181
FXUS66 KPQR 181819 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
1119 AM PDT WED MAR 18 2026
..UPDATED AVIATION DISCUSSION
SYNOPSIS
THROUGH THE REMAINDER OF THE WORK WEEK THE REGION
REMAINS ON THE NORTHERN PERIPHERY OF AN UPPER-LEVEL RIDGE OF
HIGH PRESSURE FACILITATING MUCH WARMER THAN NORMAL CONDITIONS.
HOWEVER, AN ATMOSPHERIC RIVER AIMED AT NORTHERN WASHINGTON AND
VANCOUVER ISLAND WILL OCCASIONALLY WOBBLE SOUTHWARD FROM TIME TO
TIME GIVING PORTIONS OF THE REGION CHANCES FOR LIGHT RAIN,
ESPECIALLY IN PACIFIC/WAHKIAKUM COUNTY AND ALONG THE NORTH
OREGON COAST. THEN OVER THE WEEKEND WE'LL TREND COOLER AS A
TROUGH SWINGS INTO THE PACIFIC NORTHWEST ALTHOUGH FORECAST
CONFIDENCE DEGRADES FROM THIS POINT ONWARD DUE TO INCREASING
MODEL UNCERTAINTY.
SHORT TERM...NOW THROUGH FRIDAY NIGHT
THERE REMAINS MINIMAL
OVERALL CHANGE IN THE WEATHER PATTERN THAT HAS BEEN IMPACTING
THE REGION OVER THE PAST 48 HOURS. THE TWO SIGNIFICANT SYNOPTIC
FORCES THAT WILL MAINTAIN THIS PATTERN ARE A BROAD UPPER-LEVEL
RIDGE TO OUR SOUTH-SOUTHEAST AND A BROAD TROUGH OVER THE GULF OF
ALASKA. BETWEEN THESE TWO SYSTEMS IS AN ATMOSPHERIC RIVER (AR)
WHICH REMAINS AIMED AT BRITISH COLUMBIA. WHILE THE UPPER-LEVEL
RIDGE ALMOST CERTAINLY FACILITATES SPRING LIKE CONDITIONS OVER
THE AREA, OUR FOCUS REMAINS ON THE AN AR, WHICH CONTINUES TO
TAKE AIM AT THE WESTERN OLYMPIC PENINSULA AND VANCOUVER ISLAND.
THE PUSH AND PULL OF BOTH THE AFOREMENTIONED TROUGH AND RIDGE
WILL RESULT IN THE AR "WOBBLING" AND THESE "WOBBLES" COULD BRING
ROUNDS OF PRECIPITATION INTO THE NORTHERN AREAS AS WELL AS TO
THE COAST THROUGH AT LEAST FRIDAY EVENING. IN GENERAL, WHAT YOU
HAVE EXPERIENCED OVER THE PAST 48 HOURS OR SO, IS LIKELY WHAT
YOU WILL CONTINUE TO OBSERVE THROUGH THE REMAINDER OF THE WEEK.
IE: MOST AREAS WILL SEE WARM, SPRING LIKE CONDITIONS WITH
LITTLE TO NO PRECIPITATION. HOWEVER, PACIFIC AND WAHKIAKUM
COUNTIES AS WELL AS THE NORTH OREGON COAST WILL CONTINUE TO
EXPERIENCE A COOLER AND MOISTER PATTER WITH ADDITIONAL RAIN
TOTALS RANGING BETWEEN 0.50-2.75 INCHES THROUGH 10PM FRIDAY,
WITH THE HIGHEST TOTALS IN NORTHERN PACIFIC COUNTY.
AS FOR THE OTHER AREAS WITHIN IN OUR CWA, CONDITIONS REMAIN DRY
THROUGH FRIDAY, PARTICULARLY SOUTH OF THE PORTLAND/VANCOUVER
METRO AREA. BROAD, SOUTHWESTERLY FLOW ALOFT AND 850MB TEMPERATURES
OF 8 TO 11 DEGREES C, MEANS THAT DAYTIME HIGH TEMPERATURES ARE
FORECASTED TO BE IN THE MID 60S TO LOW 70S ACROSS THE LOWLANDS.
WARMEST DAYTIME HIGHS ARE EXPECTED SOUTH OF SALEM, OR WITH
EUGENE, OR LIKELY WARMING INTO THE LOW 70S TODAY AND TOMORROW.
HOWEVER, IF SKIES REMAIN CLEAR, THEN DAYTIME HIGHS ACROSS THE
CWA COULD EASILY BE WARMER THAN WHAT IS FORECASTED AT THIS TIME.
TWICE DAILY UPPER AIR SOUNDINGS ALONG WITH OBSERVATIONS FROM
VARIOUS REMOTE SENSORS SPREAD ACROSS OUR CWA, ARE ALSO SUPPORTING
A VERY DRY AIRMASS. THIS IS RESULTING IN VERY LOW RELATIVE
HUMIDITIES AND POOR OVERNIGHT RECOVERIES, ESPECIALLY FOR
LOCATIONS AT HIGHER ELEVATIONS WITHIN THE CASCADES, CASCADES
FOOTHILLS AND THE COAST RANGE. /42
LONG TERM...SATURDAY THROUGH WEDNESDAY
LOOKING FORWARD INTO
THE WEEKEND THE LARGE SCALE PATTERN FINALLY SHOWS SIGNS OF
PROGRESSING. HOWEVER, EXACTLY WHAT THAT WILL LOOK LIKE IS STILL
IN QUESTION. UNCERTAINTY REMAINS HIGH, BUT THE CURRENT
CONSENSUS IS FOR AN UPPER-LEVEL TROUGH AND ASSOCIATED COLD
FRONT WILL BE ABLE TO FURTHER DISPLACE THE SOUTHERLY RIDGE
MENTIONED IN THE SHORT TERM DISCUSSION. THIS SCENARIO WILL
ENABLE COOLER 850 MB TEMPERATURES OF 0 TO 3 DEGREES C TO
INFILTRATE INTO THE PACIFIC NW BY SATURDAY AND WHILE A FRONTAL
SYSTEM WILL NORMALLY BRING PRECIPITATION WITH IT, THAT MIGHT BE
A CHALLENGE AS THE STRENGTH OF THE SYSTEM REMAINS IN QUESTION,
IN ADDITION TO THE ALREADY ENTRENCHED DRY AIRMASS COULD EASILY
SCOUR OUT THE MAJORITY OF ANY MOISTURE. AS WE MOVE INTO THE
START OF NEXT WEEK, UNCERTAINTY IN THE FORECAST REMAINS HIGH.
THE MAJORITY OF MODELS AND THEIR ENSEMBLES SHOW A BROAD UPPER
LEVEL TROUGH DEVELOPING WITHIN THE GULF OF ALASKA AND SAID
TROUGH COULD SWING SOUTHWARD INTO THE PAC NW OR REMAIN SOMEWHAT
STATIONARY, YET STILL SEND SLUGS OF COOL AND MOIST AIR INTO THE
REGION. OVERALL, FOR THE START OF NEXT WEEK THROUGH THE MIDDLE
OF NEXT WEEK, CONDITIONS ARE MOST LIKELY TO COOL DOWN WITH SOME
PRECIPITATION AS THE MAJORITY OF MODELS HAVE A TROUGH IMPACTING
THE PAC NW BY THE START OF NEXT WEEK. /42
AVIATION
RADAR IMAGERY AS OF LATE WEDNESDAY MORNING DEPICTS A
BAND OF LIGHT TO MODERATE RAIN OVER THE NORTH OREGON AND SOUTH
WASHINGTON COAST AS AN ATMOSPHERIC RIVER IS SQUEEZED BETWEEN AN
UPPER LEVEL RIDGE TO THE SOUTH AND A BROAD UPPER LEVEL TROUGH OVER
THE GULF OF ALASKA. RAIN IS EXPECTED TO CONTINUE THROUGHOUT THE TAF
PERIOD AT KAST, WHILE CONDITIONS REMAIN DRIER FURTHER SOUTH.
HIGH PRESSURE WILL ALSO KEEP MARINE STRATUS ALONG THE COAST AND THUS
IFR/MVFR CONDITIONS. OCCASIONAL DROPS TO 3-5 SM EXPECTED AROUND AST
DURING PERIODS OF HEAVIER RAIN OR MIST. MEANWHILE, WILLAMETTE VALLEY
TERMINALS REMAIN VFR WITH HIGH CLOUDS THROUGHOUT THE TAF PERIOD AS
THESE LOCATIONS STAY UNDER THE INFLUENCE OF THE UPPER LEVEL RIDGE.
WINDS GENERALLY SOUTHERLY TO SOUTHWESTERLY AND UNDER 10 KT, EXCEPT
FOR OCCASIONAL GUSTS UP TO 20 KT ALONG THE COAST.
KPDX AND APPROACHES...PREDOMINATELY VFR CONDITIONS WITH HIGH CLOUDS
THROUGH THE TAF PERIOD. SOUTHERLY TO SOUTHEASTERLY WINDS UNDER 10
KT. -10
MARINE
SOUTHERLY WINDS ACROSS ALL WATERS EXPECTED THROUGH THE
MIDDLE OF THE WEEK. OCCASIONAL WIND GUSTS UP TO 25 KT WILL BE
POSSIBLE FOR ZONES PZZ251, PZZ271 AND THE COLUMBIA RIVER BAR THROUGH
THURSDAY. SEAS OF 7 TO 10 FEET AT 10 TO 13 SECONDS AS WINDS INCREASE
AND A SOUTHWESTERLY TO WESTERLY SWELL MOVES INTO THE WATERS. CHANCES
FOR SMALL CRAFT CONDITIONS REMAIN LOW FOR THE WEAK SYSTEM THAT MOVES
THROUGH ON THURSDAY. /42-19
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
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