424  
FXUS66 KMFR 211631  
AFDMFR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MEDFORD OR  
931 AM PDT SAT SEP 21 2019  
   
UPDATE
 
LOW CLOUDS AND FOG ARE COMMON IN THE WEST SIDE VALLEYS  
THIS MORNING, AND ARE PRESENT, BUT NOT AS WIDESPREAD, IN THE  
VALLEYS EAST OF THE CASCADES AS WELL. THESE AREAS SHOULD BURN OFF  
QUICKLY THIS MORNING, AND SKIES SHOULD BE MOSTLY CLEAR THIS  
AFTERNOON. HAVE ADJUSTED THE FORECAST THIS MORNING TO ACCOUNT FOR  
THE LOW CLOUDS, BUT NO OTHER UPDATES ARE NEEDED. FOR THE REST OF  
THE FORECAST, INCLUDING THE UPCOMING RAIN TOMORROW, SEE THE  
PREVIOUS FORECAST BELOW. -BPN  
 

 
   
AVIATION...FOR THE 21/12Z TAFS
 
AREAS OF MVFR/IFR/LIFR LOW CLOUDS  
AND FOG CAN BE EXPECTED THIS MORNING ALONG THE COAST FROM CAPE  
BLANCO NORTHWARD, AND IN THE UMPQUA VALLEY. ALSO, LATE NIGHT INTO  
EARLY MORNING PATCHY FOG IS POSSIBLE AGAIN IN THE KLAMATH BASIN.  
AFTER 15Z, THE STRATUS WILL BEGIN TO DIMINISH WITH VFR EXPECTED  
ACROSS THE AREA FROM LATE MORNING INTO SATURDAY EVENING. SOME LOW  
CLOUDS MAY RETURN AGAIN LATE SATURDAY NIGHT. -SPILDE  
 

 
   
MARINE...UPDATED 853 AM PDT SATURDAY 21 SEPTEMBER 2019
 
HIGH  
PRESSURE OFFSHORE AND A THERMAL TROUGH ALONG THE COAST WILL PERSIST  
THROUGH THIS EVENING. GUSTY NORTH WINDS WILL LEAD TO STEEP SEAS  
HAZARDOUS TO SMALL CRAFT SOUTH OF PORT ORFORD.  
 
CONDITIONS IMPROVE TONIGHT INTO SUNDAY AS THE THERMAL TROUGH PATTERN  
GETS INTERRUPTED AHEAD OF THE NEXT FRONT. THE FRONT IS EXPECTED  
SUNDAY. WINDS WILL BRIEFLY TURN SOUTHERLY AHEAD OF THIS FRONT, BUT  
ARE EXPECTED TO REMAIN BELOW ADVISORY LEVEL. EXPECT A PERIOD OF  
SHOWERS AND THE POSSIBILITY OF THUNDERSTORMS AS THE FRONT MOVES  
INLAND SUNDAY AFTERNOON AND EVENING. SEAS WILL ALSO BUILD WITH THIS  
FRONTAL PASSAGE AS NORTHWEST SWELL MOVES INTO THE WATERS. MONDAY  
INTO WEDNESDAY, THE THERMAL TROUGH QUICKLY REDEVELOPS, BRINGING THE  
RETURN OF NORTHERLY WINDS (POSSIBLE GALES) AND STEEP WIND DRIVEN  
SEAS, ESPECIALLY SOUTH OF CAPE BLANCO. THE NEXT DISTURBANCE IS  
EXPECTED AROUND THURSDAY AND MAY BE ACCOMPANIED BY A BUILDING, LARGE  
NORTHWEST SWELL. -SPILDE/SVEN  
 

 
   
PREV DISCUSSION
 
/ISSUED 330 AM PDT SAT SEP 21 2019/  
 
DISCUSSION...  
 
SATELLITE SHOWS FOG AND STRATUS FORMING OVER THE UMPQUA VALLEY AND  
THE CENTRAL COAST THIS MORNING. IN FACT, NORTH BEND IS CURRENTLY  
REPORTING 1/4 MILE VISIBILITY AND FOG. IN ADDITION, SOME UPPER  
LEVEL CLOUDS ARE MOVING THROUGH EAST OF THE CASCADES. WITH THE  
LIGHT WINDS, COOL TEMPERATURES AND RECENT RAINFALL, WE STILL FEEL  
PATCHY FROST WILL FORM LATER THIS MORNING IN VALLEYS EAST OF THE  
CASCADES. AS FOR THE REMAINDER OF THE DAY, TEMPERATURES WILL PUSH  
INTO THE LOWER 70'S AND THE LOWER 80'S IN SOME OF THE VALLEYS WEST  
OF THE CASCADES.  
 
SUNDAY WILL TURN WETTER WITH A LOW AND WEAK COLD FRONT APPROACHING  
THE COAST. IT LOOKS LIKE THE COLD FRONT WILL MOVE ONSHORE DURING  
THE LATE MORNING HOURS. THE KEY TALKING POINT HERE IS THAT MOST OF  
THE RAIN WILL PROBABLY FALL IN THE AFTERNOON FOR AREAS FARTHER  
INLAND. FOR AREAS EAST OF THE CASCADES, SUNDAY SHOULD BE PRETTY  
NICE BEFORE THE RAIN FINALLY MOVES DURING THE LATE AFTERNOON AND  
EARLY EVENING. WE'LL SEE AROUND 0.1 TO 0.25 INCHES OF RAIN WITH  
THE HIGHER TOTALS LOCATED FARTHER NORTH IN THE UMPQUA VALLEY AND  
ALONG THE COASTAL RANGE. THERE IS STILL A SLIGHT CHANCE FOR SOME  
THUNDERSTORMS ON SUNDAY AS THIS LOW MOVES THROUGH. POTENTIAL  
INSTABILITY WILL BE PRETTY LOW, SO LIGHTNING ACTIVITY SHOULD BE  
LOW AND LIMITED ACROSS THE REGION.  
 
AFTER THIS LOW PASSES THROUGH, WE'LL SEE HIGH PRESSURE AND QUIET  
WEATHER FOR THE START OF THE WORK WEEK UNTIL ROUGHLY THURSDAY.  
SOME MODEL GUIDANCE SUGGESTS THIS IS WHEN WE'LL HAVE A SLIGHT  
CHANCE FOR SOME SHOWERS MOVING THROUGH THE REGION. THE BEST CHANCE  
WILL IN FACT BE AROUND FRIDAY WHEN ALL THE MODELS SHOW A DEEP LOW  
OVER OREGON. THE OTHER NOTEWORTHY FEATURE HERE IS SNOW LEVELS  
WILL BE AROUND 5500 TO 6500 FEET WHEN THIS LOW HOVERS OVER THE  
REGION. THEREFORE, MT ASHLAND AND CRATER LAKE WILL LIKELY SEE SOME  
ACCUMULATING SNOW NEXT WEEKEND. JUST ANOTHER SIGN THAT FALL IS  
RIGHT AROUND THE CORNER.  
 
-SMITH  
 

 
   
MFR WATCHES/WARNINGS/ADVISORIES
 
 
OR...NONE.  
 
CA...NONE.  
 
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 5 AM PDT SUNDAY FOR PZZ356-376.  
 

 
 
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