421
FXUS66 KMFR 161110
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
310 AM PST THU JAN 16 2025
DISCUSSION
A STRONG HIGH PRESSURE RIDGE REMAINS IN PLACE OVER
THE REGION THIS MORNING. THIS PATTERN WILL BRING CONTINUED DRY
WEATHER AND STABLE CONDITIONS TO THE AREA TODAY. STRONG
INVERSIONS ALONG WITH LIGHT WINDS AND LINGERING BOUNDARY LAYER
MOISTURE ARE RESULTING IN AREAS OF VALLEY FOG AND FREEZING FOG
THIS MORNING, WITH FOG MOST WIDESPREAD IN SOUTHWEST OREGON VALLEYS
WEST OF THE CASCADES. AREAS OF DENSE FOG ARE PRESENT, ESPECIALLY
IN THE UMPQUA BASIN AND NEAR GRANTS PASS, AND FREEZING FOG IS
OCCURING FOR VALLEYS IN JOSEPHINE COUNTY AND PORTIONS OF THE ROGUE
VALLEY IN JACKSON COUNTY. ACROSS JACKSON COUNTY, AREAS OF VALLEY
FOG AND FREEZING FOG HAVE DEVELOPED NORTH AND NORTHWEST OF MEDFORD
(INCLUDING WHITE CITY, EAGLE POINT, CENTRAL POINT, GOLD HILL AND
ROGUE RIVER) AND HAS BEEN MORE PATCHY FROM MEDFORD SOUTH. AREAS OF
FREEZING FOG MAY INCREASE EARLY THIS MORNING IN THE MEDFORD AREA
AND TO THE SOUTH, BUT OVERALL, EXPECT THE WORST CONDITIONS TO BE
NORTH OF MEDFORD. DENSE FOG AND FREEZING FOG ADVISORIES ARE IN
EFFECT THROUGH THIS MORNING. PLEASE SEE THE NPWMFR FOR DETAILS.
UNDER STRONG HIGH PRESSURE, AIR STAGNATION AND THE POTENTIAL FOR
REDUCED AIR QUALITY WITH TRAPPED POLLUTANTS, REMAINS A CONCERN
TODAY. MODELS CONTINUE TO SHOW LOW MIXING HEIGHTS AND LIGHT
TRANSPORT WINDS INTO FRIDAY. SO, THE AIR STAGNATION ADVISORY
(NPWMFR) REMAINS IN EFFECT THROUGH FRIDAY AFTERNOON FOR INLAND
VALLEYS ACROSS SOUTHWEST OREGON.
THE RIDGE WILL WEAKEN SLIGHTLY TONIGHT AS AN UPPER LEVEL
SHORTWAVE TROUGH MOVES DOWN THE EASTERN SIDE OF THE RIDGE AND INTO
THE REGION, PASSING BY EAST OF THE AREA ON FRIDAY. A DRY COLD
FRONT IS FORECAST TO ONSHORE THURSDAY EVENING AND NIGHT. HOWEVER
PRECIPITATION CHANCES ARE GENERALLY BELOW 10% EVEN ALONG THE
COASTAL MOUNTAINS. AS THIS DISTURBANCE MOVES DOWN THE RIDGE AND TO
THE EAST, IT WILL WEAKEN THE INVERSIONS SLIGHTLY AND MODELS
CONTINUE TO SHOW A SLIGHTLY IMPROVEMENT IN MIXING BY LATE FRIDAY
AFTERNOON. HOWEVER, EXPECT ANY IMPROVEMENTS TO BE BRIEF AS MODELS
AND ENSEMBLES CONTINUE TO SHOW HIGH CONFIDENCE IN THE UPPER RIDGE
STRENGTHENING THIS WEEKEND AND REMAINING CENTERED JUST OFFSHORE.
TO EAST OF THE AREA, A DEEPENING LONGWAVE TROUGH WILL DEVELOP.
THIS PATTERN MAY RESULT IN BREEZY TO GUSTY EASTERLY WINDS
DEVELOPING LATER IN THE WEEKEND. THIS PATTERN CONTINUES INTO
MONDAY.
UNDER THIS PATTERN OF THE RIDGE CENTERED OFFSHORE AND A DEEPENING
LONGWAVE TROUGH TO THE EAST, EXPECT EASTERLY FLOW OVER THE AREA,
WITH SOME BREEZY TO GUSTY WINDS DEVELOPING ON THE RIDGES FRIDAY
NIGHT INTO THE WEEKEND. ADDITIONALLY, TEMPERATURES WILL TREND
COOLER FRIDAY AND ON THE WEEKEND, WITH COLDER THAN NORMAL
OVERNIGHT LOW TEMPERATURES EXPECTED. THE PROBABILITY FOR LOW
TEMPERATURES LESS THAN 28 DEGREES IS FAIRLY HIGH(~80-100%) FOR
MANY INLAND VALLEY WEST OF THE CASCADES SATURDAY MORNING THROUGH
MONDAY MORNING. NOTE, THE UMPQUA VALLEY MAY REMAIN SLIGHTLY LESS
COLD, BUT STILL NEAR OR BELOW FREEZING. EAST OF THE CASCADES,
SUMMER LAKE AND LOCATIONS IN THE HIGH DESERT ARE EXPECTED SEE
TEMPERATURES IN THE LOWER TEENS TO SINGLE DIGITS WITH TEMPERATURES
IN THE TEENS FOR KLAMATH FALLS, LAKEVIEW AND ALTURAS. DAYTIME
TEMPERATURES ARE EXPECTED TO BE NEAR NORMAL DURING THIS PERIOD.
EARLY TO MID NEXT WEEK, ENSEMBLES CONTINUE TO SHOW DRY WEATHER IS
LIKELY WITH A HIGH PRESSURE RIDGE IN PLACE. WHILE SOME WEAK
DISTURBANCES ARE FORECAST TO MOVE IN FROM THE WEST AND NORTHWEST,
MODELS CONTINUE TO SHOW DRY WEATHER DURING THIS PERIOD. LATE NEXT
WEEK, BEGINNING AROUND THURSDAY NIGHT AND FRIDAY THERE IS A
SLIGHT CHANCE FOR A SHORTWAVE TROUGH AND FRONT TO MOVE INTO THE
REGION AND BRING SOME LIGHT PRECIPITATION INTO THE AREA. THIS CHANCE
IS LOW AND NATIONAL BLEND OF MODELS SHOWS 10-25% CHANCES FOR
PRECIPITATION FROM THE CASCADES WEST, BEGINNING THURSDAY NIGHT.
AVIATION
MARINE STRATUS EXTENDS TO THE BEACHES, AND
LIFR VALLEY FOG COVERS MANY OF THE WEST SIDE VALLEYS. OTHERWISE,
CONDITIONS ARE VFR.
WESTSIDE VALLEY FOG IS EXPECTED TO FOLLOW THE TYPICAL DIURNAL
PATTERN TONIGHT WITH LIFR EXPANDING IN COVERAGE OVERNIGHT INTO
THURSDAY MORNING. THE LIFR STRATUS NEAR THE COAST, INCLUDING NORTH
BEND AND THE COQUILLE VALLEY, IS ALSO EXPECTED TO EXPAND OVERNIGHT.
DURING THURSDAY, WEST SIDE INLAND VALLEYS ARE EXPECTED TO FOLLOW THE
TYPICAL PATTERN OF GRADUAL LIFTING AND EROSION OF THE STRATUS TO VFR
IN THE AFTERNOON. MEANTIME, THE COASTAL STRATUS IS EXPECTED TO LIFT
TO MVFR BUT THICKEN DURING THE DAY.
A WEAK FRONT IS EXPECTED TO ENHANCE THE RE-FORMATION OF VALLEY
LIFR/IFR THURSDAY NIGHT, PRIMARILY FOR THE WEST SIDE, BUT WITH EAST
SIDE PATCHES POSSIBLE AS WELL. -DW
MARINE...UPDATED 830 PM WEDNESDAY, JANUARY 15, 2025
SEAS REMAIN
BELOW ADVISORY LEVEL EARLY THIS MORNING, WITH MARINE STRATUS
DEVELOPING OVER AREA WATERS. A THERMAL TROUGH IS FORECAST TO REBUILD
THIS AFTERNOON, BRINGING GUSTY NORTHERLY WINDS THAT WILL REBUILD
STEEP SEAS IN WATERS SOUTH OF COOS BAY.
THE THERMAL TROUGH STRENGTHENS EARLY FRIDAY MORNING, WITH WINDS
INCREASING SOUTH OF CAPE BLANCO. THESE WINDS ARE EXPECTED TO BUILD
VERY STEEP AND HAZARDOUS SEAS IN WATERS SOUTH OF CAPE BLANCO, WITH
STEEP SEAS CONTINUING IN OTHER WATERS SOUTH OF COOS BAY. SMALL CRAFT
ADVISORIES AND A HAZARDOUS SEAS WARNING ARE IN PLACE TO DESCRIBE
THESE DETERIORATING CONDITIONS.
CONDITIONS IMPROVE ON SATURDAY NIGHT BUT ADVISORY LEVEL SEAS LOOK TO
CONTINUE THROUGH SUNDAY AND POSSIBLY INTO EARLY MONDAY MORNING. -TAD
BEACH HAZARDS
UPDATED 830 PM PST WEDNESDAY, JANUARY 15,
2025...ANOTHER EPISODE OF SNEAKER WAVES WILL BE POSSIBLE SATURDAY
AFTERNOON INTO SUNDAY EVENING. THIS WOULD BE DUE TO A COMBINATION OF
NORTHERLY WIND WAVES, NORTHWEST SWELL AT 11 SECONDS, AND A LONG
PERIOD WEST-NORTHWEST SWELL AT 22 SECONDS. THE RISK IS EXPECTED TO
DIMINISH EARLY NEXT WEEK WITH A DIMINISHING SWELL PERIOD AND LESS
CHAOTIC SEA STATE.
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 MAY OCCUR 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 NOON PST FRIDAY FOR ORZ021-023>026-
029>031.
BEACH HAZARDS STATEMENT FROM SATURDAY AFTERNOON THROUGH SUNDAY
AFTERNOON FOR ORZ021-022.
DENSE FOG ADVISORY UNTIL 10 AM PST THIS MORNING FOR ORZ023.
FREEZING FOG ADVISORY UNTIL 10 AM PST THIS MORNING FOR ORZ024-
026.
CA...NONE.
PACIFIC COASTAL WATERS...BEACH HAZARDS STATEMENT FROM SATURDAY
AFTERNOON THROUGH SUNDAY AFTERNOON FOR PZZ350-356.
SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM PST FRIDAY
FOR PZZ350-356-370-376.
HAZARDOUS SEAS WATCH FROM FRIDAY MORNING THROUGH LATE FRIDAY
NIGHT FOR PZZ376.
CC
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