855
FXUS66 KPQR 200440 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
940 PM PDT THU MAR 19 2026
UPDATED AVIATION DISCUSSION...
SYNOPSIS
A SLOW-MOVING COLD FRONT WILL MOVE SOUTHEASTWARD ACROSS
SOUTHWEST WA AND NORTHWEST OR FRIDAY AFTERNOON THROUGH FRIDAY NIGHT,
BRINGING INCREASING CHANCES FOR LIGHT RAIN LATE IN THE DAY, EXCEPT
EARLY IN THE DAY FOR THE NORTH OR COAST AND PACIFIC/WAHKIAKUM
COUNTIES. ISOLATED POST-FRONTAL SHOWERS SATURDAY MORNING WILL
DIMINISH SATURDAY AFTERNOON AS SURFACE HIGH PRESSURE BUILDS INTO THE
AREA UNDER ZONAL FLOW ALOFT. 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 OVER WITH BY THE
TIME SNOW LEVELS FALL BELOW THE CASCADE PASSES, MOST LIKELY RESULTING
IN MINIMAL SNOW ACCUMULATION AND TRAVEL IMPACTS AT THE PASSES.
DISCUSSION...NOW THROUGH WEDNESDAY NIGHT
SATELLITE OBSERVATIONS
FROM MID THURSDAY AFTERNOON DEPICTED INCREASING CLOUD COVER FROM
NORTH TO SOUTH ACROSS THE AREA, WHILE RADAR OBSERVATIONS SHOWED
OCCASIONAL LIGHT RAIN ALONG AND NEAR THE NORTH OR COAST AND ACROSS
SOUTHWEST WA. LIGHT RAIN WAS IN THE VICINITY OF THE PORTLAND METRO,
FOCUSED NORTH OF THE COLUMBIA RIVER. EXPECT THIS TREND TO CONTINUE
THROUGH FRIDAY MORNING BEFORE LIGHT RAIN BEGINS SPREADING SOUTHWARD
ACROSS NORTHWEST OR FRIDAY AFTERNOON THROUGH FRIDAY NIGHT ALONG AND
AHEAD OF A COLD FRONT THAT WILL SLOWLY PUSH SOUTHEASTWARD. RAIN
AMOUNTS WILL BE QUITE LIGHT IN THE WILLAMETTE VALLEY, WITH SOME
LOCATIONS 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, ALBEIT NOT
ENOUGH FOR FLOODING OR NOTABLE IMPACTS.
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. THOSE WITH SENSITIVE OUTDOOR POTTED PLANTS
SHOULD CONSIDER BRINGING PLANTS INDOORS FOR THE NIGHT IF POSSIBLE, OR
TAKE PRECAUTIONS TO PROTECT VEGETATION FROM FROST. NOTE 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, HOWEVER
MODEL ENSEMBLE GUIDANCE CONTINUES TO SHOW TIMING DIFFERENCES AND
DIFFERENCES ON EXACT PRECIPITATION AMOUNTS (HOWEVER 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. HOWEVER,
CONFIDENCE IS HIGH SNOW LEVELS WILL DROP CONSIDERABLY BEHIND THE COLD
FRONTAL PASSAGE WHENEVER THAT OCCURS, WHICH WOULD OCCUR BY WEDNESDAY
EVENING AT THE LATEST. 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 500-100 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 LOWLAND SNOW IS NOT EXPECTED GIVEN CONDITIONS WILL BE DRYING OUT
BY THE TIME TEMPERATURES BECOME COLDER. -23
AVIATION
AN ATMOSPHERIC RIVER CONTINUES OVER WESTERN
WASHINGTON, BRINGING LIGHT RAIN SHOWERS ALONG THE COAST (GENERALLY
KTMK NORTHWARD). CAN'T RULE OUT A FEW STRAY SHOWERS OR SPRINKLES
OVER THE NORTHERN WILLAMETTE VALLEY, WITH RECENT OBSERVATIONS
SHOWING LIGHT RAIN OVER THE KPDX. DURING EARLY FRI, THE UPPER
RIDGE WILL MOVE EASTWARD, ALLOWING FOR TROUGHING TO SHIFT THE
ATMOSPHERIC RIVER SOUTHWARD AND IN TURN BRINGING STRATUS AND LIGHT
RAIN TOWARDS KONP.
EXPECT CONDITIONS TO DIFFER FROM NORTH TO SOUTH ALONG THE COAST
THROUGH THE TAF PERIOD. WHILE KAST WILL HAVE MOSTLY MVFR CONDS
WITH A 20-40% CHANCE OF LIFR/IFR CONDS BETWEEN 14Z FRI AND 00Z
SAT, KONP WILL HAVE VFR CONDS TRANSITIONING TOWARDS LIFR/IFR
CONDS BY 16Z FRI (20-30% CHANCE OF LIFR; 40-60% CHANCE OF IFR).
INLAND, EXPECT VFR CONDS UNTIL 15-18Z FRI, THEN POSSIBLE MVFR
CONDS AT MOST TERMINALS THROUGH THE REST OF THE TAF PERIOD.
GUIDANCE CONTINUES TO SUGGEST A 30-50% CHANCE OF MVFR CONDITIONS
AFTER 15-18Z FRI, SO CONFIDENCE FOR MVFR CONDS AT ANY GIVEN
TERMINAL REMAINS LOW TO MODERATE. WINDS GENERALLY SOUTHERLY TO
SOUTHWESTERLY ACROSS THE AREA AND UNDER 10 KT, WITH OCCASIONAL
GUSTS UP TO 20 KT ALONG THE COAST BEFORE 18Z FRI. WINDS WILL SHIFT
MORE WESTERLY AFTER 21-23Z FRI FOR ALL TERMINALS.
KPDX AND APPROACHES...VFR CONDS WILL CONTINUE UNTIL 15-17Z FRI,
THEN POSSIBLE MVFR CIGS THROUGH THE REST OF THE TAF PERIOD (40-50%
CHANCE OF MVFR). SOUTHERLY TO SOUTHEASTERLY WINDS UNDER 10 KT,
THEN SHIFTING TO WESTERLY AROUND 21-23Z FRI.
~12
MARINE
LOW PRESSURE OFFSHORE WILL MAINTAIN BREEZY SOUTHERLY
WINDS THROUGH LATE TONIGHT/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 HAS BEEN
EXTENDED 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
7-8 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 SYSTEM RETURNS TUESDAY INTO WEDNESDAY. THIS SYSTEM WILL
BRING A RETURN OF BREEZY SOUTHERLY WINDS ACROSS ALL WATERS.
CURRENT GUIDANCE SUGGESTS MODERATE TO HIGH CONFIDENCE (50-70%
CHANCE) FOR WIDESPREAD AND FREQUENT SMALL CRAFT WIND GUSTS OF 21
KT OR GREATER, AND A 10-20% 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 50-70%. SEAS ON TUESDAY
AND WEDNESDAY ARE ALSO EXPECTED TO BUILD TO AROUND 13-15 FT IN
RESPONSE TO INCREASING WIND WAVES, WITH A 2-5% CHANCE FOR SEAS
EXCEEDING 20 FT. -10
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 8 AM PDT FRIDAY FOR PZZ210.
SMALL CRAFT ADVISORY UNTIL 5 AM PDT FRIDAY FOR PZZ251-271.
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