515
FXUS66 KPQR 201815 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
1115 AM PDT FRI MAR 20 2026
..UPDATED AVIATION DISCUSSION
SYNOPSIS
LIGHT SCATTERED SHOWERS CONTINUE IN FAR WESTERN WA
AND NORTHWESTERN OR THROUGH MOST OF THE DAY. A SLOW- MOVING
COLD FRONT WILL MOVE SOUTHEASTWARD ACROSS SOUTHWEST WA AND
NORTHWEST OR LATE FRIDAY AFTERNOON THROUGH FRIDAY NIGHT,
SPREADING LIGHT SHOWERS SOUTHEAST ACROSS THE REGION. ISOLATED
POST- FRONTAL SHOWERS SATURDAY MORNING WILL DIMINISH SATURDAY
AFTERNOON AS SURFACE HIGH PRESSURE BUILDS INTO THE AREA. THIS
PATTERN WILL THEN HOLD STEADY FOR A FEW DAYS, BRINGING COOLER
AND DRIER CONDITIONS SATURDAY AFTERNOON THROUGH MONDAY. A
STRONGER PACIFIC COLD FRONT ARRIVES SOMETIME ON TUESDAY,
BRINGING WIDESPREAD RAIN AND BREEZY WINDS TO THE AREA. SNOW
LEVELS FALL BEHIND THE FRONT LATE WEDNESDAY, HOWEVER THE BULK OF
THE PRECIPITATION ASSOCIATED WITH THIS SYSTEM SHOULD BE FINISHED
BY THE TIME SNOW LEVELS FALL BELOW THE CASCADE PASSES. MINIMAL
SNOW ACCUMULATION AND TRAVEL IMPACTS EXPECTED AT THE PASSES.
DISCUSSION...FRIDAY THROUGH THURSDAY
RADAR IMAGERY EARLY
FRIDAY MORNING SHOWS SCATTERED SHOWERS MAINLY IN SW WASHINGTON
AND ALONG THE NORTH NEAR AND NORTH OF ASTORIA. LATEST GUIDANCE
HAS SLOWED THE PROGRESSION OF THE APPROACHING COLD FRONT
THROUGH SW WA AND NW OR TODAY, SO SHOWERS ARE EXPECTED TO REMAIN
IN THIS GENERAL AREA THROUGH MOST OF THE DAY, FINALLY SPREADING
SOUTHEASTWARD THROUGH NW OR LATE THIS AFTERNOON THROUGH EARLY
SATURDAY MORNING. RAIN AMOUNTS WILL BE QUITE LIGHT OVERALL,
WITH SOME LOCATIONS IN THE INTERIOR LOWLANDS PICKING UP ONLY A
TRACE TO A FEW HUNDREDTHS OF AN INCH. MEANWHILE, RAIN AMOUNTS
WILL BE HIGHER ACROSS SOUTHWEST WA, THE CASCADES, THE NORTH OR
COAST, AND NORTH OR COAST RANGE, UP TO 0.25-0.75 INCH.
THERE IS VERY LITTLE CHANGE IN THE FORECAST THROUGH THE REST OF
THE WEEK. MODELS AND THEIR ENSEMBLES REMAIN IN AGREEMENT FOR
SURFACE HIGH PRESSURE AND ZONAL FLOW ALOFT BEHIND THE FRONTAL
PASSAGE FOR THE SATURDAY THROUGH MONDAY TIME FRAME. THIS WILL
BRING DRIER WEATHER AND RELATIVELY COOLER TEMPERATURES WITH
HIGHS CLOSE TO AVERAGE FOR THIS TIME OF YEAR (MAINLY IN THE MID
TO UPPER 50S). WINDS WILL ALSO BE LIGHT, ESPECIALLY DURING THE
OVERNIGHT HOURS EACH DAY. THE LIGHT WINDS WILL BE IN CONJUNCTION
WITH CLEARING SKIES SATURDAY AFTERNOON INTO SATURDAY NIGHT,
RESULTING IN AN IDEAL SET-UP FOR RADIATIONAL COOLING. AS SUCH,
FORECAST LOW TEMPERATURES REMAIN COLDEST SATURDAY NIGHT WITH
WIDESPREAD LOWS IN THE 30S. AREAS OF FROST WILL LIKELY DEVELOP
AS A RESULT. SUNDAY NIGHT INTO MONDAY MORNING WILL BE CHILLY
ONCE AGAIN, THOUGH LOW TEMPERATURES WILL BE A FEW DEGREES
WARMER IN THE MID TO UPPER 30S. THOSE WITH SENSITIVE OUTDOOR
PLANTS SHOULD TAKE PRECAUTIONS TO PROTECT VEGETATION FROM FROST.
NOTE THAT NWS PORTLAND WILL NOT BEGIN ISSUING FROST ADVISORIES
AND FREEZE WATCHES/WARNINGS FOR AGRICULTURAL PURPOSES UNTIL
APRIL 1ST WHEN THE GROWING SEASON BEGINS TO RAMP UP MORE AND
IMPACTS FROM FROST AND FREEZE CONDITIONS BECOME MORE
SIGNIFICANT.
CONFIDENCE REMAINS HIGH FOR WIDESPREAD RAIN AND BREEZY WINDS
TUESDAY INTO WEDNESDAY AS A STRONGER PACIFIC COLD FRONT MOVES
INLAND. MODEL ENSEMBLE GUIDANCE CONTINUES TO SHOW UNCERTAINTY
ON TIMING AND EXACT PRECIPITATION AMOUNTS. HOWEVER, CONFIDENCE
IS HIGH THAT RIVER FLOODING IS NOT EXPECTED, EVEN IN THE WETTEST
POSSIBLE SCENARIO. THIS FRONT COULD ARRIVE AS EARLY AS LATE
MONDAY NIGHT OR AS LATE AS TUESDAY NIGHT, WITH THE MOST LIKELY
ARRIVAL TIME BEING SOMETIME BETWEEN TUESDAY AFTERNOON AND
TUESDAY EVENING. AS A RESULT OF THESE TIMING DIFFERENCES, THE
NBM 10-90TH PERCENTILE FOR SNOW LEVELS CONTINUES TO SHOW LARGE
SPREAD ON TUESDAY, RANGING FROM 4500-9000 FT. CONFIDENCE IS
HIGH THAT SNOW LEVELS WILL DROP CONSIDERABLY BEHIND THE COLD
FRONTAL PASSAGE, AND CONTINUE DROPPING INTO WEDNESDAY NIGHT AND
THURSDAY MORNING. THIS IS WHEN EVEN THE NBM 90TH PERCENTILE
SUGGESTS SNOW LEVELS WILL BE BELOW THE LEVEL OF THE CASCADE
PASSES, WHILE THE 10TH PERCENTILE DROPS TO 500-1500 FEET. THAT
BEING SAID, ENSEMBLE GUIDANCE FOR QPF CLEARLY SHOWS
PRECIPITATION BEGINNING TO END BY THAT TIME, MEANING CONDITIONS
WILL TREND COLDER AND DRIER WITH LITTLE ACCUMULATING SNOW AND
TRAVEL IMPACTS AT PASS LEVEL. NBMV5.0 PROBABILITIES FOR 6 INCHES
OF SNOW OR MORE IN A 48-HOUR PERIOD ENDING AT 5AM PDT THURSDAY
CONTINUE TO BACK THIS EXPECTATION UP, AS CHANCES ARE ONLY AROUND
5-10% AT PASS LEVEL AND NEAR 0% BELOW PASS LEVEL. NOTE THAT
LOWLAND SNOW IS NOT EXPECTED GIVEN CONDITIONS WILL BE DRYING OUT
BY THE TIME TEMPERATURES BECOME COLDER.
BY THURSDAY, THE WEATHER SYSTEM IS EXPECTED TO MOVE OUT OF THE
AREA WITH UPPER LEVEL FLOW BECOMING MORE ZONAL. EXPECTING DRY
CONDITIONS WITH CLEARING SKIES BY MIDDAY THURSDAY, WHICH COULD
ALLOW FOR TEMPERATURES TO WARM INTO THE UPPER 50S. -23/03
AVIATION
RADAR IMAGERY AS OF LATE FRIDAY MORNING SHOWS A BAND
OF RAIN ACROSS THE NORTH OREGON AND SOUTH WASHINGTON COAST WHICH IS
ASSOCIATED WITH A FRONT. LATER TODAY, THIS FRONT WILL MOVE SOUTHWARD
AS AN UPPER LEVEL RIDGE TO THE SOUTH SHIFTS EASTWARD. RAIN SHOULD
BEGIN ACROSS THE NORTHERN WILLAMETTE VALLEY AFTER 21Z FRI, AND
GRADUALLY SPREAD INTO THE CENTRAL AND SOUTHERN WILLAMETTE VALLEY
THROUGH 00-03Z SAT. CHANCES FOR MVFR CIGS WILL INCREASE TO 40-60% AT
ANY GIVEN HOUR BETWEEN 21Z FRI-03Z SAT, WITH HIGHER CHANCES OF 60-
80% AROUND KEUG AFTER 03-06Z SAT. MEANWHILE IFR/MVFR CIGS PERSIST
ALONG THE COAST TODAY. TONIGHT, DRY CONDITIONS RETURN BEHIND THE
FRONT, RETURNING VFR CONDITIONS TO MOST PLACES BY 12Z SAT. WINDS
GENERALLY SOUTHERLY TO SOUTHWESTERLY TODAY AND UNDER 10 KT, EXCEPT
FOR OCCASIONAL GUSTS UP TO 20 KT ALONG THE COAST. LATER THIS
EVENING, WINDS WILL GRADUALLY TURN MORE NORTHERLY TO NORTHWESTERLY
AS HIGH PRESSURE RE-BUILDS.
KPDX AND APPROACHES...PREDOMINATELY VFR CONDITIONS THROUGH EARLY
THIS AFTERNOON. AFTER 21Z FRI, LIGHT RAIN RETURNS ALONG WITH
INTERMITTENT MVFR CIGS. GUIDANCE SUGGESTS A 30-50% CHANCE FOR MVFR
CIGS AT ANY GIVEN HOUR FROM 21Z FRI THROUGH 06Z SAT. SOUTHERLY WINDS
UNDER 10 KT TURN MORE WESTERLY TO NORTHWESTERLY AFTER 21Z FRI. -10
MARINE
LOW PRESSURE OFFSHORE WILL MAINTAIN BREEZY SOUTHERLY
WINDS THROUGH EARLY FRIDAY MORNING, MAINLY FOR THE WATERS NORTH
OF CAPE FALCON INCLUDING THE COLUMBIA RIVER BAR. THE SMALL CRAFT
ADVISORY FOR THESE WATERS REMAIN IN EFFECT THROUGH 5 AM FRIDAY FOR
SOUTHERLY WIND GUSTS UP TO 25 KT. AN EXCEPTION IS THE COLUMBIA
RIVER BAR, WHERE THE SMALL CRAFT ADVISORY CONTINUES THROUGH 8 AM
FRIDAY DUE TO A STRONG EBB CURRENT AROUND 6 AM WHICH WILL BUILD
SEAS TO 8-9 FT ALONG THE MAIN CHANNEL OF THE BAR. GENERAL SEAS FOR
THE REST OF THE WATERS ARE FORECAST AROUND 6-8 FT AT 10-11 SEC.
SURFACE HIGH PRESSURE RE-BUILDS THIS WEEKEND, TURNING WINDS MORE
NORTHERLY AND REMAINING UNDER 20 KT. SEAS ALSO GRADUALLY FALL TO
5-7 FT AT 11 SEC BY LATE SATURDAY NIGHT INTO SUNDAY. BENIGN
MARINE CONDITIONS CONTINUE THROUGH MONDAY BEFORE ANOTHER, MORE
ROBUST WEATHER SYSTEM RETURNS TUESDAY INTO WEDNESDAY. THIS SYSTEM
WILL BRING A RETURN OF BREEZY SOUTHERLY WINDS ACROSS ALL WATERS.
CURRENT GUIDANCE SUGGESTS HIGH CONFIDENCE (70-90% CHANCE) FOR
WIDESPREAD AND FREQUENT SMALL CRAFT WIND GUSTS OF 21 KT OR
GREATER, AND A 10-30% CHANCE FOR WIDESPREAD AND FREQUENT GALE
FORCE WIND GUSTS OF 34 KT OR GREATER ON TUESDAY. CHANCES FOR
ISOLATED GALE FORCE WIND GUSTS ARE AROUND 50-75%. SEAS ON TUESDAY
AND WEDNESDAY ARE ALSO EXPECTED TO BUILD TO AROUND 13-15 FT IN
RESPONSE TO INCREASING WIND WAVES ALONG WITH A BUILDING WESTERLY
SWELL. THERE'S A 25-50% CHANCE SEAS COULD EXCEED 15 FT WITH A
5-15% CHANCE FOR SEAS EXCEEDING 20 FT. CHANCES INCREASE FROM SOUTH
TO NORTH, PEAKING IN ZONES PZZ271-272. -10/03
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
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