686  
FXUS66 KPQR 031128 AAB  
AFDPQR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PORTLAND OR  
327 AM PST SUN MAR 3 2024  
   
SYNOPSIS
 
A LONG WAVE TROUGH REMAINS NEARLY STATIONARY OVER  
THE REGION WHICH IS PRODUCING A SERIES OF SHOWERS. SHOWERS HAVE  
BEEN OBSERVED AS BOTH SNOW AND RAIN WITH THE PRECIPITATION TYPE  
MAINLY DUE TO THE PRECIPITATION RATES AND THE COLD AIR PRESENT.  
WILL SEE MINIMAL CHANGE IN THE FORECAST OVER THE NEXT FEW DAYS  
AS THERE WILL BE LITTLE ALTERING OF THE PATTERN ITSELF. COOLER  
AIRMASS ARRIVES TUESDAY MORNING.  
 

 
   
SHORT TERM...MONDAY THROUGH TUESDAY NIGHT
 
AS OF 3:30AM MONDAY, A  
MORE PROMINENT WAVE OF SHOWERY MOISTURE IS BREAKING UP OVER THE COAST  
RANGE, WITH ANOTHER ONE RAPIDLY APPROACHING FROM OFFSHORE. THE  
LONG-WAVE TROUGH CONTINUES TO REMAIN OFF THE COAST, SPINNING A FEW  
PROGRESSIVELY WEAKER ROUNDS OF PRECIPITATION THROUGH TUESDAY  
MORNING. SNOW LEVELS ARE CURRENTLY AROUND 300-500 FEET THROUGHOUT THE  
REGION, WITH LIGHT SNOW ACCUMULATIONS IN THE COAST RANGE ABOVE 500  
FEET. THE WINTER WEATHER ADVISORY FOR THE COAST RANGE HAS BEEN  
EXTENDED TO 10AM DUE TO PRECIPITATION CONTINUING LONGER THAN  
PREVIOUSLY FORECAST, NOW INCLUDING AREAS DOWN TO 500 FEET DUE TO  
LOWERED SNOW LEVELS. MOST OF THIS MOISTURE IS EXPECTED TO BREAK UP AS  
IT HEADS FURTHER EAST, AND THE WILLAMETTE VALLEY COULD SEE  
POTENTIALLY SOME MINOR IMPACTS EARLY MONDAY MORNING AT SLIGHTLY  
HIGHER ELEVATION AREAS. SNOW LEVELS RISE TO AROUND 1200-1500 FEET BY  
MONDAY AFTERNOON, ENDING CONCERNS FOR AREAS BELOW THAT. THE CASCADES  
FOOTHILLS CONTINUE TO SEE SOME MORE SIGNIFICANT HIGHER ELEVATION  
ACCUMULATIONS ABOVE 1500 FEET, CAUSED BY SHOWERS FUELED BY OROGRAPHIC  
LIFT. ENSEMBLE GUIDANCE SUGGESTS A 50-70% CHANCE OF ACCUMULATIONS  
OVER 4 INCHES FROM 4AM MON TO 4AM TUE IN THE FOOTHILLS.  
 
WITH NW WINDS BRINGING COLD AIR ALOFT AND S WINDS BRINGING WARMER  
TEMPERATURES AT THE SURFACE, INSTABILITY REMAINS RELATIVELY HIGH AT  
THE COAST, SPREADING TO THE WILLAMETTE VALLEY BY MONDAY AFTERNOON.  
CAPE VALUES ARE AROUND 150-250 J/KG THROUGHOUT THE AREA, AND A  
WIDESPREAD 20-30% OF THUNDERSTORMS IS EXPECTED WEST OF THE CASCADES  
THROUGHOUT MONDAY, BUT PARTICULARLY IN THE AFTERNOON. THREAT  
DECREASES MONDAY EVENING, THOUGH THE COAST AND COAST RANGE COULD SEE  
SOME WEAK ISOLATED THUNDERSTORMS AS LATE AS TUESDAY AFTERNOON.  
 
MODEL GUIDANCE IS BEGINNING TO TREND TOWARDS THE TROUGH PASSING  
FURTHER TO OUR SOUTH IN NORTHERN CALIFORNIA, AND IT LOOKS LIKE  
TUESDAY SHOULD SEE PRECIPITATION TAPERING OFF. WHILE SNOW LEVELS WILL  
LOWER BACK DOWN TO 500 FEET OR SO TUESDAY NIGHT, PRECIPITATION SHOULD  
BE VERY WEAK, AND MINIMAL IMPACTS ARE CURRENTLY EXPECTED.  
   
LONG TERM...WEDNESDAY THROUGH SUNDAY
 
00Z WPC CLUSTER ANALYSIS  
SHOWS TROUGHLIKE CONDITIONS CONTINUING, WITH A BRIEF SHORTWAVE RIDGE  
ARRIVING NEAR THE END OF THE WEEK. THERE IS CURRENTLY A 70% CHANCE OF  
THE RIDGE ARRIVING BY FRIDAY, THOUGH UNCERTAINTY EXISTS REGARDING HOW  
LONG ITS EXPECTED TO STICK AROUND. UNTIL THEN, A FEW MORE WEAK WAVES  
OF MOISTURE WILL CONTINUE BEING SPUN AT US, WITH POSSIBLY SOME LIGHT  
SNOW AT ELEVATION ON WEDNESDAY MORNING. TEMPERATURES WILL WARM ENOUGH  
THAT THE PREDOMINANT PRECIPITATION TYPE WILL BE RAIN FROM THURSDAY  
ONWARDS THROUGHOUT THE REGION. /JLIU  
 

 
   
AVIATION
 
A BROAD UPPER LEVEL TROUGH REMAINS OVER THE REGION WIT  
MOIST, WESTERLY FLOW ALOFT. CONTINUED ONSHORE FLOW WILL MAINTAIN  
SHOWERS AND A CHANCE OF THUNDERSTORMS (MAINLY FOR THE COAST)  
THROUGH TONIGHT. AS SUCH, EXPECT A MIX OF MVFR AND VFR CONDITIONS  
THROUGH THE PERIOD, WITH IFR CONDITIONS POSSIBLE WITH HEAVIER  
SHOWERS. THIS MORNING, OBSERVATIONS SHOW PREDOMINATELY MVFR  
INLAND, WITH CIGS AROUND 1000-1500 FT. RADAR AND SATELLITE IMAGERY  
(AS OF 10Z) SHOW SHOWER ACTIVITY PICKING UP, WITH A MIX OF RAIN  
AND SNOW LIKELY THROUGH THIS MORNING. SOUTHERLY WINDS UP TO 10-12  
KT EXPECTED AT THE SURFACE.  
 
PDX AND APPROACHES...PREDOMINATELY MVFR CONDITIONS EXPECTED  
THROUGH 20Z, WITH IFR POSSIBLE (20-30% CHANCE) THROUGH 16Z THIS  
MORNING. VFR BECOMES MORE LIKELY THIS AFTERNOON (60-70% CHANCE),  
ALTHOUGH HEAVIER SHOWERS WILL LIKELY BRING PERIODS OF MVFR. WILL  
CONTINUE TO MONITOR CHANCES FOR SNOW THIS MORNING, ALTHOUGH  
TEMPERATURES ARE AGAIN EXPECTED TO REMAIN ABOVE FREEZING.  
SOUTHEAST WINDS THIS MORNING EXPECTED TO BECOME SOUTHERLY AROUND  
8-10 KT THIS AFTERNOON. /DH  
 

 
   
MARINE
 
LOW PRESSURE OFF THE WASHINGTON COAST WILL MAINTAIN  
BREEZY SOUTHWEST TO WESTERLY WINDS ACROSS THE COASTAL WATERS  
TODAY, WITH GUSTS UP TO 25 KT. AN UNSTABLE ATMOSPHERE WILL ALSO  
MAINTAIN A CHANCE FOR THUNDERSTORMS ACROSS THE WATERS THROUGH  
TONIGHT. LOCALLY STRONG AND ERRATIC WIND GUSTS ARE LIKELY WITH ANY  
THUNDERSTORM THAT DOES DEVELOP. A WESTERLY SWELL AROUND 10 TO 12  
FT AT 11-12 SECONDS WILL GRADUALLY SUBSIDE WITH SEAS EXPECTED TO  
FALL BELOW 10 FT BY MONDAY MORNING. HIGH PRESSURE BEGINS TO BUILD  
ACROSS THE WATERS LATE MONDAY, WHICH SHOULD PUSH A LOW PRESSURE  
SYSTEM SOUTH OF THE AREA TOWARD NORTHERN CALIFORNIA. WINDS TURN  
NORTHERLY AND SEAS CONTINUE TO FALL TO AROUND 5 TO 7 FT THROUGH  
THE MIDDLE OF NEXT WEEK AS TRANSITION TOWARD MORE TRANQUIL  
CONDITIONS. /DH  
 

 
   
PQR WATCHES/WARNINGS/ADVISORIES
 
 
OR...WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING FOR CENTRAL  
 
COAST RANGE OF WESTERN OREGON-COAST RANGE OF NORTHWEST  
OREGON.  
 
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR  
CASCADE FOOTHILLS IN LANE COUNTY-NORTHERN OREGON CASCADE  
FOOTHILLS.  
 
WA...WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING FOR WILLAPA  
 
HILLS.  
 
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR SOUTH  
WASHINGTON CASCADE FOOTHILLS.  
 
PZ...SMALL CRAFT ADVISORY UNTIL 4 AM PST EARLY THIS MORNING FOR  
COLUMBIA RIVER BAR.  
 
SMALL CRAFT ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR COASTAL  
WATERS FROM CAPE SHOALWATER WA TO CAPE FALCON OR OUT 60 NM.  
 
SMALL CRAFT ADVISORY UNTIL 10 PM PST THIS EVENING FOR COASTAL  
WATERS FROM CAPE FALCON OR TO CAPE FOULWEATHER OR OUT 60 NM.  
 
SMALL CRAFT ADVISORY UNTIL 1 AM PST MONDAY FOR COASTAL WATERS  
FROM CAPE FOULWEATHER TO FLORENCE OR OUT 10 NM-WATERS FROM  
CAPE FOULWEATHER TO FLORENCE OR FROM 10 TO 60 NM.  
 

 
 

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