882
FXUS66 KMFR 100024
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
524 PM PDT TUE SEP 9 2025
DISCUSSION
UPDATED AVIATION DISCUSSION.
AVIATION...10/00Z TAFS
A MOIST PATTERN CONTINUES, WITH WIDESPREAD
SHOWERS FROM THE CASCADES WEST AND SCATTERED SHOWERS EAST OF THE
CASCADES. ADDITIONALLY THERE WILL BE CHANCES FOR EMBEDDED
THUNDERSTORMS, MAINLY IN THE AFTERNOON AND EVENING. MAIN RISKS WITH
THUNDERSTORMS WILL BE HEAVY DOWNPOURS AND LIGHTNING, BUT GUSTY WINDS
ALSO CANNOT BE RULED OUT.
ALONG THE COAST, MVFR AND IFR WITH AREAS OF LIFR ARE EXPECTED
OVERNIGHT AND WEDNESDAY MORNING, LIFTING TO A MIX OF VFR AND MVFR IN
THE AFTERNOON. INLAND, CONDITIONS WILL BE MAINLY VFR WITH AREAS OF
MOUNTAIN OBSCURATIONS AS WELL AS AS AREAS OF MVFR CEILINGS IN THE
UMPQUA VALLEY THIS EVENING THROUGH WEDNESDAY MORNING.
PREV DISCUSSION
/ISSUED 220 PM PDT TUE SEP 9 2025/
DISCUSSION...LOW PRESSURE WILL SLOWLY MOVE ONSHORE THIS THROUGH
THIS EVENING. THE UPPER LOW IS EXPECTED TO PIVOT NEAR THE COAST,
CONSOLIDATE, AND THEN HEAD ACROSS NORCAL TONIGHT INTO WEDNESDAY.
THE AIR MASS IS QUITE JUICY FOR THIS TIME OF YEAR. KMFR SOUNDINGS
FROM MONDAY EVENING INDICATE PWATS AT AROUND 1.20", WHICH IS UP
AROUND THE 90TH PERCENTILE FOR THE DATE. WITH THE UPPER LOW MOVING
OVERHEAD TODAY, WE'LL SEE A CONTINUATION OF SHOWERS WITH EMBEDDED
THUNDERSTORMS, AND IN LINE WITH THAT IDEA, CURRENT RADAR IS
SHOWING WIDESPREAD SHOWERS ACROSS THE AREA THIS AFTERNOON, WITH
DRIER AREAS ALONG THE FAR EAST SIDE AND A "HOLE-IN-THE-DONUT"
RIGHT OVER THE ROGUE VALLEY. RAINFALL WITH THESE SHOWERS HAS BEEN
MOSTLY LIGHT TO MODERATE, ALTHOUGH A FEW HAVE RESULTED IN SOME
BRIEF HEAVY DOWNPOURS. THERE HASN'T BEEN ANY LIGHTNING IN THE AREA
SO FAR THIS AFTERNOON, BUT MODEL SOUNDINGS SHOW SOME TALL, SKINNY
CAPE AND THIS MAY LEAD TO SOME LIGHTNING AGAIN, ESPECIALLY THIS
AFTERNOON AND EVENING. PROFILES WEST OF THE CASCADES ARE
EXHIBITING ALMOST- TROPICAL CHARACTERISTICS, SO STORMS SHOULD HAVE
FAIRLY WEAK UPDRAFTS, BUT DUE TO THE HIGH MOISTURE CONTENT IN THE
ATMOSPHERE, THE MAIN RISK WITH STORMS TODAY WILL BE HEAVY
DOWNPOURS. EXPECT HIGH TEMPS ABOUT 10-15F BELOW NORMAL FOR MOST
INLAND AREAS, UP TO 20F IN SOME CASES. HOWEVER, COASTAL AREAS WILL
HAVE HIGH TEMPS RIGHT AROUND NORMAL.
THE MAIN AXIS OF ACTIVITY (SHOWERS AND THUNDERSTORMS) WILL SHIFT
FROM WEST OF THE CASCADES TODAY TO NORCAL AND FROM THE CASCADES
EASTWARD (80% POPS) ON WEDNESDAY AS THE CORE OF THE UPPER LOW
MOVES INTO NE CALIFORNIA. THE RESULTING FLOW WILL LEAD TO UPSLOPE
RAIN PRODUCTION ON THE EAST SLOPES OF THE CASCADES, BUT THE
DOWNSLOPING WILL RESULT IN LESS SHOWER CHANCES TO THE WEST. THERE
WILL STILL BE SOME SHOWERS FROM THE CASCADE FOOTHILLS WESTWARD ON
WEDNESDAY, BUT SHOWER CHANCES DIMINISH TO 30% OR LESS NEAR THE
COAST. WE'RE EXPECTING ANOTHER COOL AFTERNOON WITH HIGH TEMPS
LARGELY 10-15F (UP TO 20F IN SOME AREAS AGAIN) BELOW NORMAL,
EXCEPT NEAR NORMAL AT THE COAST. WETTING RAINFALL SHOULD BE
REALIZED IN MOST AREAS EAST OF THE CASCADES.
ON THURSDAY, WE EXPECT A BROAD CIRCULATION TO BE OVER THE GREAT
BASIN, SO THIS SHOULD PUSH THE MAIN FOCUS AREAS FOR SHOWERS AND
THUNDERSTORMS TO NEAR AND EAST OF THE CASCADES.
BY FRIDAY, A SHORT WAVE UPPER RIDGE WILL BUILD INTO THE WEST
COAST, SO MOST AREAS WILL DRY OUT AND WARM UP. HIGH TEMPS WILL BE
CLOSER TO NORMAL WEST OF THE CASCADES, BUT ISOLATED TO SCATTERED
SHOWERS COULD LINGER OVER PORTIONS OF THE EAST SIDE WHERE HIGHS
TEMPS WILL STILL BE ABOUT 10F BELOW NORMAL. THE UPPER RIDGE WILL
REMAIN IN PLACE THROUGH SATURDAY AND SHOWER CHANCES SHOULD REMAIN
LOW INLAND (BUT UP TO 30% AT THE COAST DURING THE AFTERNOON).
THEN, MODELS ARE SHOWING ANOTHER TROUGH MOVING IN SATURDAY NIGHT
INTO SUNDAY. THERE ARE STILL SOME UNCERTAINTIES WITH TIMING AND
STRENGTH OF THIS SYSTEM, BUT SHOWERS CHANCES INCREASE TO LIKELY
(~60%) NEAR THE COAST SATURDAY NIGHT AND EVENTUALLY INLAND DURING
SUNDAY. THIS BRINGS A BRIEF COOL DOWN, BUT ANOTHER UPPER RIDGE
COULD RETURN BY EARLY NEXT WEEK. -SPILDE/BPN
MARINE...UPDATED 200 PM PDT TUESDAY, SEPTEMBER 9, 2025...SHOWERS
WILL DIMINISH THROUGH THIS AFTERNOON AND EVENING. BELOW ADVISORY
CONDITIONS LIKELY PERSIST THROUGH MIDWEEK, THOUGH NORTH WINDS
COULD BE BRIEFLY GUSTY, ESPECIALLY SOUTH OF CAPE BLANCO, TONIGHT
INTO WEDNESDAY.
NORTHERLY WINDS COULD BE A BIT STRONGER IN THE FAVORED
LOCATION SOUTH OF PORT ORFORD AND BETWEEN 5 AND 30 NM FROM SHORE
DURING THE AFTERNOONS TUESDAY AND WEDNESDAY. WHILE SUB-ADVISORY
CONDITIONS ARE LIKELY TO PERSIST THROUGH THE END OF THE WEEK AND
INTO THE WEEKEND, SEAS DO INCREASE SOME DURING THE LATTER HALF OF
THE WEEK (FROM 3-5 FT TO 5-7 FT)AS A LOW NORTHWEST SWELL (5-6 FT @
12-14 SECONDS) BUILDS INTO THE WATERS STARTING THURSDAY AND
PERSISTING INTO THE WEEKEND.
MFR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...NONE.
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