045  
FXUS66 KPQR 310446 AAA  
AFDPQR  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE PORTLAND OR  
946 PM PDT SAT AUG 30 2025  
 
UPDATED AVIATION DISCUSSION.  
   
SYNOPSIS
 
A CUTOFF LOW LINGERING OFFSHORE OF NORTHWESTERN  
OREGON AND SOUTHWESTERN WASHINGTON WILL BRING CONTINUED  
SEASONABLE TEMPERATURES THROUGH LABOR DAY WEEKEND WITH MORNING  
INCURSIONS OF MARINE CLOUDS GIVING WAY TO BREAKS OF AFTERNOON  
SUN. BUILDING HIGH PRESSURE WILL YIELD A WARMING TREND EARLY IN  
THE WEEK, WITH THE POTENTIAL FOR HIGH TEMPERATURES REACHING THE  
90S AND MODERATE TO MAJOR HEATRISK TUESDAY THROUGH AT LEAST  
THURSDAY ACROSS INLAND AREAS. INCREASING CHANCES OF SCATTERED  
SHOWERS AND ISOLATED THUNDERSTORMS MIDWEEK.  
 

 
   
SHORT TERM...SATURDAY AFTERNOON THROUGH MONDAY
 
SATELLITE  
IMAGERY SATURDAY AFTERNOON DEPICTS TWO CLASSIC LOW PRESSURE  
SYSTEMS, ONE JUST WEST OF THE OREGON/WASHINGTON COAST AND ONE  
FARTHER SOUTHWEST IN THE PACIFIC, CENTERED AROUND 40N 155W. THE  
LOW PRESSURE SYSTEM JUST TO THE WEST OF OUR COAST WILL REMAIN  
FAIRLY STATIONARY THROUGH MONDAY, ONLY MOVING SLIGHTLY TO THE  
NORTHWEST. TODAY IT IS CLOSEST TO THE NW OREGON AND SW  
WASHINGTON COAST, AND IT IS PRODUCING SHOWERS OVER THE COASTAL  
WATERS THAT ARE PUSHING JUST ALONG THE COAST. MOST OF THESE  
SHOWERS ARE DRYING AND BECOMING VIRGA AS SOON AS THEY REACH  
LAND, THOUGH A FEW OBSERVATION STATIONS HAVE REPORTED A TRACE TO  
0.01 INCH OF RAIN THROUGHOUT THE DAY. MID TO UPPER LEVEL CLOUDS  
ARE STREAMING ACROSS MUCH OF THE REGION, WITH ALONG WITH THE  
COOLER AIR FUNNELED INTO THE REGION FROM THE UPPER LOW ARE  
HELPING TO KEEP TEMPERATURES ON THE COOLER SIDE. OBSERVED  
TEMPERATURES AS OF 3 PM ARE ONLY IN THE UPPER 60S FOR THE SW  
WASHINGTON LOWLANDS, MID 70S NORTH OF SALEM, AND UPPER 70S TO  
LOW 80S SOUTH OF SALEM WHERE THERE IS LITTLE TO NO CLOUD COVER.  
CONDITIONS TOMORROW INTO MONDAY WILL BE SIMILAR WITH JUST LESS  
WIDESPREAD CLOUD COVER, LEADING TO SLIGHTLY WARMER TEMPERATURES  
EACH DAY. MARINE STRATUS FORMATION IS LIKELY EACH NIGHT INTO THE  
MORNING HOURS, WITH STRATUS INTRUSION POSSIBLE THROUGH COAST  
RANGE GAPS EACH MORNING. -HEC  
   
LONG TERM...TUESDAY THROUGH FRIDAY
 
THE FORECAST BECOMES MORE  
UNCERTAIN IN THE LONG TERM. ENSEMBLES INDICATE THE LOW PRESSURE  
SYSTEM OFF OF THE COAST WILL BEGIN RETROGRADING ON TUESDAY, WITH  
HIGH PRESSURE CURRENTLY OVER THE GREAT BASIN BEGINNING TO MOVE  
WEST INTO OREGON AND WASHINGTON. THIS WILL ALLOW TEMPERATURES TO  
WARM A BIT ON TUESDAY INTO THE UPPER 80S TO LOW 90S. HOWEVER,  
ENSEMBLES ARE IN GOOD AGREEMENT OF A COMPACT CLOSED LOW MOVING  
INTO CENTRAL CALIFORNIA LATE MONDAY/EARLY TUESDAY, THEN MOVING  
NORTH THROUGH CALIFORNIA INTO OREGON SOMETIME AFTER THAT. THE  
UNCERTAINTY NOW COMES INTO PLAY IN THE TIMING OF WHEN THE LOW  
WILL MOVE INTO OREGON AS WELL AS THE STRENGTH OF IT, BOTH OF  
WHICH COULD IMPACT HOW FAR WEST THE HIGH PRESSURE CAN SPREAD  
INTO THE AREA AND THEREFORE WHETHER TEMPERATURES CONTINUE  
WARMING INTO MIDWEEK OR REMAIN STEADY. ADDITIONALLY, THIS LOW  
WILL PRODUCE SHOWER AND THUNDERSTORM CHANCES OVER OREGON, BUT  
DUE TO THE PREVIOUSLY MENTIONED UNCERTAINTY, THAT INTRODUCES  
UNCERTAINTY IN LOCATION AND TIMING OF SHOWER AND THUNDERSTORM  
CHANCES. IF SHOWERS/THUNDERSTORMS FORM, THIS WOULD PRODUCE CLOUD  
COVER THAT COULD ALSO IMPACT THE POTENTIAL FOR WARMING  
TEMPERATURES.  
 
THE 13Z NBM RUN HAS TONED DOWN ON THE WARMING TEMPERATURES, WITH  
DETERMINISTIC HIGHS REMAINING IN THE LOW 90S FOR WEDNESDAY AND  
THURSDAY. PROBABILITIES FOR REACHING 95 DEGREES FOR BOTH DAYS  
HAVE ALSO DECREASED A BIT TO 40-55% FOR INLAND VALLEYS.  
OVERNIGHT TEMPERATURE FORECAST STILL REMAINS ON THE SLIGHTLY  
WARMER SIDE WITH MANY INLAND LOCATIONS FORECAST TO REMAIN ABOVE  
60 DEGREES. THERE IS STILL WIDESPREAD MODERATE HEATRISK FOR  
INLAND AREAS FOR TUESDAY THROUGH THURSDAY, BUT MAJOR HEATRISK IS  
NOW MORE LIMITED TO THE PORTLAND AND SALEM URBAN AREAS AND THE  
COLUMBIA RIVER GORGE. THESE TEMPERATURES COULD STILL IMPACT  
VULNERABLE POPULATIONS, ESPECIALLY THOSE SPENDING EXTENDED TIME  
OUTDOORS OR THOSE WITHOUT ADEQUATE AIR CONDITIONING.  
BY FRIDAY, TEMPERATURES ARE EXPECTED TO BEGIN A DOWNWARD TREND  
INTO THE 80S, THOUGH THERE'S STILL A 10-25% CHANCE TEMPERATURES  
COULD BE AS WARM AS 95 DEGREES. -HEC  
 

 
   
AVIATION
 
A WEAK UPPER LOW OFFSHORE THE WASHINGTON AND OREGON  
COAST WILL SUPPORT A DEEPENING MARINE LAYER TONIGHT AND RETURN MVFR-  
IFR STRATUS TO THE COAST AND PORTIONS OF INLAND VALLEYS TONIGHT  
INTO SUNDAY MORNING. THAT SAID, GUIDANCE SUGGESTS MARINE STRATUS  
WILL HOLD OFF UNTIL 09-12Z AT THE COAST AND UNTIL 12-16Z FOR  
INLAND VALLEYS, WITH STRATUS MOST LIKELY FOCUSED OVER THE NORTHERN  
WILLAMETTE VALLEY. AS SUCH, KUAO, KPDX, KTTD AND KHIO HAVE THE  
BEST CHANCE FOR HIGH-END IFR TO LOW-END MVFR CIGS TO DEVELOP, WITH  
PROBABILITIES RANGING BETWEEN 30-60% (LOWEST AT KHIO AND HIGHEST  
AT KTTD AND KUAO). KSLE AND KEUG ONLY HAVE A 20-25% CHANCE AND  
WILL MOST LIKELY REMAIN VFR. HAVE INCLUDED A MENTION OF LOWERING  
CIGS FOR ALL OTHER TAF SITES, HOWEVER CONFIDENCE IS LOW FOR KHIO.  
 
PDX AND APPROACHES...THERE IS A 35-45% CHANCE OF MVFR CEILINGS  
RETURNING TO PDX SOMETIME BETWEEN 12-16Z SUNDAY. ANY STRATUS THAT  
FORMS SHOULD CLEAR TO VFR AROUND 20Z SUNDAY. LIGHT WINDS OF 5 KT  
OR LESS WILL PREVAIL. -TK  
 

 
   
MARINE
 
LOW PRESSURE WILL MAINTAIN LIGHT WINDS ACROSS THE  
COASTAL WATERS THROUGH MONDAY. HIGH PRESSURE BUILDS TUESDAY AND  
WEDNESDAY FOR INCREASING NORTH WINDS. THE WINDS WILL BE STRONGEST  
IN THE AFTERNOONS AND EVENINGS, ESPECIALLY TO THE SOUTH WHERE THE  
SURFACE PRESSURE GRADIENT WILL BE THE STRONGEST. THE NORTH WIND  
GUSTS WILL FLIRT WITH SMALL CRAFT CONDITIONS TUESDAY AND WEDNESDAY  
AFTERNOONS WHERE THERE IS A 40% CHANCE OF WIND GUSTS GREATER THAN  
20 KT. SEAS WILL BE BELOW 4 FT THROUGH MONDAY, WITH AN INCREASE  
IN WIND WAVES BUILDING SEAS TO 5-6 FT TUESDAY THROUGH THURSDAY. -TJ  
 

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

 
 

 
 
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