451  
FXUS66 KPQR 182302  
AFDPQR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PORTLAND OR  
302 PM PST FRI JAN 18 2019  
   
SYNOPSIS
 
A WARM FRONT WILL LIFT ACROSS THE REGION TODAY, WITH  
HEAVY RAIN AT TIMES THIS AFTERNOON AND TONIGHT. SNOW LEVELS JUMP  
WAY HIGH TODAY AND TONIGHT, THEN SLOWLY LOWER OVER THE WEEKEND. WILL  
SEE ADDITIONAL RAIN AND CASCADE SNOW SATURDAY EVENING INTO SUNDAY.  
ALSO SOME CHANCE OF LIGHT PRECIPITATION AROUND THE REGION TO START  
NEXT WEEK.  
 

 
   
SHORT TERM...THIS AFTERNOON THROUGH MONDAY
 
RADAR AND SURFACE  
OBSERVATIONS THIS AFTERNOON SHOW RAIN HAS SPREAD INTO THE AREA AS A  
WARM FRONT LIFTS NORTH. AS THE WARM FRONT MOVES THROUGH, IT WILL DRAG  
A MODERATELY STRONG ATMOSPHERIC RIVER INTO THE AREA, WITH MODERATE TO  
HEAVY RAIN EXPECTED LATER THIS AFTERNOON THROUGH THIS EVENING. THE  
WARM FRONT WILL LIFT INTO WASHINGTON STATE THIS EVENING, BUT A COLD  
FRONT WILL APPROACH FROM THE WEST, CONTINUING RAIN OVERNIGHT. APPEARS  
THAT THE COLD FRONT WILL PUSH ONSHORE LATE TONIGHT, BUT LIKELY HOLD  
UP TO THE SOUTH OVER SOUTHWEST OREGON AND PARTS OF LANE COUNTY. SO,  
RAIN WILL TURN TO SHOWERS NORTH OF ABOUT A FLORENCE TO SALEM TO MT  
HOOD LINE, BUT STEADY RAIN WILL CONTINUE TO THE SOUTH.  
 
UPPED RAINFALL AMOUNTS A LITTLE BIT FOR THIS EVENT, BUT STILL DON'T  
EXPECT MUCH IN THE WAY OF FLOODING. DRY ANTECEDENT CONDITIONS SHOULD  
KEEP RIVERS BELOW FLOOD STAGE. COULD SEE SOME PONDING OF WATER IN  
LOW-LYING AREAS OF ROADS OR URBAN AREAS, BUT LIKELY JUST TO THE LEVEL  
OF BEING A NUISANCE INSTEAD OF PRESENTING A SERIOUS THREAT TO LIFE OR  
PROPERTY.  
 
SNOW LEVELS WILL RISE WELL ABOVE 6000 FT BY THIS EVENING, SO WHILE  
PRECIP THIS AFTERNOON MAY BE FALLING AS SNOW, IT WILL QUICKLY TURN  
OVER TO RAIN IN THE CASCADES. WITH HEAVY RAIN AT TIMES AND OVERALL  
IMPRESSIVE RAIN TOTALS OVER THE NEXT 18 HOURS, WILL KEEP AS CLOSE OF  
AN EYE AS POSSIBLE ON THE LARGE BURN AREAS FROM THE LAST COUPLE OF  
YEARS, PARTICULARLY THOSE IN THE SOUTHERN HALF OF THE FORECAST AREA,  
WHICH HASN'T SEEN THIS AMOUNT OR INTENSITY OF RAIN YET THIS SEASON.  
 
WEAK LOW PRESSURE APPROACHES FROM THE SOUTHWEST SATURDAY NIGHT,  
MOVING NORTHEAST THROUGH OREGON. THIS LOW WILL BRIEFLY REINVIGORATE  
MOISTURE, AGAIN WITH THE FOCUS OVER THE SOUTHWESTERN QUADRANT OF  
OREGON. IT WILL ALSO DRAG THE LEFTOVER COLD FRONT/WEAK BOUNDARY OUT  
OF THE AREA BY SUNDAY AFTERNOON. HOWEVER, ANOTHER LOW APPROACHES FROM  
THE WEST JUST BEHIND IT ON SUNDAY, BRINGING ANOTHER SHOT OF MOISTURE,  
AGAIN MOSTLY TO THE SAME AREA THROUGH SUNDAY NIGHT.  
 
THE PRECIPITATION ASSOCIATED WITH BOTH OF THESE LOWS WON'T BE NEARLY  
AS MUCH AS WITH THE INITIAL SYSTEM FRIDAY EVENING. HOWEVER, BY THAT  
TIME SNOW LEVELS WILL HAVE DROPPED BACK BELOW THE PASSES, SO COULD  
SEE AS MUCH AS A FOOT OF SNOW AT THE PASSES BETWEEN SATURDAY NIGHT  
AND SUNDAY, PARTICULARLY SOUTH OF MT. HOOD. WON'T ISSUE ANY WINTER  
WEATHER HEADLINES FOR THE CASCADES AT THIS POINT TO TRY TO AVOID  
CONFUSION ABOUT WHEN THE SNOW WILL ACTUALLY BE FALLING (I.E. NOT WITH  
THIS FIRST SYSTEM TONIGHT), BUT WILL ALMOST CERTAINLY NEED AT LEAST  
AN ADVISORY AND POSSIBLY MORE ONCE THE SNOW LEVELS FALL.  
 
UNRELATED TO THE RAIN AND SNOW, WILL ISSUE A COASTAL FLOOD ADVISORY  
FOR MINOR TIDAL OVERFLOW FOR THE HIGHEST TIDE EACH DAY OVER THE  
WEEKEND. ALTHOUGH THE COMBINED FORECAST TIDE AND EXPECTED ANOMALY  
WILL LIKELY END UP SLIGHTLY UNDER CRITERIA, THERE HAVE BEEN REPORTS  
OF MINOR TIDAL FLOODING IN THE USUAL LOCATIONS AROUND TILLAMOOK  
DURING HIGH TIDE TODAY. THE HIGHEST TIDE OCCURS SUNDAY, BUT THE  
ADVISORY MAY NEED TO BE EXTENDED FOR THE MONDAY HIGHEST TIDE AS WELL.  
 
COLDER AIR BECOMES MORE ENTRENCHED MONDAY, BRINGING SNOW LEVELS DOWN  
EVEN FURTHER, BUT BY THAT TIME THE MOISTURE WILL HAVE MOSTLY DRIED  
UP. MODELS CONTINUE TO INDICATE SOME CHANCE FOR SHOWERS ON MONDAY AS  
WE REMAIN UNDER THE INFLUENCE OF AN UPPER TROUGH, SO HAVE KEPT POPS  
AROUND OR BELOW CLIMATOLOGY FOR THIS TIME OF YEAR. WOULDN'T BE  
SURPRISED IF MONDAY CONTINUES TO TREND DRIER, THOUGH. BOWEN  
   
LONG TERM...MONDAY NIGHT THROUGH FRIDAY
 
MODELS CONTINUE TO SHOW A  
BROAD UPPER LEVEL RIDGE BUILDING INTO THE PACIFIC NW NEXT WEEK. THE  
RIDGE AXIS LOOKS TO INITIALLY REMAIN OFFSHORE EARLY NEXT WEEK, WITH  
NORTHWESTERLY FLOW OVER THE FORECAST AREA. GUIDANCE CONTINUES TO  
SHOW A SHORTWAVE DISTURBANCE RIDING OVER THE TOP OF THE RIDGE EARLY  
NEXT WEEK. THIS SHOULD ALLOW A WARM FRONT TO MOVE ACROSS THE  
FORECAST AREA ON TUESDAY FOLLOWED BY A WEAK COLD FRONT ON WEDNESDAY.  
SNOW LEVELS WILL QUICKLY RISE TO ABOVE 5000 FT BY TUESDAY AFTERNOON  
AS THE WARM FRONT SWINGS INLAND WHICH SHOULD MINIMIZE TRAVEL IMPACTS  
ACROSS THE CASCADES. THE UPPER LEVEL RIDGE LOOKS TO FINALLY  
STRENGTHEN ITS GRASP ON THE REGION LATE NEXT WEEK. THIS SHOULD ALLOW  
CONDITIONS TO DRY OUT ON THURSDAY AND FRIDAY, WITH FOGGY CONDITIONS  
LIKELY DEVELOPING IN THE INTERIOR VALLEY DURING THE OVERNIGHT/EARLY  
MORNING HOURS. /64  
 

 
   
AVIATION
 
WARM FRONT ACROSS SW OREGON EARLY THIS AFTERNOON.  
MVFR COVERAGE STARTING TO INCREASE AS OF 21Z, ESPECIALLY ALONG  
THE COAST. THE WARM FRONT IS EXPECTED TO LIFT INTO SW WASHINGTON  
BY EARLY EVENING. FLIGHT CONDITIONS WILL CONTINUE TO LOWER  
THROUGH THE EARLY EVENING AS THE WARM FRONT MIGRATES NORTH.  
COASTAL AREAS LIKELY TO BECOME IFR BY 00Z SAT AND REMAIN THERE  
THROUGH 12Z SAT. SOME IMPROVEMENT EXPECTED AFTER 12Z. INLAND  
AREAS TO BE A MIX OF IFR AND MVFR THROUGH SAT MORNING. SOUTH TO  
SOUTHWEST WIND 25-35 KT WITH GUSTS TO 45 KT OCCURS ALONG THE  
COAST LATE THIS AFTERNOON THROUGH TONIGHT. LLWS POSSIBLE FOR  
INLAND TAF SITES LATE THIS AFTERNOON THROUGH THE EVENING,  
ESPECIALLY NEAR THE GORGE. FINALLY, MOUNTAINS AND HIGHER TERRAIN  
WILL BE OBSCURED THROUGH AT LEAST SAT MORNING.  
 
KPDX AND APPROACHES...VFR CONDITIONS AT 21Z. WARM FRONT EXPECTED  
TO REACH THE TERMINAL AND VICINITY BY 00Z SAT, WITH CONDITIONS  
LOWERING TO MVFR. AREAS OF IFR POSSIBLE 00Z TO 15Z SAT,  
ESPECIALLY IN THE TUALATIN VALLEY. LLWS POTENTIAL LATE THIS  
AFTERNOON THROUGH THE EVENING WITH E-SE SURFACE WIND AND  
INCREASING S-SW WIND ALOFT. WEISHAAR  
 

 
   
MARINE
 
A 980 MB LOW PRES CENTER WAS NOTED NEAR 46N 137W AT  
21Z. 19Z ASCAT PASS SHOWED WIND SPEEDS PRIMARILY 30 KT OR LESS,  
WITH SOME POCKETS OF 35-40 KT OVER THE SOUTH OREGON OFFSHORE  
WATERS. THE LOW WILL CONTINUE TO DEEPEN AND MOVE NORTH TO NORTHEAST  
THROUGH TONIGHT, WITH A MINIMUM LOW PRES AROUND 970 MB 06Z SAT.  
THE LOW EVENTUALLY REACHES HAIDA GWAII EARLY SAT MORNING. WILL  
MAINTAIN CURRENT GALE WARNING. MODELS WERE A LITTLE TOO STRONG  
WITH THE PREVIOUS SYSTEM SO HAVE TRENDED WIND SPEEDS DOWN JUST A  
LITTLE FROM THE EARLIER FORECAST. STILL LOOKING FOR MAX GUSTS TO  
AROUND 45 KT LATE THIS AFTERNOON THROUGH THIS EVENING. THE 12Z  
NAM WOULD SUGGEST POSSIBLE STORM FORCE GUSTS OVER PZZ275 LATE  
THIS AFTERNOON WITH 50-55 KT 975 MB WIND SPEEDS. GALE WARNING  
RUNS THROUGH 14Z SAT, BUT MAY BE ABLE TO END IT A LITTLE EARLIER.  
WIND SPEEDS DIMINISH LATE TONIGHT THROUGH SAT, FALLING BELOW 15  
KT OVER THE CENTRAL ZONES AND TO 20 KT OVER THE NORTH ZONES BY  
SAT AFTERNOON.  
 
ANOTHER LOW PRESSURE SYSTEM MOVES ACROSS THE WATERS ON SUNDAY,  
THOUGH THE EXACT TRACK OF THIS LOW IS UNCERTAIN, WITH DIFFERENCES  
BETWEEN THE VARIOUS FORECAST MODELS. THIS WILL BE A WEAKER SYSTEM,  
WITH 20-25 KT GUSTS POSSIBLE OVER PZZ275 SUN AFTERNOON. WEAK HIGH  
PRES DEVELOPS SUN NIGHT AND MON, FOLLOWED BY THE NEXT FRONTAL  
SYSTEM MON NIGHT AND TUE. GFS AND ECMWF IN GENERAL AGREEMENT ON  
THIS SYSTEM. WILL INDICATE 30 KT GUSTS ACROSS THE NORTH ZONES  
TUE, BUT GALES NOT OUT OF THE QUESTION. HIGH PRES RETURNS FOR  
THE LATTER HALF OF NEXT WEEK.  
 
SEAS HAVE EASED TO AROUND 15 FT EARLY THIS AFTERNOON. MAX SEAS  
EXPECTED TO BE 17-20 FT LATE TONIGHT THROUGH SAT, WITH THE  
HIGHEST SEAS OVER THE OUTER WATERS. INITIALLY THIS EVENING, THERE  
WILL BE A PRIMARY WEST SWELL AROUND 10 FT WITH A SIGNIFICANT  
SOUTH WIND WAVE COMPONENT. OVERNIGHT, THE PRIMARY WEST SWELL  
BUILDS AS THE WIND WAVE PORTION DIMINISHES. WAVE HEIGHTS FALL  
TO THE LOWER TEENS BY SUN MORNING AND THEN EASE TO NEAR 10 FT BY  
LATE AFTERNOON. SEAS EXPECTED TO REACH THE MID TEENS TUE NIGHT  
AND WED. WEISHAAR  
 

 
   
PQR WATCHES/WARNINGS/ADVISORIES
 
 
OR...COASTAL FLOOD ADVISORY FROM 10 AM TO 1 PM PST SATURDAY FOR  
NORTH OREGON COAST.  
 
COASTAL FLOOD ADVISORY FROM 11 AM TO 2 PM PST SUNDAY FOR NORTH  
OREGON COAST.  
 
WA...COASTAL FLOOD ADVISORY FROM 10 AM TO 1 PM PST SATURDAY FOR  
SOUTH WASHINGTON COAST.  
 
COASTAL FLOOD ADVISORY FROM 11 AM TO 2 PM PST SUNDAY FOR SOUTH  
WASHINGTON COAST.  
 
PZ...GALE WARNING UNTIL 6 AM PST SATURDAY FOR COASTAL WATERS FROM  
CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.  
 
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM  
PST SATURDAY.  
 

 
 

 
   
PQR WATCHES/WARNINGS/ADVISORIES
 
 
OR...NONE.  
WA...NONE.  
PZ...SMALL CRAFT ADVISORY UNTIL 10 AM PST THIS MORNING FOR COASTAL  
WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.  
 
GALE WARNING UNTIL 6 AM PST SATURDAY FOR COASTAL WATERS FROM  
CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.  
 
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 6 AM  
PST SATURDAY.  
 

 
 

 
 
INTERACT WITH US VIA SOCIAL MEDIA:  
WWW.FACEBOOK.COM/NWSPORTLAND  
WWW.TWITTER.COM/NWSPORTLAND  
 
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON  
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THIS AREA IS  
COMMONLY REFERRED TO AS THE FORECAST AREA.  
 
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