116
FXUS66 KMFR 162221
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
221 PM PST FRI JAN 16 2026
DISCUSSION
AN UPPER LEVEL RIDGE WILL REMAIN IN CONTROL OVER THE
AREA FOR SEVERAL MORE DAYS. TEMPERATURES WILL BE UNSEASONABLY WARM
OUTSIDE OF THE WEST SIDE VALLEYS, WITH STRONG INVERSIONS RESULTING
IN COLDER TEMPERATURES WITHIN THOSE VALLEYS.
PERSISTENCE REMAINS THE APPROPRIATE DESCRIPTION FOR THE DURATION
OF THE FORECAST. WHILE AREAS OUTSIDE OF THE INLAND VALLEYS WILL BE
RELATIVELY WARM, DRY, AND WITH CLEAR SKIES, THE INTERIOR VALLEYS
WILL CONTINUE TO EXPERIENCE STRONG INVERSIONS AND STAGNANT AIR.
ACCORDING TO THE NBM, THERE IS A 30-40 PERCENT CHANCE FOR FOG IN
THE VALLEYS WEST OF THE CASCADES TONIGHT, AND ROUGHLY 25 PERCENT
CHANCE OF TEMPERATURES AT OR BELOW FREEZING. TYPICALLY, THIS
PATTERN RESULTS IN PERSISTENT FOG AND FREEZING FOG WITHIN THE
VALLEYS, WITH SOME AREAS CLEARING IN THE AFTERNOON, AND OTHERS
NEVER CLEARING AT ALL, BEFORE FOG REFORMS AND SPREADS OUT WITHIN
THE VALLEYS ONCE AGAIN AFTER SUNSET. WITH THE EARLIER CLEARING IN
THE UPPER ROGUE VALLEY TODAY, FOG MAY BE MUCH LATER TO REFORM
THERE TONIGHT, IF AT ALL. IN SOME SITUATIONS IN THE PAST, FOG
NEVER FORMS AND INSTEAD A VERY HEAVY FROST DEVELOPS INSTEAD.
DESPITE THE HIGHER PROBABILITY IN THE NBM, WHICH WAS DRASTICALLY
UNDERDONE YESTERDAY, THE PATTERN TODAY LENDS ITSELF TO MUCH MORE
UNCERTAINTY, MAINLY IN FOG ONSET TIMES AND LOCATIONS. THEREFORE,
HAVE HELD OF ON ANY NEW FOG/FREEZING FOG ADVISORIES UNTIL
CONFIDENCE IMPROVES, OR FOG FORMS, WHICHEVER COMES FIRST.
AN AIR STAGNATION ADVISORY REMAIN IN EFFECT OUT TO TUESDAY NEXT
WEEK, ALONG WITH A STATE ISSUED AIR QUALITY ADVISORY FOR LAKE
COUNTY, ALSO THROUGH TUESDAY.
THE MODELS CONTINUE TO SHOW THE RIDGE BREAKING DOWN AND THE
INTRODUCTION OF PRECIPITATION CHANCES AND MIXING AIR. THESE
RIDGES ARE VERY WELL KNOWN TO TAKE A LONG TIME TO BREAK DOWN, AND
THIS ONE IS NO EXCEPTION. DESPITE THE NBM SAYING THE BREAKDOWN
OCCURS WEDNESDAY OR THURSDAY, EXPERIENCE AND THE BULK OF THE
LONGER RANGE MODEL SUITES SAY IT COULD BE AS LATE AS LATE NEXT
WEEK, RIGHT AROUND THE END OF THE MONTH. -BPN
AVIATION...16/18Z TAFS
HIGH PRESSURE ALOFT JUST OFF THE PACNW
COAST AND A THERMAL TROUGH ALONG THE COAST ARE BRINGING MOSTLY
MODERATE OFFSHORE FLOW ACROSS INTERIOR SW OREGON AND NORTHERN
CALIFORNIA. MOST AREAS HAVE CLEARED TO VFR, BUT PERSISTENT LIFR
LOW CLOUDS AND FOG ARE IMPACTING THE UMPQUA BASIN AND ROGUE
VALLEY, INCLUDING ROSEBURG AND GRANTS PASS. IFR/LIFR WILL PERSIST
IN THESE AREAS, WITH NO OR VERY BRIEF CLEARING LATE AFTERNOON OR
EVENING.
LOW CLOUD/FOG IS EXPECTED TO FORM IN MOST WEST SIDE INLAND VALLEYS
AGAIN THIS EVENING AND TONIGHT, SIMILAR TO THE PAST SEVERAL
NIGHTS. HOWEVER, SOME INDICATION ARE THAT FOG MAY BE SLOWER TO
DEVELOP AND LESS WIDESPREAD. OTHERWISE, THE SAME GENERAL
CYCLE OF NIGHT/MORNING FOG AND DAYTIME IMPROVEMENT WILL PERSIST.
MODEL GUIDANCE INDICATES OFFSHORE FLOW EASING AS THE THERMAL TROUGH
WEAKENS TODAY. THIS COULD LEAD TO A SOUTHERLY STRATUS SURGE UP THE
COAST OR THROUGH THE COASTAL WATERS LATER TONIGHT.
MARINE...UPDATED 200 PM PST FRIDAY, JANUARY 16, 2026.
SEAS REMAIN
BELOW ADVISORY LEVEL THROUGH THE WEEKEND. NORTHERLY WINDS LOOK TO
INCREASE ON MONDAY, WHICH MAY BUILD LOCALIZED AREAS OF STEEP SEAS IN
OUTER WATERS. WINDS LOOK TO EASE INTO TUESDAY AND WEDNESDAY. -TAD
MFR WATCHES/WARNINGS/ADVISORIES
OR...AIR STAGNATION ADVISORY UNTIL 10 AM PST TUESDAY FOR ORZ023-024-
026-029>031.
CA...NONE.
PACIFIC COASTAL WATERS...NONE.
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