593  
FXUS66 KPQR 021002  
AFDPQR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PORTLAND OR  
302 AM PDT SAT AUG 2 2025  
   
SYNOPSIS
 
NEAR AVERAGE TEMPERATURES EXPECTED TODAY. GENERAL  
TROUGHING AND INCREASING ONSHORE FLOW WILL BRING RELATIVELY COOLER  
TEMPERATURES SUNDAY THROUGH THURSDAY WITH INCREASING CHANCES FOR  
CLOUD COVER, ESPECIALLY DURING THE MORNING HOURS. CHANCES FOR  
WIDESPREAD RAIN INCREASE WEDNESDAY INTO THURSDAY, HOWEVER  
UNCERTAINTY IS HIGH REGARDING EXACT RAIN AMOUNTS, IF ANY RAIN FALLS  
AT ALL. A WARMING TREND APPEARS LIKELY INTO NEXT WEEKEND AS HIGH  
PRESSURE POTENTIALLY BUILDS OVER THE REGION, HOWEVER UNCERTAINTY IS  
HIGH REGARDING HOW HOT TEMPERATURES MAY REACH.  
 

 
   
SHORT TERM...TODAY THROUGH MONDAY
 
VERY LITTLE CHANGE TO THE  
OVERALL PATTERN TODAY, THOUGH MARINE STRATUS MAY BRING A FEW LOW  
CLOUDS UP THE LOWER COLUMBIA THIS MORNING. EXPECT CLOUDS TO GIVE WAY  
TO MOSTLY SUNNY SKIES BY MID-DAY WITH TEMPERATURES AGAIN WARMING  
INTO THE 80S, ALONG WITH A SLIGHT CHANCE (10-20%) OF THUNDERSTORMS  
ALONG THE CASCADE CREST NEAR THE WILLAMETTE PASS EASTWARD. BREEZY  
ONSHORE WINDS RETURN LATER IN THE AFTERNOON.  
 
CONDITIONS TREND COOLER AND CLOUDIER ON SUNDAY AS A WEAK UPPER LEVEL  
SHORTWAVE TROUGH MOVES OVER THE COASTAL WATERS AND ACROSS THE  
PACIFIC NORTHWEST LATE SUNDAY. EXPECT MID AND HIGH CLOUDS TO  
INCREASE FROM WEST TO EAST BY SUNRISE. THE INCREASING CLOUD COVER,  
COMBINED WITH COOLER TEMPERATURES ALOFT, WILL SUPPORT COOLER  
TEMPERATURES WITH DAYTIME HIGHS GENERALLY IN THE 70S, ALTHOUGH IF  
SKIES CLEAR SOMEWHAT, COULD SEE TEMPS PUSHING BACK TOWARD 80  
DEGREES, ESPECIALLY THROUGH THE SOUTHERN AND CENTRAL WILLAMETTE  
VALLEY. SUNDAY ALSO FEATURES A 15-30% CHANCE OF SHOWERS OVER THE  
OREGON CASCADES DURING THE AFTERNOON AND EVENING HOURS. DEPENDING ON  
HOW MUCH INSTABILITY RESIDES, NBM MAINTAINS A SLIGHT (15%) CHANCE OF  
THUNDERSTORMS NEAR THE CREST OF THE CASCADES IN LANE COUNTY.  
 
WITH COOLER AIR LINGERING ACROSS THE AREA, COMBINED WITH ONSHORE  
FLOW ON MONDAY, EXPECT SIMILARLY MILD CONDITIONS. NEAR TO SLIGHTLY  
BELOW AVERAGE TEMPERATURES EXPECTED MONDAY WITH SOME LINGERING  
CLOUDS POSSIBLE OVER NORTHERN PORTIONS OF THE FORECAST AREA. /DH  
   
LONG TERM...TUESDAY THROUGH FRIDAY
 
NOT MUCH CHANGE TO THE LONG  
TERM FORECAST. GENERAL LOW AMPLITUDE TROUGHING WITH EMBEDDED UPPER  
LEVEL SHORTWAVE TROUGH WILL MAINTAIN ONSHORE FLOW THROUGH AT LEAST  
THE MIDDLE OF NEXT WEEK. EXPECT NEAR TO SLIGHTLY BELOW AVERAGE  
TEMPERATURES WITH A MIX OF SUN AND CLOUDS EACH DAY. COULD SEE THE  
MARINE LAYER DEEPEN WITH AROUND A 10-20% CHANCE OF LIGHT RAIN OR  
DRIZZLE ALONG THE NORTHERN COAST TUESDAY, WITH INCREASING CHANCES  
(UP TO 40%) ALONG MUCH OF THE COAST ON WEDNESDAY.  
 
MODELS AND THEIR ENSEMBLES ARE SHOWING INCREASING CHANCES FOR MORE  
WIDESPREAD RAIN LATE WEDNESDAY INTO THURSDAY WITH THE POSSIBILITY OF  
A WEAK LOW PRESSURE SYSTEM APPROACHING THE WEST COAST. THE NBM IS  
SHOWING INCREASING CHANCES (ALBEIT STILL IN THE MINORITY) OF 24-HOUR  
RAINFALL PROBABILITIES EXCEEDING 0.25 INCH OF AROUND 20-30%. STILL,  
THERE ARE AROUND 50% OF ENSEMBLE MEMBERS THAT SHOW NO PRECIPITATION  
AT ALL.  
 
BY THE END OF THE WEEK, WPC CLUSTERS ARE SHOWING A GENERAL TREND  
TOWARD UPPER LEVEL RIDGING BUILDING OVER THE EASTERN PACIFIC  
BRINGING POTENTIAL FOR WARMER TEMPERATURES INTO NEXT WEEKEND. THE  
CPC DOES INDICATE THERE IS A SLIGHT RISK OF EXTREME HEAT ALONG THE I-  
5 CORRIDOR, BEGINNING SATURDAY; WHILE THE NBM SUGGESTS THERE IS  
AROUND A 30-50% CHANCE OF EXCEEDING 100 DEGREES NEXT SUNDAY THROUGH  
THE WILLAMETTE VALLEY. /DH  
 

 
   
AVIATION
 
CURRENTLY AS OF 09Z SATURDAY, LIFR/IFR CONDITIONS  
PERSIST ALONG THE COAST AND VFR CONDITIONS INLAND. THESE  
CONDITIONS ALONG THE COAST WILL LIKELY PERSIST UNTIL 17-18Z  
SATURDAY, WITH CHANCES FOR LIFR/IFR CIGS AROUND 40-80% (LOWEST TO  
HIGHEST CHANCES FROM NORTH TO SOUTH). BY 18-19Z SATURDAY, COULD  
SEE MVFR CONDITIONS AS CHANCES LOWER TO 10-30% FOR IFR CIGS AND  
50-60% FOR MVFR CIGS. BY 03-06Z SUNDAY, DETERIORATED CONDITIONS  
BEGIN TO REDEVELOP ALONG THE COAST AND WILL PERSIST THROUGH THE  
REST OF THE TAF PERIOD (EARLIEST TO LATEST FROM SOUTH TO NORTH).  
OTHERWISE, NORTHWESTERLY WINDS WILL INCREASE AT COASTAL TERMINALS  
AROUND 20Z SATURDAY TO 03Z SUNDAY, WITH GUSTS 20 TO 25 KT  
EXPECTED.  
 
INLAND, TERMINALS WILL STAY VFR THROUGH MOST OF THE TAF PERIOD.  
THE ONLY EXCEPTION WILL BE IN THE MORNING FROM 12Z TO 18Z  
SATURDAY, WHERE COASTAL STRATUS MAY PUSH UP THE COLUMBIA RIVER  
AND INTO KPDX, KHIO, KTTD, AND KVUO. ADDITIONALLY, COASTAL STRATUS  
COULD PUSH THROUGH THE COASTAL GAPS INTO KEUG. MODEL GUIDANCE  
SUGGESTS A 20-30% CHANCE FOR MVFR CIGS TO DEVELOP AT THESE INLAND  
TERMINALS DURING THE AFOREMENTIONED TIME. CONSIDERING CURRENT  
OBSERVATIONS OF STRATUS AT KKLS, THE PATTERN LOOKS ON TRACK FOR  
CONDITIONS TO BRIEFLY DETERIORATE AT MOST INLAND TERMINALS. THE  
ONLY UNCERTAINTY WILL BE IF THE CLOUD DECK FORMS UNIFORMLY ENOUGH,  
AS YESTERDAY MORNING OBSERVATIONS WERE FEW AND SCATTERED AROUND  
FL015. OTHERWISE, EXPECT NORTHWESTERLY WINDS AROUND 6 TO 10 KT  
WITH BRIEF GUSTS TO 18 KT POSSIBLE AT A FEW TERMINALS BETWEEN 00Z  
AND 08Z SUNDAY.  
 
PDX AND APPROACHES...VFR CONDITIONS WILL PERSIST THROUGH MOST OF  
THE TAF PERIOD. BETWEEN 12Z AND 18Z SATURDAY, COULD SEE  
CONDITIONS DETERIORATE TO MVFR AT THE TERMINAL. UNCERTAIN WHETHER  
THE CLOUD DECK WILL BE MORE UNIFORM (BROKEN OR OVERCAST), AS  
YESTERDAY WAS ONLY FEW OR SCATTERED AROUND FL015. WHILE  
PROBABILISTIC GUIDANCE SUGGESTS A 20-30% CHANCE OF MVFR CIGS,  
DETERMINISTIC GUIDANCE SUGGESTS CIGS WILL STAY ABOVE FL030.  
OTHERWISE, EXPECT NORTHWESTERLY WINDS 8 TO 10 KT WITH GUSTS UP TO  
18 KT BETWEEN 00Z AND 08Z SUNDAY.  
~HALL  
 

 
   
MARINE
 
OVERALL FAIRLY CALM CONDITIONS PERSIST THROUGH THE  
WEEKEND AS AN AREA OF SURFACE HIGH PRESSURE SITS ACROSS THE  
WATERS. NORTHWEST WINDS IN THE AFTERNOON AND EVENING HOURS WILL  
OCCASIONALLY GUST UP TO 14-20 KNOTS BUT SMALL CRAFT CONDITIONS ARE  
NOT ANTICIPATED. MARINE STRATUS IS RATHER PROLIFIC THIS MORNING  
AND WHEN CONSIDERING THE CURRENT PATTERN, MORNING STRATUS WILL  
LIKELY REOCCUR EVERY MORNING THROUGH THE WEEKEND AND INTO MONDAY.  
 
COME TUESDAY, AN APPROACHING SURFACE TROUGH BRINGS ABOUT A  
SOUTHERLY WIND SHIFT ACROSS ALL WATERS FOR ALBEIT WITH WIND GUSTS  
LIKELY REMAINING BELOW SMALL CRAFT CONDITIONS. LATER IN THE WEEK  
GUIDANCE DOES HINT AT THE POTENTIAL ARRIVAL OF A SLIGHTLY STRONGER  
TROUGH WHICH WOULD PUSH WIND GUSTS CLOSER TO 21 KNOTS - THE NBM  
SUGGESTS A 30-50% CHANCE FOR SMALL CRAFT WINDS ACROSS THE  
SOUTHERN WATERS BY FRIDAY.  
~HALL/SCHULDT  
 

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

 
 

 
 
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