534
FXUS66 KMFR 182129
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
229 PM PDT SUN MAY 18 2025
DISCUSSION
NORTHWESTERLY FLOW ALOFT CONTINUES TO BRING CLOUDY
SKIES TO THE UMPQUA VALLEY AND OVER ELEVATED TERRAIN, BUT OTHERWISE
COOL TEMPERATURES AND MILD CONDITIONS CONTINUE THIS AFTERNOON.
UPPER FLOW LOOKS TO BECOME MORE ZONAL ON MONDAY. THIS WILL ALLOW FOR
MOST INLAND AREAS TO WARM TO SEASONAL LEVELS, ALTHOUGH COASTAL
AREAS AND THE UMPQUA VALLEY MAY STAY COOLER. A WEAK FRONT WILL MOVE
ALONG THE ZONAL FLOW, BRINGING THE POSSIBILITY OF LIGHT SHOWERS WEST
OF THE CASCADES. SHOWER CHANCES OVER CURRY, COOS, AND DOUGLAS
COUNTIES WILL BE MODERATE TO HIGH (40-80% CHANCES) THROUGH THE DAY
MONDAY, BUT AMOUNTS WILL BE LIGHT. HIGHER TERRAIN COULD SEE UP TO
0.3 TO 0.5 INCHES, WITH WEST SIDE VALLEYS GETTING LESS THAN 0.1
INCH OF RAIN.
ZONAL FLOW CONTINUES THROUGH THE WEEK, ALLOWING TEMPERATURES TO WARM
SLIGHTLY AND STEADILY THROUGH THE WEEK. FROM THE MIDDLE TO THE END
OF THE WEEK, THE OREGON COAST WILL BE IN THE LOW TO MID 60S. WEST
SIDE VALLEYS WILL BE IN THE MID TO HIGH 70S, WHILE AREAS EAST OF THE
CASCADES LOOK TO BE IN THE LOW TO MID 70S. SOME SMALLER ATMOSPHERIC
DISTURBANCES REMAIN IN THE FORECAST. A BUNDLE OF UPPER LEVEL
INSTABILITY LOOKS TO MOVE OVER THE AREA WEDNESDAY AND THURSDAY.
WHILE SLIGHT SHOWER CHANCES (10-30%) ARE IN THE FORECAST, ANYTHING
THAT DOES FORM WILL BE OVER HIGHER TERRAIN AND WILL BE JUST BARELY
MORE THAN A TRACE AT MOST. ON FRIDAY, A WEAK FRONT LOOKS TO PASS
OVER THE AREA WITH EVEN LOWER SHOWER CHANCES (5-15%) AND SOME GUSTY
WINDS TO HIGHER TERRAIN.
AN UPPER RIDGE LOOKS TO START BUILDING ON SATURDAY, BRINGING STABLE
CONDITIONS THROUGH THE WEEKEND AND WARMER TEMPERATURES ON SUNDAY.
CURRENT DETERMINISTIC GUIDANCE MOVES THE RIDGE AXIS TO THE EAST AS
THE RIDGE DEVELOPS, WHICH WILL LIMIT ADDITIONAL HEATING. CURRENT NBM
AND ECMWF GUIDANCE BRINGS THE OREGON COAST UP TO THE HIGH 60S WHILE
WEST SIDE VALLEYS LOOK TO BE IN THE LOW TO MID 80S. AREAS EAST OF
THE CASCADES COULD REACH THE MID 70S TO LOW 80S. THERE IS SOME
UNCERTAINTY WITH THIS WARMING, AS GFS DETERMINISTIC IMAGERY SHOWS A
TROUGH MOVING SOUTH OF THE AREA, WHICH WOULD ALLOW FOR COOLER
TEMPERATURES. METEOGRAM MEMBERS FOR THE GFS GENERALLY LEAN A LITTLE
COOLER AS WELL, WITH HIGHS SAYING IN THE MID TO HIGH 70S. A FEW
MEMBERS DO MATCH UP WITH THE RIDGE TEMPERATURES, REACHING THE LOW TO
MID 80S.
GIVEN THE DIVERGING MODEL OUTCOMES FOR THE WEEKEND, THERE'S NO
SURPRISE THAT UNCERTAINTY CONTINUES INTO THE FOLLOWING WEEK.
METEOGRAMS FOR BOTH ECMWF AND GFS SHOW CHANCES FOR PRECIPITATION,
BUT THE TIMING IS SOMEWHAT SCATTERED THROUGH THE WEEK AND AMOUNTS
VARY. FORECAST HIGHS DO TREND BACK DOWN TO SEASONAL LEVELS FOR
MEMORIAL DAY AND BEYOND, AT LEAST FOR NOW. -TAD
AVIATION...18/18Z TAFS
VFR LEVELS ARE PRESENT ACROSS NORTHERN
CALIFORNIA AND SOUTHERN OREGON. THE ONE EXCEPTION IS SOME LOCAL MVFR
CEILINGS THROUGH 20Z IN THE UMPQUA, INCLUDING AT ROSEBURG AND AREAS
OF HIGHER MOUNTAIN OBSCURATIONS OVER THE SOUTHERN OREGON CASCADES
THROUGH EARLY AFTERNOON. GUSTY WINDS ARE FORECAST OVER AREAS EAST OF
THE CASCADES THIS AFTERNOON, THEN CALMING INTO THE EVENING. LATE
THIS EVENING, MVFR CEILINGS ARE EXPECTED TO DEVELOP ALONG THE COAST.
MARINE....UPDATED 200 PM SUNDAY, MAY 18, 2025
QUIET CONDITIONS
CONTINUE TODAY. A WEAK FRONTAL SYSTEM WILL MOVE ACROSS THE WATERS
MONDAY, WITH GUSTY SOUTH WINDS DEVELOPING FROM PORT ORFORD
NORTHWARD. WINDS WILL VEER TO NORTHWEST BEHIND THE FRONT LATE MONDAY
AFTERNOON. STEEP WEST-NORTHEST SWELL BUILDS INTO THE WATERS TUESDAY
MORNING AND AFTERNOON. THEN, A THERMAL TROUGH ALONG THE COAST WILL
RESULT IN THE POTENTIAL FOR GUSTY NORTH WINDS AND STEEP SEAS FOR
AREAS SOUTH OF CAPE BLANCO LATE TUESDAY AFTERNOON INTO WEDNESDAY.
STEEP SEAS LATE TUESDAY AND WEDNESDAY WILL BE DUE TO A MIX WEST-
NORTHWEST SWELL AT 12 TO 13 SECONDS AND SHORT PERIOD WIND SEAS.
WINDS AND SEAS TREND LOWER ON THURSDAY.
MFR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FROM 5 AM TO 5 PM PDT
MONDAY FOR PZZ350-356-370-376.
TAD/CC
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page