189
FXUS66 KMFR 122138
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
238 PM PDT SUN OCT 12 2025
DISCUSSION
RAIN SHOWERS ARE MOVING ACROSS SOUTHERN OREGON AND
NORTHERN CALIFORNIA THIS AFTERNOON AS A LOW PRESSURE SYSTEM
TRAVELS SOUTH ALONG THE PACIFIC COAST. ACTIVITY WILL CONTINUE
THROUGH THE DAY MONDAY. THE HIGHEST FORECAST PRECIPITATION TOTALS
ARE OVER COASTAL AREAS, WHERE COASTAL TERRAIN COULD GET UP TO AN
INCH OF RAINFALL WHILE LOWER ELEVATIONS COULD GET BETWEEN HALF AND
THREE-QUARTERS OF AN INCH IN THIS TIMEFRAME. WEST SIDE VALLEYS
COULD GET UP TO HALF AN INCH OF RAINFALL. TERRAIN IN SISKIYOU
COUNTY COULD ALSO SEE UP TO AN INCH OF PRECIPITATION. EAST SIDE
BASINS COULD SEE UP TO ONE-QUARTER OF AN INCH THROUGH MONDAY
EVENING.
A COLD AIR MASS MOVING WITH THE LOW PRESSURE SYSTEM LOOKS TO LOWER
SNOW LEVELS TO 4500 FEET ALONG THE CASCADES, WITH 5000 TO 5500 FEET
SNOW LEVELS EAST OF THE CASCADES. UNDER THESE CONDITIONS, SNOW
SHOWERS ARE EXPECTED ALONG THE CASCADES THIS EVENING THROUGH MONDAY
EVENING. 2 TO 4 INCHES OF SNOW POSSIBLE OVER THE HIGHEST PARTS OF
HIGHWAYS 230 AND 138 NEAR DIAMOND LAKE AND 3 TO 5 INCHES OF
SNOWFALL OVER PARTS OF HIGHWAY 62 NEAR CRATER LAKE. PARTS OF
SAWYERS BAR ROAD WEST OF ETNA COULD ALSO SEE 2 TO 4 INCHES OF
SNOWFALL IN THIS PERIOD. PEAKS AND RIDGELINES ALONG THE CASCADES
COULD SEE UP TO 8 INCHES OF SNOWFALL, WHILE TERRAIN IN SISKIYOU
COUNTY AND EAST OF THE CASCADES COULD SEE 4 TO 6 INCHES. MOST OF
THE SNOWFALL ALONG THE CASCADES LOOKS TO BE TONIGHT INTO EARLY
MONDAY MORNING. THESE AMOUNTS DO NOT REPRESENT ADVISORY-LEVELS
THREATS FOR THIS AREA OVER THE 24-HOUR TIMEFRAME, AND PERSISTING
SURFACE WARMTH WILL HELP TO LIMIT ROAD ACCUMULATIONS. AS THIS IS
THE FIRST SOMEWHAT SIGNIFICANT SNOWFALL OF THE SEASON, EXTRA
CAUTION IS ENCOURAGED WHILE TRAVELING THROUGH ELEVATED AREAS.
THE LOW PRESSURE SYSTEM LOOKS TO REACH CENTRAL CALIFORNIA BEFORE
MOVING TO THE NORTHEAST INTO THE CONUS ON TUESDAY. DAYTIME HIGHS
START TO WARM ON TUESDAY, BUT WILL REMAIN BELOW SEASONAL NORMS
UNTIL FRIDAY OR SATURDAY. LINGERING CLOUD COVER AROUND THE LOW
COULD HELP TO KEEP OVERNIGHT LOWS FROM DROPPING TOO FAR THROUGH
THE MIDDLE OF THE WEEK. MOST EAST SIDE AREAS LOOK TO STAY AT 32 TO
35 DEGREES OVERNIGHT, WITH PARTS OF NORTHERN LAKE AND KLAMATH
COUNTIES POSSIBLY DROPPING INTO THE HIGH 20S. THE SHASTA VALLEY
MAY ALSO SEE OVERNIGHT LOWS REACH FREEZING OR JUST BELOW FREEZING
THROUGH THE WEEK, DEPENDING ON HOW CLOUD COVER CONTINUES INTO THE
NIGHT.
WEST SIDE AREAS WILL SEE DRIER CONDITIONS FOR TUESDAY AND THROUGH
THE WEEK. NORTHERN CALIFORNIA COUNTIES AS WELL AS SOUTHERN LAKE AND
KLAMATH COUNTIES MAY SEE SHOWERS CONTINUE THROUGH WEDNESDAY MORNING
DEPENDING ON THE PATH THAT THE LOW TAKES. PRECIPITATION AMOUNTS
WOULD BE LOW, WITH NBM PROBABILISTIC GUIDANCE HAVING A 15-30% CHANCE
OF THESE AREAS GETTING ONE-TENTH OF AN INCH OF RAINFALL FROM TUESDAY
THROUGH WEDNESDAY. SNOW LEVELS FOR THESE AREAS RISE TO 6000-6500
FEET, LIMITING THE CHANCE OF SNOW SHOWERS. ALL AREAS LOOK TO
REMAIN DRY FROM WEDNESDAY THROUGH SATURDAY. SOME GUIDANCE IS
SHOWING A FRONT PASSING TO THE NORTH BRINGING VERY LIGHT SHOWERS
TO COOS AND DOUGLAS COUNTIES ON FRIDAY, BUT CONFIDENCE IN THAT
OUTCOME IS LOW AT THIS MOMENT.
WIDESPREAD RAINFALL COULD RETURN NEXT SUNDAY AS AN UPPER TROUGH IS
PRESENT IN BOTH THE ECMWF AND GFS MODELS. THE POSITION AND TIMING
VARY SLIGHTLY BETWEEN THE TWO MODELS, MAKING ANY MORE DETAILED
CONDITIONS DIFFICULT TO FORECAST WITH HIGH CONFIDENCE. GIVEN THE
WARM PERIOD BEFORE THIS TROUGH, WINTER IMPACTS DO NOT LOOK LIKELY
IF THIS OUTCOME DOES DEVELOP. -TAD
AVIATION...12/18Z TAFS
LOW PRESSURE WILL MOVE SOUTHWARD ALONG THE
COAST TONIGHT THROUGH MONDAY. SOME LIGHT RAIN AND MVFR CEILINGS ARE
DEVELOPING ALONG THE COAST AND NW PORTIONS OF THE FORECAST AREA NOW,
WHILE AREAS FARTHER INLAND TO THE SOUTH AND EAST ARE VFR. EXPECT
CEILINGS TO LOWER WEST OF THE CASCADES THIS AFTERNOON AND,
ESPECIALLY TONIGHT FOR MOST OF THE REMAINDER OF THE REGION AS THE
LOW PUSHES SOUTHWARD. THIS LOW WILL BRING WIDESPREAD LIGHT RAIN AND
SNOW IN THE MOUNTAINS WITH AREAS OF MVFR AND HIGHER TERRAIN
OBSCURATIONS. LOCAL IFR CEILINGS AND/OR VISIBILITIES ARE POSSIBLE IN
HEAVIER RAIN. FREEZING LEVELS WILL BE PRETTY LOW FOR THIS TIME OF
YEAR, GENERALLY 4500-5500 FEET. THERE IS ALSO ABOUT A 20-30% RISK OF
THUNDERSTORMS OVER THE MARINE WATERS AND ALONG THE IMMEDIATE COAST
LATER TONIGHT INTO MONDAY. THE MAIN AXIS OF PRECIPITATION WILL SHIFT
SOUTHWARD INTO NORCAL MONDAY, BUT SHOWERS CAN PERSIST INTO THE
AFTERNOON JUST ABOUT ANYWHERE BENEATH CYCLONIC FLOW ALOFT. -SPILDE
MARINE...UPDATED 200 PM PDT SUNDAY, OCTOBER 12, 2025
STEEP
NORTHWEST SWELL WILL PERSIST TONIGHT. LOW PRESSURE WILL MOVE IN FROM
THE NORTH TONIGHT AND PERSIST INTO MONDAY EVENING BRINGING
WIDESPREAD SHOWERS AND A CHANCE OF THUNDERSTORMS. SEAS WILL BECOME
MORE CHAOTIC MONDAY INTO TUESDAY AS STRONGER NORTH WINDS GENERATE
STEEP WIND WAVES AS WELL. THIS WILL MAINTAIN STEEP TO VERY STEEP
SEAS, HIGHEST OVER THE OUTER WATERS THROUGH TUESDAY. LIGHTER WINDS
AND LOWER SEAS SHOULD RETURN ON WEDNESDAY. -SPILDE
MFR WATCHES/WARNINGS/ADVISORIES
OR...CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 5 PM PDT TUESDAY
FOR PZZ350-356-370-376.
HAZARDOUS SEAS WARNING FROM 5 AM MONDAY TO 5 PM PDT TUESDAY FOR
PZZ370-376.
TAD/MAS
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