746
FXUS66 KMFR 141202
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
402 AM PST TUE JAN 14 2025
..UPDATED AVIATION DISCUSSION
DISCUSSION
AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL PERSIST
OVER THE PACIFIC NORTHWEST THROUGH EARLY THURSDAY. THIS IS
RESULTING IN DRY WEATHER, STABLE CONDITIONS AND STRONG VALLEY
INVERSIONS ACROSS THE AREA. EXPECT FOG/FREEZING FOG AND LOW
CLOUDS EACH OVERNIGHT AND MORNING IN VALLEYS WEST OF THE SOUTHERN
OREGON CASCADES. ISOLATED VALLEY FOG MAY ALSO OCCUR EAST OF THE
CASCADES AND FOR SOME VALLEYS IN NORTHERN CALIFORNIA (SISKIYOU AND
MODOC COUNTIES) BUT CONFIDENCE IS LOWER. STRONG INVERSIONS AND
LITTLE MIXING WILL ALSO RESULT IN CONTINUED AIR STAGNATION
CONDITIONS FOR INLAND VALLEYS THROUGH EARLY THURSDAY. OTHERWISE,
TEMPERATURES WILL GRADUALLY TREND WARMER THROUGH THURSDAY,
ALTHOUGH ANY VALLEY AREAS THAT SEE PERSISTENT FOG OR LOW CLOUDS
INTO THE AFTERNOON MAY STAY COOLER WITH LITTLE CHANGE IN
TEMPERATURE.
DENSE FOG AND FREEZING FOG ARE A CONCERN THROUGH THIS MORNING FOR
VALLEYS WEST OF THE CASCADES. OBSERVATIONS INDICATE THAT AREAS OF
DENSE FOG AND FREEZING FOG ARE OCCURING IN VALLEYS IN DOUGLAS,
EASTERN CURRY, JOSEPHINE AND JACKSON COUNTY. THIS IS RESULTING IN
LOW VISIBILITIES, DOWN TO LESS THAN A QUARTER MILE. FREEZING FOG
MAY ALSO RESULT IN ICY SPOTS ON ROADWAYS, ESPECIALLY FOR BRIDGES
AND OVERPASSES. WE HAVE ISSUED A DENSE FOG ADVISORY (DOUGLAS
COUNTY) AND FREEZING FOG ADVISORY (EASTERN CURRY, JOSEPHINE AND
JACKSON COUNTIES) FOR THESE CONDITIONS, WHICH IS IN EFFECT THROUGH
LATE TUESDAY MORNING. PLEASE SEE THE NPWMFR FOR DETAIL.
AIR STAGNATION WILL BE A CONCERN THROUGH AT LEAST THURSDAY
MORNING, WITH STRONG VALLEY INVERSIONS AND VERY LITTLE MIXING. AN
AIR STAGNATION ADVISORY (NPWMFR) REMAINS IN PLACE FOR INLAND
VALLEYS THROUGH THURSDAY MORNING. A WEAK FRONT WILL PASS JUST
NORTH AND EAST OF THE AREA THURSDAY, AND THIS MAY HELP BREAK THE
INVERSIONS AT LEAST BRIEFLY, BUT CONTINUED HIGH PRESSURE AFTER
THAT IS EXPECTED TO ONCE AGAIN LOCK THE AREA DOWN UNDER STRONG
INVERSIONS.
THE RIDGE OVER THE AREA WILL WEAKEN THURSDAY EVENING THROUGH
FRIDAY MORNING AS A SHORTWAVE TROUGH AND A WEAKENING FRONT MOVE
INTO THE PACNW. AS THE FRONT PASSES BY TO THE NORTH, THERE IS A
LOW CHANCE (5-10%) FOR LIGHT SHOWERS ACROSS COOS AND DOUGLAS
COUNTIES AND INTO THE SOUTHERN OREGON CASCADES. THEN, THE THE
UPPER LEVEL RIDGE RESTRENGTHENS, CENTERED OFFSHORE, WHILE AN UPPER
LEVEL TROUGH DEEPENS EAST OF THE AREA. THIS WILL BRING A DRY,
STABLE, AND NORTHERLY FLOW PATTERN TO THE AREA THROUGH THE WEEKEND
AND INTO EARLY NEXT WEEK.
AVIATION...14/12Z TAFS
VFR LEVELS ARE EXPECTED ACROSS MOST OF
NORTHERN CALIFORNIA AND SOUTHERN CALIFORNIA THROUGH THIS TAF PERIOD.
FOG HAS DEVELOPED IN VALLEYS WEST OF THE CASCADES, BRINGING IFR AND
LIFR LEVELS AT ROSEBURG AND MEDFORD TERMINALS. THESE LEVELS LOOK TO
CONTINUE THROUGH THE MORNING. VISIBILITIES ARE LIKELY TO IMPROVE IN
WEST SIDE VALLEYS, BUT GUIDANCE IS SPLIT ON IF CEILINGS WILL CLEAR
OUT OR PERSIST. FOR BOTH TERMINALS, IFR OR LIFR CONDITIONS ARE
EXPECTED TO RETURN THIS EVENING. -TAD
MARINE...UPDATED 200 AM TUESDAY, JANUARY 14, 2025
STEEP SEAS
CONTINUE TODAY FOR AREAS SOUTH OF COOS BAY AND BEYOND 10 NM FROM
SHOES. GUSTY NORTHERLY WINDS AND PERSISTING WESTERLY SWELL ARE
BUILDING SEAS HAZARDOUS TO SMALL CRAFT AND COULD CONTINUE TO DO SO
FOR THESE AREAS THROUGH WEDNESDAY MORNING.
SEAS ARE FORECAST TO BE BELOW ADVISORY LEVELS WEDNESDAY MORNING AND
THROUGH THE DAY THURSDAY. BY LATE THURSDAY AFTERNOON, A DEVELOPING
THERMAL TROUGH COULD BRING GUSTY NORTHERLY WINDS TO MOST AREA
WATERS. STEEP TO VERY STEEP AND HAZARDOUS SEAS ARE EXPECTED BY
THURSDAY EVENING AND COULD CONTINUE THROUGH THE WEEKEND. THE
STRONGEST WINDS AND HAZARDOUS SEAS ARE FORECAST TO BE SOUTH OF CAPE
BLANCO. ADDITIONAL GUIDANCE WILL HELP TO SOLIDIFY THE TIMING AND
AREAS AFFECTED BY THESE CONDITIONS. -TAD
BEACH HAZARDS
UPDATED 1000 AM PST MONDAY, JANUARY 13,
2025...WE EXTENDED THE BEACH HAZARDS STATEMENT. SEAS ARE STILL IN
THE 9-12 FT RANGE AT 16 SECONDS THIS MORNING AND THIS COULD LAST
THROUGH THIS EVENING. EVEN THOUGH SEAS ARE EXPECTED TO COME DOWN
BRIEFLY THIS AFTERNOON AND TONIGHT, ANOTHER LONG PERIOD WEST-
NORTHWEST SWELL (6-8 FT/19 SECONDS) WILL MOVE IN ON TUESDAY
MAINTAINING A MODERATE RISK OF SNEAKER WAVES ALONG SOUTHERN OREGON
BEACHES. THE RISK IS HIGHER FOR WEST FACING BEACHES AND ON INCOMING
TIDES. HIGH TIDES DURING THE EVENT ARE THIS EVENING, TUESDAY MORNING
AND AFTER 7 PM TUESDAY EVENING.
SNEAKER WAVES ARE A TYPE OF WAVE THAT CAN RUN HIGHER UP THE BEACH
THAN A NORMAL WAVE. SNEAKER WAVES CAN POSSIBLY WASH OVER PATHWAYS OR
ROCK OUTCROPPINGS. THEY CAN LIFT AND CARRY LOGS, WHICH CAN THEN
STRIKE OR PIN BEACHGOERS. SNEAKER WAVES CAN KNOCK A PERSON OFF THEIR
FEET AND CARRY THEM OUT TO DEEPER WATERS, WHERE HYPOTHERMIA BECOMES
POSSIBLE. SNEAKER WAVES CAN POSE A LETHAL THREAT. AS THESE
CONDITIONS ARE EXPECTED WHILE THE SUN IS DOWN, VISIBILITY WILL BE
LIMITED. ALWAYS KEEP YOUR EYES ON THE SEA AND USE EXTRA CAUTION.
MFR WATCHES/WARNINGS/ADVISORIES
OR...AIR STAGNATION ADVISORY UNTIL 10 AM PST THURSDAY FOR ORZ021-
023>026-029>031.
BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR ORZ021-022.
CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 10 AM PST
WEDNESDAY FOR PZZ370-376.
CC
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