307  
FXUS66 KMFR 021554  
AFDMFR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MEDFORD OR  
854 AM PDT THU OCT 2 2025  
   
DISCUSSION
 
THE FORECAST, PARTICULARLY THE PROBABILITY OF  
SHOWERS, WAS UPDATED THIS MORNING TO ADJUST THE FORECAST BOTH FOR  
A STRONGER DEPICTION OF A SHORTWAVE THIS AFTERNOON INTO THIS  
EVENING AND AN OVERALL SLOWER, LESS PROGRESSIVE MOVEMENT INTO  
THIS WEEKEND OF A TROUGH. TODAY'S SHORTWAVE IS IN ADVANCE OF THE  
TROUGH, WITH THE TROUGH CENTERED NEAR VANCOUVER ISLAND. THIS IS A  
HIGH PROBABILITY OF PRECIPITATION, LOW PRECIPITATION AMOUNT  
SCENARIO WITH AMOUNTS OF MAINLY LESS THAN A TENTH OF AN INCH.  
ISOLATED THUNDERSTORMS ARE POSSIBLE LATE TODAY FROM SISKIYOU  
COUNTY INTO SOUTHWEST AND SOUTH CENTRAL OREGON, MAINLY BETWEEN  
THE COAST RANGE AND THE CASCADES, INCLUDING WESTERN SISKIYOU  
COUNTY. THE TROUGH WILL TRACK ACROSS OUR AREA TONIGHT INTO  
FRIDAY, WITH SHOWERS LINGERING ON FRIDAY MAINLY IN LAKE AND MODOC  
COUNTIES. ANOTHER CHANGE IS A STRONGER DEPICTION OF A WEAK  
SHORTWAVE IN THE NORTHWEST FLOW BEHIND THE TROUGH, FRIDAY NIGHT  
INTO SATURDAY MORNING. THIS WILL BRING A CHANCE OF LIGHT SHOWERS  
FOR COOS AND DOUGLAS COUNTIES NORTHWARD. OUR WARMING AND DRYING  
TREND WILL PICK UP SPEED WITH CLEARING SKIES ON SUNDAY. PLEASE SEE  
THE PREVIOUS DISCUSSION BELOW FOR FURTHER DETAILS. -DW  
 

 
   
PREV DISCUSSION
 
/ISSUED 346 AM PDT THU OCT 2 2025/  
 
DISCUSSION...SATELLITE IMAGE SHOWS AN UPPER LOW JUST WEST OF  
VANCOUVER ISLAND WITH A UPPER TROUGH AXIS WEST OF THE FORECAST AREA.  
SATELLITE IMAGE SLOW SHOWS A SHORTWAVE ROUNDING THE BASE OF THE  
UPPER TROUGH AND THIS WILL MOVE INTO THE AREA LATER THIS MORNING.  
THE NET RESULT WILL BE INCREASING SHOWERS OVER THE FORECAST AREA  
LATE THIS MORNING INTO THIS AFTERNOON. FOR THIS MORNING, SHOWERS  
WILL BE ISOLATED, WITH MOST FOCUSED OVER THE MARINE WATERS AND  
COAST.  
 
INSTABILITY WILL INCREASE ENOUGH THIS AFTERNOON AND GUIDANCE SUGGEST  
ISOLATED THUNDERSTORMS COULD DEVELOP ALONG THE NORTHERN CASCADES  
LATER THIS AFTERNOON.  
 
SHOWERS WILL CONTINUE INTO TONIGHT, BUT WILL GRADUALLY DIMINISH AS  
MOST OF THE SIGNIFICANT ENERGY SHIFTS SOUTH OF THE FORECAST AREA AS  
THE UPPER TROUGH AXIS MOVES OVERHEAD AND ANOTHER UPPER LOW DEVELOPS  
SOUTH OF THE AREA AS THE UPPER FLOW SPLITS.  
 
THE UPPER LOW WILL MOVE SOUTH THROUGH THE AREA FRIDAY. MOST  
LOCATIONS WILL BE DRY, EXCEPT FOR A FEW SHOWERS IN SOUTHEAST LAKE,  
AND MODOC COUNTY ON THE BACKSIDE OF THE DEPARTING UPPER LOW.  
 
DRY WEATHER IS LIKELY THIS WEEKEND INTO THE EARLY PART OF NEXT WEEK  
WITH A DRY NORTHERLY FLOW ALOFT WITH A STRONG UPPER RIDGE POSITIONED  
OFFSHORE. IT WILL BE MILDER WITH AFTERNOON TEMPERATURES SLIGHTLY  
ABOVE NORMAL FOR THE INTERIOR. OVERNIGHT LOWS WILL BE CHILLY,  
ESPECIALLY EAST OF THE CASCADES STARTING SATURDAY MORNING WITH  
MOSTLY CLEAR SKIES AND LONGER NIGHTS.  
 
AT THE SAME TIME, THERMAL TROUGH WILL DEVELOP WITH OFFSHORE FLOW  
SETTING UP WITH GUSTY BREEZES NEAR AND AT THE RIDGES IN SOUTHWEST  
OREGON AND WESTERN SISKIYOU COUNTY SATURDAY AND THIS WILL PERSIST  
INTO THE EARLY PART OF NEXT WEEK.  
 
IT WILL REMAIN DRY FOR AT LEAST THE FIRST HALF OF NEXT WEEK, BEYOND  
THAT, THE OPERATIONAL ECMWF AND ENSEMBLE MEAN SHOWS ANOTHER TROUGH  
DROPPING IN FROM THE NORTHWEST THE LATTER PART OF NEXT WEEK AND  
EVENTUALLY BECOMING CUT OFF FROM THE MAIN FLOW. IN CONTRAST THE GFS  
AND ENSEMBLE MEANS SHOW MORE RIDGING WITH THE ENSEMBLE MEAN SHOWING  
MORE OF A ZONAL TO WEAK RIDGING SCENARIO. THE NBM IN THE EXTENDED  
SUGGEST IT WAS LEANING MORE TOWARDS THE WETTER SOLUTION. EVEN IF  
ONE TAKES THE OPERATIONAL AND ENSEMBLE MEAN ECMWF SOLUTION AT FACE  
VALUE, THE MAIN QUESTION WILL BE THE OVER WATER TRAJECTORY WHICH  
RIGHT NOW SUGGEST IT'S NOT SUFFICIENT ENOUGH TO WARRANT THE HIGH  
POPS BEING INDICATED BY THE NBM, THEREFORE POPS BEYOND WEDNESDAY  
HAVE BEEN ADJUSTED DOWNWARD. -PETRUCELLI  
 
AVIATION...02/12Z TAFS......VFR CONDITIONS WILL BE THE PREDOMINATE  
CONDITION THROUGH THE TAF PERIOD WITH WEAK INSTABILITY OVER THE  
AREA. THERE COULD BE BRIEF PERIODS OF MVFR CEILINGS IN SHOWERS ALONG  
THE COAST, BUT CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE THE LOWER  
CONDITIONS IN THE NORTH BEND TAF. -PETRUCELLI  
 
MARINE...UPDATED 215 AM PDT THURSDAY, OCTOBER 2, 2025...STEEP SEAS  
WILL CONTINUE TODAY, BUT WILL GRADUALLY DIMINISH. A THERMAL TROUGH  
WILL DEVELOP SATURDAY WITH INCREASING NORTH WINDS NEAR OR ABOVE  
ADVISORY STRENGTH AND STEEP SEAS LIKELY LATER SATURDAY INTO SUNDAY  
NIGHT. -PETRUCELLI  
 

 
   
MFR WATCHES/WARNINGS/ADVISORIES
 
 
OR...CA...NONE.  
 
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 9 PM PDT THIS  
EVENING FOR PZZ350-356-370-376.  
 

 
 

 
 
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