474  
FXUS66 KMFR 191701  
AFDMFR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MEDFORD OR  
907 AM PDT FRI APR 19 2024  
 
.UPDATED AVIATION DISCUSSION FOR 18Z TAFS.  
 

 
   
DISCUSSION
 
NO MAJOR UPDATES NEEDED THIS MORNING; JUST SOME FINE  
TUNING OF WINDS AND SKY FOR THIS AFTERNOON. QUIET SPRING LIKE  
WEATHER IS EXPECTED TODAY, AND ASIDE FROM A WEAK FRONT EXPECTED ON  
SATURDAY, QUIET WEATHER IS EXPECTED TO CONTINUE INTO EARLY NEXT  
WEEK. THE REST OF THE FORECAST IS ON TRACK AND NO OTHER UPDATES  
ARE NEEDED. SEE THE PREVIOUS DISCUSSION FOR DETAILS ON THE  
UPCOMING WEATHER. /BR-Y  
 

 
   
AVIATION...19/18Z TAFS
 
OTHER THAN SOME HIGH CLOUDS AT TIMES AND A  
SLIGHT UPTICK IN DIURNAL BREEZES THIS AFTERNOON, VFR WILL PREVAIL  
AREA WIDE THROUGH THE NEXT 24 HOURS. COASTAL AREAS WON'T BE NEARLY  
AS GUSTY AS YESTERDAY. A VERY WEAK COLD FRONT APPROACHES THE COAST  
AT THE END OF THE TAF PERIOD, WHICH WILL BRING INCREASED CLOUDINESS  
AND LIGHT RAIN SATURDAY AFTERNOON. -SPILDE/CSP  
 

 
   
MARINE...UPDATED 840 AM FRIDAY, APRIL 19, 2024
 
THE THERMAL TROUGH  
WILL WEAKEN TODAY WITH RELATIVELY CALM CONDITIONS THIS AFTERNOON  
THROUGH TONIGHT. A WEAK COLD FRONT WILL BRING INCREASING SOUTH WINDS  
EARLY SATURDAY MORNING, BUT THEY ARE EXPECTED TO REMAIN BELOW SMALL  
CRAFT. THE FRONT WILL MOVE INLAND LATE SATURDAY MORNING WITH WINDS  
BECOMING WESTERLY. A THERMAL TROUGH WILL SET UP ALONG THE SOUTH  
COAST SUNDAY WITH NORTH WINDS INCREASING, WITH MODERATE TO STRONG  
WINDS SOUTH OF CAPE BLANCO SUNDAY AFTERNOON. MODERATE TO STRONG  
NORTH WINDS WILL PERSIST INTO EARLY NEXT WEEK. -PETRUCELLI  
 

 
   
PREV DISCUSSION
 
/ISSUED 238 AM PDT FRI APR 19 2024/  
 
DISCUSSION...HIGH PRESSURE WILL MAINTAIN VERY NICE EARLY SPRING  
WEATHER ACROSS MOST OF SW OREGON AND NORTHERN CALIFORNIA TODAY.  
SOME HIGH CLOUDS WILL DRIFT BY AT TIMES, BUT OVERALL, EXPECT  
MAINLY SUNNY SKIES WITH A MILD AFTERNOON. HIGH TEMPERATURES WILL  
BE LARGELY IN THE 70S IN THE VALLEYS WEST OF THE CASCADES AND INTO  
THE 60S OVER THE EAST SIDE. THE AIR MASS IS QUITE DRY, SO HUMIDITY  
THIS AFTERNOON WILL DROP INTO THE TEENS AND 20S IN MANY AREAS --  
KEEP THE LIP BALM AND SKIN MOISTURIZER HANDY. THIS WILL ALSO  
LIKELY PREVENT ANY POTENTIAL POP-UP SPRINKLES/SHOWERS FROM  
REACHING THE GROUND OVER SE SECTIONS OF THE CWA (THOUGH THERE IS A  
ABOUT A 5-10% CHANCE) DUE TO SOME WEAK INSTABILITY OVER THERE.  
BETTER CHANCE FOR THIS IS OVER THE SIERRA/NW NEVADA.  
 
DRY WEATHER IS EXPECTED TONIGHT INTO SATURDAY AS A WEAK SHORT WAVE  
UPPER RIDGE SWINGS THROUGH. HOWEVER, A COLD FRONT WILL APPROACH  
THE COAST ON SATURDAY. SOME RAIN SHOWERS ARE LIKELY TO MOVE INTO  
THE COASTAL WATERS DURING THE MORNING, AND THEN EVENTUALLY MOVE  
ONSHORE SATURDAY AFTERNOON. GIVEN THE PRECEDING DRY AIR MASS, IT  
WILL BE DIFFICULT FOR THESE SHOWERS TO GET VERY FAR INLAND  
SATURDAY AFTERNOON/EVENING. THIS IS EVIDENT IN THE POP FORECAST  
WITH POPS NOT EVEN REACHING 15% HERE IN MEDFORD. POPS WILL BE  
HIGHEST ALONG THE COAST 18Z SAT-00Z SUN (50-70%), THEN LOWER TO  
20-40% SATURDAY EVENING. FARTHEST EAST PRECIP CHANCES (20-40%)  
REACH THE CASCADES NORTH OF HIGHWAY 140. IT SHOULD BE NOTED THAT  
IT WILL GET BREEZY SATURDAY AFTERNOON/EVENING IN MANY AREAS FROM  
THE WSW, SHIFTING TO NW AS THE FRONT MOVES THROUGH (PEAK GUSTS  
25-35 MPH).  
 
THE FRONT SHIFTS EAST OF THE AREA SATURDAY NIGHT WITH HIGH  
PRESSURE BUILDING IN ON SUNDAY/MONDAY. FROST/FREEZING CONDITIONS  
ARE POSSIBLE DURING THIS PERIOD OF DRY WEATHER DURING THE LATE  
NIGHTS/EARLY MORNINGS IN THE VALLEYS WEST OF THE CASCADES. IT WILL  
ONLY BE NOMINALLY COOLER ON SUNDAY, WITH HIGH TEMPERATURES CLOSER  
TO NORMAL ACROSS NW SECTIONS, BUT REMAINING AT LEAST A FEW  
DEGREES ABOVE NORMAL ELSEWHERE. MONDAY WILL WARM UP SUBSTANTIALLY  
(UP 5-10 F OVER SUNDAY). ANOTHER THERMAL TROUGH WILL STRENGTHEN IN  
NORCAL RESULTING IN ANOTHER ROUND OF N-NE WINDS LATE SUNDAY  
THROUGH MONDAY. THIS SHOULD EVEN BRING THE MILDER WEATHER TO  
PORTIONS OF THE SW COAST (BROOKINGS).  
 
THE NEXT CHANCE AT PRECIP WON'T COME UNTIL TUESDAY OF NEXT WEEK.  
SOME GUIDANCE IS SHOWING THE UPPER TROUGH OFFSHORE STAYING WELL TO  
OUR NORTH AND WEST WITH A BIT OF A MOISTURE SURGE FROM THE SOUTH.  
THIS COULD CAUSE SOME SHOWERS (THUNDER?) IN PARTS OF NORCAL AND  
MAYBE FROM THE CASCADES EASTWARD TUESDAY AFTERNOON/EVENING. MODELS  
AREN'T TOO BULLISH ON THIS JUST YET WITH NBM POPS ONLY PEAKING UP  
AROUND 20%. THE UPPER TROUGH SHOULD SEND A COLD FRONT ONSHORE AT  
MIDWEEK WITH A BIT OF A COOL DOWN AND A CHANCE OF SHOWERS.  
-SPILDE  
 
AVIATION...OTHER THAN SOME HIGH CLOUDS AT TIMES AND A SLIGHT  
UPTICK IN DIURNAL BREEZES THIS AFTERNOON, VFR WILL PREVAIL AREA  
WIDE THROUGH THE NEXT 24 HOURS. COASTAL AREAS WON'T BE NEARLY AS  
GUSTY AS YESTERDAY. -SPILDE  
 
MARINE...UPDATED 200 AM FRIDAY, APRIL 19, 2024...A WEAKENING  
THERMAL TROUGH WILL MAINTAIN STEEP, HAZARDOUS SEAS THROUGH EARLY  
THIS MORNING. STEEP SEAS WILL SHIFT TO BEYOND 10 NM FROM SHORE AND  
SOUTH OF CAPE BLANCO BY LATE MORNING, THEN SUBSIDE BELOW SMALL CRAFT  
ADVISORY LEVELS THIS AFTERNOON. CONDITIONS IMPROVE TONIGHT WITH  
RELATIVELY LIGHT WINDS AND LOW SEAS INTO SATURDAY, THOUGH A WEAK  
COLD FRONT WILL MOVE THROUGH ON SATURDAY WITH SOME RAIN. GUSTY NORTH  
WINDS AND STEEP SEAS ARE EXPECTED TO RETURN LATER IN THE WEEKEND  
WITH POSSIBLE GALES AND VERY STEEP, HAZARDOUS SEAS SOUTH OF CAPE  
BLANCO LATE SUNDAY INTO MONDAY. -SPILDE  
 

 
   
MFR WATCHES/WARNINGS/ADVISORIES
 
 
OR...NONE.  
 
CA...NONE.  
 
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 11 AM PDT THIS  
MORNING FOR PZZ370.  
 
SMALL CRAFT ADVISORY UNTIL 2 PM PDT THIS AFTERNOON FOR PZZ376.  
 

 
 

 
 
MNF/MAS/MCB  
 
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