336
FXUS66 KPQR 211102
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
222 AM PST SAT DEC 21 2024
SYNOPSIS
RAIN WILL SPREAD ACROSS THE REGION THIS MORNING AS A
FRONT MOVES INLAND. SHOWERS THIS AFTERNOON, DECREASING OVERNIGHT.
NEXT FRONT BRINGS RAIN FOR SUNDAY, AND SHOWERS SUNDAY NIGHT INTO
MONDAY. MOST OF THE DAY ON MONDAY LOOKS TO BE DRY, BUT RAIN/SHOWERS
AGAIN LATER MONDAY NIGHT INTO TUESDAY. THEN, A RATHER WET AND BREEZY
CHRISTMAS DAY, WITH RAIN AND BREEZY WEATHER CONTINUING THROUGH FRI.
SHORT TERM...(TODAY THROUGH MONDAY)
AT 2 AM, NOAA SATELLITE IMAGERY SHOWED A LOW PRESSURE CENTERED NEAR
45N 130W, OR ROUGHLY ABOUT 400 MILES WEST OF ASTORIA. COLD FRONT
EXTENDS FROM THIS LOW TO THE SOUTH-SOUTHEAST TO 40N 127W. THE LOW
WILL CONTINUE MOVING NORTHWARD, WITH THE FRONT LIFTING NORTHEAST
TODAY, AND INLAND LATER THIS MORNING. TIMING WOULD PUT RAIN ON THE
COAST BETWEEN 4 AND 6 AM, WITH RAIN SPREADING INLAND AFTERWARDS.
WILL MAINTAIN BREEZY EAST WINDS IN/AROUND THE WESTERN COLUMBIA RIVER
GORGE WHERE IS GUSTING 45 TO 65 MPH. BIT LESS ACROSS THE EAST
PORTLAND/VANCOUVER METRO, BUT STILL BREEZY WITH GUSTS 35 TO 50 MPH
IN THOSE AREAS. THESE EAST WINDS WILL EASE AS THE FRONT ARRIVES.
FRONT WILL PUSH ONSHORE ABOUT 10 AM ALONG THE COAST, MOVING TO THE
CASCADES BY 1 PM. NOT A BIG RAIN MAKER, BUT WILL PRODUCE ABOUT 0.25
TO 0.50 INCH ACROSS MUCH OF THE REGION. ONCE THE FRONT PASSES, WILL
TRANSITION TO SHOWERS FOR REST OF THE AFTERNOON, WITH SHOWERS
DECREASING LATER THIS EVENING. CAN NOT RULE OUT A STRAY THUNDERSTORM
ALONG THE COAST/COAST RANGE FROM LATE MORNING THROUGH THIS AFTERNOON,
AND PERHAPS INTO THE WILLAMETTE VALLEY LATER TODAY.
NEXT SYSTEM ARRIVES SUN MORNING, WITH RAIN INCREASING. OVERALL,
SHOULD BE RATHER WET AND GRAY DAY, ESPECIALLY FOR LATE MORNING AND
THE AFTERNOON. RAINFALL WILL BE BIT MORE HEFTY THAT THAT OF TODAY,
WITH 0.50 TO 0.75 INCH FOR MOST AREAS, AND 0.75 TO 1.25 INCH FOR THE
COAST RANGE, WILLAPA HILLS, AND CASCADES. ONCE THE FRONT MOVES
ONSHORE AND INLAND (LATE AFTERNOON/EARLY EVENING), WILL TRANSITION TO
SHOWERS AGAIN. SHOWERS WILL GRADUALLY DECREASE LATE SUN NIGHT INTO
EARLY MON MORNING. AT THIS TIME, DOES APPEAR THAT GOOD PART MON WILL
BE DRY. BUT, THAT ENDS LATER IN THE DAY, AS NEXT APPROACHING FRONT
BRINGS CLOUDS IN THE AFTERNOON, WITH RAIN BY EVENING.
SNOW LEVELS WILL BE ON A ROLLER COASTER RIDE FOR THE NEXT 2 TO 3
DAYS, RUNNING AT/ABOVE 6500 FT, THEN DROPPING TO NEAR 4500 FT IN THE
POST-FRONT AIR (LATE TODAY/TONIGHT AND AGAIN SUN NIGHT INTO MON).
COULD GET 2 TO 8 INCHES LATER TODAY INTO TONIGHT, MAINLY ABOVE 5000
FT. NO ADVISORIES AT THIS TIME, AS MOST OF THE MAIN PASSES WILL
REMAIN WET DURING THE DAY, WITH 1 TO 3 INCHES OF SNOW EXPECTED AT
NIGHT WITH THE SNOW SHOWERS. /ROCKEY
LONG TERM...(TUESDAY TO FRIDAY)
FORECAST IS CHARACTERIZED BY A
SERIES OF FRONTS MOVING INTO THE PACIFIC NORTHWEST, WITH A
POTENTIALLY VERY WET FRONTS LATER THIS WEEK AS POTENT ATMOSPHERIC
RIVER TAKES AIM AT THE REGION. HOWEVER, THE SHORT-DURATION OF EACH
ONE WITH BREAKS IN BETWEEN WILL HELP MINIMIZE CONCERNS FOR
WIDESPREAD, LARGE-SCALE IMPACTS.
NEXT SYSTEM ARRIVES MONDAY NIGHT INTO TUESDAY, WITH RAIN TURNING TO
SHOWERS ON TUESDAY. SHOWERS DECREASING TUESDAY NIGHT.
THEN THE MAIN SHOW ARRIVES. NO, NOT CHRISTMAS AND SANTA. RATHER A
STRONG FRONT WILL APPROACH, WITH RATHER RAINY AND BREEZY CONDITIONS
FOR LATE WED AFTERNOON OR EVENING, LASTING INTO THURSDAY. MODELS
STILL SHOWING MODERATE TO STRONG ATMOSPHERIC RIVER TIED TO THIS
FRONT, ENHANCING THE RAINFALL. OVERALL, TOTAL RAINFALL FOR WED INTO
THU COULD RUN AT 2 TO 4 INCHES ALONG THE COAST, WITH 3 TO 6 INCHES
ACROSS THE COAST RANGE AND WILLAPA HILLS. EVEN INLAND, RAINFALL OF 1
TO 3 INCHES LOOKS REASONABLE FOR THIS TIMEFRAME, WITH 2 TO 5 INCHES
ACROSS THE CASCADES. THIS INDEED WILL PUSH RIVERS UPWARD. HARD TO
SAY IF WILL HAVE FLOODING, BUT AT THIS TIME, APPEARS HAVE A 25-45%
CHANCE SOME RIVERS (SUCH AS WILSON AND THE NEHALEM, AS WELL AS THE
GRAYS AND NASELLE) COULD REACH FLOOD STAGE GIVEN THIS RAINFALL. SO,
WILL HAVE TO WATCH LATER NEXT WEEK CLOSELY, PARTICULARLY THE RAINFALL
FORECASTS AS THAT WILL HEAVILY AFFECT WHICH RIVERS SEE SIGNIFICANT
RISES, AND WHETHER OR NOT THEY REACH FLOOD STAGE TOWARDS THU OR FRI.
GIVEN SNOW LEVELS WILL BE ON THE RISE, WILL HAVE CONTINUED SNOWMELT,
GIVING MORE WATER TO FLOW INTO THE RIVERS.
YET ANOTHER STRONG FRONT WILL ARRIVE ON FRIDAY, BUT TOO EARLY TO TELL
HOW MUCH RAIN OR WIND IT WILL BRING. THIS MAINLY DUE TO MODEL
DIFFERENCES ON STRENGTH/LOCATION OF THE MAIN SURFACE LOW. HOWEVER,
GIVEN RATHER MOIST JET STREAM OVER THE REGION, ODDS AREA GOOD FOR
ANOTHER ROUND OF HEAVY RAIN. /ROCKEY
AVIATION
EARLY THIS MORNING MOST TERMINALS ARE VFR ACROSS THE
REGION WITH THE EXCEPTION OF KEUG AND TO SOME EXTENT KSLE WHERE
FOG IS REDUCING CIGS/VIS. AROUND 12-15Z TODAY THE NEXT WAVE OF
PRECIPITATION MOVES INTO THE REGION. THIS SHOULD BRING SOME RAIN
TO ALL TERMINALS, HELP CLEAR OUT THE FOG, AND CREATE MIXED
MVFR/VFR CONDITIONS AT ALL TERMINALS. SOUTHEASTERLY WINDS WILL
ALSO PICK UP THIS MORNING IN THE MIDDAY HOURS, WITH GUSTS UP TO
20-30 KTS POSSIBLE AT MOST TERMINALS. RAIN BECOMES MORE SHOWERY
AROUND 20-22Z SAT, AND THEN DECREASING SIGNIFICANTLY 00-06Z
SUNDAY. GENERALLY VFR CONDITIONS AFTERWARDS ALTHOUGH WE'LL HAVE TO
KEEP AN EYE OUT FOR FOG, PARTICULARLY IN THE SOUTHERN WILLAMETTE
VALLEY.
PDX AND APPROACHES...LIKELY VFR CONDITIONS THROUGHOUT THE TAF
PERIOD, THOUGH AROUND A 20-40% CHANCE OF SOME BRIEF BURSTS OF
MVFR BETWEEN 16-22Z AS RAIN PASSES OVERHEAD AND CIGS DECREASE.
WINDS PICK UP AROUND THAT TIME AS WELL, WITH SOUTHEASTERLY GUSTS
UP TO 18-25 KT POSSIBLE. RAIN GRADUALLY BECOMES SHOWERY AND
TAPERS OFF AFTER 20Z SAT TO 00Z SUN. -SCHULDT
MARINE
GOING THROUGH THE NEXT WEEK A VERY ACTIVE WEATHER
PATTERN IS ANTICIPATED AS A BROAD UPPER-LEVEL LOW REMAINS PARKED
OVER THE NE PACIFIC AIMING A PARADE OF WEATHER DISTURBANCE AT THE
PACIFIC NORTHWEST. OUR NEXT FRONTAL BOUNDARY IS BEGINNING TO
ENTER THE COASTAL WATERS EARLY THIS MORNING WITH WINDS QUICKLY
JUMPING TO GALE CRITERIA AFTER 4-6AM. THROUGH THE MIDDAY HOURS
EXPECT GUSTS BETWEEN 35-45 KNOTS WITH SEAS INCREASING INTO THE LOW
TEENS BY FOLLOWED BY SEAS PEAKING IN THE UPPER TEENS TO AROUND 20
FEET THIS AFTERNOON. SEAS MAY DECREASE A FEW FEET INTO THE MID
TEENS TONIGHT BUT WILL JUMP BACK UP INTO THE UPPER TEENS WITH THE
NEXT FRONTAL SYSTEM ON SUNDAY. MOVING INTO MONDAY WE'LL SEE THE
ARRIVAL OF A LONG PERIOD SWELL (~20 SECONDS) WITH SIGNIFICANT
WAVE HEIGHTS LIKELY PEAKING IN THE LOW 20S. AFTER A LULL TUESDAY
INTO EARLY WEDNESDAY MORNING A STRONGER SYSTEM MID TO LATE WEEK
WILL INCREASE WINDS TO AT LEAST GALES AND USHER IN SEAS NEAR 20
FEET YET AGAIN. THE NBM CURRENTLY PROJECTS A 30-40% CHANCE FOR
STORM FORCE (>48 KNOT GUSTS) IN THE WEDNESDAY AFTERNOON THROUGH
THURSDAY TIME PERIOD TOO - SOMETHING TO WATCH. MARINERS SHOULD BE
PREPARED FOR CONTINUED HAZARDOUS CONDITIONS THROUGH THE END OF
NEXT WEEK. -SCHULDT
BEACH HAZARDS
A LARGE, ENERGETIC WESTERLY SWELL WILL BUILD
OVER THE COASTAL WATERS AND BEGIN IMPACTING THE COASTLINE SATURDAY
INTO EARLY NEXT WEEK. SEAS IN EXCESS OF 18 TO 20 FEET WITH A
PERIOD OF AROUND 19-21 SECONDS WILL LIKELY RESULT IN BREAKING
WAVES APPROACHING 25 TO 30 FEET IN THE SURF ZONE. THE HIGH SURF
ADVISORY WILL BE MAINTAINED FOR SATURDAY MORNING THROUGH MONDAY
EVENING. MONDAY IN PARTICULAR WILL SEE THE LARGEST WAVES,
POTENTIALLY APPROACHING HIGH SURF WARNING CRITERIA, ALTHOUGH THERE
ISN'T ENOUGH CONFIDENCE IN DEGREE OF WAVE ENERGY REQUIRED TO
UPGRADE THE HIGHLIGHT AS OF THIS FORECAST CYCLE. A SLIGHT
INCREASE IN EITHER SWELL HEIGHT/PERIOD WOULD PUSH ENERGY VALUES
TO WARNING CRITERIA. CONTINUE TO MONITOR FUTURE FORECASTS FOR
CHANGING CONDITIONS. BEACHGOERS SHOULD BE PREPARED FOR DANGEROUS
SURF CONDITIONS AND LARGE WAVES RUNNING FAR UP ONTO THE BEACH
BEGINNING LATE SUNDAY AND CONTINUING THROUGH EARLY NEXT WEEK.
-SCHULDT/BATZ
PQR WATCHES/WARNINGS/ADVISORIES
OR...HIGH SURF ADVISORY TODAY THRU MON EVENING FOR ORZ101>103.
WA...HIGH SURF ADVISORY TODAY THRU MON EVENING FOR WAZ201.
PZ...GALE WARNING UNTIL 1 PM TODAY FOR PZZ210-251>253-271>273.
SMALL CRAFT ADVISORY UNTIL 4 AM TODAY FOR PZZ210-251>253.
HAZARDOUS SEAS WARNING UNTIL 4 AM TODAY FOR PZZ271>273.
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