375  
FXUS66 KPQR 172049  
AFDPQR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PORTLAND OR  
149 PM PDT TUE JUL 17 2018  
   
SYNOPSIS
 
GRADUAL COOLING IS EXPECTED IN THE INTERIOR EACH DAY  
THROUGH THE END OF THE WEEK AS ONSHORE WINDS AND A DEEPENING MARINE  
LAYER INCREASES THE MARINE INFLUENCE. AN UPPER RIDGE BUILDS OVER THE  
WEEKEND WITH INLAND TEMPERATURES WARMING BACK INTO THE 90S EARLY NEXT  
WEEK.  
 

 
   
SHORT TERM...TONIGHT THROUGH FRIDAY
 
MARINE CLOUDS HAVE RETREATED  
TO THE COAST EARLY THIS AFTERNOON AND WILL CONTINUE TO RETREAT TO  
NEAR THE BEACHES THIS AFTERNOON. CLEAR SKIES INLAND CONTINUE TO THE  
DRY AND WARM WEATHER WITH LITTLE CHANGE IN THE TEMPERATURES FROM 24  
HOURS AGO. ALTHOUGH THE TEMPERATURES ARE SIMILAR EARLY THIS  
AFTERNOON, A SLIGHTLY COOLER AIRMASS (MOSTLY MID AND HIGH LEVELS)  
SHOULD RESULT IN HIGH TEMPERATURES LATE THIS AFTERNOON A FEW DEGREES  
COOLER THAN YESTERDAY.  
 
SATELLITE IMAGERY SHOWS EXTENSIVE STRATUS OFFSHORE AND OVER THE NE  
PACIFIC BUILDING FURTHER CONFIDENCE THAT MARINE CLOUDS WILL QUICKLY  
RETURN TO THE COAST THIS EVENING (IF THEY CLEAR AT ALL). A PASSING  
UPPER TROUGH WILL RESULT IN A DEEPER MARINE LAYER OVERNIGHT AND ALLOW  
THE MARINE CLOUDS TO MOVE FURTHER INLAND WEDNESDAY MORNING. AM FAIRLY  
CONFIDENT THAT CLOUDS WILL MOVE UP THE LOWER COLUMBIA RIVER VALLEY  
INTO THE NORTH WILLAMETTE VALLEY EARLY WEDNESDAY MORNING, THEN MOVE  
FURTHER SOUTH INTO PARTS OF THE CENTRAL WILLAMETTE VALLEY.  
 
THIS INLAND INTRUSION OF MARINE AIR WILL RESULT IN A MUCH COOLER  
AFTERNOON ON WEDNESDAY WITH INLAND TEMPERATURES PEAKING IN THE 80S  
RATHER THAN THE 90S OF LATE. EXPECT AROUND 10 DEGREES OF COOLING  
NORTH OF SALEM AND AROUND 5 DEGREES OF COOLING SOUTH OF SALEM.  
 
ANOTHER UPPER TROUGH WEDNESDAY NIGHT AND THURSDAY WILL DEEPEN THE  
MARINE LAYER A BIT MORE FOR SLIGHTLY MORE EXPANSIVE INLAND CLOUDS  
THURSDAY MORNING AND 3-5 DEGREE COOLER TEMPERATURES THURSDAY  
AFTERNOON.  
 
A CLOSED UPPER LOW DROPS SOUTH FROM THE GULF OF ALASKA INTO BRITISH  
COLUMBIA THURSDAY NIGHT AND FRIDAY SUSTAINING A DEEP MARINE LAYER,  
INLAND CLOUDS AND SLIGHTLY COOLER AFTERNOON TEMPERATURES. THIS WILL  
LIKELY BE THE COOLEST DAY OF THE WEEK WITH THE TEMPERATURES IN THE  
WILLAMETTE VALLEY PEAKING IN THE UPPER 70S TO LOW 80S. ~TJ  
   
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
 
AN UPPER LEVEL TROUGH  
CONTINUES TO MOVE THROUGH THE AREA ON FRI. THE 12Z GFS AND 12Z EURO  
ARE SHOWING A SLIGHT COOLING TREND FOR FRI. HOWEVER, FRI NIGHT INTO  
SAT, THE MODELS AGREE THAT THIS COOLING TREND WILL BE SHORT LIVED.  
AS BOTH MODELS ARE AGREEING THAT A RIDGE WILL START TO PUSH THE  
TROUGH OUT OF THE AREA ON SAT, WHICH WILL LEAD TOWARDS A WARMING  
TREND FOR THE AREA. WHAT NEEDS TO BE NOTED IS THAT THE GFS IS  
SHOWING A SLOWER TRANSITION INTO THE RIDGE THAN THE EURO CURRENTLY.  
THIS COULD CHANGE AS THE MODELS OUT INTO THE EXTENDED TIME FRAME  
HAVE BEEN DIVERGING IN THE PAST MODEL RUNS. HOWEVER, BOTH MODELS  
SHOW THE RIDGE FLATTENING OUT, AND MAINTAINING THE WARMING TREND  
THROUGH THE MIDDLE OF THE WEEK. /42  

 
   
AVIATION
 
MARINE STRATUS IS HUGGING THE COASTAL STRIP THIS  
AFTERNOON. THE STRATUS WILL LIKELY THIN AND LIFT FOR A FEW HOURS THIS  
AFTERNOON IMPROVING CONDITIONS TO VFR. HOWEVER, THE STRATUS WILL  
MOVE BACK INTO THE COASTAL TAF SITES LATE THIS AFTERNOON OR  
EARLY EVENING BRINGING MVFR CIGS. THE CEILING WILL LOWER TO IFR  
BY MORNING WITH SOME PATCHY FOG. EXPECT THE STRATUS TO MOVE UP  
THE COLUMBIA RIVER TO ABOUT KPDX-KTTD EARLY WED MORNING IN THE  
10Z- 14Z TIME FRAME BRINGING MVFR CIGS. THERE IS ALSO SOME  
POTENTIAL FOR SOME LOW CLOUDS TO GET CLOSE TO KEUG EARLY WED  
MORNING, BUT LIKELY REMAIN SCATTERED.  
 
PDX AND APPROACHES...VFR CONDITIONS THROUGH THE EVENING WITH  
BREEZY NW WINDS DEVELOPING LATE THIS AFTERNOON AND EVENING. MVFR  
CIGS EXPECTED TO DEVELOP AROUND 12Z-14Z WED MORNING.  
 

 
   
MARINE
 
A TYPICAL SUMMER-TIME PATTERN WILL PERSIST FOR THE  
NEXT SEVERAL DAYS. HIGH PRESSURE WILL RESIDE OVER THE NE PAC,  
WITH A THERMALLY-INDUCED TROUGH OVER THE NORTHERN CALIFORNIA AND  
SOUTHERN OREGON. THIS WILL MAINTAIN NORTHERLY WINDS OVER THE  
COASTAL WATERS THROUGH NEXT WEEKEND. WINDS SHOULD GENERALLY  
REMAIN 20 KT OR LESS THROUGH MIDDAY WED. THE WINDS WILL BECOME A  
BIT STRONGER WED AFTERNOON AND EVENING WITH GUSTS NEAR 25 KTS  
OVER THE CENTRAL OR WATERS, MAINLY SOUTH OF CASCADE HEAD. WINDS  
THEN STRENGTHEN FURTHER THU AFTERNOON AND EVENING AND REMAIN  
GUSTY THROUGH THE WEEKEND. EXPECT GUSTS OF 25 TO 30 KT IN THE  
AFTERNOONS AND EVENINGS WITH A LITTLE LESS WIND DURING THE  
MORNING HOURS.  
 
SEAS WILL REMAIN AROUND 5 TO 6 FT THROUGH THURSDAY. SEAS LOOK TO  
BUILD TO AROUND 7 TO 8 FT NEAR THE END OF THE WEEK AND OVER THE  
WEEKEND AND WILL BECOME CHOPPY AND POTENTIALLY STEEP AS THE GUSTY  
NORTHERLY WINDS RETURN. TW  
   
PQR WATCHES/WARNINGS/ADVISORIES
 
 
OR...NONE.  
WA...NONE.  
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 2 PM WEDNESDAY TO 5 PM PDT  
THURSDAY FOR COASTAL WATERS FROM CASCADE HEAD OR TO  
FLORENCE OR OUT 60 NM.  
 

 

 
 
INTERACT WITH US VIA SOCIAL MEDIA:  
WWW.FACEBOOK.COM/NWSPORTLAND  
WWW.TWITTER.COM/NWSPORTLAND  
 
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON  
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THIS AREA IS  
COMMONLY REFERRED TO AS THE CWA OR FORECAST AREA.  
 
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