822
FXUS66 KPQR 310501
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1001 PM PDT SUN MAR 30 2025
SYNOPSIS
RIDGING BUILDS INTO THE AREA BRINGING A BRIEF BREAK
IN PRECIPITATION AS WELL AS A SLIGHT WARMING TREND TODAY. THIS
WILL BE SHORT LIVED AS A BROAD AREA OF LOW PRESSURE WILL BRING
COOL AND WET CONDITIONS BACK TO THE REGION THROUGH THE LATTER
PART OF THE UPCOMING WEEK. ANOTHER SHORTWAVE RIDGE LOOKS TO
DEVELOP WEDNESDAY EVENING/THURSDAY WHICH WILL BRING WARM AND DRY
CONDITIONS ONCE AGAIN.
DISCUSSION...TODAY THROUGH SATURDAY
A PATTERN CHANGE IS
CURRENTLY OCCURRING AS TROUGHING BEGINS TO BUILD BACK INTO THE
REGION, AND RAIN IS CURRENTLY PUSHING INTO THE REGION FROM THE
SOUTH. THIS MARKS THE BEGINNING OF A FEW COOL AND SHOWERY DAYS
AS AN OFFSHORE LOW SPINS A FEW ROUNDS OF MOISTURE BETWEEN NOW
AND THURSDAY.
THE INITIAL WAVE OF MOISTURE IS CURRENTLY PUSHING INTO THE AREA,
THOUGH QPF LOOKS FAIRLY LOW AND RAINFALL WILL LIKELY BE NON-
IMPACTFUL. BETWEEN 5PM SUN TO 5PM MONDAY, ONLY AROUND A 40-50%
CHANCE OF LOWLAND RAINFALL IN THE WILLAMETTE VALLEY AND SW
WASHINGTON LOWLANDS TO EXCEED 0.25 INCHES. AT THE COAST AND
COAST RANGE, SLIGHTLY HIGHER ACCUMULATIONS CLOSER TO 0.5-1.0
INCHES IS EXPECTED DURING THIS PERIOD. SNOW LEVELS ARE CURRENTLY
AROUND 5000 FEET, BUT WILL BE FALLING TO AROUND 2500-3000 FT BY
THE END OF SUNDAY NIGHT. AS SUCH, CASCADES SNOW ACCUMULATION
CAN BE EXPECTED WITH THIS INITIAL WAVE OF MOISTURE. THAT SAID,
ACCUMULATIONS ARE EXPECTED TO REMAIN BELOW ADVISORY LEVEL,
THOUGH SNOW ACCUMULATIONS WILL CONTINUE IN THE MOUNTAINS
THROUGHOUT THE WEEK. INITIAL SNOW BETWEEN NOW AND 5PM MONDAY
LOOKS TO BE ONLY AROUND 3-4 INCHES AT THE CENTRAL OREGON
CASCADES PASSES, EVEN LESS AT THE NORTHERN OREGON CASCADES.
EASTERLY GUSTS THROUGH THE COLUMBIA GORGE ARE CURRENTLY AROUND
30-35 KTS, INCLUDING THE PORTLAND METRO AREA. THESE WILL
CONTINUE TO DECREASE THROUGH THIS EVENING AND TONIGHT, SHIFTING
SOUTHERLY WITH GUSTS UP TO 10 KTS BY AROUND MIDNIGHT TONIGHT.
AFTERWARDS WINDS REMAIN ONSHORE AND FAIRLY WEAK THROUGH
THURSDAY. ADDITIONALLY, SOME WEAK INSTABILITY IS EXPECTED AT THE
COAST BEGINNING THIS EVENING, ENHANCED IN PART DUE TO
OROGRAPHIC LIFT. THIS WILL PRODUCE A 10-15% CHANCE OF SOME WEAK
ISOLATED THUNDERSTORMS TONIGHT AT THE COAST. MONDAY SEES SHOWERS
CONTINUING, WITH THUNDERSTORMS AT THE COAST REMAINING POSSIBLE
(10-15% CHANCE) THROUGH EVENING HOURS.
HEADING INTO MONDAY NIGHT, THE MAIN LOW PASSES SOUTH OF THE AREA
(NEAR THE OR/CA BORDER). TUESDAY AND WEDNESDAY SEE GENERALLY
UNSETTLED CONDITIONS REMAINING, WITH WEAK SHOWERS AT TIMES.
ACCUMULATIONS WILL BE GENERALLY NEGLIGIBLE. DAYTIME HIGH
TEMPERATURES GENERALLY AROUND THE MID 50S FOR MOST INLAND
LOCATIONS, CLOSER TO THE LOW 50S AT THE COAST.
THURSDAY THROUGH SATURDAY LOOK TO BE VERY SIMILAR TO EACH OTHER
AS A SHORTWAVE RIDGE BUILDS ACROSS THE REGION. DAYTIME HIGHS
WILL STARTING THE 50S ON THURSDAY AND WARMING AROUND 5-7 DEGREES
EACH DAY WITH DAYTIME HIGHS IN THE UPPER 60S TO LOW 70S
EXPECTED BY SATURDAY. /JLIU/42
AVIATION
LIGHT RAIN CONTINUES AS A FRONTAL BOUNDARY LIFTS
NORTHWARD ACROSS THE REGION. FLYING CONDITIONS REMAIN LARGELY VFR
AT AREA TERMINALS, WITH MVFR CIGS/VIS ALONG THE COAST AND WITHIN
HEAVIER RAIN SHOWERS. RADAR TRENDS SUGGEST CONTINUED DECREASING
COVERAGE OF SHOWER ACTIVITY FROM SOUTH TO NORTH BEHIND THE FRONT,
ALTHOUGH THIS SHOULD HAVE LITTLE IMPACT AS CIGS REMAIN AT 2-4 KFT
GIVEN ABUNDANT SURFACE MOISTURE. FOLLOWING A BRIEF BREAK, RENEWED
SHOWER ACTIVITY SHOULD ARRIVE FROM THE SOUTH AFTER 09-12Z MON,
CONTINUING THROUGH THE REMAINDER OF THE PERIOD WITH INCREASED
LIKELIHOOD OF MVFR CIGS/VIS ACROSS THE REGION. WINDS HAVE TURNED
OUT OF THE SOUTHEAST TO SOUTH AT INLAND TERMINALS, AND SOUTH TO
SOUTHWEST ALONG THE COAST. SPEEDS OF 8-15 KT THIS EVENING WILL
DIMINISH TO 10 KT OR LESS, ALTHOUGH GUSTS TO 20 KT ARE POSSIBLE
AT AST/ONP. RENEWED RAIN SHOWERS AFTER 09-12Z MON MAY BRING
ADDITIONAL GUSTS OF 15-20 KT INLAND.
PDX AND APPROACHES...MIXED LOW-VFR/MVFR CIGS WITH LARGELY
UNRESTRICTED VIS ARE EXPECTED THROUGH TONIGHT, ALTHOUGH PERIODS OF
MVFR VIS WITHIN HEAVIER RAIN SHOWERS CANNOT BE RULED OUT, MOST
LIKELY AFTER 12Z MON WHEN ADDITIONAL RAIN SHOWERS ARRIVE FROM THE
SOUTH. SOUTH TO SOUTHEAST WINDS AT 8-12 KT ARE EXPECTED
THROUGH MONDAY MORNING, WITH GUSTS TO 20 KT DIMINISHING LATER
THIS EVENING. BY MONDAY AFTERNOON, WINDS WILL BEGIN TO TURN OUT
OF THE SOUTH TO SOUTHWEST. -PICARD
MARINE
A FRONTAL SYSTEM EXITING THE COASTAL WATERS THIS
EVENING HAS YIELDED WINDS TURNING SOUTHERLY TO SOUTHWESTERLY.
BUOY OBSERVATIONS HAVE SHOWN GUSTS OF ONLY 25-30 KT, AND HAVE
THEREFORE CANCELLED THE GALE WARNING EARLY, HOWEVER SMALL CRAFT
ADVISORIES REMAIN IN EFFECT THROUGH MONDAY EVENING AS ANOTHER
LOW PRESSURE SYSTEM APPROACHES THE WATERS. THE SMALL CRAFT
ADVISORY MAY NEED TO BE DRAWN OUT FURTHER FOR AT LEAST THE INNER
AND OUTER WATERS SOUTH OF CAPE FALCON WHERE HIGHER SEAS AND
WINDS MAY PERSIST.
SEAS AROUND 10 FT TONIGHT WILL BEGIN TO DIMINISH FOLLOWING
MODESTLY WEAKENING WINDS BEFORE A FRESH SOUTHWESTERLY SWELL
ARRIVES, BUILDING SEAS UP INTO THE 10-14 FT RANGE. SEAS THEN
DECREASE LATE TUESDAY INTO WEDNESDAY, LEVELING OUT AROUND 5 TO 7
FT AT 9 SECONDS BY WEDNESDAY AFTERNOON, REMAINING THERE FOR THE
MIDDLE TO END OF THE WEEK AS NORTH TO NORTHWESTERLY FLOW RESIDES
ALOFT, KEEPING WINDS FAIRLY LOW, AND THE PREVAILING SWELL LOW
AS WELL. -SCHULDT/PICARD
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 11 PM PDT MONDAY FOR PZZ210-251>253-
271>273.
WWW.WEATHER.GOV/PORTLAND
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