870
FXUS66 KMFR 181127
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
327 AM PST SAT JAN 18 2025
DISCUSSION
FOG AND LOW STRATUS HAVE FILLED IN THE ROGUE,
UMPQUA, ILLINOIS, AND APPLEGATE VALLEYS THIS MORNING AS HIGH
PRESSURE REMAINS IN CONTROL OVERHEAD. DESPITE THIS LOW LEVEL
MOISTURE, JUST ABOVE THE INVERSIONS THERE IS VERY DRY AIR IN THE
MID LAYERS WITH LIGHTER EAST FLOW ALOFT, KEEPING THE HIGHER
TERRAIN AND THE EAST SIDE UNDER CLEAR SKIES. MOST OF THESE CLOUDS
AND FOG SHOULD BURN OFF BY LATE MORNING AND EARLY AFTERNOON, BUT
CANNOT RULE OUT THE POSSIBILITY THAT SOME AREAS MAY REMAIN SOCKED
IN ALL DAY.
WITH THE STRONG INVERSIONS IN PLACE, AND WITH NO ACTIVE WEATHER TO
BREAK THEM, STAGNATE AIR CONDITIONS ARE ONCE AGAIN EXPECTED IN
AREA VALLEYS. AN AIR STAGNATION ADVISORY HAS BEEN ISSUED FOR THIS,
WITH THE NEXT CHANCE TO BREAK INVERSIONS ARRIVING IN THE FORM OF A
WEAK TROUGH THAT MAY PASS THROUGH THE AREA TUESDAY OR WEDNESDAY.
A COASTAL THERMAL TROUGH HAS DEVELOPED, AND WITH THE DRY EAST
FLOW, TEMPERATURES WILL STAY WARM AROUND THE BROOKINGS AREA.
GUIDANCE IS SUGGESTING HIGHS IN THE MID 50'S, WHICH SHOULD BE THE
WARMEST LOCATION IN OUR FORECAST AREA THIS AFTERNOON.
THE RIDGE WILL REMAIN JUST TO OUR WEST, AND WITH THE VERY BROAD,
DEEP TROUGH COVERING ALMOST THE ENTIRE CONTINENT, WE WILL REMAIN
UNDER NORTH FLOW ALOFT. A FEW SHORTWAVES MAY PASS OVERHEAD OVER
THE NEXT SEVERAL DAYS AS THEY TRAVERSE THIS FLOW, BUT THERE WILL
BE LITTLE TO NO DISCERNIBLE EFFECTS AT THE SURFACE. IN OTHER
WORDS, THE DAY-TO-DAY FORECAST WILL CHANGE VERY LITTLE FOR MUCH OF
THE WEEK.
THERE IS A CHANCE FOR CHANGE BY THE END OF THE WEEK. THE MAJORITY
OF ENSEMBLE MEMBERS ARE BRINGING PRECIPITATION TO THE PACIFIC
NORTHWEST FRIDAY OR PERHAPS OVER THE WEEKEND, BUT THE NATURE OF
THE SYSTEM IS VERY DIFFERENT ACROSS THE VARIOUS SOLUTIONS IN THE
ENSEMBLE SUITES. AS OF NOW, IT LOOKS LIKE INCREASED CHANCES FOR
LIGHT PRECIPITATION, WITH LIGHT SNOW ABOVE ROUGHLY 4000 FEET, BUT
THE DETAILS REMAIN VERY UNCERTAIN. -BPN
AVIATION...18/12Z TAFS
A DEEP MARINE LAYER IS IMPACTING
INTERIOR WEST SIDE VALLEYS THIS MORNING. ROSEBURG IS CURRENTLY MVFR
WITH A CEILING WAVERING BETWEEN 1100-1600 FT. THIS COULD LOWER TO
IFR THIS MORNING FOR A WHILE BEFORE LIFTING BACK TO MVFR LATE
MORNING/AFTERNOON. CEILINGS COULD THEN RISE TO VFR BRIEFLY LATE
THIS AFTERNOON, BUT IFR/MVFR CONDITIONS RETURN TONIGHT. A SIMILAR
SITUATION IS OCCURRING IN MEDFORD, BUT LIFR FOG IS LIMITING
VISIBILITY TO 1/4 OF A MILE AT TIMES. THIS WILL CONTINUE THROUGH MID-
LATE MORNING BEFORE LIFTING TO A CEILING, THEN BREAKING FOR A
COUPLE OF HOURS THIS AFTERNOON/EVENING. EXPECT LOWER CONDITIONS TO
RETURN AS WELL TONIGHT. ELSEWHERE, VFR WILL PREVAIL THROUGH LATE
TONIGHT.
-SPILDE
MARINE...UPDATED 200 AM SATURDAY, JANUARY 18, 2025
VARYING
STRENGTH IN A THERMAL ALONG THE COAST WILL KEEP MODERATE NORTH
WINDS AND STEEP SEAS OVER THE WATERS SOUTH OF CAPE BLANCO AT TIMES
THIS WEEKEND. CONDITIONS WILL BE HAZARDOUS TO SMALL CRAFT TODAY,
ESPECIALLY BEYOND 10 NM FROM SHORE. WINDS EASE A BIT TONIGHT, BUT
MAY INCREASE AGAIN SUNDAY AFTERNOON AND NIGHT RESULTING IN STEEP
SEAS. WINDS DO WEAKEN ENOUGH MONDAY INTO TUESDAY FOR CONDITIONS
TO FALL BELOW ADVISORY LEVELS AND REMAIN THAT WAY THROUGH
THURSDAY. ANOTHER PERIOD OF MODERATE TO STRONG NORTH WINDS
AND STEEP SEAS IS POSSIBLE FRIDAY INTO NEXT WEEKEND. -SPILDE
BEACH HAZARDS...UPDATED 230 AM PST SATURDAY, JANUARY 18, 2025
CONDITIONS CONDUCIVE TO HAZARDOUS SNEAKER WAVES RISE AGAIN THIS
AFTERNOON THROUGH EARLY SUNDAY EVENING. ANOTHER LONG PERIOD WEST-
NORTHWEST SWELL ARRIVES EARLY THIS AFTERNOON WITH A PERIOD AROUND 21
SECONDS. THESE LONG PERIOD WAVES CAN CAUSE WAVE RUN UP MUCH HIGHER
THAN USUAL AT AREA BEACHES. THE RISK IS HIGHEST ON INCOMING TIDES.
THE THREAT IS EXPECTED TO DIMINISH SUNDAY NIGHT WITH A LOWERING
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 10 AM PST TUESDAY FOR ORZ021-
023>026-029>031.
BEACH HAZARDS STATEMENT FROM 1 PM PST THIS AFTERNOON THROUGH
SUNDAY AFTERNOON FOR ORZ021-022.
FREEZING FOG ADVISORY UNTIL NOON PST TODAY FOR ORZ024-026.
CA...NONE.
PACIFIC COASTAL WATERS...BEACH HAZARDS STATEMENT FROM 1 PM PST THIS
AFTERNOON THROUGH SUNDAY AFTERNOON FOR PZZ350-356.
SMALL CRAFT ADVISORY UNTIL 4 AM PST EARLY THIS MORNING FOR
PZZ350-356-370-376.
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