992  
FXUS66 KPQR 181236  
AFDPQR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PORTLAND OR  
436 AM PST SAT JAN 18 2025  
   
SYNOPSIS  
HIGH PRESSURE IS EXPECTED TO REMAIN IN PLACE INTO  
NEXT WEEK, MAINTAINING COOL TEMPS AND DRY CONDITIONS. EXPECT  
HIGHS IN THE UPPER 30S TO LOW 40S AND LOW IN THE UPPER 20S TO  
LOW 30S FOR INLAND VALLEY LOCATIONS INTO EARLY NEXT WEEK.  
 
 
   
DISCUSSION...TONIGHT THROUGH FRIDAY  
CONDITIONS LARGELY REMAIN  
SIMILAR TO 24 HOURS AGO WITH RIDGING OFFSHORE AND TROUGHING  
ACROSS MUCH OF THE CONTINENTAL US. NORTH WINDS AT THE SURFACE  
HAVE BROUGHT IN COOLER, DRIER AIR INTO THE AREA, WHICH HASN'T  
COMPLETELY ERODED STRATUS BUT HAS IMPROVED CEILINGS TO MVFR  
ACROSS MUCH OF THE WILLAMETTE VALLEY. SHORT WAVE ENERGY DROPPING  
SOUTHWARD OVER EASTERN OR/WA AND IDAHO IS HELPING LOWER THE  
PRESSURE ON THE EAST SIDE OF THE CASCADES, SUPPORTING AN  
INCREASING PRESSURE GRADIENT BETWEEN TROUTDALE AND THE DALLES.  
TROUTDALE BRIEFLY REPORTED WEAK EASTERLY WINDS WHICH HAS  
PARTIALLY BROKEN UP THE STRATUS AROUND MUCH OF THE METRO AREA.  
MODELS SUPPORT THE INCREASING PRESSURE GRADIENT TODAY AND INTO  
SUNDAY WITH A PEAK OF -3-5 MB EXPECTED LATE TONIGHT INTO SUNDAY  
MORNING. THESE EASTERLY WINDS ARE EXPECTED TO HELP SCOUR OUR  
THE STRATUS AROUND THE METRO THROUGH THE DAY, LEADING TO  
SLIGHTLY HIGHER HIGHS THIS AFTERNOON IN THE NORTH VALLEY.  
 
COLD OVERNIGHT LOWS ARE EXPECTED FROM SATURDAY NIGHT THROUGH MONDAY  
NIGHT. LOWS BELOW FREEZING ARE EXPECTED WITH POSSIBLE MID 20S TO  
VARYING PROBABILITIES EACH NIGHT. PROBABILITIES FOR 25 OR LOWER  
TONIGHT ARE ON THE LOW SIDE AT 10-50% FOR THE WILLAMETTE VALLEY AND  
LESS THAN 10% FOR THE PORTLAND/VANCOUVER METRO AS EASTERLY WINDS KEEP  
THE AREA FROM DECOUPLING. SUNDAY NIGHT ODDS ARE A BIT HIGHER AT 20-  
70% THOUGH THE METRO IS STILL NOT SHOWING A GOOD SIGNAL FOR TEMPS  
REACHING 25 OR LOWER. PROBS AROUND THE HILLSBORO AREA ARE 30-40% BUT  
NOTHING FARTHER EAST TOWARD DOWNTOWN. MONDAY NIGHT COULD BE THE MOST  
WIDESPREAD FOR THE WILLAMETTE VALLEY WITH PROBS OF 30-70% AND 30% AS  
FAR EAST AS BEAVERTON AND 20-30% IN VANCOUVER. COLD WEATHER  
ADVISORIES ARE POSSIBLE BUT THE CONFIDENCE IS NOT QUITE THERE,  
ESPECIALLY FOR TONIGHT. WOULD EXPECT HIGHER PROBS FOR SUNDAY AND  
MONDAY NIGHTS WHICH ARE EXPECTED TO BE THE COLDEST.  
 
LATER NEXT WEEK, THERE IS A 10-15% CHANCE THAT THE RIDGE WILL WEAKEN  
AND INCREASING ZONAL FLOW WILL LEAD TO A SLIGHT CHANCE FOR LIGHT  
PRECIPITATION WEDNESDAY FOR PRIMARILY SOUTHWEST WASHINGTON. WHILE  
SNOW LEVELS APPEAR MOST LIKELY TO BE WELL ABOVE THE VALLEY FLOOR  
THERE IS A 10% CHANCE THAT SNOW LEVELS START OFF INITIALLY NEAR SEA  
LEVEL BEFORE QUICKLY RISING SO EVEN THE WORST CASE SCENARIO PRODUCES  
FEW IMPACTS.  
 
ENSEMBLE GUIDANCE CONTINUES TO REVEAL QUITE A BIT OF UNCERTAINTY  
REGARDING THE LARGE SCALE WEATHER PATTERN AT THE END OF THE WEEK.  
NONETHELESS, CONFIDENCE IS INCREASING THAT AT LEAST SOME LIGHT  
PRECIPITATION WILL SPREAD INTO THE REGION NEXT FRIDAY. THE  
PROBABILITY OF IT COMING IN AS VALLEY SNOW APPEARS TO BE LESS THAN  
5% AT THIS POINT. -BATZ/CN  
 
 
   
AVIATION  
HIGH PRESSURE CONTINUES, BUT CONDITIONS ARE GRADUALLY  
EASING AS DRIER AND COLDER AIR CONTINUES TO COME IN TO THE REGION  
FROM THE NORTH. ALL INLAND TERMINALS CURRENTLY SEE MIXED MVFR/VFR  
CIGS AS THE LOW STRATUS DECK REMAINS IN THE AREA. NORTHERN  
TERMINALS (KPDX, KTTD, KHIO) ARE TRENDING SLIGHTLY MORE TOWARDS  
VFR AS OFFSHORE FLOW IS SLIGHTLY STRONGER. IN THE SOUTHERN  
WILLAMETTE VALLEY, MORE CONFIDENCE OF CEILINGS TRENDING TOWARDS  
MVFR, OR EVEN IFR IN THE CASE OF KEUG.  
 
AFTER SUNRISE ON SATURDAY, CONDITIONS CONTINUE TO IMPROVE AS  
EASTERLY WINDS THROUGH THE COLUMBIA RIVER GORGE INCREASE. NORTHERN  
WILLAMETTE VALLEY TERMINALS WILL TREND VFR DURING DAYTIME HOURS.  
FURTHER SOUTH, LESS IMPROVEMENT IS EXPECTED. KUAO AND KSLE WILL  
LIKELY SEE SOME IMPROVEMENT AS WELL, WHILE KEUG LIKELY REMAINS  
MVFR OR LOWER THROUGHOUT THE TAF PERIOD. WINDS FOR THE REST OF  
THE AIRSPACE REMAIN NORTHERLY AND UNDER 5-10 KT. AT THE COAST, NO  
REAL CONCERNS AS CLEAR SKIES ARE EXPECTED THROUGHOUT THE TAF  
PERIOD.  
 
PDX AND APPROACHES...MVFR CIGS FOR THE REST OF OVERNIGHT HOURS AT  
LEAST, WITH CLEARING EXPECTED AROUND 18-22Z SAT AS EAST WINDS  
BEGIN TO PICK UP SLIGHTLY THROUGH THE COLUMBIA RIVER GORGE, THOUGH  
CONFIDENCE IS FAIRLY LOW REGARDING EXACT TIMING. THIS SHOULD  
SCOUR OUT CLOUD COVER, AND WE TREND TOWARDS VFR CONDITIONS  
AFTERWARDS FOR THE REST OF THE TAF PERIOD. /JLIU  
 
 
   
MARINE  
OFFSHORE WINDS GENERALLY BELOW 15-20 KT SATURDAY. WINDS  
WILL BECOME MORE NORTHEASTERLY AS A THERMAL TROUGH RETURNS TO THE  
OREGON COAST AND PERSISTS THROUGH THE WEEKEND AND INTO EARLY NEXT  
WEEK. SEAS LIKELY HOVER AROUND 6 TO 9 FT THROUGH THE WEEKEND. A  
LONG PERIOD SWELL IS EXPECTED TO PUSH INTO THE COASTAL WATERS ON  
SATURDAY WITH A PERIOD OF AROUND 20 SECONDS, WITH SEAS LIKELY  
REMAINING AROUND 7 TO 8 FT THROUGH SUNDAY. RELATIVELY QUIET  
WEATHER CONTINUES INTO EARLY NEXT WEEK. ~HALL  
 
 
   
PQR WATCHES/WARNINGS/ADVISORIES  
 
OR...NONE.  
WA...NONE.  
PZ...NONE.  
 
 
 
 
 
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