993
FXUS66 KMFR 211742
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
1042 AM PDT MON SEP 21 2026
..UPDATED AVIATION DISCUSSION FOR 18Z TAFS
KEY MESSAGES
* SEASONABLE TEMPERATURES AND DRY CONDITIONS WILL PREVAIL MOST OF
THE UPCOMING WEEK BUT TEMPERATURES TREND BELOW NORMAL END OF
WEEK
* RAIN CHANCES INCREASE THURS/FRI (20%-60%) WITH ISOLATED
THUNDERSTORM POSSIBLE (10%-20%)
DISCUSSION
A CLOSED LOW IS PASSING SOUTH OF THE FORECAST AREA TODAY. AS WE
REACH PEAK HEATING TODAY, THERE IS A VERY SMALL CHANCE FOR SOME
CUMULUS BUILDUPS, AND THIS MEANS WE HAVE ABOUT A 5%-10% CHANCE OF
ONE OR TWO BECOMING A SHOWER/THUNDERSTORM OVER NORTHERN CALIFORNIA
WHERE SOME LIFT WILL BE POSSIBLE. MOST LIKELY THERE WONT BE MUCH
ACTIVITY TODAY, AND IT MAY END UP BEING CUMULUS SCATTERED ACROSS
THE AREA. HIGH CLOUDS WILL LIKELY LIMIT DESTABILIZATION AS WELL,
SO THIS IS AN EXTREMELY LOW CHANCE FOR LIGHTNING TODAY BUT WORTH
MENTIONING.
AS THE LOW EXITS TO THE EAST, WE WILL EXPERIENCE MOSTLY ZONAL
FLOW OVER THE FORECAST AREA WHICH WILL LEAD TO GENERALLY QUIET
WEATHER WITH VERY LITTLE IMPACTS/HAZARDS FOR THE FOLLOWING
COUPLE DAYS. THAT SAID, BY THURSDAY THE UPPER FLOW BECOMES MORE
SOUTHWESTERLY AS A TROUGH DEVELOPS OVER THE PACIFIC. DETERMINISTIC
MODELS DIFFER IN THE TROUGH AXIS TIMING COMING OVER THE WEST
COAST AND THE FORECAST AREA, SO CONFIDENCE IS LOW FOR
TIMING/COVERAGE OF POTENTIAL RAIN AND ISOLATED THUNDERSTORMS, BUT
GENERALLY LOOKING AT INCREASING CHANCES FOR BOTH STARTING THURSDAY
AND CONTINUING THROUGH FRIDAY. ACTIVITY AT THIS TIME APPEARS TO
STAY MOSTLY OVER WESTSIDE AREAS. CURRENTLY, INSTABILITY IS VERY
MEAGER, SO NOT EXPECTING MUCH IN THE REALM OF THUNDERSTORM
CHANCES, BUT WE COULD SEE LIGHT RAINFALL ACROSS WESTSIDE AREAS.
THEREAFTER, TEMPERATURES DROP AS THE TROUGH PUSHES EASTWARD. FOR
EXAMPLE, MEDFORD MAY ONLY REACH THE UPPER 60S FOR A HIGH ON FRIDAY
WITH TEMPERATURES STRUGGLING TO REACH THE LOWER 70S THROUGH THE
WEEKEND. IN OTHER WORDS, EXPECTING A COOL DOWN LATER IN THE WEEK
TO BELOW NORMAL TEMPERATURES IN THE WAKE OF THE UPPER TROUGH
ACROSS THE REGION.
AVIATION...21/18Z TAFS
MARINE STRATUS PERSISTS OVER BROOKINGS AND
IN THE UMPQUA VALLEY, WITH IFR/LIFR LEVELS PRESENT AT THE START OF
THE TAF PERIOD. VFR LEVELS ARE PRESENT OVER NORTH BEND FOR THE
MOMENT, WITH EXPECTATION OF STRATUS CLEARING OVER OTHER AREAS BY
EARLY AFTERNOON. A DEEPER MARINE PUSH IS EXPECTED THIS EVENING INTO
EARLY TUESDAY MORNING. THIS PUSH LOOKS TO BRING LEVELS ALONG THE
COAST AND INTO THE UMPQUA VALLEY TO MVFR/IFR LEVELS, WITH CHANCES OF
MVFR CEILINGS REACHING INTO THE ROGUE VALLEY. THESE CEILINGS COULD
LAST THROUGH THE TAF PERIOD BUT CLEAR LATER TUESDAY MORNING.
FOR OTHER INLAND AREAS, VFR LEVELS WITH NORMAL DIURNAL WINDS ARE
EXPECTED THE TA PERIOD. -TAD
MARINE...UPDATED 330 AM PDT MONDAY, SEPTEMBER 21, 2026
GUSTY
NORTH WINDS WILL MAINTAIN STEEP SEAS SOUTH OF CAPE ARAGO THROUGH
THIS EVENING WITH VERY STEEP SEAS OVER THE INNER AND PARTIAL OUTER
WATERS SOUTH OF BROOKINGS STARTING THIS AFTERNOON AS WINDS
INCREASE. WINDS EASE SOME ON TUESDAY AND CONDITIONS WILL IMPROVE
NORTH OF CAPE BLANCO AS SEAS BECOME LESS STEEP AND TRANSITION TO
SWELL DOMINATED. HOWEVER, STEEP TO VERY STEEP SEAS LIKELY PERSIST
SOUTH OF CAPE BLANCO THROUGH TUESDAY EVENING. CONDITIONS GRADUALLY
IMPROVE WEDNESDAY INTO THURSDAY.
MFR WATCHES/WARNINGS/ADVISORIES
OR...CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 11 PM PDT TUESDAY
FOR PZZ356-376.
HAZARDOUS SEAS WARNING FROM 2 PM THIS AFTERNOON TO 11 PM PDT
TUESDAY FOR PZZ356-376.
SMALL CRAFT ADVISORY UNTIL 2 PM PDT THIS AFTERNOON FOR PZZ350-
370.
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