS COUNTY,
NORTHERN KLAMATH COUNTY AND NORTHERN/EASTERN LAKE COUNTY WITH
LESSER CHANCES ACROSS OTHER PARTS OF SOUTHWEST OREGON. SNOW
LEVELS WILL RISE AHEAD OF THIS FRONT (RISING TO 7000-8500 FEET)
AND REMAIN HIGH ON THURSDAY.
FRIDAY INTO SATURDAY, THE POTENTIAL FOR PRECIPITATION INCREASES
ACROSS THE AREA AS ADDITIONAL A SHORTWAVE TROUGH AND FRONT MOVE
INTO THE REGION. THE NATIONAL BLEND OF MODELS SUPPORTS HIGH
CHANCES (60-95%) FOR LIGHT TO LOCALLY MODERATE PRECIPITATION
ALONG THE COAST, INTO DOUGLAS COUNTY AND THE SOUTH-CENTRAL OREGON
CASCADES ON FRIDAY. THERE ARE ALSO LOW TO MODERATE CHANCES
(10-50%) FOR LIGHT PRECIPITATION ACROSS OTHER PARTS OF SOUTHWEST
OREGON AND INTO FAR WESTERN SISKIYOU COUNTY IN NORTHERN
CALIFORNIA. PRECIPITATION CHANCES INCREASE FRIDAY INTO SATURDAY,
HIGHEST FROM THE CASCADES WEST (70-100%) AND INTO AREAS EAST OF
THE CASCADES AND OVER WESTERN SISKIYOU (50-80%). OTHER AREAS IN
CENTRAL/EASTERN SIKSYOU AND MODOC WILL ALSO SEE CHANCES FOR
PRECIPITATION (20-50% CHANCE) LATE FRIDAY INTO SATURDAY.
PRECIPITATION WILL BE MAINLY LIGHT AND SINCE SNOW LEVELS WILL
REMAIN ELEVATED (GENERALLY 6500 FT OR HIGHER), EXPECT THIS TO FALL
AS MOSTLY RAIN EXCEPT OVER THE HIGHEST PEAKS. THEN, MODELS
INDICATE CHANCES FOR PRECIPITATION PERSIST INTO SUNDAY. OF NOTE,
WITH ANY BREAKS IN PRECIPITATION, EXPECT CHANCES FOR VALLEY FOG
AND LOW CLOUDS TO DEVELOP IN THE NIGHTTIME AND MORNING PERIODS.
NEXT WEEK: LOOKING AHEAD, CLUSTER ANALYSIS FOR 500MB ANOMALIES IS
SPLIT SHOWING A POTENTIAL TROUGH MOVING IN THE AREA DEC 9TH-12TH
WHICH COULD LEAD TO A SLIGHT RISK OF MODERATE TO HEAVY RAINFALL
AND MODERATE TO HEAVY, HIGHER ELEVATION, SNOWFALL. HOWEVER, GIVEN
THE SPLIT THERE IS A LOT OF UNCERTAINTY. ADDITIONALLY, THIS IS
PRETTY FAR OUT AND A LOT COULD CHANGE. WE ARE WATCHING THIS TIME
PERIOD FOR POTENTIAL ACTIVE WEATHER. SOON, WE WILL BE ABLE TO
NARROW DOWN THE TIMING, IMPACTS, AND OVERALL HAZARDS. FOR NOW, WE
WILL WAIT FOR NEW DATA AND CONTINUE TO MONITOR.
MARINE...UPDATED 200 AM PST WEDNESDAY, DECEMBER 3,
2025...ADVISORY LEVEL NORTH WINDS WILL MAINTAIN STEEP SEAS SOUTH
OF CAPE BLANCO THROUGH THURSDAY MORNING. LONG PERIOD, SWELL
DOMINATED SEAS WILL PERSIST NORTH OF CAPE BLANCO. CONDITIONS
IMPROVE THURSDAY AFTERNOON AS WINDS WEAKEN AND SEAS WILL LOWER
THROUGH FRIDAY. HAZARDOUS CONDITIONS MAY RETURN OVER THE WEEKEND A
FRONT MOVES INTO THE AREA FROM THE NORTH-NORTHWEST. GUSTY SOUTH
WINDS AND STEEP SEAS MAY DEVELOP OVER PORTIONS OF THE WATERS,
MAINLY NORTH OF CAPE BLANCO, SATURDAY NIGHT INTO SUNDAY.
MFR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 10 AM PST
THURSDAY FOR PZZ356-376.
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