882
FXUS66 KMFR 281451
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
651 AM PST SUN DEC 28 2025
DISCUSSION
AVIATION DISCUSSION UPDATED.
AVIATION...28/12Z TAFS
A WEAK DISTURBANCE MOVING OVERHEAD HAS
BROUGHT HIGH CLOUDS INLAND. THESE CLOUDS ARE SHIFTING EASTWARD EARLY
THIS MORNING. OFFSHORE FLOW WILL MINIMIZE CHANCES FOR
OVERNIGHT/MORNING LOW CLOUDS AND FOG DEVELOPMENT ALONG THE COAST,
BUT INLAND VALLEYS WILL SEE IFR TO LIFR CONDITIONS THIS MORNING. LOW
CLOUDS AND AREAS OF FOG HAVE DEVELOPED IN THE UMPQUA VALLEY
(INCLUDING ROSEBURG), THE GRANTS PASS AREA, AS WELL AS THE ILLINOIS
VALLEY. GUIDANCE AND MODEL SOUNDINGS SUPPORT LOW CLOUDS OR FOG
DEVELOPING IN THE MEDFORD AREA. HOWEVER CONFIDENCE IS LOW FOR IFR OR
LIFR AT MEDFORD THIS MORNING DUE TO LIGHT SURFACE WINDS OF 2 TO 3
KT. LOW CLOUDS AND FOG WILL CLEAR IN THE LATE MORNING AND EARLY
AFTERNOON WITH VFR EXPECTED AREAWIDE. EAST OF THE CASCADES,
CONDITIONS ARE MAINLY VFR WITH ONLY ISOLATED LOW CLOUDS OR FOG.
LATE TONIGHT AND MONDAY MORNING, VALLEY FOG AND LIFR IS EXPECTED
TO DEVELOP ONCE AGAIN, INCLUDING AT ROSEBURG, GRANTS PASS AND
MEDFORD.
PREV DISCUSSION
/ISSUED 257 AM PST SUN DEC 28 2025/
DISCUSSION...A WEAK UPPER LEVEL DISTURBANCE IS MOVING DOWN THE
EASTERN SIDE OF THE PACIFIC HIGH AND ACROSS THE AREA THIS
MORNING. THIS IS BRINGING HIGH CLOUDS INTO THE AREA. THE HIGH
PRESSURE RIDGE, CENTERED JUST OFFSHORE, WILL STRENGTHEN OVER THE
AREA TODAY, THEN REMAIN IN PLACE THROUGH WEDNESDAY. THIS PATTERN
WILL BRING STABLE AND DRY WEATHER TO THE AREA WITH LIGHT EASTERLY
FLOW OVER THE RIDGES. VALLEYS ARE EXPECTED TO SEE NIGHTTIME AND
MORNING FOG OR LOW CLOUDS.
OVERNIGHT, AREAS OF LOW CLOUDS AND FOG HAVE DEVELOPED IN THE
UMPQUA VALLEY AND GRANTS PASS AREAS. AS HIGH CLOUDS SHIFT
EASTWARD EARLY THIS MORNING, EXPECT PARTIAL CLEARING OVER THE
MEDFORD AREA WITH CHANCES FOR FOG TO DEVELOP IN THE MORNING HOURS.
FURTHER EAST AND SOUTH, CONFIDENCE IS LOWER AND HIGH CLOUDS MAY
LIMIT THE DEVELOPMENT OF FOG AND LOW CLOUDS. NATIONAL BLEND OF
MODELS CONTINUES TO SHOW CHANCES (20%) FOR LOW CLOUDS AND FOG
DEVELOPING IN THE KLAMATH BASIN THOUGH. FOG AND LOW CLOUDS IS
EXPECTED TO CLEAR IN THE LATE MORNING AND EARLY AFTERNOON.
TEMPERATURES TODAY WILL TREND SLIGHTLY WARMER COMPARED TO
YESTERDAY FOR MOST AREAS.
THIS GRADUAL WARMING TREND CONTINUES THROUGH WEDNESDAY. THE
AMOUNT OF VALLEY FOG MAY VARY EACH DAY. HOWEVER, GUIDANCE
INDICATES FOG AND LOW CLOUDS ARE LIKELY IN VALLEYS DURING THE
OVERNIGHT AND MORNING HOURS TONIGHT THROUGH WEDNESDAY DUE TO
LINGERING BOUNDARY LAYER MOISTURE COMBINED WITH STABLE CONDITIONS,
LIGHT WINDS AND CLEAR SKIES. IN ADDITION TO VALLEY FOG, THE HIGH
PRESSURE OVER THE AREA WILL BRING A POTENTIAL FOR STAGNANT AIR
CONDITIONS, WITH LIMITED MIXING AND LIGHT WINDS. WE ARE MONITORING
FOR AIR STAGNATION CONDITIONS AND WILL UPDATE AS NEEDED.
LATE IN THE WEEK, MODEL SOLUTIONS CONTINUE TO POINT TO A MORE
ACTIVE WEATHER PATTERN DEVELOPING WITH LOW PRESSURE SYSTEM MOVING
TOWARDS THE AREA FROM THE NORTHWEST AND ANOTHER LOW MOVING UP
FROM THE SOUTHWEST. THIS PATTERN WILL RESULT IN CHANCES FOR
PRECIPITATION MOVING INTO THE AREA BEGINNING AROUND NEW YEAR'S
DAY. FOR DETAILS ON THIS PATTERN, PLEASE SEE THE EXTENDED
DISCUSSION BELOW.
MARINE...GUSTY NORTH WINDS AND STEEP SEAS ARE OCCURRING THIS
MORNING OVER THE WATERS SOUTH OF CAPE BLANCO BEYOND 10 NM FROM
SHORE. GUSTY NORTH WINDS AND STEEP SEAS WILL EXPAND LATE THIS
AFTERNOON AND EVENING TO INCLUDE THE WATERS SOUTH OF BANDON BEYOND
5 NM FROM SHORE AND THE WATERS BETWEEN COOS BAY AND BANDON BEYOND
10 NM FROM SHORE. WINDS AND SEAS WILL LOWER SUNDAY NIGHT INTO
MONDAY MORNING, THEN REMAIN RELATIVE LIGHT THROUGH WEDNESDAY.
PREV EXTENDED DISCUSSION... /ISSUED 329 PM PST SAT DEC 27 2025/
DISCUSSION...BEYOND WEDNESDAY AFTERNOON, A BROAD TROUGH IN THE
GULF OF ALASKA, AND A WEAKER (BUT, POTENTIALLY DEVELOPING) TROUGH
OFFSHORE FROM CENTRAL CALIFORNIA WILL SHIFT TOWARD THE WEST COAST.
THE NBM LOOKS A HIGHLY APPROPRIATE SOLUTION FOR THE LATTER PART
OF THE WEEK, INDICATING GRADUALLY INCREASING PRECIPITATION
CHANCES, WITH THE HIGHEST PROBABILITY THURSDAY NIGHT INTO FRIDAY
NIGHT. THE ECMWF ENSEMBLE, IN COMPARISON WITH THE GEFS, HAS A MORE
SIZABLE MINORITY OF MEMBERS THAT MORE STRONGLY DEEPEN THE
CALIFORNIAN TROUGH AND WOULD CREATE A SCENARIO AROUND NEW YEAR'S
DAY WITH SOME RESEMBLANCE TO THE WEATHER OF CHRISTMAS DAY. THIS
WOULD BE RELATIVELY HIGH SNOW LEVELS (ABOVE 4500 FEET OR HIGHER),
BUT WITH MODERATE TO HEAVY PRECIPITATION FOR NORTHERN CALIFORNIA.
OF HIGHER PROBABILITY IS THAT THE FLOW ALOFT WILL MORE BROADLY
SPLIT WITH OUR REGION AFFECTED BY THE GENERALLY WEAKER SOUTHERN
PORTION OF THE NORTHERN BRANCH OF THE JET STREAM. THIS WOULD BE
COLDER, PLACING SNOW LEVELS AROUND 3000 TO 4500 FEET, BUT WITH
LOWER PRECIPITATION AMOUNTS THAN IN THE AFOREMENTIONED SCENARIO.
MORE IN THE REALM OF POTENTIAL ADVISORY LEVEL SNOWFALL LATE IN THE
WEEK WITH A FOCUS FOR THE CASCADES, RATHER THAN A WARNING EVENT.
PLEASE STAY TUNED FOR UPDATES.
MFR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FROM 4 PM THIS
AFTERNOON TO 4 AM PST MONDAY FOR PZZ350-356-370-376.
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