536  
FXUS66 KPQR 232225  
AFDPQR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PORTLAND OR  
325 PM PDT THU MAR 23 2017  
   
SYNOPSIS
 
AN OCCLUDING PACIFIC FRONTAL SYSTEM WILL SPREAD RAIN  
ACROSS SOUTHWEST WASHINGTON AND NORTHWEST OREGON THIS AFTERNOON INTO  
TONIGHT, WITH SHOWERS AND A FEW THUNDERSTORMS LINGERING INTO FRIDAY.  
HIGH PRESSURE WILL CAUSE SHOWERS TO TAPER OFF LATE SATURDAY, BUT THE  
NEXT FRONTAL SYSTEM WILL LIKELY BRING MORE RAIN SUNDAY FOLLOWED BY  
SHOWERS MONDAY. OCCASIONALLY WET WEATHER IS EXPECTED TO LINGER  
THROUGH THE MIDDLE OF NEXT WEEK.  
 

 
   
SHORT TERM...TONIGHT THROUGH SUNDAY
 
VISIBLE SATELLITE IMAGERY  
CONTINUES TO SHOW MID AND HIGH CLOUDS FILTERING INTO SOUTHWEST  
WASHINGTON AND NORTHWEST OREGON THIS AFTERNOON AHEAD OF AN  
APPROACHING FRONTAL SYSTEM. DOPPLER RADAR IS ALSO STARTING TO SHOW  
SOME LIGHT RETURNS THIS AFTERNOON, BUT BASED ON RECENT SURFACE  
OBSERVATIONS SUSPECT THIS IS MAINLY FALLING AS VIRGA AT THE MOMENT.  
OTHERWISE, THE FORECAST REMAINS ON TRACK FOR THIS AFTERNOON AND  
TONIGHT WITH RAIN ARRIVING AT THE COAST IN THE NEXT SEVERAL HOURS AND  
PUSHING INLAND THIS EVENING. RAIN WITH THIS FRONT COULD BE HEAVY AT  
TIMES, BUT MODELS CONTINUE TO KEEP THE HIGHEST QPF OVER SOUTHERN  
OREGON. IN GENERAL, EXPECT AROUND 1 TO 1.5 INCHES OF RAIN ALONG THE  
COAST AND IN THE COAST RANGE AND PORTIONS OF THE CASCADES THROUGH  
FRIDAY. THE INTERIOR COULD SEE AROUND 0.5 TO 1 INCH. SNOW LEVELS LOOK  
TO REMAIN ABOVE THE PASSES TONIGHT AND FRIDAY, WITH THE HIGH CASCADES  
LIKELY GETTING ANOTHER 4 TO 6 INCHES OF NEW SNOW.  
 
RAIN WILL TURN TO SHOWERS ALONG THE COAST BY FRIDAY MORNING AND  
INLAND BY THE AFTERNOON AS THE COOL UPPER LEVEL TROUGH STARTS TO MOVE  
ONSHORE. MODELS CONTINUE TO SHOW AROUND 200 TO 500 J/KG OF CAPE OVER  
THE FORECAST AREA TOMORROW AFTERNOON, WITH 0 TO 3 KM BULK SHEAR  
AROUND 25 KT. IF WE ARE ABLE TO GET ANY SUNBREAKS TOMORROW AFTERNOON  
WE COULD SEE A FEW THUNDERSTORMS DEVELOP ACROSS THE REGION. HOWEVER,  
THIS IS A BIG IF. DESPITE THIS HAVE DECIDED TO KEEP THE MENTION OF  
THUNDER IN THE FORECAST, BUT WILL HOLD OFF ADDING THE MENTION OF  
GUSTY WINDS OR SMALL HAIL.  
 
SHOWERS LOOK TO CONTINUE INTO EARLY SATURDAY, BUT AS HIGH PRESSURE  
BUILDS INTO THE PACIFIC NORTHWEST LATE SATURDAY THESE SHOWERS WILL  
LIKELY COME TO AN END FOR A BRIEF PERIOD OF DRY WEATHER SATURDAY  
NIGHT. THE NEXT FRONTAL SYSTEM LOOKS TO IMPACT THE FORECAST AREA ON  
SUNDAY BRINGING THE RETURN OF COOL AND WET WEATHER. /64  
   
LONG TERM...SUNDAY NIGHT THROUGH THURSDAY
 
12Z GLOBAL MODELS ARE  
IN GENERAL AGREEMENT WITH EVOLUTION OF THE LONG WAVE PATTERN,  
HOWEVER, DETAILS ARE FAR TOO SKETCHY TO PIN DOWN SPECIFIC DRY  
PERIODS. THIS IS SOMEWHAT OF A SHIFT FROM EARLIER RUNS WHERE THE  
EARLY PART OF NEXT WEEK SHOWED SIGNS OF A BRIEF DRY PERIOD. COLD  
FRONT SUNDAY NIGHT WILL PUSH EAST THROUGH EARLY MONDAY. PLENTY OF  
OROGRAPHIC SHOWERS WILL FOLLOW THROUGH MONDAY EVENING. THERE, THE  
GFS AND ECMWF START TO SHOW DIFFERENCES AMONG THE OPERATIONAL RUNS.  
HAVE THEREAFTER DECIDED TO STICK FAIRLY CLOSE TO A BLEND OF THE  
ENSEMBLE MEANS AS THE ECMWF IS SLIGHTLY MORE PROGRESSIVE WITH THE  
WESTERLY FLOW WHILE THE GFS IS CONTINUING MORE OF THE AMPLIFIED  
PATTERN IT'S SHOWN THE LAST FEW DAYS. THE 12Z RUNS DO COME BACK  
TOGETHER ON WEDNESDAY/WEDNESDAY NIGHT WITH A TROUGH SWEEPING EAST  
ACROSS THE REGION. FOR NOW, THAT LOOKS LIKE THE WETTEST DAY ALTHOUGH  
GIVEN THE RUN TO RUN INCONSISTENCY, HAVE KEPT LOWER END LIKELY POPS  
FOR NOW. REGARDLESS OF THE DETAILS, OVERALL CONDITIONS WILL CLOSE TO  
SEASONAL TEMPERATURE NORMS WHICH KEEPS SNOW LEVELS BOUNCING BETWEEN  
4000 AND 6000 FEET. /JBONK  
 

 
   
AVIATION
 
VFR CONDITIONS THIS AFTERNOON ARE LIKELY TO GIVE  
WAY TO MVFR CONDITIONS ALONG THE COAST BETWEEN 22Z AND 02Z LATE TODAY  
AS RAIN ASSOCIATED WITH A COLD FRONT INCREASES. THERE IS A CHANCE  
FOR SEEING SHORT-LIVED PERIODS OF IFR VISIBILITIES DURING PERIODS OF  
HEAVIER RAIN MAINLY BETWEEN 02Z AND 06Z. ONCE THE FRONT MOVES INLAND  
EXPECT CONDITIONS TO IMPROVE BACK TO MAINLY VFR CONDITIONS WITH  
SHOWERS AFTER 11Z. INLAND EXPECT MAINLY VFR CONDITIONS TO PREVAIL  
TONIGHT INTO FRI, BUT FROM 04Z THROUGH 13Z EXPECT AT LEAST A  
CHANCE FOR TEMPORARY MVFR CONDITIONS ASSOCIATED WITH THE FRONT.  
 
KPDX AND APPROACHES...VFR CONDITIONS REMAIN MOST LIKELY TONIGHT  
THROUGHOUT TONIGHT, BUT THERE IS A CHANCE FOR SEEING MVFR CONDITIONS  
IN RAIN BETWEEN 04Z AND 13Z AS A COLD FRONT SLOWLY MOVES THROUGH.  
AFTER 13Z VFR CONDITIONS ARE EXPECTED TO PREVAIL.  
 

 
   
MARINE
 
COLD FRONT WILL MOVE EAST ACROSS THE COASTAL WATERS EARLY  
THIS EVENING, LIKELY REACHING THE COAST BETWEEN 6 AND 8 PM. BY EARLY  
AFTERNOON WINDS OVER THE OUTER WATERS WERE APPROACHING GALE FORCE,  
AND ARE EXPECTED TO BECOME SOLIDLY GALE UNTIL AFTER THE FRONT MOVES  
THROUGH OVER THE OUTER WATERS. INNER WATERS WILL BE A LITTLE SLOWER  
COMING UP TO GALES THIS EVENING DUE TO A LITTLE BIT OF AN OFFSHORE  
COMPONENT TO THE WIND. WILL SEE WINDS TURN MORE TO THE WEST AND  
DECREASE BEHIND THE FRONT LATER TONIGHT INTO FRI, BUT WITH GUSTS  
STILL ON THE ORDER OF 20 TO 25 KT THROUGH FRI. SEAS WILL RESPOND TO  
THE LOCAL WINDS TONIGHT MEANING THEY WILL BE STEEP, AND ARE EXPECTED  
TO RISE TO AROUND 15 FT. BY LATE TONIGHT THOUGH AS WINDS SUBSIDE SO  
TOO WILL SEAS, DOWN TO AROUND 10 FT FRI. A RIDGE OF HIGH PRES MOVES  
SLOWLY EAST ACROSS THE COASTAL WATERS FRI NIGHT THROUGH SAT NIGHT  
FOR QUIETER WEATHER.  
 
SUN ANOTHER COLD FRONT APPROACHES FROM THE WEST, INCREASING WINDS  
AGAIN. WINDS WITH THIS SYSTEM EXPECTED TO GUST AS HIGH AS 30 TO 35  
KT LATE SUN.  
 

 
   
PQR WATCHES/WARNINGS/ADVISORIES
 
 
OR...NONE.  
WA...NONE.  
PZ...GALE WARNING UNTIL 1 AM PDT FRIDAY FOR WATERS FROM CAPE  
SHOALWATER WA TO FLORENCE OR FROM 10 TO 60 NM.  
 
GALE WARNING UNTIL 3 AM PDT FRIDAY FOR COASTAL WATERS FROM CAPE  
SHOALWATER WA TO FLORENCE OR OUT 10 NM.  
 
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 9 PM  
THIS EVENING TO 5 AM PDT FRIDAY.  
 

 
 

 
 
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. THE AREA IS  
COMMONLY REFERRED TO AS THE FORECAST AREA.  
 
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