032  
FXUS66 KPQR 260402 AAA  
AFDPQR  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE PORTLAND OR  
901 PM PDT MON MAR 25 2019  
 
UPDATED AVIATION AND MARINE SECTIONS  
   
SYNOPSIS
 
GENERALLY COOL AND SHOWERY WEATHER WILL PERSIST OVER  
NORTHWEST OREGON AND SOUTHWEST WASHINGTON THIS WEEK EXCEPT FOR  
TUESDAY AND SATURDAY, WHICH WILL STAND THE BEST CHANCE OF ENDING UP  
DRY.  
 

 
   
SHORT TERM...TODAY THROUGH THURSDAY
 
VISIBLE SATELLITE IMAGERY  
THIS AFTERNOON SHOWS A SURFACE LOW PRESSURE OFF THE PACIFIC NORTHWEST  
COAST. AN OCCLUDED FRONT IS CURRENTLY IN THE PROCESS OF MOVING ACROSS  
WESTERN OREGON. THIS IS RESULTING IN WIDESPREAD LIGHT RAIN FALLING  
ACROSS NORTHWEST OREGON AND SOUTHWEST WASHINGTON. AS COLDER AIR ALOFT  
FILTERS OVER THE REGION THIS AFTERNOON, EXPECT THE LOWER TO MIDDLE  
PART OF THE ATMOSPHERE TO DESTABILIZE AND PRECIPITATION TO TURN MORE  
SHOWERY IN NATURE. THERE REMAINS A CHANCE THIS DESTABILIZATION ALOFT  
WILL COUPLE AT LEAST BRIEFLY WITH DAYTIME HEATING TO ALLOW A STRONG  
SHOWER OR TWO TO POP BETWEEN 4-7 PM, PARTICULARLY ACROSS THE CENTRAL  
AND SOUTHERN WILLAMETTE VALLEY. SHEAR PROFILES SUGGEST THERE COULD BE  
A LOW END WIND THREAT IF SOMETHING DEVELOPS. MODEL SOUNDINGS APPEAR A  
BIT BETTER FOR THUNDER CHANCES OVER THE WATERS, BUT THE CONTINUED  
LACK OF SUSTAINED CONVECTION UPSTREAM SUGGESTS THIS REMAINS A LOW  
THREAT AS WELL.  
 
GIVEN THERE SHOULD BE AT LEAST SOME CLEARING OVERNIGHT AND WITH  
WEAKENING SURFACE WINDS, SOME PATCHY FOG SHOULD DEVELOP LATE TONIGHT  
INTO TUESDAY MORNING IN THE VALLEYS OF THE COAST RANGE AND IN THE  
WILLAMETTE AND LOWER COLUMBIA RIVER VALLEYS. WEAK SHORTWAVE RIDGING  
WILL PUSH ACROSS THE REGION ON TUESDAY, WHICH SHOULD LEAD TO A  
MAINLY DRY DAY ACROSS THE AREA WITH TEMPERATURES TOPPING OUT AROUND  
60F.  
 
HOWEVER, THE AFOREMENTIONED SURFACE LOW PRESSURE CURRENTLY FOUND OFF  
THE OREGON COAST WILL DUMBBELL AROUND ITSELF AND EVENTUALLY MOVE  
CLOSE ENOUGH TO BRING ANOTHER ROUND OF RAIN SPREADING  
NORTH-NORTHEASTWARD ACROSS THE REGION ON WEDNESDAY. DEPENDING ON THE  
TRACK OF THE SURFACE LOW PRESSURE, WE COULD SEE ADDITIONAL SHOWERS  
LINGER INTO WEDNESDAY NIGHT, BUT GENERALLY WE SHOULD SEE A REDUCTION  
OF RAIN CHANCES WITH THE LOSS OF DAYTIME HEATING. WITH THE COOL UPPER  
LEVEL TROUGH STILL OVERHEAD ON THURSDAY, WE SHOULD SEE SHOWER  
ACTIVITY INCREASE IN COVERAGE AND INTENSITY DURING THE AFTERNOON AND  
EARLY EVENING HOURS ONCE AGAIN. /NEUMAN  
 
   
LONG TERM...THURSDAY NIGHT THROUGH MONDAY
 
MODELS ARE IN GOOD  
AGREEMENT THE SHORTWAVE TROUGH BRINGING SHOWERS TO THE AREA ON  
WEDNESDAY AND THURSDAY WILL BE SLOWLY EXITING THE REGION ON FRIDAY.  
THIS SHOULD BRING A BIT MORE SUNSHINE TO THE AREA, BUT THERE MAY YET  
BE ANOTHER ROUND OF AFTERNOON AND EARLY EVENING SHOWERS ON FRIDAY,  
PARTICULARLY FOR AREAS AWAY FROM THE COAST AND ACROSS THE HIGHER  
TERRAIN. MODELS AND THEIR ENSEMBLES ARE IN FAIR AGREEMENT SHORTWAVE  
RIDGING WILL MOVE OVER THE PACIFIC NORTHWEST SOMETIME SATURDAY. THIS  
SHOULD LEAD TO A MAINLY DRY DAY WITH LOWLAND LOCATIONS LIKELY RISING  
WELL INTO THE 60S SATURDAY AFTERNOON. MODELS THEN SUGGEST THE  
SHORTWAVE RIDGE WILL SHIFT EAST OF THE REGION SATURDAY NIGHT INTO  
SUNDAY AND OPEN THE DOOR TO INCREASINGLY MOIST SOUTHWESTERLY FLOW.  
THIS WILL LIKELY RESULT IN ANOTHER FRONTAL STORM SYSTEM BRINGING  
ANOTHER ROUND OF COOL AND SHOWERY WEATHER TO THE AREA SUNDAY AND/OR  
MONDAY, BUT TIMING UNCERTAINTY REMAINS. AS A RESULT, POPS WERE  
INCREASED TO NEAR OR ABOVE CLIMATOLOGY PER A BLEND OF MODEL AND  
ENSEMBLE GUIDANCE. /NEUMAN  
 

 
   
AVIATION
 
THE OCCLUDED FRONT MOVED NORTH INTO WA LATE THIS  
AFTERNOON. POST FRONTAL SHOWERS WILL CONTINUE THIS EVENING WITH A  
MIX OF VFR AND MVFR CONDITIONS. SHOWERS WILL EASE OVERNIGHT WITH  
A WEAK SURFACE RIDGE DEVELOPING OVER WESTERN OREGON. A BIT OF A  
CHALLENGE FOR LATE TONIGHT WITH REGARDS TO CIGS AND VIS, BUT  
THINK THERE WILL BE ENOUGH MOISTURE MORE STABLE CONDITIONS FOR  
MVFR CIGS TO DEVELOP. ALSO MAY SEE IFR CIGS AND VIS DEVELOP AS  
WELL BUT DO NOT EXPECT IT TO BE WIDESPREAD. MODELS INDICATE THE  
AIR MASS DRYING BY MIDDAY TUE, SO EXPECT VFR CONDITIONS THEN.  
 
KPDX AND APPROACHES...A MIX OF VFR AND MVFR CONDITIONS IN POST  
FRONTAL SHOWERS THROUGH TONIGHT, BUT MAY SEE MORE PERSISTENT MVFR  
CIGS DEVELOP AFTER 10-12Z TUE AS THE AIR MASS SETTLES. DRIER  
OFFSHORE FLOW WILL BRING VFR CONDITIONS BY MIDDAY TUE. /MH  
 

 
   
MARINE
 
SOUTHERLY WINDS CONTINUE TO GUST TO AROUND 25 KT OVER  
THE WATERS, BUT A LITTLE LESS NEARSHORE. EXPECT WINDS WILL  
GRADUALLY SUBSIDE EARLY TUE, AND GENERALLY REMAIN 20 KT OR LESS  
THROUGH TUE NIGHT. A SECOND SURFACE LOW WILL APPROACH THE COAST  
ON WED, RESULTING IN ANOTHER OCCLUDED FRONTAL PASSAGE. THIS ONE  
LOOKS TO BE A BIT STRONGER THAN TODAY'S FRONT, SO EXPECT ANOTHER  
ROUND OF SOLID SMALL CRAFT ADVISORY WINDS, WITH AN OUTSIDE SHOT  
AT SOME LOW-END GALES. WINDS SUBSIDE JUST A LITTLE ON THU, BUT  
PROBABLY REMAIN GUSTY AS THE WEAKENING SURFACE LOW SLOWLY PUSHES  
ONTO THE CENTRAL OR SOUTHERN OREGON COAST. ANOTHER FRONT MAY  
ARRIVE OVER THE WEEKEND.  
 
SEAS WILL BE HOVERING AROUND 10 FT THROUGH TONIGHT. IN ADDITION,  
THEY WILL BE QUITE CHOPPY AS LONGER-PERIOD WESTERLY SWELL  
INTERACTS WITH SHORT-PERIOD WIND WAVES AND FRESH SWELL BEING  
GENERATED BY THE GUSTY SOUTHERLY WINDS. SEAS SHOULD DROP BACK  
BELOW 10 FT BY EARLY TUE. THE WED/THU SYSTEM SHOULD PUSH SEAS  
BACK INTO THE LOW TEENS FOR A PERIOD, BEFORE THEY DROP BACK BELOW  
10 FT LATE IN THE WEEK. PYLE  
 

 
   
PQR WATCHES/WARNINGS/ADVISORIES
 
 
OR...NONE.  
WA...NONE.  
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 3 AM PDT TUESDAY FOR  
COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT  
60 NM.  
 
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM PDT TUESDAY  
FOR COASTAL WATERS FROM CAPE SHOALWATER WA 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 FORECAST AREA.  
 
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