206
FXUS66 KMFR 161752
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
951 AM PST SUN FEB 16 2020
.UPDATED AVIATION DISCUSSION.
UPDATE
MADE A FEW MINOR CHANGES TO THE FORECAST TODAY BY LOWERING THE
CHANCE OF PRECIPITATION AFTER 1PM. LOOKING AT SURFACE OBSERVATIONS
AND CURRENT SATELLITE OBSERVATIONS, THERE APPEARS TO BE A FAIR
AMOUNT OF DRY AIR BEHIND THE FRONT. RIGHT NOW IT LOOKS PRETTY
CLEAR IN THE WILLAMETTE VALLEY EXCEPT FOR SOME HIGHS CLOUDS AND
PATCHY CUMULUS MOVING THROUGH. THE HIGH CLOUDS WILL CLEAR OUT
BY THIS EVENING AS THE FRONT DIPS SOUTH.
-SMITH
DISCUSSION
/ISSUED 300 AM PST SUN FEB 16 2020/
A FRONT IS NOW MOVING THROUGH THE MEDFORD CWA, BRINGING
WIDESPREAD BUT MOSTLY LIGHT PRECIPITATION TO THE AREA. THE 16/00Z
KMFR SOUNDING INDICATED A FREEZING LEVEL OF 6200 FEET, SO THE SNOW
LEVEL THEN WAS AROUND 5200 FEET. TRAFFIC CAMS SHOW THAT THE SNOW
LEVEL HAS FALLEN A BIT IN THE NIGHTTIME HOURS, SO THE WINTER
WEATHER ADVISORY ABOVE 4500 FEET IN THE CASCADES LOOKS GOOD AT
THIS TIME. WINDS ARE GUSTY IN PLACES, BUT NOTHING EVEN CLOSE TO
ADVISORY CRITERIA.
THE FRONT WILL SAG SOUTH INTO SUNDAY, WEAKENING AS IT DOES SO DUE
TO THE LOSS OF UPPER LEVEL SUPPORT. SHOWERS WILL DIMINISH DURING
THE DAY SUNDAY.
THE LONG WAVE RIDGE WILL BUILD OFFSHORE BEGINNING SUNDAY, AND
NORTHWEST FLOW ALOFT WILL RETURN OVER THE AREA. THE SHOWERS WILL
END FOR THE MOST PART SUNDAY EVENING, BUT ISOLATED SHOWERS MAY
PERSIST INTO MONDAY AROUND DIAMOND LAKE.
A THERMAL TROUGH WILL SET UP NEAR THE COAST SUNDAY NIGHT, KICKING
OFF SEVERAL DAYS OF LOW LEVEL EASTERLY FLOW, WHICH WILL DRY OUT
THE AIR MASS CONSIDERABLY. IT WILL ALSO BE FAIRLY COLD.
LONG TERM DISCUSSION FROM THE SATURDAY AFTERNOON AFD...TUE 18 FEB
THROUGH SATURDAY 22 FEB 2020. DRY WEATHER IS EXPECTED MUCH OF
NEXT WEEK. SINCE THE AIR MASS WILL BE QUITE DRY, AREAS OF LATE-
NIGHT/EARLY MORNING LOW CLOUDS/FOG SHOULD BE FAIRLY LIMITED. LARGE
DIURNAL RANGES IN TEMPERATURE ARE ALSO LIKELY, ESPECIALLY IN
NORTHERN CALIFORNIA AND EAST OF THE CASCADES. THE COLDEST MORNINGS
WILL LIKELY BE TUESDAY AND WEDNESDAY, WHERE LOWS IN THE SINGLE
DIGITS AND TEENS WILL BE COMMON EAST OF THE CASCADES. WEST SIDE
VALLEYS WILL HAVE LOWS FROM THE MID 20S TO LOWER 30S WITH THE
POTENTIAL FOR FROST/FREEZE HEADLINES AT THE COAST NORTH OF CAPE
BLANCO. DAYTIME HIGHS WILL BE CLOSE TO NORMAL, BUT THE VALLEYS OF
SW SISKIYOU COUNTY, THE SOUTHWEST COAST NEAR BROOKINGS AND PERHAPS
EVEN UP THE COAST TOWARD NORTH BEND (WEDNESDAY) COULD HAVE HIGHS
5-10 ABOVE NORMAL DUE TO OFFSHORE EAST WINDS.
THURSDAY INTO FRIDAY, A VERY WEAK UPPER TROUGH IS EXPECTED TO MOVE
THROUGH. THIS WON'T PRODUCE ANY PRECIPITATION, BUT IT'LL PROBABLY
COOL COASTAL AREAS A BIT. IT WILL ALSO UNSEAT THE COLD, CONTINENTAL
AIR MASS THAT WAS IN PLACE EARLIER IN THE WEEK, SO TEMPERATURES
SHOULD MODERATE SOME EAST OF THE CASCADES.
THE NEXT WEATHER-MAKER LOOKS TO BE ABOUT A WEEK AWAY, PROBABLY NOT
REACHING THE PACNW UNTIL SOMETIME NEXT WEEKEND.
-SPILDE
AVIATION...FOR THE 16/18Z TAF CYCLE
A FRONT IS MOVING
EAST OF THE CASCADES THIS MORNING AND A MIX OF MVFR/IFR CEILINGS AND
MOUNTAIN OBSCURATION CONTINUES ALONG AND BEHIND THE FRONT.
CONDITIONS SHOULD IMPROVE TO VFR IN MOST PLACES THIS AFTERNOON, BUT
CONFIDENCE IS LOW ON THIS FOR THE UMPQUA BASIN WHICH TENDS TO
MAINTAIN CLOUDS LONGEST IN THIS PATTERN. GUSTY WINDS AND MOUNTAIN
TURBULENCE IS POSSIBLE EAST OF THE CASCADES THROUGHOUT THE DAY. AS
SKIES CLEAR TONIGHT AND CONDITIONS BECOME STABLE, CONFIDENCE IS HIGH
THAT IFR/LIFR CEILINGS AND VISIBILITIES WILL DEVELOP IN VALLEYS WEST
AND EAST OF THE CASCADES LATE TONIGHT INTO MONDAY MORNING. LOWEST
CONFIDENCE FOR TONIGHT'S CONDITIONS IS AT THE COAST WHERE A BATTLE
BETWEEN DRYING NORTHERLY FLOW AND LINGERING MOISTURE WILL OCCUR, BUT
WE EXPECT ANOTHER ROUND OF LOW CEILINGS EARLY MONDAY MORNING BEFORE
THE REALLY DRY AIR PUSHES IN. BR-Y/KEENE
MARINE...UPDATED 800 AM PST SUNDAY, 16 FEB 2020
CONDITIONS
WILL CONTINUE TO IMPROVE THIS MORNING WITH SEAS TRANSITIONING TO
SWELL DOMINATED AND BECOMING LESS STEEP. THESE IMPROVED CONDITIONS
WILL PERSIST THROUGH TONIGHT AS HIGH PRESSURE BUILDS AND A
THERMAL TROUGH DEVELOPS ALONG THE COAST. NORTH WINDS INCREASE
OVERNIGHT AS THE THERMAL TROUGH STRENGTHENS AND SEAS WILL BECOME
WIND DRIVEN AND STEEP TO VERY STEEP SOUTH OF CAPE BLANCO BY EARLY
MONDAY MORNING. THE THERMAL TROUGH STRENGTHENS FURTHER INTO
TUESDAY AND STEEP SEAS WILL EXPAND NORTH TO REEDSPORT BY TUESDAY
AFTERNOON. CONDITIONS WILL IMPROVE SIGNIFICANTLY MID-WEEK, AND
SHOULD REMAIN RELATIVELY CALM THROUGH THE REST OF THE WEEK.
/BR-Y
MFR WATCHES/WARNINGS/ADVISORIES
OR...WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING ABOVE 4500
FEET IN THE FOR ORZ027-028.
CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FROM 4 AM MONDAY TO 10
PM PST TUESDAY FOR PZZ356-376. HAZARDOUS SEAS WARNING FROM
4 PM MONDAY TO 10 PM PST TUESDAY FOR PZZ356-376. SMALL
CRAFT ADVISORY FROM 4 PM MONDAY TO 10 PM PST TUESDAY FOR PZZ350-
370.
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