531  
FXUS66 KMFR 281510  
AFDMFR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MEDFORD OR  
810 AM PDT TUE MAR 28 2017  
   
DISCUSSION
 
28/12Z NAM IN.  
 
THE NORTHERN HEMISPHERIC PROJECTION CONTINUES TO SHOW A WAVE  
NUMBER OF FOUR AROUND THE GLOBE AND OCCASIONALLY HINTS AT A FIVE  
OVER THE NEXT SEVERAL DAYS. THIS ARGUES FOR A MODERATELY  
PROGRESSIVE PATTERN. THAT IS WHAT WE WILL GET OVER THE NEXT FEW  
DAYS...BUT IT WILL SLOW DOWN TOWARDS THE END OF THE WEEK. OVERALL  
THE PATTERN LOOKS QUITE SPRING LIKE...WITH WEAKER STORMS DRIVEN BY  
LOW AMPLITUDE UPPER LEVEL TROUGHS. THE PRIMARY STORM TRACK WILL  
REMAIN TO THE NORTH OF THE AREA...BUT THERE WILL BE SOME ACTION  
DOWN HERE.  
 
A LONG WAVE RIDGE CONTINUES TO BUILD INTO THE WEST COAST THIS  
MORNING. THERE WAS SOME LIGHT SHOWER ACTIVITY OVER THE  
UMPQUA...WESTERN SISKIYOU COUNTY...AND THE COAST EARLIER THIS  
MORNING BUT ALL APPEARS QUIET NOW.  
 
THE RIDGE WILL BRING DRY AND WARMER WEATHER TO THE AREA TODAY.  
THE RIDGE AXIS WILL FLATTEN AND BREAK TO THE EAST OF THE AREA LATE  
TONIGHT INTO EARLY WEDNESDAY. A SHORT WAVE RIDING UP THE BACK  
SIDE OF THE RIDGE WILL MOVE ONSHORE TO THE NORTH OF THE AREA  
WEDNESDAY MORNING. A WARM FRONT WILL MOVE ONSHORE TUESDAY  
NIGHT...FOLLOWED BY A TRAILING COLD FRONT WEDNESDAY AFTERNOON.  
WITH MOST OF THE UPPER LEVEL SUPPORT REMAINING TO THE NORTH...BOTH  
FRONTS WILL BE RELATIVELY WEAK THIS FAR SOUTH. EVEN SO...MOST IF  
NOT ALL OF THE MEDFORD CWA WILL GET SOME LIGHT PRECIPITATION  
TUESDAY NIGHT INTO WEDNESDAY NIGHT. SNOW LEVELS WILL BE WAY UP  
THERE...AROUND 8000 FEET. A STRONGER SHORT WAVE WITH A MORE  
SOUTHERLY TRAJECTORY WILL MOVE ONSHORE LATE WEDNESDAY NIGHT OR  
EARLY THURSDAY MORNING WITH THE LONG WAVE TROUGH. THIS ALONG WITH  
SHORT WAVES DIVING DOWN THE BACK SIDE OF THE TROUGH WILL SUPPORT  
POST-FRONTAL SHOWERS LASTING INTO THURSDAY EVENING...BUT SHOWER  
INTENSITY AND COVERAGE WILL DIMINISH THROUGH THE DAY THURSDAY.  
SNOW LEVELS WILL DROP TO 3000-4000 FEET WITH THE TROUGH...BUT THE  
HEAVIEST PRECIPITATION WILL HAVE ALREADY FALLEN BY THAT TIME.  
 
COLD AIR WILL POUR INTO THE REGION BEHIND THE SYSTEM, AND THIS  
TRANSITION WILL RESULT IN GUSTY NORTHWEST WINDS ACROSS THE EAST  
SIDE THURSDAY AFTERNOON AND EVENING. TEMPERATURES WILL THEN BE  
MUCH COLDER OVER THE ENTIRE REGION, ALTHOUGH NOT MUCH BELOW  
NORMAL FOR THIS TIME OF YEAR. AREAS OF FROST ARE POSSIBLE IN THE  
WEST SIDE VALLEYS FRIDAY MORNING, WHERE SOME SENSITIVE VEGETATION  
MAY HAVE STARTED SPRING GROWTH.  
 
AFTER THAT...ANOTHER LONG WAVE RIDGE WILL BUILD INTO THE WEST  
COAST AND THIS WILL BRING ANOTHER ROUND OF DRY AND WARMER WEATHER  
BEGINNING FRIDAY AND CONTINUING INTO SATURDAY.  
 

 
   
AVIATION...28/12Z TAF CYCLE
 
VFR CONDITIONS ARE EXPECTED ACROSS  
THE AREA TODAY WITH PARTIAL MOUNTAIN OBSCURATIONS. RAIN AND MID  
LEVEL CLOUDS WILL INCREASE TONIGHT AS A FRONT APPROACHES THE AREA.  
CEILINGS WILL LOWER AT THE COAST AND APPROACH MVFR AROUND 06Z.  
INLAND EXPECT VFR TO CONTINUE TONIGHT BUT MOUNTAIN OBSCURATIONS WILL  
INCREASE FROM THE CASCADES WEST. /CC  
 

 
   
MARINE...UPDATED 300 AM PDT TUESDAY 28 MARCH 2017
 
HIGH PRESSURE  
WILL REMAIN OVER THE WATERS TODAY AND SEAS WILL BE DOMINATED BY A  
WEST SWELL AT 12 SECONDS AND ANOTHER WEST SWELL AT 18 SECONDS. SEAS  
WILL REMAIN HIGH AND STEEP THROUGH WEDNESDAY NIGHT...LARGELY DUE TO  
A FRONT WHICH WILL BRING INCREASING SOUTHERLY WINDS AND STEEP SEAS  
TUESDAY NIGHT INTO WEDNESDAY MORNING. WIND SPEEDS ARE EXPECTED TO  
REACH ADVISORY STRENGTH FOR AREAS NORTH OF GOLD BEACH. WINDS WILL  
DECREASE WEDNESDAY EVENING AND THEN VEER TO THE NORTH WEDNESDAY  
NIGHT INTO THURSDAY. WINDS MAY REACH ADVISORY STRENGTH IN THE OUTER  
WATERS SOUTH OF GOLD BEACH LATE THURSDAY AFTERNOON INTO SATURDAY.  
CONFIDENCE IS LOW IN THE FORECAST BEGINNING SATURDAY AND INTO EARLY  
NEXT WEEK WITH ADDITIONAL STORMS POSSIBLE. /CC  
 

 
   
MFR WATCHES/WARNINGS/ADVISORIES
 
 
OR...NONE.  
 
CA...NONE.  
 
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FROM 11 PM THIS  
EVENING TO 5 PM PDT WEDNESDAY FOR PZZ350-356-370-376.  
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM PDT THURSDAY  
FOR PZZ350-356-370-376.  
 

 
 
15/15/15  
 
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