333
FXUS66 KPQR 210911
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
211 AM PDT SAT MAR 21 2026
SYNOPSIS
LIGHT RAIN SHOWERS CONTINUE EARLY SATURDAY MORNING,
CLEARING BY 9 AM. DRY WEATHER AND NEAR NORMAL HIGH TEMPERATURES
THROUGH MONDAY WITH MORNING LOW TEMPERATURES IN THE 30S,
PRODUCING WIDESPREAD FROST SATURDAY AND SUNDAY NIGHTS. A WEATHER
SYSTEM BRINGS WIDESPREAD RAIN AND BREEZY WINDS TUESDAY INTO
WEDNESDAY ALONG WITH LIGHT CASCADES SNOW TUESDAY NIGHT INTO
WEDNESDAY. NO SNOW OR FLOODING IMPACTS EXPECTED. DRY WEATHER
RETURNS THURSDAY INTO FRIDAY.
DISCUSSION...SATURDAY THROUGH FRIDAY
AT 2 AM PDT SATURDAY,
RADAR IMAGERY SHOWS A BAND OF LIGHT PRECIPITATION SLOWLY MOVING
SOUTHEAST THROUGH NW OR, STRETCHING FROM FLORENCE ALONG THE
COAST TO THE DALLES. THIS BAND WILL CONTINUE MOVING SOUTHEAST
OVER THE EARLY MORNING HOURS, ENDING BY 7-9 AM. ENSEMBLE
GUIDANCE INDICATES UPPER LEVEL FLOW BECOMES MORE ZONAL OVER THE
PACNW AS SURFACE HIGH PRESSURE SPREADS INLAND FROM THE EASTERN
PACIFIC THIS AFTERNOON INTO MONDAY. THIS WILL BRING DRY WEATHER
ALONG WITH HIGH TEMPERATURES RIGHT AROUND DAILY NORMALS FOR LATE
MARCH, MAINLY IN THE MID TO UPPER 50S FOR THE INTERIOR
LOWLANDS. WINDS WILL ALSO BE LIGHT, ESPECIALLY DURING THE
OVERNIGHT HOURS EACH DAY. THE LIGHT WINDS WILL BE IN CONJUNCTION
WITH CLEARING SKIES IN THE OVERNIGHT HOURS, RESULTING IN AN
IDEAL SET- UP FOR RADIATIONAL COOLING. AS SUCH, EXPECT COLDER
THAN NORMAL FORECAST LOW TEMPERATURES FOR THE INTERIOR LOWLANDS
SUNDAY MORNING AND MONDAY MORNING. TONIGHT INTO SUNDAY MORNING
REMAINS THE COLDEST WITH WIDESPREAD LOWS IN THE LOW TO MID 30S.
WIDESPREAD 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 WITH LESS WIDESPREAD FROST DEVELOPMENT. THOSE WITH SENSITIVE
OUTDOOR PLANTS SHOULD TAKE PRECAUTIONS TO PROTECT VEGETATION
FROM FROST THIS WEEKEND. NOTE THAT NWS PORTLAND WILL NOT BEGIN
ISSUING FROST ADVISORIES AND FREEZE WATCHES/WARNINGS FOR
AGRICULTURAL PURPOSES UNTIL APRIL 1ST AS THIS IS WHEN THE
GROWING SEASON BEGINS TO RAMP UP AND IMPACTS FROM FROST AND
FREEZE CONDITIONS BECOME MORE SIGNIFICANT.
WIDESPREAD RAIN AND BREEZY WINDS ARE EXPECTED TO RETURN TUESDAY
INTO WEDNESDAY AS ENSEMBLES ARE IN GOOD AGREEMENT OF A PACIFIC
LOW PRESSURE SYSTEM MOVING EAST INTO BRITISH COLUMBIA WITH THE
ASSOCIATED COLD FRONT PUSHING EAST INTO WA AND OR. ENSEMBLES ARE
IN MUCH BETTER AGREEMENT ON THE INITIAL TIMING OF PRECIPITATION
BEGINNING ON TUESDAY WITH RAIN CONTINUING INTO WEDNESDAY. LATEST
GUIDANCE IS HINTING AT THE POSSIBILITY OF ANOTHER, WEAKER
SURFACE LOW PRESSURE SYSTEM AND ASSOCIATED UPPER LEVEL SHORTWAVE
PUSHING ANOTHER BURST OF RAIN INTO THE REGION LATE WEDNESDAY
INTO THURSDAY MORNING, AND NBM IS HINTING AT THIS AS WELL BY
KEEPING PROBABILITY OF PRECIPITATION AROUND 30-50% FOR THE
INTERIOR LOWLANDS AND 50-70% FOR THE COAST AND TERRAIN WEDNESDAY
NIGHT INTO THURSDAY MORNING. UNCERTAINTY STILL REMAINS ON EXACT
PRECIPITATION AMOUNTS TUESDAY INTO THURSDAY, THOUGH HIGH
CONFIDENCE REMAINS IN LIMITED FLOODING IMPACTS. EVEN THE WETTEST
POSSIBLE SCENARIO SUGGESTS LESS THAN 1 INCH OF RAIN IN THE
WETTEST 24 HOUR PERIOD OVER THE COAST, COAST RANGE, AND WILLAPA
HILLS, AND LESS THAN 1.25 INCH OVER THE CASCADES. BREEZY WINDS
ARE ALSO EXPECTED WITH THE FRONTAL PASSAGE ON TUESDAY.
STRONGEST WINDS WILL BE ALONG THE COAST WHERE THERE'S A 50-60%
CHANCE OF WIND GUSTS OVER 40 MPH AND A 10-20% CHANCE OF GUSTS
OVER 50 MPH. INLAND AREAS COULD SEE PEAK GUSTS UP TO 30-35 MPH
AS THERE'S A 50-70% CHANCE OF GUSTS OVER 30 MPH.
IN TERMS OF CASCADE SNOW, THE HEAVIEST PRECIPITATION IS
EXPECTED TO FALL AHEAD OF AND ALONG THE COLD FRONT WHEN SNOW
LEVELS ARE GENERALLY HIGHER THAN PASS LEVEL. SNOW LEVELS WILL
FALL QUICKLY AFTER THE FRONT PASSES LATE TUESDAY INTO
WEDNESDAY TO AROUND 3500-4500 FT. HOWEVER, THE LOWEST SNOW
LEVELS WILL BE IN SW WA CASCADES WITH SNOW LEVELS RISING MOVING
SOUTH INTO THE CENTRAL OR CASCADES. AS SHOWERS WILL CONTINUE
INTO WEDNESDAY, THERE IS THE POTENTIAL FOR SOME ACCUMULATING
SNOW, THOUGH DUE TO THE CURRENT SUN ANGLE ALONG WITH WARMER ROAD
TEMPERATURES, IT MIGHT BE DIFFICULT FOR MUCH ACCUMULATION IN
SCATTERED SHOWERS. SNOW LEVELS WILL CONTINUE FALLING THROUGH
WEDNESDAY, ESPECIALLY WEDNESDAY NIGHT, FALLING TO AROUND
2000-3000 FT BY THURSDAY MORNING. THE 10TH PERCENTILE (ONLY 10%
CHANCE OF SNOW LEVELS THIS LOW) DOES INDICATE SNOW LEVELS COULD
FALL AS LOW AS 500-1500 FT BY THURSDAY MORNING. HOWEVER, IF
PRECIPITATION REALLY IS DECREASING BY THIS TIME, THEN THERE WILL
BE LIMITED PRECIPITATION TO EVEN CAUSE SNOW. NBM 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% AT WILLAMETTE AND SANTIAM PASSES, AND 10-20%
ALONG HIGHWAY 26 NEAR GOVERNMENT CAMP.
BY THURSDAY AFTERNOON INTO FRIDAY, 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 ON THURSDAY AND RIGHT AROUND 60 ON FRIDAY FOR THE
INTERIOR LOWLANDS. -03/23
AVIATION
AT 09Z SAT, A BAND OF RAIN SHOWERS STRETCHING FROM
K4S2 ALONG THE COAST TO KDLS IN NORTHERN OR CONTINUES MOVING
SOUTHEAST. THIS RAIN IS EXPECTED TO BE OUT OF THE AREA (EAST OR
SOUTH OF LANE COUNTY) BY 14-16Z SAT. MVFR CIGS WITH OCCASIONAL
DROPS TO IFR CIGS/VIS IN HEAVIER SHOWERS ARE EXPECTED WITH THE
PRECIPITATION. NORTHWEST OF THE RAIN WHERE SKIES HAVE BEGUN
CLEARING, LOW STRATUS IS FORMING, CAUSING MVFR CIGS BOTH FOR
INLAND TERMINALS AND ALONG THE COAST. IN GENERAL, EXPECT
CONDITIONS TO IMPROVE TO VFR BY 12-15Z SAT FOR MOST LOCATIONS
EXCEPT FOR THE SOUTHERN WILLAMETTE VALLEY, INCLUDING KEUG, AND
THE CASCADES, WHICH SHOULD IMPROVE BY 15-18Z SAT. WINDS WILL BE
NORTH TO NORTHWEST, GENERALLY LESS THAN 10 KTS EXCEPT FOR
OCCASIONAL GUSTS UP TO 20 KTS ALONG THE COAST NEAR AND SOUTH OF
KTMK AS WELL AS ALONG THE COLUMBIA RIVER NEAR AND NORTH OF KPDX
DUE TO FUNNELING OF NORTHWEST WINDS THROUGH THE RIVER.
KPDX AND APPROACHES...EXPECT MAINLY VFR CONDITIONS THROUGH THE TAF
PERIOD, EXCEPT FOR A 20-40% CHANCE OF OCCASIONAL MVFR CIGS THROUGH
12Z SAT. NORTHWEST WINDS 5-10 KTS WITH AN OCCASIONAL GUST UP TO 20
KTS. -03
MARINE
HIGH PRESSURE CONTINUES BUILDING IN OVER THE WATERS
EARLY SATURDAY MORNING, TURNING WINDS MORE NORTHERLY OVER THE
WATERS. PRESSURE GRADIENTS HAVE TIGHTENED A BIT BEHIND THE COLD
FRONTAL PASSAGE, ALLOWING FOR A PERIOD OF NORTH WIND GUSTS UP TO
21-25 KTS OUTSIDE OF THE COLUMBIA RIVER BAR. AS HIGH PRESSURE
CONTINUES BUILDING EAST INTO THE WATERS INTO THE WEEKEND, THE
PRESSURE GRADIENT DECREASES OVER THE WATERS AND WIND GUSTS FALL
BELOW 21 KTS BY 8 AM THIS MORNING. A SMALL CRAFT ADVISORY REMAINS
IN EFFECT FOR ALL WATERS THROUGH 8 AM SATURDAY DUE TO MARGINAL
SMALL CRAFT WIND GUSTS. AN EXCEPTION IS THE COLUMBIA RIVER BAR,
WHERE A SMALL CRAFT ADVISORY IS IN EFFECT BETWEEN 5-10 AM SATURDAY
FOR A VERY STRONG EBB CURRENT THAT WILL BRING SEAS TO AROUND 9
FEET. BENIGN MARINE CONDITIONS CONTINUE THROUGH MONDAY AS HIGH
PRESSURE PERSISTS. SEAS OF 7-9 FT AT 10 SEC TODAY FALL TO 5-7 FT
BY LATE TONIGHT, BUT RE- BUILD TO 8-9 FT HEADING INTO MONDAY.
HOWEVER, CONFIDENCE IS GROWING FOR PRESSURE GRADIENTS TIGHTENING
AGAIN SUNDAY AFTERNOON AND EVENING, BRINGING ANOTHER ROUND OF
SMALL CRAFT NORTHERLY WIND GUSTS UP TO 21-25 KTS, MAINLY SOUTH OF
CAPE FALCON.
THE NEXT 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 25-45% 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 75-90%, WITH THE
HIGHEST CHANCES BEYOND 20 NM OFFSHORE. SEAS ON TUESDAY AND
WEDNESDAY ARE ALSO EXPECTED TO BUILD TO AROUND 14-16 FT IN
RESPONSE TO INCREASING WIND WAVES ALONG WITH AN INCREASING
WESTERLY SWELL. THERE'S A 30-60% CHANCE SEAS COULD EXCEED 15 FT
WITH A 15-25% CHANCE FOR SEAS EXCEEDING 20 FT. CHANCES INCREASE
FROM SOUTH TO NORTH, PEAKING ACROSS THE WATERS NORTH OF CAPE
FALCON AND MAINLY BEYOND 40 NM OFFSHORE. -10/03
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 5 AM TO 10 AM PDT SATURDAY FOR
PZZ210.
SMALL CRAFT ADVISORY UNTIL 8 AM PDT SATURDAY FOR PZZ251>253-
271>273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page