244
FXUS66 KMFR 311206
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
506 AM PDT TUE MAR 31 2026
DISCUSSION
UPDATED AVIATION DISCUSSION.
AVIATION...31/12Z TAFS
VARYING AMOUNTS OF CLOUD COVER CAN BE
EXPECTED TODAY WITH SCATTERED SHOWERS. CEILINGS WILL BE A MIX OF VFR
AND MVFR WITH AREAS OF HIGHER TERRAIN OBSCURED. AREA TAF SITES ARE
EXPECTED TO SEE MOSTLY VFR EARLY THIS MORNING, THOUGH PERIODS OF
MVFR AND EVEN LOCAL IFR (UMPQUA BASIN) ARE POSSIBLE. CONDITIONS ARE
FORECAST TO BE VFR LATE THIS MORNING/AFTERNOON THOUGH COULD BE
TEMPORARILY REDUCED TO MVFR IN SHOWERS. AN ISOLATED THUNDERSTORM
CANNOT BE RULED OUT OVER THE EAST SIDE THIS AFTERNOON OR EARLY THIS
EVENING.
A STRONG FRONT WILL APPROACH THE COAST LATER TONIGHT WITH MORE
WIDESPREAD MVFR CEILINGS AND PERIODS OF RAIN WHICH WILL MOVE INLAND
DURING WEDNESDAY. EXPECT BREEZY TO WINDY CONDITIONS AHEAD OF THE
FRONT, ESPECIALLY OVER THE EAST SIDE. -SPILDE
PREV DISCUSSION
/ISSUED 320 AM PDT TUE MAR 31 2026/
DISCUSSION...AN UPPER TROUGH OFFSHORE WILL GET A PUSH EASTWARD
AND MOVE INLAND TODAY. AT THIS EARLY HOUR, SATELLITE IMAGERY IS
SHOWING THE GREATEST CLOUD COVER OVER OUR FORECAST AREA WITH RADAR
INDICATING SOME LIGHT RAIN SHOWERS OVER THE CASCADES/FOOTHILLS
NEAR AND NORTH OF CRATER LAKE, ACROSS NORTHERN KLAMATH/LAKE
COUNTIES AND ALSO ACROSS PORTIONS OF NW CAL INTO COASTAL SW OREGON
NEAR BROOKINGS. THIS WILL BE WHAT IT'S LIKE MOST OF THIS MORNING,
SHOWERS HERE AND THERE, BUT IT WON'T BE RAINING EVERYWHERE. AS
THE TROUGH MOVES INLAND AND THINGS DESTABILIZE A BIT THIS
AFTERNOON, WE EXPECT SHOWERS TO EXPAND IN COVERAGE, ESPECIALLY
FROM JUST WEST OF THE CASCADES OVER TO THE EAST SIDE. INSTABILITY
THIS AFTERNOON IS GREATEST OVER PORTIONS OF LAKE COUNTY, BUT ALSO
MODOC AND SOUTHEAST KLAMATH COUNTIES, WHERE THERE CAN BE AN
ISOLATED THUNDERSTORM OR TWO. RAIN AMOUNTS SINCE YESTERDAY WERE
HIGHEST FROM THE FOOTHILLS WEST OF THE CASCADES EASTWARD ACROSS
KLAMATH/LAKE COUNTIES. GENERALLY, THOSE AREAS RECEIVED A TENTH TO
A THIRD OF AN INCH OF PRECIPITATION. MOST OF THE REST OF THE AREA
HAD LESS THAN THAT. TODAY LOOKS VERY SIMILAR WITH THE BEST CHANCE
OF WETTING RAINFALL (MORE THAN 0.10) IN THOSE SAME GENERAL
LOCATIONS, FOCUSED IN THE MOUNTAINS. AT THIS POINT, ANY
PRECIPITATION IS WELCOME, ESPECIALLY GIVEN THE DRY, WARM START TO
SPRING SO FAR.
A BIG CHANGE IS COMING BEGINNING LATE TONIGHT AND CONTINUING
WEDNESDAY INTO THURSDAY. MODELS CONTINUE TO SHOW A STRONG UPPER
TROUGH MOVING SOUTHWARD FROM THE GULF OF ALASKA. THE LEADING EDGE
OF THIS SYSTEM WILL BE A COLD FRONT THAT WILL APPROACH THE COAST
LATER TONIGHT, AND MOVE ONSHORE WEDNESDAY. THE UPPER LEVEL COLD
POOL WILL THEN MOVE ONSHORE INTO WASHINGTON/OREGON WEDNESDAY
NIGHT INTO THURSDAY. PRESSURE GRADIENTS IN ADVANCE OF THIS SYSTEM
INCREASE WEDNESDAY AFTERNOON, WITH MID-LEVEL WINDS PEAKING AROUND
55 KT. THIS SHOULD RESULT IN WIDESPREAD PEAK WIND GUSTS IN THE
40-50 MPH RANGE FOR AREAS FROM THE CASCADES EASTWARD, PERHAPS 55
MPH IN SOME AREAS. WIND ADVISORIES HAVE BEEN ISSUED FOR PORTIONS
OF LAKE/MODOC COUNTIES. THE SHASTA VALLEY WILL BE BREEZY AT
LEAST, DUE TO THE FAIRLY STRONG PRESSURE GRADIENT, BUT THE MID
LEVEL FLOW WILL NOT BE ALIGNED WITH THE TERRAIN, KEEPING WINDS
THERE WEAKER THAN MAY OTHERWISE BE EXPECTED, BUT STILL CLOSE TO
ADVISORY LEVEL STRENGTH. PEAK GUSTS OF 40-45 MPH ARE POSSIBLE, BUT
WE'LL FOREGO AN ADVISORY FOR NOW.
THE MAIN FRONTAL BAND WILL BE ACCOMPANIED BY A PERIOD OF
MODERATE RAINFALL WITH THE HEAVIEST PRECIPITATION FROM THE COAST
TO THE CASCADES FROM LATE WEDNESDAY MORNING THROUGH THE
AFTERNOON. WE ARE NOT CONCERNED ABOUT FLOODING WITH THIS EVENT,
OTHER THAN SOME MINOR/TYPICAL NUISANCE PONDING OF WATER ON
ROADWAYS. SINCE RIVER LEVELS ARE VERY LOW FOR THIS TIME OF YEAR,
MOST OF THE RAIN EXPECTED FROM THIS SYSTEM WILL BE
BENEFICIAL/WELCOME. AMOUNTS OF 1-3 INCHES ARE LIKELY ALONG THE
COAST, WITH 0.50-1.00 INCH COMMON INLAND TO THE CASCADES WITH
0.25-0.50 INCH OVER THE EAST SIDE. SNOW LEVELS OF 5000-5500 FEET
WEDNESDAY WILL DROP TO 2500-3000 FEET BY THURSDAY MORNING.
IT LOOKS LIKE A PRETTY HEALTHY SNOW STORM FOR THE CASCADES AND
SISKIYOUS WITH 6-12 INCHES COMMON ABOVE 5000 FEET. WINTER STORM
WATCHES REMAIN UP FOR THE CASCADES. A WINTER WEATHER ADVISORY HAS
BEEN ADDED FOR THE HIGHWAY 97 CORRIDOR FROM CHILOQUIN NORTHWARD
FOR WEDNESDAY NIGHT INTO THURSDAY MORNING AND ADDITIONAL
ADVISORIES MAY BE NECESSARY FOR PORTIONS OF THE EAST SIDE, AND/OR
FOR THE HIGHER TERRAIN OF SISKIYOU COUNTY. THE HEAVIEST SNOW WILL
FALL NEAR CRATER/DIAMOND LAKES AND NEAR WILLAMETTE PASS WHERE IT
WILL BE A BIT COLDER, WITH NBM PROBABILITIES SHOWING A HIGH
PROBABILITY (>80%) OF >12 INCHES OF SNOW. AT CRATER LAKE (~7000
FEET), THE 48-HOUR PROBABILITY OF >18 INCHES OF SNOW ENDING
THURSDAY EVENING IS NOW NEARLY 100%! ALL IN ALL, EXPECT WINTER
TRAVEL IMPACTS IN THE MOUNTAINS AND OVER SOME OF THE HIGHER
PASSES, ESPECIALLY AT LAKE OF THE WOODS BY THURSDAY MORNING. MAIN
I-5 PASSES SHOULD BE OK, BUT SOME SLIPPERY SPOTS COULD DEVELOP AT
SISKIYOU SUMMIT AND/OR AROUND MT SHASTA CITY/SNOWMAN SUMMIT EARLY
THURSDAY MORNING.
WITH THE CORE OF THE COLD POOL SHIFTING INTO NORTHEAST OREGON AND
IDAHO ON THURSDAY, SHOWERS AND EVEN AN ISOLATED THUNDERSTORM OR
TWO WILL CONTINUE FOR A WHILE INTO THURSDAY AFTERNOON, BUT THEN
DIMINISH RAPIDLY AROUND SUNSET THURSDAY EVENING AS HIGH PRESSURE
BUILDS IN. IT SHOULD BE NOTED THAT MODELS ARE STILL SHOWING A
FAIRLY HIGH PROBABILITY (50-70% CHANCE) THAT TEMPERATURES DROP
INTO THE LOW TO MID 30S FOR THE WEST SIDE VALLEYS BY FRIDAY
MORNING. SO, THAT WILL INTRODUCE SOME FROST/FREEZE RISK. GREATEST
RISK OF THAT OCCURRING IS IN THE ILLINOIS VALLEY (CAVE
JUNCTION/OBRIEN/SELMA). THE PROBABILITY OF TEMPERATURES LESS THAN
28F, HOWEVER, ARE QUITE LOW, GENERALLY 10% OR LESS.
MODELS ARE SHOWING THE UPPER RIDGE REBUILDING ACROSS THE AREA
FRIDAY INTO THE WEEKEND, SO LOOK FOR TEMPERATURES TO REBOUND TO
ABOVE NORMAL LEVELS AGAIN (HIGHS IN THE 70S AGAIN WEST SIDE
VALLEYS) ALONG WITH LITTLE TO NO CHANCE AT PRECIPITATION. -SPILDE
AVIATION...31/06Z TAFS...A WEAK FRONT WILL LINGER OVER THE AREA
INTO TUESDAY. THIS WILL RESULT IN VARIABLE AMOUNTS OF CLOUD
COVER AND SHOWERS. CEILINGS WILL BE A MIX OF VFR WITH AREAS OF MVFR
AND MOUNTAIN OBSCURATIONS OVERNIGHT AND TUESDAY MORNING. AREA TAF
SITES ARE EXPECTED TO SEE PERIODS OF MVFR (OR LOCAL IFR) OVERNIGHT
AND EARLY TUESDAY MORNING. THEN CONDITIONS ARE FORECAST TO RETURN TO
VFR LATE TUESDAY MORNING INTO TUESDAY AFTERNOON. LINGERING SHOWERS
DURING THE TUESDAY AFTERNOON AND EVENING WILL ALLOW FOR PARTIAL
MOUNTAIN OBSCURATIONS.
MARINE...UPDATED 230 AM PDT TUESDAY, MARCH 31, 2026...CONDITIONS
GENERALLY IMPROVE BRIEFLY TODAY WITH SEAS SUBSIDING TO AROUND 4
FT. SEAS ARE FORECAST TO BECOME STEEP AGAIN LATE TONIGHT WITH SOUTH
GALES AND VERY STEEP SEAS POSSIBLE WEDNESDAY. A GALE WATCH REMAINS
IN EFFECT. STEEP SEAS ARE EXPECTED TO BECOME SWELL DOMINATED ON
WEDNESDAY NIGHT AND BUILD TO A PEAK ON THURSDAY. ADVISORY STRENGTH
NORTH WINDS ARE LIKELY TO RETURN LATE IN THE WEEK WHILE SEAS REMAIN
STEEP. -SPILDE
MFR WATCHES/WARNINGS/ADVISORIES
OR...WINTER WEATHER ADVISORY FROM 8 PM WEDNESDAY TO 11 AM PDT
THURSDAY FOR ORZ029-030.
WIND ADVISORY FROM 11 AM TO 11 PM PDT WEDNESDAY FOR ORZ031.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH THURSDAY AFTERNOON
FOR ORZ025-027-028.
CA...WINTER WEATHER ADVISORY FROM 8 PM WEDNESDAY TO 11 AM PDT
THURSDAY FOR CAZ080.
WIND ADVISORY FROM 11 AM TO 11 PM PDT WEDNESDAY FOR CAZ085.
PACIFIC COASTAL WATERS...GALE WATCH FROM LATE TONIGHT THROUGH
WEDNESDAY AFTERNOON FOR PZZ350-356-370-376.
MAS/MAS/MAS
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