661
FXUS66 KMFR 211959
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
1259 PM PDT MON SEP 21 2026
KEY MESSAGES
* SEASONABLE TEMPERATURES AND DRY CONDITIONS WILL PREVAIL MOST OF
THIS WEEK.
* RAIN CHANCES INCREASE THURS/FRI (20%-60%) WITH ISOLATED
THUNDERSTORM POSSIBLE (10%-20%) ALONG AND WEST OF THE CASCADES.
* THE FRONT WILL BE MOSTLY DRY EAST OF THE CASCADES, BUT WILL
PRODUCE GUSTY SOUTHWEST WINDS.
* COOLER TEMPERATURES AND DRY CONDITIONS ARE THEN EXPECTED THROUGH
THE WEEKEND.
DISCUSSION
A CLOSED UPPER-LEVEL LOW IS PASSING TO THE SOUTH OF
THE FORECAST AREA TODAY, PLACING SOUTHERN OREGON AND FAR NORTHERN
CALIFORNIA UNDER THE DEFORMATION ZONE BETWEEN IT AND THE MAIN BELT
OF WESTERLIES TO OUR NORTH. THIS WILL KEEP CONDITIONS QUIET
ACROSS THE AREA TODAY, WITH PLENTY OF HIGH LEVEL CLOUDS AND SOME
LOCALIZED CUMULUS BUILDUPS, MAINLY OVER HIGHER TERRAIN. THERE IS A
VERY LOW CHANCE ONE OF THE CUMULUS COULD DEEPEN ENOUGH TO FORM A
LIGHT SHOWER, AND AN EVEN SMALLER CHANCE FOR A THUNDERSTORM TO
DEVELOP, HOWEVER, GIVEN THAT HIGH CLOUDS WILL LIKELY LIMIT DAYTIME
HEATING AND DESTABILIZATION, NEITHER OF THESE IS LIKELY TO OCCUR.
AS THE LOW OPENS AND EXITS TO THE EAST, WE WILL EXPERIENCE MOSTLY
ZONAL FLOW OVER THE FORECAST AREA FOR THE NEXT SEVERAL DAYS,
WHICH WILL LEAD TO GENERALLY QUIET WEATHER WITH VERY LITTLE
IMPACTS OR HAZARDS. THE NEXT UPPER-LEVEL TROUGH ARRIVES OFFSHORE
BY EARLY THURSDAY MORNING, THEN IT AND AN ASSOCIATED COLD FRONT
WILL MOVE ONSHORE LATE THURSDAY INTO EARLY FRIDAY THIS WILL
INTRODUCE A CHANCE OF SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS
ALONG AND WEST OF THE CASCADES, BUT THE FRONT WILL BE MOSTLY DRY
AND WILL MAINLY PRODUCE GUSTY WINDS TO THE EAST OF THE CASCADES.
THERE IS STILL SOME UNCERTAINTY ABOUT THE EXACT TIMING OF THESE
FEATURES, WHICH COULD MAKE A DIFFERENCE IN THUNDERSTORM CHANCES.
CURRENT MODEL TRENDS SUGGEST INSTABILITY WILL BE VERY MEAGER, SO
WE ARE NOT EXPECTING MUCH IN THE REALM OF THUNDERSTORM CHANCES,
BUT LIGHT RAINFALL SEEMS LIKELY, ESPECIALLY ALONG THE COAST AND
COASTAL MOUNTAINS.
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 1200 PM PDT MONDAY, SEPTEMBER 21, 2026
GUSTY
NORTH WINDS WILL MAINTAIN STEEP SEAS SOUTH OF CAPE ARAGO THROUGH
THIS EVENING WITH VERY STEEP SEAS DEVELOPING THIS AFTERNOON AS WINDS
INCREASE SOUTH OF BROOKINGS. 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 UNTIL 11 PM PDT TUESDAY FOR PZZ356-376.
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