415  
FXUS66 KMFR 140530  
AFDMFR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MEDFORD OR  
ISSUED BY NATIONAL WEATHER SERVICE PORTLAND OR  
1030 PM PDT TUE MAY 13 2025  
   
UPDATE  
UPDATED AVIATION DISCUSSION.  
 
 
   
AVIATION...14/006 TAFS.  
AREAS OF MVFR CEILINGS ALONG THE  
SOUTHERN OREGON COAST WILL BECOME WIDESPREAD MVFR AND LOCAL IFR TONIGHT  
THROUGH WEDNESDAY MORNING . INLAND, CONDITIONS ARE MAINLY VFR  
WITH LOCAL MVFR AND MOUNTAIN OBSCURATIONS. AREAS OF MVFR  
CONDITIONS WILL DEVELOP WEST OF THE CASCADES TONIGHT AND WEDNESDAY  
MORNING, LIFTING TO VFR WEDNESDAY AFTERNOON. VFR WILL PERSIST INTO  
WEDNESDAY EVENING.  
 
 
 
   
PREV DISCUSSION  
/ISSUED ISSUED BY NATIONAL WEATHER SERVICE  
PORTLAND OR/  
 
DISCUSSION...SATELLITE IMAGE SHOWS PLENTY OF CUMULUS CLOUDS OVER  
THE AREA ALONG WITH ISOLATED SHOWERS. THIS WILL CONTINUE INTO  
EARLY THIS EVENING. ONCE WE LOSE DAYTIME HEATING, ISOLATED SHOWERS  
WILL DIMINISH EARLY THIS EVENING WITH DRY CONDITIONS MOST HOURS  
AND LOCATIONS TONIGHT. THE EXCEPTION WILL BE ALONG THE CASCADES  
AND EASTERN LAKE COUNTY WHERE A FEW SHOWERS ARE POSSIBLE.  
 
A WEAK DISTURBANCE WILL MOVE INTO THE AREA WEDNESDAY MORNING AND  
COULD BRING A FEW SHOWERS NORTH OF THE UMPQUA DIVIDE AND COOS  
COUNTY. THE AFTERNOON SHOULD BE DRY ONCE THE DISTURBANCE MOVES  
EAST.  
 
WEDNESDAY NIGHT WILL BE DRY, WITH WEAK UPPER RIDGING BUILDING INTO  
THE AREA. CLOUD COVER SHOULD BE SUFFICIENT ENOUGH TO KEEP  
TEMPERATURES FROM DROPPING TOO MUCH AT NIGHT. LESS CLOUD COVER  
EAST OF THE CASCADES WILL RESULT IN COLDER OVERNIGHT LOWS.  
 
THE UPPER RIDGE WILL FLATTEN OUT SOME THURSDAY AFTERNOON AND  
EVENING AS ANOTHER WEAK SHORTWAVE MOVES INTO THE AREA. THIS WILL  
RESULT IN A FEW SHOWERS MAINLY NORTH OF THE UMPQUA DIVIDE AND  
CASCADES, BUT ALSO COULD NOT RULE OUT A FEW SHOWERS IN NORTHERN  
KLAMATH AND LAKE COUNTY.  
 
WEAK RIDGING WILL BUILD IN LATER THURSDAY NIGHT INTO FRIDAY WITH  
DRY AND MILDER WEATHER FOR THE INTERIOR.  
 
ANOTHER, BUT STRONGER UPPER TROUGH WILL MOVE IN FROM THE NORTHWEST  
LATE FRIDAY NIGHT INTO SATURDAY, WITH SHOWERS FROM LATE SATURDAY  
MORNING THROUGH SATURDAY AFTERNOON. SHOWERS SATURDAY WILL TEND TO  
BE ISOLATED IN THE MORNING, THEN INCREASING IN COVERAGE AS THE  
UPPER TROUGH MOVES OVERHEAD IN COMBINATION WITH DAYTIME HEATING.  
INSTABILITY IS MARGINAL, AND WILL BE GREATEST EAST OF THE  
CASCADES, THEREFORE COULD NOT RULE OUT ISOLATED AFTERNOON AND  
EARLY EVENING THUNDERSTORMS. SHOWERS WILL CONTINUE SATURDAY NIGHT  
AS THE UPPER TROUGH REMAINS OVERHEAD. PRECIPITATION AMOUNTS WILL  
GENERALLY BE LIGHT SATURDAY THROUGH SATURDAY NIGHT. SNOW LEVELS  
SATURDAY NIGHT ARE EXPECTED TO BE AROUND 5000 FEET AND COULD  
RESULT IN A BRIEF ACCUMULATION OF SNOW AROUND CRATER AND DIAMOND  
LAKE, BUT WITH ROAD TEMPERATURES WARM DUE TO STRONGER MID MAY  
SUN, SNOW FOR THE MOST PART SHOULD JUST MELT.  
 
SUNDAY WILL BE A TRANSITION DAY AS THE UPPER TROUGH DEPARTS WITH  
UPPER RIDGING NOSING INTO THE AREA. THEREFORE ANY SHOWERS WILL BE  
ISOLATED AND CONFINED TO THE MORNING HOURS ALONG THE NORTHERN  
CASCADES AND NORTH OF THE UMPQUA DIVIDE.  
 
ALL SIGNS ARE POINTING TOWARDS DRY WEATHER FOR MOST OF NEXT WEEK.  
THE OPERATIONAL ECMWF SHOWS A STRONGER UPPER TROUGH MOVING INTO  
THE AREA THURSDAY WITH COOLER AND UNSETTLED WEATHER. HOWEVER, THE  
MAJORITY OF THE INDIVIDUAL ECMWF ENSEMBLES MEMBERS SHOW A DRY  
SOLUTION AND THE OPERATIONAL GFS AND THEIR INDIVIDUAL ENSEMBLE  
MEMBERS SHOW A DRY SOLUTION. ADDITIONALLY, THE MAJORITY OF THE  
CLUSTER SOLUTIONS FAVOR STRONGER UPPER RIDGING. -PETRUCELLI  
 
MARINE...UPDATED 200 PM WEDNESDAY, MAY 7, 2025...STEEP SEAS ALONG  
WITH PERIODS OF RAIN WILL PERSIST THROUGH WEDNESDAY MORNING. A  
PATTERN CHANGE WILL COME ON WEDNESDAY WITH THE RETURN OF A THERMAL  
TROUGH AND ASSOCIATED GUSTY NORTH WINDS AND WIND-DRIVEN SEAS  
THROUGH FRIDAY MORNING. -SPILDE/HERMANSEN  
 
 
   
MFR WATCHES/WARNINGS/ADVISORIES  
 
OR...CA...NONE.  
 
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 5 AM PDT  
WEDNESDAY FOR PZZ350-356-370-376.  
 
 
 
 
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