042  
FXUS66 KPQR 201045  
AFDPQR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PORTLAND OR  
345 AM PDT SUN JUL 20 2025  
   
SYNOPSIS
 
 
SEASONABLE TEMPERATURES CONTINUE THROUGH EARLY THIS WEEK, WITH A  
SLIGHT CHANCE (10-20%) FOR SHOWERS FROM TONIGHT INTO MONDAY AS  
A WEAK UPPER LOW MOVES ACROSS THE REGION. A WARMING TREND  
RETURNS MIDWEEK, BRINGING ABOVE NORMAL TEMPERATURES BY  
WEDNESDAY.  
 

 
   
DISCUSSION...NOW THROUGH FRIDAY
 
A MODEST SHORTWAVE ALOFT  
CONTINUES TO SLIDE ACROSS THE PACIFIC NORTHWEST THIS MORNING. AS  
THIS DISTURBANCE DROPS SOUTHWARD OVER THE NEXT 24 HOURS,  
ENSEMBLES SHOW A GRADUAL LOWERING OF 500 MB HEIGHTS ACROSS THE  
REGION. THIS PATTERN WILL HELP REINFORCE THE MARINE LAYER,  
POTENTIALLY LEADING TO GREATER INLAND CLOUD COVER THIS MORNING  
COMPARED TO YESTERDAY. HOWEVER, HIGH RES ENSEMBLE GUIDANCE  
SUGGESTS THAT MAY NOT MATERIALIZE FOR ALL AREAS.  
 
THIS AFTERNOONS HIGH TEMPERATURES WILL REMAIN NEAR SEASONAL  
AVERAGES, WITH INLAND VALLEYS REACHING THE MID TO UPPER 70S. AS  
THE UPPER TROUGH TRANSITIONS INTO A CLOSED LOW SUNDAY NIGHT  
INTO MONDAY, SOME MOISTURE AND WEAK LIFT WILL ACCOMPANY IT,  
OPENING THE DOOR TO LIGHT SHOWER ACTIVITY, MAINLY ACROSS THE  
CASCADES. WHILE SOME ENSEMBLE MEMBERS SUPPORT ISOLATED  
PRECIPITATION, MOST KEEP CONDITIONS LARGELY DRY ELSEWHERE. THIS  
ALIGNS WELL WITH NBM PROBABILITIES, WHICH MAINTAIN 10-20%  
CHANCES FOR SHOWERS, HIGHEST OVER THE HIGHER TERRAIN AND  
ESPECIALLY ACROSS THE LANE AND LINN COUNTY CASCADES. OVERALL,  
MONDAY WILL BRING ANOTHER ROUND OF MILD TEMPERATURES AND  
VARIABLE CLOUD COVER, WITH NO SIGNIFICANT IMPACTS EXPECTED  
OUTSIDE OF LOCALIZED SPRINKLES IN ELEVATED TERRAIN.  
 
THE PATTERN UNDERGOES A MORE NOTABLE SHIFT MIDWEEK, AS ENSEMBLE  
SOLUTIONS INCREASINGLY FAVOR RISING HEIGHTS AND RIDGING ALOFT  
BEGINNING TUESDAY. THIS TRANSLATES INTO A WARMING TREND, WITH  
INLAND AREAS CLIMBING BACK INTO THE UPPER 80S TO LOW 90S BY  
WEDNESDAY. ENSEMBLE PROBABILITIES SUGGEST MODERATE CONFIDENCE  
IN THE WARM UP, WITH A 60-80% CHANCE OF THE WILLAMETTE VALLEY  
REACHING AT LEAST 90 DEGREES OR HIGHER. THE MOST LIKELY RANGE  
FOR THE WILLAMETTE VALLEY MIDWEEK APPEARS TO BE 88-93 DEGREES.  
ONSHORE FLOW WILL PERSIST, KEEPING THE COAST MILD AND STABLE,  
WITH HIGHS HOLDING NEAR AVERAGE VALUES.  
 
TOWARD THE LATTER HALF OF THE WEEK, THERE IS GROWING ENSEMBLE  
SUPPORT FOR A SECONDARY DISTURBANCE BREAKING OFF FROM THE  
EARLIER TROUGH AND RETROGRADING OFF THE CALIFORNIA COAST. IF IT  
LIFTS NORTHEAST LATER THURSDAY OR FRIDAY, THERE IS POTENTIAL FOR  
ELEVATED INSTABILITY AND ISOLATED THUNDERSTORM DEVELOPMENT,  
PARTICULARLY IN THE LANE LINN COUNTY CASCADES. CURRENT GUIDANCE  
PLACES THE 48 HOUR THUNDERSTORM POTENTIAL IN THE 10-30% RANGE,  
THOUGH EXACT TIMING AND TRACK REMAIN UNCERTAIN. NORTH AND WEST  
OF THIS AREA, STORM PROBABILITIES DECREASE QUICKLY. GIVEN THE  
CURRENT SPREAD IN TIMING, 12 HOUR THUNDERSTORM PROBABILITIES  
REMAIN TOO LOW TO INCLUDE IN THE OFFICIAL FORECAST, THOUGH THIS  
WILL BE MONITORED CLOSELY AS MODEL SPREAD NARROWS.  
~HALL  
 

 
   
AVIATION
 
SATELLITE IMAGERY AS OF EARLY SUNDAY MORNING DEPICTS  
MARINE STRATUS ALONG THE NORTH OREGON COAST AS WELL AS HIGH LEVEL  
CLOUDS AS AN UPPER LEVEL TROUGH MOVES OVER THE REGION. EXPECT  
MVFR CIGS AT KAST TO CONTINUE THROUGH 18-20Z SUN; HOWEVER, THERE  
IS LOW TO MODERATE CONFIDENCE (30-50% CHANCE) THAT MARINE STRATUS  
MAKES IT TO KONP BETWEEN 12-18Z SUN. LOW STRATUS ALONG THE COAST  
SHOULD SCATTER OUT AND RETURN VFR CONDITIONS BY EARLY AFTERNOON  
AS DAYTIME HEATING PROGRESSES. VFR PREVAILS ACROSS THE WILLAMETTE  
VALLEY WITH SCT-BKN HIGH CLOUDS. EXPECT NORTHERLY TO NORTHWESTERLY  
WINDS UNDER 10 KT ACROSS THE AREA.  
 
PDX AND APPROACHES...PREDOMINATELY VFR THROUGH THE TAF PERIOD WITH  
HIGH CLOUDS. 10% CHANCE FOR MVFR STRATUS BETWEEN 13-16Z SUN.  
EXPECT NORTHWESTERLY WINDS AROUND 5-7 KT. -ALVIZ  
 

 
   
MARINE
 
BENIGN WEATHER EXPECTED ACROSS THE WATERS THIS WEEKEND  
INTO EARLY NEXT WEEK. HIGH PRESSURE WILL MAINTAIN NORTHERLY TO  
NORTHWESTERLY WINDS, GENERALLY LESS THAN 10 KTS. EXPECT WAVE  
HEIGHTS OF 2-4 FEET. THESE WIND AND WAVE CONDITIONS ARE FORECAST  
TO CONTINUE THROUGH AT LEAST MID-WEEK. -ALVIZ/HEC  
 

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

 
 

 
 
WWW.WEATHER.GOV/PORTLAND  
 
INTERACT WITH US VIA SOCIAL MEDIA:  
WWW.FACEBOOK.COM/NWSPORTLAND  
X.COM/NWSPORTLAND  
 
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