993  
FXUS66 KPQR 222211  
AFDPQR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PORTLAND OR  
311 PM PDT SAT SEP 22 2018  
 
   
SYNOPSIS
 
SHOWERS WILL DECREASE TONIGHT. DRY BUT SEASONALLY COOL  
WEATHER IS EXPECTED FOR SUNDAY. HIGH PRESSURE AND OFFSHORE WINDS WILL  
RESULT IN WARM AND DRY WEATHER TUESDAY THROUGH FRIDAY. MORE SEASONAL  
WEATHER RETURNS NEXT WEEKEND.  
 

 
   
SHORT TERM...TONIGHT THROUGH TUESDAY
 
A SHORT WAVE UPPER TROUGH  
WILL MAINTAIN A CHANCE FOR SHOWERS LATE THIS AFTERNOON AND EVENING  
BEHIND A DEPARTING FRONT. THE BEST CHANCE FOR SHOWERS IS TO THE NORTH  
AND OVER THE HIGHER TERRAIN. RAINFALL TOTALS ARE NOT EXPECTED TO BE  
HIGH, BUT AN UNSTABLE AIRMASS MAY RESULT IN ISOLATED MODERATE TO  
HEAVE SHOWERS. EXPECT RAINFALL TOTALS TO GENERALLY BE LIGHT TONIGHT  
THOUGH (LESS THAN 0.10 INCH). THE SHOWERS WILL BE CONFINED TO THE  
HIGHER TERRAIN TONIGHT, AND END NEAR OR JUST AFTER MIDNIGHT.  
 
DRY N-NW FLOW WILL GRADUALLY CLEAR SKIES ON SUNDAY, THE FIRST DAY OF  
AUTUMN, AND THE DEPARTING UPPER TROUGH WILL KEEP THE AFTERNOON  
TEMPERATURES BELOW 70 DEGREES IN MOST LOCATIONS. HIGH PRESSURE BUILDS  
ALOFT MONDAY AND TUESDAY AS A SURFACE THERMAL TROUGH EXPANDS UP THE  
COAST FROM CALIFORNIA. OFFSHORE WINDS SHOULD DEVELOP MONDAY NIGHT AND  
HOLD THROUGH TUESDAY SUPPORTING CLEAR SKIES AND WARMING TEMPERATURES.  
INTERIOR DAYTIME TEMPERATURES WILL PEAK IN THE MID 70S ON MONDAY AND  
LOW 80S ON TUESDAY .COASTAL REGIONS LIKELY WARM INTO THE 70S TUESDAY  
AFTERNOON. ~TJ  
   
LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
 
STRONG RIDGE REMAINS  
IN PLACE THROUGH MUCH OF NEXT WEEK. BOTH THE GFS AND ECMWF START TO  
BREAK DOWN THE RIDGE LATE NEXT WEEK, BUT IN TWO DIFFERENT WAYS. THE  
ECMWF BRINGS THE LOW OFF THE COAST OF CALIFORNIA NORTH UP INTO  
OREGON, WHILE THE GFS BRINGS A STRONG TROUGH DOWN OUT OF ALASKA/B.C.  
TO BREAK DOWN THE RIDGE. THESE TWO DIFFERENT SCENARIOS BRING A LOT  
OF UNCERTAINTY TO THE FORECAST GOING INTO NEXT WEEKEND.  
 
WITH THE RIDGE IN PLACE THROUGH MUCH OF THIS WEEK, EXPECT CONTINUING  
OFFSHORE WINDS AND ABNORMALLY WARM TEMPERATURES THROUGH THURSDAY.  
FRIDAY IS WHEN BOTH MODELS START TO BREAK DOWN THE RIDGE IN PLACE  
OVER THE AREA, WHICH SHOULD MEAN COOLER TEMPERATURES STARTING FRIDAY  
GOING INTO NEXT WEEKEND. BOTH MODELS KEEP US DRY THROUGH AT LEAST  
SATURDAY, BUT TEMPERATURES SHOULD DROP DOWN TO BE CLOSER TO NORMAL  
FRIDAY AND SATURDAY. -MCCOY  

 
   
AVIATION
 
SURFACE TROUGH OVER THE COASTAL AREAS EARLY THIS  
AFTERNOON HELPING TO MAINTAIN SHOWER ACTIVITY. GENERALLY VFR,  
BUT AREAS OF MVFR, MAINLY ALONG THE COAST. COASTAL AREAS LIKELY  
TO SEE A MIX OF VFR AND MVFR THROUGH 06Z SUN, THEN INCREASING  
MVFR AS THE AIR MASS STABILIZES WITH PLENTY OF LOW-LEVEL  
MOISTURE. CANNOT RULE OUT LOCAL IFR OR WORSE CONDITIONS IN THE  
10Z TO 16Z TIME FRAME SHOULD SKIES CLEAR. INLAND TAF SITES WILL  
BE GENERALLY VFR THROUGH ABOUT 10Z SUN, WITH HIGHEST CHANCE OF  
SHOWERS THROUGH 23Z. THERE IS THE POTENTIAL FOR BRIEF MVFR  
INLAND WITH ANY SHOWER, THEN A CHANCE OF MVFR 10Z TO 18Z SUN.  
 
KPDX AND APPROACHES...VFR TO BE THE PREDOMINANT CATEGORY THROUGH  
18Z SUN. CANNOT RULE OUT BRIEF MVFR THROUGH EARLY AFTERNOON WITH  
ANY SHOWERS. CONSIDERABLE CLOUD COVER TONIGHT WILL PRECLUDE FOG  
FORMATION, BUT THERE IS A CHANCE OF MVFR STRATUS TOWARD DAWN.  
WEISHAAR.  
 

 
   
MARINE
 
WIND SPEEDS SLOWLY DECREASING EARLY THIS AFTERNOON AND  
WILL ALLOW THE SMALL CRAFT ADVISORY FOR WIND TO EXPIRE. WIND  
SPEEDS CONTINUE TO DIMINISH THIS EVENING THROUGH TONIGHT. NORTH  
WIND DEVELOPS OVER THE WATERS SUN AND CONTINUES THROUGH EARLY  
NEXT WEEK. A SURFACE THERMAL TROUGH FORMS OVER THE SOUTH OREGON  
WATERS SUN AND THEN EXPANDS A LITTLE MORE NORTH SUN NIGHT. GUSTS  
TO 25 KT LIKELY ACROSS PZZ275 BEGINNING SUN NIGHT AND POSSIBLY  
GETTING CLOSE TO 30 KT MON AND MON NIGHT. SMALL CRAFT ADVISORY  
WIND CONDITIONS LIKELY TO SPREAD INTO PZZ270 BY MON AFTERNOON.  
MODEL SOLUTIONS SHOW LARGER VARIATIONS FOR THE LATTER HALF OF  
NEXT WEEK. USED THE GFS IN THE THU-SAT TIME FRAME, WHICH  
MAINTAINS NW-N WIND 10 TO 20 KT OVER THE WATERS. HOWEVER,  
CONFIDENCE IS LOW FOR ANY SINGLE SOLUTION.  
 
SEAS GENERALLY 8 TO 10 FT ACROSS THE NORTH WATERS EARLY THIS  
AFTERNOON. EXPECT LITTLE CHANGE THROUGH THE EVENING. PERIODS 8  
TO 9 SECONDS WILL RESULT IN STEEP, CHOPPY SEA CONDITIONS AND WILL  
MAINTAIN THE SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS. WAVE  
HEIGHTS START TO EASE TONIGHT. INCREASING NORTH WIND SUN NIGHT  
THROUGH EARLY NEXT WEEK WILL PRODUCE CHOPPY WIND-DRIVEN SEA  
CONDITIONS, MAINLY SOUTH OF NEWPORT. WEISHAAR  
 

 
   
PQR WATCHES/WARNINGS/ADVISORIES
 
 
OR...NONE.  
WA...NONE.  
PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PDT THIS  
EVENING FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO  
CASCADE HEAD OR OUT 60 NM.  
 
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 6 PM  
PDT THIS EVENING.  

 
 

 
 
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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