866  
FXUS66 KPQR 202307  
AFDPQR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PORTLAND OR  
306 PM PST THU FEB 20 2020  
   
SYNOPSIS
 
VARYING DEGREES OF HIGH PRESSURE OVER THE PACIFIC  
NORTHWEST WILL BRING COOL NIGHTS, MILD DAYS, AND MAINLY DRY WEATHER  
THROUGH NEXT WEEK. THE MAIN EXCEPTION TO THIS WILL BE ON SUNDAY INTO  
MONDAY WHEN A STORM SYSTEM WILL BRING THE RETURN OF VALLEY RAIN AND  
MOUNTAIN SNOW.  
 

 
   
SHORT TERM...TONIGHT THROUGH SUNDAY
 
WATER VAPOR SATELLITE IMAGERY  
CONTINUES TO SHOW A CLOSED UPPER LEVEL LOW DROPPING SOUTHWARD OFF THE  
CALIFORNIA COAST, WITH SHORTWAVE RIDGING OVER THE PACIFIC NORTHWEST.  
ASIDE FROM SOME MID AND HIGH CLOUDS STREAMING OVER THE REGION THIS  
AFTERNOON CONDITIONS REMAIN RATHER MILD. EXPECT THESE CONDITIONS TO  
GENERALLY CONTINUE THROUGH SATURDAY. THE EXCEPTION TO THIS WILL BE  
THE INCREASE OF MARINE CLOUDS ALONG THE COAST STARTING FRIDAY AS  
ONSHORE FLOW TAKES OVER AHEAD OF AN INCOMING SHORTWAVE DISTURBANCE.  
 
GUIDANCE CONTINUES TO SHOW A WEAK FRONT BRUSHING BY THE FAR NORTHERN  
PORTIONS OF THE FORECAST AREA ON SATURDAY WHICH COULD BRING SOME  
LIGHT RAIN TO AREAS NORTH OF THE COLUMBIA RIVER. A MUCH STRONGER  
FRONT LOOKS TO THEN MOVE ACROSS THE FORECAST AREA LATE SATURDAY INTO  
SUNDAY. THIS FRONT WILL BRING THE RETURN OF WIDESPREAD VALLEY RAIN  
AND MOUNTAIN SNOW ON SUNDAY, WITH SNOW LEVELS LOWERING BELOW CASCADES  
PASSES. THERE IS STILL SOME UNCERTAINTY WITH QPF AND SNOW AMOUNTS  
OVER THE WEEKEND, BUT BASED ON THE LATEST GUIDANCE IT STILL LOOKS  
LIKE ADVISORY LEVEL SNOW IS POSSIBLE OVER THE NORTH OREGON AND SOUTH  
WASHINGTON CASCADES. /64/NEUMAN  
   
LONG TERM...SUNDAY NIGHT THROUGH WEDNESDAY
 
MODELS AND THEIR  
ENSEMBLES ARE IN GOOD AGREEMENT THE SHORTWAVE TROUGH IMPACTING THE  
PACIFIC NORTHWEST ON SUNDAY WILL SLIDE EASTWARD AND BE REPLACED BY  
SHORTWAVE RIDGING. THIS WILL RESULT IN DECREASING SHOWERS AND CLOUDS  
ACROSS THE AREA SUNDAY NIGHT INTO MONDAY. THERE IS STRONG CONSENSUS  
THE PACIFIC NORTHWEST WILL THEN BE UNDER THE INFLUENCE OF A SHORTWAVE  
RIDGE FOR MUCH OF NEXT WEEK. THIS WILL BRING COOL NIGHTS, HIGH  
TEMPERATURES NEAR AVERAGE AND MAINLY DRY WEATHER. VARIOUS OPERATIONAL  
AND ENSEMBLE MEMBERS DO SUGGEST A SHORTWAVE TROUGH WILL TRY TO SLIDE  
INTO THE RIDGE TOWARDS THE MIDDLE OF NEXT WEEK AND POTENTIALLY BRING  
LIGHT PRECIPITATION TO THE AREA. HOWEVER, THERE'S VERY LITTLE  
CONSENSUS ON HOW THIS MIGHT TAKE SHAPE AND WHEN EXACTLY IT WILL OCCUR  
AMONG MODEL AND ENSEMBLE GUIDANCE. AS A RESULT, THE NBM SLIGHT CHANCE  
POPS TOWARDS THE END OF THE LONG TERM FORECAST SEEM REASONABLE GIVEN  
THE PATTERN AND UNCERTAINTY. /NEUMAN  
 

 
   
AVIATION
 
HIGH PRESSURE PERSISTS CREATING VFR CONDITIONS THROUGH  
FRI. GUSTY EAST WINDS CONTINUE THROUGH THE GORGE AND COAST RANGE  
THROUGH 00Z FRI WHEN THE PRESSURE GRADIENT WEAKENS. WINDS WILL  
GENERALLY BECOME LIGHT AND VARIABLE THROUGH THE VALLEY AFTER 08Z FRI.  
SLIGHT CHANCE OF PATCHY FOG AROUND SUNRISE AT 13Z FRI, BUT WITH A DRY  
BOUNDARY LAYER, CHANCES ARE LOW. IF IT DOES FORM, IT WOULD BE NEAR  
KEUG AND OTHER FOG PRONE AREAS.  
 
KPDX AND APPROACHES...VFR CONDITIONS WITH GUSTY EAST WINDS. STRONG  
EAST WINDS AROUND 2000 FT AGL WILL PERSIST THROUGH 06Z FRI. POTENTIAL  
FOR SOME PATCHY FOG AROUND THE AIRPORT IN THE EARLY MORNING FRI, BUT  
UNLIKELY DUE TO WINDS THROUGH THE EVENING. NOT INCLUDED IN TAF.  
-MUESSLE  
 

 
   
MARINE
 
HIGH PRESSURE REMAINS OVER THE AREA WITH A WESTERLY SWELL  
THROUGH SAT MORNING. SEAS AROUND 5 FT WILL PERSIST THROUGH SAT  
EVENING WITH WINDS GENERALLY CALM. SAT NIGHT, A 990 MB LOW OFF THE  
ALASKA PENINSULA WILL MOVE SOUTH TOWARDS THE CONUS PACIFIC NORTHWEST.  
WHILE THE LOW WILL STAY NORTH OF THE AREA OVER THE AK-PEN, WINDS AND  
SEAS ARE EXPECTED TO RAMP UP.  
 
THE MAIN PORTION OF THIS SYSTEM WILL MOVE OVER THE WATERS SUN  
AFTERNOON. WITH A STRONG GRADIENT, SMALL CRAFT LEVEL WINDS WITH  
STRONG SOUTHERLY GUSTS UP TO 30 KT ARE LIKELY. SEAS WILL ALSO BUILD  
TO NEAR 10 FT SAT AFTERNOON, RISING TO NEAR 16 FT SUN AFTERNOON. WITH  
THIS SYSTEM, THERE IS STILL QUITE A BIT OF UNCERTAINTY DUE TO MODEL  
DIFFERENCES WITH THE INTENSITY OF THE LOW (HOW DEEP IT IS), AND WHERE  
IT WILL TRACK. IN ANY CASE, A MORE ACTIVE PATTERN IS EXPECTED THIS  
WEEKEND. BY MON NIGHT, CONDITIONS SHOULD SETTLE AND WEAK HIGH  
PRESSURE WILL DEVELOP OVER THE PACIFIC CREATING CALM CONDITIONS ONCE  
AGAIN. -MUESSLE  
 

 
   
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 NM OFFSHORE. THIS AREA IS COMMONLY  
REFERRED TO AS THE FORECAST AREA.  
 
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