658
FXUS66 KMFR 070529
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
929 PM PST SAT DEC 6 2025
UPDATE
AVIATION DISCUSSION UPDATED.
AVIATION...07/06Z TAFS
MID AND HIGH CLOUDS OVER THE AREA TONIGHT
WITH AREAS OF IFR/LIFR CONDITIONS IN LOW CLOUDS IN VALLEYS WEST OF
THE SOUTHERN OREGON CASCADES, INCLUDING MEDFORD AND GRANTS PASS
AREAS. THESE CONDITIONS WILL PERSIST THROUGH AT LEAST SUNDAY
MORNING. IN THE UMPQUA VALLEY, CONDITIONS ARE MAINLY VFR TONIGHT
WITH MVFR/IFR EXPECTED TO DEVELOP LATE TONIGHT. ALONG THE COAST, A
FRONT ARRIVES LATE TONIGHT AND EARLY SUNDAY MORNING, BRINGING RAIN
AND A MIX MVFR/IFR CONDITIONS.
AREAS OF RAIN AND MVFR WILL SPREAD INLAND FROM THE COAST INTO THE
UMPQUA VALLEY AND INTO THE SOUTHERN OREGON CASCADES ON SUNDAY. THIS
WILL BRING LOWER CEILINGS (IFR/MFR) AND MOUNTAIN OBSCURATIONS. RAIN
WITH LOW CEILINGS (IFR AND LOCAL LIFR) AND AREAS OF LOWERED
VISIBILITIES (IFR/MVFR) WILL CONTINUE SUNDAY EVENING FOR AREAS FROM
THE SOUTHERN OREGON CASCADES WEST, WITH VFR AND LOCAL MVFR EAST OF
THE CASCADES AND ACROSS NORTHERN CALIFORNIA.
ON SUNDAY, MODERATE TO STRONG WINDS ALOFT WILL RESULT IN MOUNTAIN
WAVE TURBULENCE ALONG AND EAST OF THE CASCADES WITH STRONGER WINDS
NEAR AND AT THE RIDGES.
PREV DISCUSSION
/ISSUED 244 PM PST SAT DEC 6 2025/
DISCUSSION...WHILE SOME SUBTLE CHANGES TO THE FORECAST HAVE BEEN
MADE, THE MAIN MESSAGE REMAINS THE SAME FOR SW OREGON AND NORTHERN
CALIFORNIA. AN UPPER RIDGE OFF THE CALIFORNIA COAST WILL KEEP
MOST OF THE HIGH-IMPACT, HEAVY RAINFALL (AND SIGNIFICANT FLOOD
RISK) TO OUR NORTH THROUGH THE MIDDLE PART OF NEXT WEEK.
THE UPPER RIDGE WILL CONTINUE TO DEFLECT THE MAIN AXIS OF
SUBTROPICAL MOISTURE ASSOCIATED WITH A STRONG ATMOSPHERIC RIVER
INTO NW OREGON, WASHINGTON AND BRITISH COLUMBIA. IF YOU'RE HEADED
UP THERE, PREPARE TO GET WET. PLEASE REFER TO OUR COLLEAGUES TO
THE NORTH (PORTLAND AND SEATTLE NWS) FOR THE SPECIFICS ON RAIN
AMOUNTS, BUT SUFFICE IT TO SAY, IT WILL BE A LOT. THEY HAVE FLOOD
WATCHES UP FROM THE WILLAMETTE VALLEY NORTHWARD.
THE FRONTAL BOUNDARY THAT WILL SUPPLY ALL THIS MOISTURE TO THE
PACNW WILL WAVER NORTHWARD AND SOUTHWARD MULTIPLE TIMES THROUGH AT
LEAST WEDNESDAY. THIS WILL BRING BOUTS OF MODERATE TO PERHAPS
HEAVY RAINFALL TO NW SECTIONS OF OUR FORECAST AREA, PRIMARILY COOS
AND DOUGLAS COUNTIES (SEE HYDROLOGIC OUTLOOK FOR DETAILS), BUT
ALSO CURRY COUNTY. THESE AREAS COULD SEE 1-4 INCHES OF RAINFALL.
SOUTH AND EAST OF THE ROGUE-UMPQUA DIVIDE, MANY FOLKS WILL BE LEFT
WONDERING WHAT ALL THE HUBBUB IS ABOUT AND SOME AREAS IN NORTHERN
CALIFORNIA (EASTERN SISKIYOU/MODOC COUNTIES) MIGHT NOT EVEN GET A
DROP OF RAIN.
WE'LL HAVE A WARM FRONT MOVE INTO THE AREA LATE TONIGHT AND TO
THE NORTH SUNDAY INTO MONDAY. THIS WILL RENEW THE RISK OF
STEADIER PRECIPITATION ACROSS N&W SECTIONS OF THE CWA, BUT MOST,
IF NOT ALL, PRECIPITATION STAYS TO THE NORTH OF THE OR/CA BORDER.
WE DON'T CURRENTLY PREDICT ANY MEASURABLE RAINFALL HERE IN
MEDFORD DURING THIS TIME PERIOD, BUT THERE COULD BE A 0.10-0.50 OF
AN INCH FROM THE COAST TO THE UMPQUA DIVIDE/CASCADES (PERHAPS A
LITTLE MORE IN AREAS WHERE TERRAIN ENHANCES LIFT). SNOW LEVELS
RISE TO 7000-8000 FEET. LITTLE OR NO PRECIP IS EXPECTED SOUTHEAST
OF HIGHWAY 97.
THE MAIN PERIOD IN QUESTION IS MONDAY NIGHT THROUGH WEDNESDAY
WHEN THE FRONTAL BOUNDARY JOGS BACK TO THE SOUTH. JUST HOW FAR THE
FRONT SETTLES BACK SOUTHWARD IS THE MAIN SOURCE OF UNCERTAINTY.
THIS RESULTS IN ENHANCED RAIN RATES ACROSS NW SECTIONS, ESPECIALLY
COOS AND DOUGLAS COUNTIES, BUT COULD ALSO BRING RAIN A LITTLE
FARTHER SOUTH TO AROUND THE OR/CA BORDER. GEFS MEMBERS ARE MOST
BULLISH WITH THIS OUTCOME, BUT ACCOUNT FOR A LOWER % OF THE TOTAL
ENSEMBLES. ECMWF MEMBERS PREFER TO KEEP THE MAIN MOISTURE AXIS TO
THE NORTH. IF THE FARTHER SOUTH GEFS SOLUTIONS PAN OUT, THIS COULD
ALSO MEAN ANOTHER UPTICK IN WINDS FROM THE CASCADES EASTWARD
TUESDAY NIGHT INTO WEDNESDAY. 12Z DETERMINISTIC GFS ACTUALLY IS
SHOWING A STRONG 700MB JET OF 65-70KT, WHICH, IF CORRECT, COULD
BRING WIND HEADLINES NORTH OF HIGHWAY 140. WE HAVE INCREASED WIND
SPEEDS OVER THE EAST SIDE, BUT WILL ADJUST AS NEW DATA BECOME
AVAILABLE.
MODEL CONSENSUS IS SHOWING THE FRONTAL BOUNDARY LIFTING BACK TO
THE NORTH LATE NEXT WEEK WITH THE UPPER RIDGE RE-AMPLIFYING ALONG
THE WEST COAST. THIS WOULD LIKELY RESULT IN A DRY, MILD PERIOD
FOR MOST, IF NOT ALL, OF THE AREA INTO NEXT WEEKEND. CPC WEEK 2
OUTLOOK STILL CALLING FOR HIGHER ODDS (50-70%) OF ABOVE NORMAL
TEMPS AND SLIGHTLY FAVORING (33-40%) NEAR TO ABOVE NORMAL PRECIP.
MUCH OF THAT WILL DEPEND ON THE STRENGTH OF THE UPPER RIDGE.
-SPILDE
MARINE...UPDATED 200 PM PST SATURDAY, DECEMBER 6, 2025...STEEP
SEAS DIMINISH THROUGH THIS EVENING, THEN AFTER A BRIEF BREAK TONIGHT,
SOUTH WINDS INCREASE THROUGH THE DAY SUNDAY AS ANOTHER WET FRONT
APPROACHES THE REGION. GUSTY WINDS AND STEEP SEAS NORTH OF CAPE
BLANCO ON SUNDAY WILL SPREAD TO ALL OF THE SOUTHERN OREGON WATERS
MONDAY, WITH GALES AND/OR VERY STEEP SEAS POSSIBLE NORTH OF CAPE
ARAGO. CONDITIONS REMAIN UNSETTLED THROUGH THE FIRST PART OF NEXT
WEEK, WITH SEVERAL FRONTS BRINGING PERIODS OF GUSTY SOUTH WINDS AND
A LIKELIHOOD OF HIGH AND STEEP SEAS. -BPN/PETRUCELLI
MFR WATCHES/WARNINGS/ADVISORIES
OR...CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FROM 10 AM TO 10 PM PST
MONDAY FOR PZZ356-376.
SMALL CRAFT ADVISORY FROM 7 AM SUNDAY TO 10 AM PST MONDAY FOR
PZZ350-370.
GALE WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING FOR PZZ350-
370.
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