540  
FXUS66 KPQR 230427  
AFDPQR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PORTLAND OR  
927 PM PDT TUE AUG 22 2017  
   
SYNOPSIS
 
AN UPPER RIDGE THAT SPREAD INTO THE PACIFIC NORTHWEST  
MONDAY WILL SLOWLY MOVE EAST TONIGHT AND WEDNESDAY AS A SYSTEM SLOWLY  
APPROACHES THE B.C AND PACIFIC NORTHWEST COAST. THE MARINE LAYER WILL  
EXTEND FARTHER INLAND WEDNESDAY, RESULTING IN SOME COOLING. THERE IS  
A SLIGHT CHANCE OF A SHOWER IN THE OREGON CASCADES TONIGHT AND EARLY  
WEDNESDAY. A WEAK FRONT WILL MOVE THROUGH THE PACIFIC NORTHWEST  
WEDNESDAY NIGHT AND THURSDAY, BRINGING SIGNIFICANT COOLING AND A FEW  
SHOWERS. FRIDAY WILL SEE DRYING AND WARMING FOR A TYPICAL SUMMER DAY,  
THEN LOOK FOR SIGNIFICANT WARMING THIS WEEKEND INTO EARLY NEXT WEEK.  
 

 
   
SHORT TERM...TONIGHT THROUGH FRIDAY
 
SATELLITE IMAGERY THIS EVENING  
SHOWS MARINE STRATUS WELL ENTRENCHED ALONG THE COAST WITH A COUPLE OF  
SITES REPORTING LOWERED VISIBILITY AND EVEN SOME LIGHT RAIN. WITH  
THAT IN MIND, ADDED PATCHY LIGHT DRIZZLE AND PATCHY FOG TO THE  
FORECAST FOR THE COAST THROUGH TONIGHT. ALSO ADJUSTED CLOUD COVER TO  
REFLECT CURRENT TRENDS AS WELL AS A MARINE PUSH FURTHER INLAND  
TONIGHT. WILL ALSO SEE MORE OF A SOUTHWEST PUSH THAT WILL BRING  
CLOUDS INTO THE SOUTHERN WILLAMETTE VALLEY. RADAR TRENDS SHOW SHOWER  
AND THUNDERSTORM ACTIVITY BEGINNING TO SHIFT A LITTLE BIT NORTH AND  
WEST, AS EXPECTED, SO KEPT SOME SLIGHT CHANCE POPS ALONG THE CASCADE  
CREST FOR LATER TONIGHT. BOWEN  
 
THE REMAINDER OF THE SHORT TERM FORECAST DISCUSSION IS UNCHANGED...  
 
WEDNESDAY WILL SEE GREATER COVERAGE OF LOW CLOUDS INLAND IN THE  
MORNING WHEN COMPARED TO TODAY, COMING INLAND ALONG THE COLUMBIA  
RIVER AS WELL AS THE SOUTHERN COASTAL GAP TOWARDS AND PAST EUGENE.  
EVEN THOUGH IT WILL BURN OFF INLAND IN THE AFTERNOON, THIS WILL COOL  
TEMPS BACK DOWN CLOSER TO SEASONAL NORMALS ON WEDNESDAY. INCREASING  
SOUTHWEST FLOW ALOFT WILL ENSURE THAT ANY CONVECTION WILL BE EAST OF  
OUR CASCADES IN THE AFTERNOON.  
 
WEDNESDAY NIGHT AND THURSDAY WILL SEE THE APPROACHING OFFSHORE SYSTEM  
MOVE THROUGH THE PACIFIC NORTHWEST. THIS WILL BRING CLOUDY CONDITIONS  
TO THE AREA WITH A FEW SHOWERS, AS WELL AS COOLING OF AFTERNOON  
TEMPS. THURSDAY SHOULD SEE 60S AT THE COAST AND 70S INLAND.  
 
WESTERLY FLOW SPREADS IN THURSDAY NIGHT AND FRIDAY, WITH MORNING  
CLOUDS ESPECIALLY NORTH FRIDAY GIVING WAY TO SUNSHINE IN THE  
AFTERNOON. TEMPS WILL BE CLOSER TO SEASONAL NORMALS AS FRIDAY IS A  
VERY TYPICAL SUMMER DAY. TOLLESON  
   
LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS
 
FRIDAY NIGHT  
THROUGH TUESDAY...SHORTWAVE RIDGING WILL BUILD OVER THE PACIFIC  
NORTHWEST AND BRING WARMING TEMPERATURES THROUGH THE WEEKEND. SEVERAL  
DAYS OF 90F+ TEMPERATURES APPEAR INCREASINGLY LIKELY FOR THE  
WILLAMETTE VALLEY WITH SUNDAY AND MONDAY APPEARING THE HOTTEST. WHILE  
SOME MODELS SUGGEST EVEN HOTTER TEMPERATURES ARE POSSIBLE ON THESE  
DAYS, MOST GENERALLY KEEP TEMPERATURES CLOSER TO REASONABLE LEVELS SO  
THE FORECAST WAS TRENDED TOWARDS THIS IDEA BEING THE MOST LIKELY TO  
OCCUR.  
 
THIS UPCOMING HOT STRETCH WILL LIKELY PRODUCE A MULTI-DAY PERIOD OF  
CRITICAL FIRE WEATHER CONDITIONS AS WELL. EAST TO NORTHEASTERLY WINDS  
SHOULD ALLOW SMOKE TO FILTER BACK INTO THE REGION SUNDAY AND MONDAY.  
THE FLOW MAY TURN A LITTLE MORE SOUTHERLY ALOFT AS THE RIDGE BEGINS  
TO BREAK DOWN LATE IN THE WEEKEND OR MORE LIKELY EARLY NEXT WEEK SO  
WILL NEED TO MONITOR FOR THE POSSIBILITY OF THUNDERSTORMS EVEN THOUGH  
MODELS AT THIS TIME DO NOT REALLY SHOW IT DESPITE THE SYNOPTIC  
PATTERN APPEARING SOMEWHAT FAVORABLE. /NEUMAN/TOLLESON  
 

 
   
AVIATION
 
IFR OR LOWER FOG AND STRATUS HAS RETURNED TO THE  
COAST AND WILL PERSIST OVERNIGHT THROUGH AT LEAST 18Z WED.  
ACROSS THE INTERIOR, EXPECT CONTINUED SMOKE TO OCCASIONAL FORM  
VFR CIGS THIS EVENING THROUGH EARLY TONIGHT. ONSHORE MARINE PUSH  
WILL BRING LOWER MVFR CIGS INTO MUCH OF THE WILLAMETTE VALLEY  
BETWEEN 12-14Z THROUGH AROUND 18Z WHEN LIFTING AND SCATTERING  
WILL BRING A RETURN OF VFR CONDITIONS.  
 
KPDX AND APPROACHES...VFR THROUGH LATE TONIGHT WITH OCCASIONAL  
CIGS DUE TO SMOKE. A PERIOD OF MVFR STRATUS AROUND 2000 FT WILL  
ARRIVE BY 12Z AND WILL CONTINUE THROUGH 18Z, WITH A RETURN TO VFR  
CONDITIONS THEREAFTER. CULLEN  
 

 
   
MARINE
 
CONDITIONS REMAIN RELATIVELY BENIGN ACROSS THE COASTAL  
WATERS, WITH WINDS LESS THAN 15 KT AND SEAS AROUND 5 FT. A WEAK  
FRONT CROSSES THE WATERS ON WEDNESDAY, BUT THE PRIMARY IMPACT  
WILL BE A SLIGHT SHIFT TO WEST WINDS, WITH SPEEDS REMAINING BELOW  
ADVISORY THRESHOLDS. HIGH PRESSURE BUILDS ACROSS THE WATERS  
STARTING LATE WEDNESDAY NIGHT, AND THERMAL LOW PRESSURE  
STRENGTHENS AGAIN LATER IN THE WEEK. THIS WILL BRING A RETURN OF  
ADVISORY STRENGTH WINDS TO THE SOUTHERN ZONES BY FRIDAY AND  
ACROSS THE NORTHERN COASTAL WATERS OVER THE WEEKEND. SEAS WILL  
GENERALLY REMAIN 4 TO 6 FEET THROUGH THE WEEK, BUT MAY BUILD TO 7  
FEET AND BECOME RATHER STEEP AT TIMES THIS WEEKEND WHEN THE  
STRONGER WINDS DEVELOP. CULLEN  
 

 
   
PQR WATCHES/WARNINGS/ADVISORIES
 
 
OR...NONE.  
WA...NONE.  
PZ...NONE.  
 

 
 

 
 
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 FORECAST AREA.  
 
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