816
FXUS66 KMFR 220012
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
512 PM PDT WED OCT 21 2026
..UPDATED THE AVIATION SECTION
AVIATION...22/00Z TAFS
ISOLATED SHOWERS WILL BE MOSTLY IN
NORTHERN CALIFORNIA TO THE EAST OF INTERSTATE 5 THIS EVENING.
ISOLATED THUNDERSTORMS CANNOT BE RULED OUT AND HAVE A 10 TO 20%
CHANCE OF OCCURING IN NORTHERN CALIFORNIA. COVERAGE IS EXPECTED TO
INCREASE FROM SOUTHEAST TO NORTHWEST AFTER 09Z/THURSDAY AND CONTINUE
THROUGH THURSDAY. EXPECT LOWERING CEILINGS AND INCREASING TERRAIN
OBSCURATIONS, BUT WITH CONDITIONS EXPECTED TO REMAIN VFR THROUGH
THURSDAY AFTERNOON FOR TERMINALS EAST OF THE COASTAL RANGE. SHOWERS
ON THURSDAY WILL BE MAINLY FROM THE CASCADES EASTWARD IN NORTHERN
CALIFORNIA AND SOUTH CENTRAL OREGON (INCLUDING KLAMATH FALLS). BUT,
SOME LIGHTER SHOWERS ARE ALSO EXPECTED TO DEVELOP IN SOUTHWEST
OREGON AND WESTERN SISKIYOU COUNTY DURING THURSDAY.
IFR CEILINGS AND VISIBILITIES WILL LIKELY RETURN TO LOCATIONS ALONG
THE COAST TONIGHT INTO THURSDAY MORNING. FOG AND LIFR VISIBILITIES
ARE POSSIBLE, ALTHOUGH ODDS ARE THE BOUNDARY LAYER WILL HAVE SOME
MIXING BETWEEN THE SURFACE AND 500 FEET. THE CHANCE OF FOG AROUND
1/4 MILE NEAR KOTH IS ABOUT 40%.
MARINE...UPDATED 220 PM PDT WEDNESDAY, OCTOBER 21, 2026
A THERMAL
TROUGH WILL STRENGTHEN ALONG THE COAST THROUGH FRIDAY MORNING.
TONIGHT INTO THURSDAY, NORTH WINDS INCREASE WITH STEEP SEAS SOUTH OF
CAPE BLANCO SPREADING NORTH OF CAPE BLANCO, ESPECIALLY THURSDAY
AFTERNOON. ADVISORY LEVEL NORTH WINDS AND STEEP SEAS CONTINUE
THURDAY NIGHT INTO FRIDAY MORNING WITH VERY STEEP SEAS BEYOND 5 NM
FROM SHORE AND SOUTH OF OPHIR. CONDITIONS IMPROVE NORTH OF CAPE
BLANCO ON FRIDAY AS NORTH WINDS EASE, BUT HAZARDOUS CONDITIONS WILL
PERSIST IN THE SOUTH. IMPROVEMENT IN ALL AREAS IS EXPECTED OVER THE
WEEKEND.
PREV DISCUSSION
/ISSUED 252 PM PDT WED OCT 21 2026/
KEY MESSAGES...
* WETTING RAIN IS EXPECTED EAST OF THE CASCADES THIS EVENING INTO
TONIGHT. THERE IS A 20% CHANCE OF CLOUD TO GROUND LIGHTNING IN
NORTHERN CALIFORNIA THIS EVENING INTO THURSDAY MORNING
* A DRY COLD FRONT MOVES THROUGH THURSDAY NIGHT. COLD OVERNIGHT
LOWS AND CLEAR SKIES WILL BRING FROST AND FREEZE TO VALLEYS WEST
OF THE CASCADES.
* TEMPERATURES TREND WARMER ON SATURDAY AS A THERMAL TROUGH MOVES
INLAND.
* 20-30% CHANCE OF RAIN SUNDAY INTO MONDAY AS A LOW COULD PUSH
INTO THE STATE.
DISCUSSION...
A CLOSED LOW TO OUR SOUTH IS KICKING UP SHOWERS AND ISOLATED
THUNDERSTORMS THIS AFTERNOON. SOME CLOUD TO CLOUD FLASHES HAVE
ALREADY BEEN OBSERVED FROM THIS MORNING INTO THIS AFTERNOON. WE'LL
SEE THAT LIGHTNING POTENTIAL MOVE NORTH INTO MODOC AND SISKIYOU
COUNTY ACCORDING TO FORECAST DATA FROM THE REFS. SHOWERS SHOULD
ALSO SPREAD NORTHWARDS LATER THIS EVENING INTO TONIGHT. THE
PROBABILITY OF PRECIPITATION HAS INCREASED COMPARED TO 24 HOURS
AGO WEST OF THE CASCADES AND MEDFORD NOW HAS A 25-30% CHANCE OF
RAIN THURSDAY MORNING. HOWEVER, THE BULK OF THIS RAIN WILL STILL
FALL EAST OF THE CASCADES. WE'RE FORECASTING AROUND 0.4 INCHES
OVER ALTURAS AND LAKEVIEW WITH UNDER 0.1 INCHES FOR LOCATIONS WEST
OF THE CASCADES.
BY THURSDAY, A SHORT WAVE TROUGH WILL PUSH THROUGH THE PACIFIC
NORTHWEST AND KICK OUT THE LOW SPINNING IN CALIFORNIA. IN
ADDITION, WE'LL SEE A COLD FRONT DIVE INTO OUR REGION WITH
TEMPERATURES TRENDING NOTABLY COOLER. THE WEATHER IMPACT HERE WILL
BE FROST AND FREEZING TEMPERATURES OVERNIGHT. WE'VE ALREADY HIT
OUR FREEZE HERE IN MEDFORD AND MOST OTHER LOCATIONS WEST OF THE
CASCADES. HOWEVER, ROSEBURG COULD SEE SOME FROST BY SATURDAY
MORNING WITH CLEAR SKIES AND TEMPERATURES FALLING INTO THE MID
30'S.
A THERMAL TROUGH WILL ALSO BUILD OVER THE COAST BY THURSDAY NIGHT
INTO FRIDAY MORNING AND REALLY STRENGTHEN BY FRIDAY AFTERNOON AND
EVENING. NO MAJOR IMPACTS HERE, ALTHOUGH IT WILL BE WINDY IN THE
KALMIOPSIS WILDERNESS FRIDAY NIGHT WITH TEMPERATURES IN BROOKINGS
WARMING INTO THE UPPER 60'S BY SATURDAY. OTHER LOCATIONS WILL
TREND WARMER BY SATURDAY WITH HIGHS IN THE LOWER 70'S TO UPPER
60'S WEST OF THE CASCADES AND LOWER 60'S EAST OF THE CASCADES.
THINGS COULD CHANGE HEADING INTO SUNDAY, ALTHOUGH ENSEMBLES ARE
STILL SPLIT ON EXACTLY WHAT WILL HAPPEN. A MINORITY OF MEMBERS
30-40% ARE BRINGING A TROUGH AND COLD FRONT CLOSER TO THE COAST
AND BRINGING SOME LIGHT RAIN WEST OF THE CASCADES. MEANWHILE, THE
REST ARE KEEPING CONDITIONS DRY HERE SATURDAY NIGHT INTO SUNDAY
MORNING.
HEADING BEYOND SUNDAY CONFIDENCE IS PRETTY LOW IN THE FORECAST.
IT SEEMS ENSEMBLES WANT TO PUSH THE CLOSED LOW OVER THE PACIFIC
FARTHER INLAND, WHICH WILL INCREASE THE POP FORECAST INTO THE
LOWER 20'S. WHERE EXACTLY THIS LOW WILL TRACK IS QUESTIONABLE IN
ADDITION TO HOW MUCH MOISTURE THERE COULD BE. HOWEVER, THE QPF
VARIES FROM 0.01 TO 0.25 INCHES IF IT DOES RAIN, SO WE'RE NOT
LOOKING AT ANYTHING REALLY WET NEXT WEEK.
-SMITH
MFR WATCHES/WARNINGS/ADVISORIES
OR...CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 11 AM PDT FRIDAY
FOR PZZ350-356-370-376.
HAZARDOUS SEAS WARNING FROM 5 PM THURSDAY TO 11 AM PDT FRIDAY
FOR PZZ356-376.
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