453
FXUS66 KMFR 270453 CCA
AFDMFR
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE MEDFORD OR
953 PM PDT SUN APR 26 2026
UPDATE
UPDATED AVIATION AND MARINE DISCUSSIONS.
PREV DISCUSSION... /ISSUED 218 PM PDT SUN APR 26 2026/
KEY MESSAGES...
*COOL TEMPERATURES WITH SCATTERED SHOWERS FROM THE CASCADES
SOUTH AND EAST INTO MONDAY EVENING (FOCUSED IN NORCAL).
*ISOLATED T-STORMS IN NORCAL THIS EVENING.
*SEASONABLE ELSEWHERE WITH ISOLATED SHOWERS.
*NIGHTTIME/MORNING CLOUDS/DRIZZLE ALONG COAST/COASTAL VALLEYS
NORTH OF CAPE BLANCO, MAY REACH ROSEBURG AT TIMES MON/TUE.
*SHOWER ACTIVITY SHIFTS SOUTHEASTWARD TUESDAY.
*WARMING TREND WEDNESDAY-FRIDAY.
*MORE ACTIVE NEXT WEEKEND?
DISCUSSION...AN UPPER TROUGH IS OVERHEAD TODAY AND THIS IS
RESULTING IN WIDELY SCATTERED SHOWERS AND EVEN SOME ISOLATED
THUNDERSTORMS. THE FOCUS FOR ACTIVITY WILL BE IN NORCAL THROUGH
LATE THIS EVENING, BUT ISOLATED SHOWERS COULD POP UP HERE OR THERE
IN SW OREGON AS WELL. THIS IS BEING SUPPORTED BY COLDER AIR ALOFT
ASSOCIATED WITH THE TROUGH, MODEST MOISTURE IN THE MID-LEVELS AND
RESULTANT WEAK INSTABILITY OF 100-250 J/KG. EXPECT ACTIVITY TO
DECREASE OVERNIGHT AS INSTABILITY WANES. MARINE LAYER WILL DEEPEN
AGAIN TONIGHT WITH CLOUDS/FOG AND PERHAPS EVEN SPOTTY DRIZZLE
IMPACTING THE COAST/VALLEYS NORTH OF CAPE BLANCO. SOME OF THIS MAY
SPREAD INTO THE UMPQUA BASIN TOWARD MORNING, BUT SHOULD BREAK UP
INTO STRATOCUMULUS AND PEEL BACK CLOSER TO THE COAST MONDAY
AFTERNOON.
MEANWHILE, THE MAIN UPPER TROUGH AXIS WILL SHIFT EAST OF THE
CASCADES ON MONDAY AS AN UPPER DISTURBANCE DROPS SOUTHWARD JUST
OFF THE COAST. SOME MOISTURE/WEAK INSTABILITY WILL LINGER ACROSS
THE AREA, SO STILL EXPECT AT LEAST ISOLATED SHOWERS TO DEVELOP
FROM THE CASCADES SOUTH AND EAST MONDAY AFTERNOON/EVENING.
TEMPERATURES THROUGH MONDAY WILL BE COOLER THAN NORMAL FOR MOST,
BUT SEASONABLE WEST OF THE CASCADES.
ON TUESDAY, SHOWER CHANCES DROP OUT OF THE FORECAST, BUT THERE IS
A LOW PERCENTAGE OF MEMBERS (ABOUT 10%) THAT PRODUCE SHOWERS
ACROSS SE SISKIYOU/MODOC COUNTIES. MOST AREAS SEE MODEST WARMING
(ABOUT 3-6F) COMPARED TO SUN/MON.
AN UPPER RIDGE IS THEN EXPECTED TO MOVE IN MID-LATE THIS WEEK
BRINGING A PERIOD OF DRY AND WARMER WEATHER WITH HIGH TEMPERATURES
(AREAS INLAND FROM THE COAST) GENERALLY 10-15F ABOVE NORMAL FOR
LATE APRIL AND EARLY MAY. THIS MEANS HIGH TEMPERATURES RANGING
FROM 75-85F FOR MOST INLAND WEST SIDE VALLEYS. COASTAL AREAS COULD
CONTINUE TO EXPERIENCE INTRUSIONS OF LATE-NIGHT/MORNING MARINE
STRATUS.
MODELS THEN SHOW THE RIDGE BREAKING DOWN BY THIS WEEKEND AS AN
UPPER TROUGH JUST OFF THE WEST COAST TRIES TO CLOSE OFF OFFSHORE.
AN INCREASING NUMBER OF SOLUTIONS SHOW THE LOW CLOSING OFF TO OUR
SW, WHICH WOULD BRING AN INCREASED RISK FOR MAINLY AFTERNOON AND
EVENING SHOWERS AND THUNDERSTORMS SATURDAY, WITH THE POTENTIAL FOR
ACTIVE WEATHER PERSISTING SUNDAY INTO EARLY NEXT WEEK. MUCH WILL
DEPEND ON THE EVENTUAL TRACK OF TROUGH/LOW, HOWEVER. MANY MEMBERS,
PARTICULARLY FROM THE GEFS ENSEMBLES, MAINTAIN A WEAKER TROUGH
MOVING THROUGH, WHICH WOULD LIMIT THE OVERALL EXTENT/COVERAGE OF
PRECIPITATION. WE'LL ADJUST THE FORECAST AS THINGS COME MORE INTO
FOCUS. -SPILDE
AVIATION...27/06Z TAFS
ONSHORE FLOW HAS BROUGHT MVFR CEILINGS
AND TERRAIN OBSCURATIONS TO THE OREGON COAST AND THE COASTAL
MOUNTAINS. THESE WILL PERSIST OVERNIGHT AND INTO THE MORNING, THEN
CLEAR BACK TO THE COASTAL WATERS BY LATE MORNING OR EARLY AFTERNOON
SOME POCKETS OF DRIZZLE ARE ALSO POSSIBLE LATER TONIGHT.
THERE IS A 50% CHANCE THAT SOME OF THESE LOWER CLOUDS ARE ABLE TO
MAKE IT TO ROSEBURG AND PRODUCE MORE MVFR CEILINGS IN THE UMPQUA
BASIN, BUT NOT ENOUGH CONFIDENCE TO PUT IN THE TAF THERE.
IN NORTHERN CALIFORNIA AND OVER THE EAST SIDE, SHOWERS WILL CONTINUE
TO DIMINISH THROUGH THE EVENING, AND SOME MAY LINGER INTO THE EARLY
MORNING. SHOWERS WILL RETURN TO THESE AREAS MONDAY AFTERNOON, BUT
COVERAGE SHOULD BE MORE SCATTERED. MVFR/IFR CONDITIONS WITH TERRAIN
OBSTRUCTIONS ARE POSSIBLE IN ANY HEAVIER SHOWERS.
OTHERWISE AND ELSEWHERE, VFR WILL PREVAIL.
MARINE...UPDATED 800 PM PDT SUNDAY, APRIL 26, 2026
NORTH WINDS
WILL PERSIST THROUGH THE WEEK WITH A LOW NORTH WEST SWELL KEEPING
SEAS AROUND 5 TO 7 FEET.
NORTHERLY WINDS INCREASE AGAIN LATE TUESDAY, ESPECIALLY SOUTH OF
CAPE BLANCO, AND PERSIST THROUGH MUCH OF THE WEEK. HIGH AND STEEP
SEAS ARE LIKELY WEDNESDAY NIGHT INTO SATURDAY AS A THERMAL TROUGH
BUILDS IN AND REMAINS ALONG THE COAST.
MFR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...NONE.
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