770
FXUS66 KPQR 172332
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
332 PM PST TUE DEC 17 2024
SYNOPSIS
A STRONG FRONTAL SYSTEM WILL MAINTAIN ACTIVE
WEATHER THROUGH WEDNESDAY MORNING. MODERATE TO HEAVY RAIN
OVER THE COAST AND HIGHER TERRAIN WILL TAPER OFF LATE THIS
AFTERNOON BUT THEN RETURN LATER THIS EVENING WITH THE ARRIVAL
OF A COLD FRONT. THE FRONT WILL ALSO BRING STRONG SOUTH WINDS,
WITH GUSTS TO 60 MPH AT THE IMMEDIATE COAST AND AS HIGH AS 45
MPH FOR THE INLAND VALLEYS THROUGH EARLY WEDNESDAY MORNING.
DRIER CONDITIONS LIKELY LATER WEDNESDAY THROUGH FRIDAY, ALTHOUGH
WEATHER REMAINS ACTIVE OVER THE PACIFIC AND NEAR THE COAST.
RAIN RETURNS FOR THE WEEKEND INTO EARLY NEXT WEEK AS SEVERAL
FRONTAL SYSTEMS PUSH INLAND.
SHORT TERM...THROUGH FRIDAY NIGHT
THE UPPER LEVEL PATTERN
THIS AFTERNOON IS CHARACTERIZED BY MOIST SOUTHWEST FLOW ALOFT
ON THE PERIPHERY OF AN UPPER LEVEL RIDGE CENTERED EAST OF THE
CASCADES. AT THE SURFACE, A MATURE 985 MB LOW IS CENTERED WEST
OF HAIDA GWAII, WITH AN OCCLUDED FRONT EXTENDING SOUTHEAST TO A
TRIPLE POINT OFF THE WASHINGTON COAST. A WARM FRONT EXTENDS
SOUTHEAST FROM THIS FEATURE AND IS DRAPED ACROSS SW WA AND NW OR
AS OF MID TUESDAY AFTERNOON. AN ATMOSPHERIC RIVER IS FOCUSED
ALONG THE WASHINGTON AND FAR NORTH OREGON COASTS, PRODUCING
RAIN RATES OF 0.25-0.50" PER HOUR ACROSS PARTS OF THE WILLAPA
HILLS AND NORTH OREGON COAST RANGE. HOWEVER, THE BACK EDGE OF
THE HEAVIER PRECIPITATION IS NOTED ON RADAR IMAGERY FROM ROUGHLY
THE LONG BEACH PENINSULA TO MOUNT HOOD AS THE WARM FRONT LIFTS
NORTHWARD, WITH RAIN TAPERING OFF TO SHOWERS ACROSS THE REST OF
THE AREA IN THE WAKE OF THE FRONT. THIS WILL PRESENT A BRIEF
WINDOW OF LIGHTER, MORE SHOWERY CONDITIONS THIS EVENING BEFORE
ANOTHER ROUND OF HEAVIER PRECIPITATION ARRIVES WITH THE TRAILING
COLD FRONT AROUND MIDNIGHT. WILL HAVE TO KEEP A CLOSE EYE ON
THE GRAYS RIVER IN SW WA WITH THIS SECOND ROUND OF RAIN. AS A
FEW MORE HOURS OF MODERATE TO HEAVY RAIN RATES MAY BE SUFFICIENT
TO PUSH THE RIVER INTO MINOR FLOOD STAGE EARLY WEDNESDAY
MORNING. ALL OTHER RIVERS ARE EXPECTED TO REMAIN BELOW FLOOD
STAGE AS RAIN RATES LEVEL OFF WITHIN THE NEXT FEW HOURS.
THE COLD FRONT WILL ALSO BE ACCOMPANIED BY STRONG WINDS AS IT
REACHES THE COAST LATER THIS EVENING AND THEN PUSHES INLAND
OVERNIGHT, WITH BUOY OBSERVATIONS OVERT THE COASTAL WATERS
ALREADY REPORTING 50 MPH GUSTS THIS AFTERNOON AHEAD OF THE
FRONT. A HIGH WIND WARNING REMAINS IN EFFECT FOR BEACHES AND
HEADLANDS, WHERE A FEW GUSTS TO 60 MPH ARE EXPECTED LATE THIS
EVENING INTO EARLY WEDNESDAY MORNING. INLAND COASTAL COMMUNITIES
SUCH AS ASTORIA AND TILLAMOOK WILL LIKELY SEE GUSTS TO AROUND
45 MPH, WITH A 20-30% CHANCE FOR GUSTS AS HIGH AS 60 MPH. ALSO
OPTED TO ISSUE A WIND ADVISORY FOR THE WILLAMETTE VALLEY AND THE
INTERIOR LOWLANDS OF SW WA FROM 8 PM THIS EVENING UNTIL 4 AM
WEDNESDAY AS HREF PROBS FOR 45 MPH GUSTS HAVE INCREASED TO
50-60% ACROSS THE INTERIOR VALLEYS. A STABLE LAYER ABOVE THE
SURFACE WILL INITIALLY INHIBIT THE STRONGER GUSTS FROM REACHING
THE VALLEY FLOOR, BUT EXPECT AT LEAST SOME WIND TO START TO MIX
DOWN LATER IN THE EVENING AS THE COLD FRONT MOVES INTO THE
AREA. THE MOST LIKELY TIME FOR STRONGER GUSTS WILL BE FROM 10 PM
TO 2 AM, WITH THE BEST CHANCES FROM SALEM TO PORTLAND AND INTO
SOUTHWEST WASHINGTON. CHANCES WILL BE LOWER ACROSS THE SOUTH
WILLAMETTE VALLEY, WITH AROUND A 20% CHANCE TO SEE 45 MPH GUSTS
IN THE EUGENE AREA.
EXPECT A PERIOD OF QUIETER WEATHER THROUGH THE END OF THE WORK
WEEK AS THE FRONT CLEARS THE AREA WEDNESDAY MORNING, WITH MODELS
IN GOOD AGREEMENT ON UPPER LEVEL RIDGING PREVAILING OVER THE
PACIFIC NORTHWEST WEDNESDAY THROUGH FRIDAY. ANOTHER SYSTEM MAY
CLIP THE WASHINGTON COAST LATE THURSDAY, BUT PRECIPITATION
CHANCES SHOULD MAINLY STAY CONFINED TO THE COASTAL AREAS, WITH
THE MAJORITY OF GLOBAL ENSEMBLE MEMBERS KEEPING INLAND LOCATIONS
DRY THROUGH THE PERIOD. EXPECT TEMPS TO REMAIN ABOVE SEASONAL
NORMALS WITH DAYTIME HIGHS IN THE 50S AND OVERNIGHT LOWS MAINLY
IN THE 40S THROUGH THE REST OF THE WEEK. /CB
LONG TERM...SATURDAY THROUGH TUESDAY
CLUSTERS ARE IN GOOD
AGREEMENT THAT THE UPPER LEVEL RIDGE SHIFTS EAST BY THE WEEKEND,
ALLOWING FOR FRONTAL SYSTEMS TO PUSH BACK INLAND. THERE IS HIGH
CONFIDENCE THAT WET WEATHER OVER THE WEEKEND CONTINUES INTO
NEXT WEEK. SNOW LEVELS APPEAR TO STAY RELATIVELY HIGH ABOVE
5000-6000 FT INTO EARLY NEXT WEEK. /DH
AVIATION
ACTIVE WEATHER CONTINUES ACROSS THE AIRSPACE AS A
SERIES OF FRONTS WILL CONTINUE TO BRING WIDESPREAD RAIN AND
DEGRADING CONDITIONS. EXPECT THE CURRENT MIXTURE OF VFR/MVFR
CONDITIONS TO BECOME PREDOMINATELY MVFR THROUGH 00Z WED, WITH A
20-25% PROBABILITY FOR INTERMITTENT PERIODS OF IFR ACROSS THE
AIRSPACE. THESE FRONTAL SYSTEMS WILL ALSO BRING THE POTENTIAL FOR
LLWS (IN THE FORM OF SPEED SHEAR) TO MOST OF THE TERMINALS AT
VARIOUS TIMES THROUGH THE TAF PERIOD, WITH INLAND LOCATIONS
EXPECTED TO HAVE A LLWS PROBABILITY THROUGH 12Z WED. SOUTHERLY
WINDS WILL PERSIST WITH GUSTS UP TO 45 KT ALONG THE COAST, WITH
GUSTS UP TO 30 KT FOR INLAND LOCATIONS THROUGH AROUND 12Z WED.
PDX AND APPROACHES...CURRENTLY MVFR CONDITIONS WITH RAIN. FRONTAL
PASSAGES WILL RESULT IN INCREASED LLWS (IN THE FORM OF SPEED
SHEAR)PROBABILITIES THROUGH AROUND 12Z WED. SOUTHERLY WINDS WILL
PERSIST WITH GUSTS UP TO 25 KT. /42
MARINE
ACTIVE WEATHER CONTINUES THROUGH THE MAJORITY OF THE
WEEK AS A SERIES OF SYSTEMS MOVE THROUGH THE REGION. EACH SYSTEM
WILL BRING INCREASING WINDS AND SEAS ACROSS ALL WATERS. THE FIRST
SYSTEM CURRENTLY CONTINUES TO BRING LOW-END STORM FORCE GUSTS UP
TO 50 KT THROUGH AT LEAST WEDNESDAY MORNING. HOWEVER, MORE SYSTEMS
ARE READY TO TAKE A SHOT AT THE REGION THROUGH THE REMAINDER OF
THE WEEK AND INTO THE START OF NEXT WEEK.
GALES FRIDAY AND SATURDAY (60-80% PROBABILITY) WITH STORM FORCE
(50-75% PROBABILITY) SUNDAY/MONDAY. SEAS BUILD TOWARDS 20 FT ON
FRIDAY AND SATURDAY AND WILL LIKELY TOP OUT AROUND 20-23 FT ON
SUNDAY/MONDAY.
CURRENTLY, THERE IS A 60% PROBABILITY THAT THE OUTER COASTAL
WATERS WILL EXCEED 20 FT FOR SATURDAY AND A 50% PROBABILITY OF
SEAS GREATER THAN 20 FT ON SUNDAY AND MONDAY. /42
PQR WATCHES/WARNINGS/ADVISORIES
OR...HIGH WIND WARNING UNTIL 4 AM PST WEDNESDAY FOR ORZ101>103.
WIND ADVISORY FROM 8 PM THIS EVENING TO 4 AM PST WEDNESDAY FOR
ORZ108>118.
WA...HIGH WIND WARNING UNTIL 4 AM PST WEDNESDAY FOR WAZ201.
WIND ADVISORY FROM 8 PM THIS EVENING TO 4 AM PST WEDNESDAY FOR
WAZ204>207.
PZ...STORM WARNING UNTIL 1 AM PST WEDNESDAY FOR PZZ210-251>253-
271>273.
GALE WARNING FROM 1 AM TO 4 AM PST WEDNESDAY FOR PZZ210-
251>253-271>273.
HAZARDOUS SEAS WARNING FROM 4 AM TO 1 PM PST WEDNESDAY FOR
PZZ210-251>253-271>273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
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X.COM/NWSPORTLAND
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