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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