160
FXUS66 KPQR 292350
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
450 PM PDT SAT MAR 29 2025
SYNOPSIS
WEAKENING SHOWERS TODAY AS RIDGING BUILDS INTO THE
AREA. SATURDAY NIGHT INTO SUNDAY A BRIEF BREAK IN THE
PRECIPITATION AS WELL AS A SLIGHT WARMING TREND IS EXPECTED. BY
THE START OF THE UPCOMING WEEK, A BROAD AREA OF LOW PRESSURE
WILL BRING A RETURN OF COOLER TEMPERATURES, RAIN AND CASCADE
SNOW BY LATE SUNDAY NIGHT/MONDAY AND THESE CONDITIONS LOOK TO
PERSIST THROUGH THE UPCOMING WEEK.
DISCUSSION...TODAY THROUGH FRIDAY
THERE ARE STILL A FEW VERY
WEAK SHOWERS THROUGHOUT THE REGION, MOSTLY VIRGA, BUT ALL
PRECIPITATION TAPERS OFF THROUGHOUT THE REST OF THIS AFTERNOON.
SHORTWAVE RIDGING BUILDS IN THIS EVENING, AND THE MAJORITY OF
TONIGHT AND SUNDAY WILL BE DRY. SUNDAY'S HIGH TEMP WILL BE
SLIGHTLY WARMER THAN PREVIOUS DAYS, WITH A HIGH AROUND THE LOW
60S IN THE NORTHERN WILLAMETTE VALLEY/SW WASHINGTON LOWLANDS,
CLOSER TO THE MID/UPPER 50S AT THE SOUTHERN WILLAMETTE VALLEY
AND COAST.
THE NEXT SYSTEM ARRIVES ON SUNDAY NIGHT/MONDAY IS A RATHER
BROAD, VERTICALLY STACKED LOW, WITH THE SURFACE LOW EXPECTED
TO BE AROUND 988 MB AND CENTERED AROUND 45.75N/136.40W ON
MONDAY. THIS LOW WILL SLOWLY WEAKEN AND TRAVEL SOUTHEASTWARD
THROUGH THE UPCOMING WEEK, WITH MODELS SHOWING LANDFALL IN-
BETWEEN FLORENCE, OR AND THE OR/CA BORDER. AS THIS LOW MOVES
SOUTHEASTWARD, IT WILL SEND MULTIPLE FRONTS ACROSS THE REGION.
THIS WILL RESULT IN SOUTH/SOUTHEASTERLY FLOW, THAT ALONG WITH
MODERATE WARMING AND A MOISTURE LATENT ATMOSPHERE WILL RESULT IN
AROUND A 10-20% PROBABILITY FOR THUNDERSTORMS COME MONDAY
AFTERNOON AND CONTINUE THROUGH THE LATE MONDAY EVENING. COOL AND
MOIST CONDITIONS WILL CONTINUE AS THE LOW CONTINUES TO TRUDGE
SOUTHEASTWARD AND WILL BRING WIDESPREAD PRECIPITATION ALONG WITH
850 MB TEMPERATURES DIPPING DOWN TOWARDS -0C TO -4C. THIS WILL
RESULT IN A LOWERING OF SNOW LEVELS TO 2500-3000 FEET. HAVE
DECIDED NOT TO ISSUE A WINTER WEATHER ADVISORY FOR THE INITIAL
WAVE OF MOUNTAIN SNOW. NBM GUIDANCE SHOWS ONLY AROUND A 40-60%
CHANCE FOR 6 INCHES OR GREATER OF SNOWFALL ACCUMULATION AT
CASCADES ELEVATIONS BETWEEN 3000-5500 FT, WITH CLOSER TO 70%
CHANCE ABOVE 5500 FT. COMBINED WITH THE FACT THAT SNOW LEVELS
WILL BE CLOSER TO 4000-5000 SHORTLY BEFORE THE PRECIPITATION AND
ONLY SLOWLY FALLING ONCE THE INITIAL FRONT PUSHES IN, SNOWFALL
ACCUMULATIONS AT ANY IMPACTFUL AREAS HAS POTENTIAL TO
UNDERPERFORM MODEL GUIDANCE. ULTIMATELY, WITH SHOWERY
PRECIPITATION CONTINUING THROUGHOUT THE MAJORITY OF THE UPCOMING
WEEK, SNOW ACCUMULATIONS WILL AT SOME POINT EXCEED 6 INCHES IN
THE SOUTHERN CASCADES, BUT AT LEAST FOR THE INITIAL WAVE OF
PRECIPITATION, ADVISORY-LEVEL SNOWFALL RATES ARE NOT EXPECTED.
CLUSTER ANALYSIS SHOWS AROUND A 60% CHANCE OF RETURNING TO
RIDGING NEXT FRIDAY, POSSIBLY INDICATING DRIER CONDITIONS
RETURNING AT THAT POINT. /JLIU
AVIATION
LARGELY VFR FLYING CONDITIONS ARE EXPECTED AT ALL
TERMINALS THROUGH MUCH OF THE PERIOD. VERY ISOLATED LIGHT
SHOWERS IN THE OREGON COAST RANGE, INCLUDING INVOF AST, ARE
DIMINISHING IN COVERAGE AND INTENSITY, WITH NO ADDITIONAL
IMPACTS EXPECTED AFTER 00Z SUN. OTHERWISE, DRY CONDITIONS ARE
EXPECTED AT ALL TERMINALS WITH LIGHT NORTH WINDS AT AROUND 5 KT
TURNING OUT OF THE EAST BY 18Z SUN. CENTRAL/SOUTHERN WILLAMETTE
VALLEY TERMINALS, INCLUDING SLE/EUG, MAY SEE A PERIOD OF
RESTRICTED VIS FROM FOG OR MIST OVERNIGHT DURING A BRIEF WINDOW
OF CONDITIONS SUPPORTIVE OF EFFICIENT RADIATIVE COOLING, MOST
LIKELY FROM 10-15Z SUN. ANY INCREASE IN WINDS OR A FASTER
ARRIVAL OF HIGH-LEVEL CLOUDS FROM THE SOUTH WILL STYMIE THE
DEVELOPMENT OF ANY RADIATION FOG, AND HAVE THEREFORE INCLUDED
ONLY PREVAILING MVFR VIS AT THIS TIME GIVEN THE LOW CONFIDENCE
(20-30%) IN FOG OCCURRENCE. AS WINDS INCREASE OUT OF THE EAST
THROUGH SUNDAY MORNING, TERMINALS EAST OF THE COLUMBIA GORGE,
INCLUDING PDX/HIO WILL SEE GUSTS TO 15-20 KT AFTER 18Z SUN,
WHILE STRONGER GUSTS OF 20-30 KT ARE EXPECTED CLOSER TO THE
GORGE MOUTH AT TTD AFTER 15Z SUN. THESE EAST WINDS WILL ALSO ACT
TO LIMIT THE FOG/MIST POTENTIAL AT AFOREMENTIONED TERMINALS, AS
WELL AS AT UAO THROUGH THE OVERNIGHT PERIOD. A FRONTAL BOUNDARY
WILL ARRIVE FROM THE SOUTH LATE IN THE PERIOD, AFTER 18Z SUN,
SPREADING LOW-VFR CIGS AND RAIN SHOWERS FROM SOUTH TO NORTH,
HOWEVER MVFR CIGS/VIS CANNOT BE RULED OUT AT THIS POINT.
PDX AND APPROACHES...VFR FLYING CONDITIONS WITH SCT LOW CLOUDS
AT 5-6 KFT AND UNRESTRICTED VIS WILL CONTINUE THROUGH TONIGHT.
RECENT NORTH WINDS AT AROUND 5 KT WILL TURN OUT OF THE EAST BY
06-09Z SUN, BEFORE SPEEDS INCREASE TO 10-15 KT GUSTING 20-25 KT
AFTER 15-18Z SUN. RAIN SHOWERS ALONG A FRONTAL BOUNDARY WILL
APPROACH FROM THE SOUTH, ARRIVING BY 21-23Z SUN, HOWEVER LOW-VFR
CIGS AT 4-6 KFT AND UNRESTRICTED VIS ARE EXPECTED TO PREVAIL
WITHIN LIGHT RAIN. -PICARD
MARINE
TODAY A WEAK RIDGE OF HIGH PRESSURE HAS MOVED OVER
THE WATERS LEADING TO SOMEWHAT CALMER CONDITIONS WITH WAVE
HEIGHTS OF 6-8FT AT 10 SECONDS. GOING THROUGH TONIGHT INTO
SUNDAY MORNING WINDS LIKELY TURN OFFSHORE BECOMING LOCALLY
BREEZY THROUGH COASTAL GAPS. WINDS THEN TURN SOUTHERLY BY SUNDAY
AFTERNOON AND INCREASE THROUGH SUNDAY NIGHT AS ANOTHER FRONTAL
SYSTEM APPROACHES FROM THE SOUTHWEST. HIGH RESOLUTION GUIDANCE
INDICATES A 75-90% CHANCE FOR LOW END GALE FORCE WINDS LATER
SUNDAY AFTERNOON INTO SUNDAY NIGHT ACROSS THE INNER AND OUTER
WATERS SOUTH OF CAPE FALCON WHICH HAS PROMPTED THE ISSUANCE OF A
GALE WARNING. HOWEVER, CONFIDENCE IS A BIT LOWER FOR FREQUENT
GUSTS ABOVE 34 KT NORTH OF CAPE FALCON SO HAVE DECIDED TO ISSUE
A SMALL CRAFT ADVISORY HERE - WE'LL ALMOST CERTAINLY SEE GUSTS
BETWEEN 25-30 KNOTS LATE SUNDAY THROUGH MONDAY MORNING. IT'S
WORTH NOTING THERE IS AT LEAST SOME MINOR UNCERTAINTY AS TO THE
LOCATION/STRENGTH OF A SURFACE LOW ASSOCIATED WITH THE FRONTAL
BOUNDARY AND SHOULD MODELS TREND STRONGER WITH THIS FEATURE THE
SMALL CRAFT MAY NEED TO BE UPGRADED - SOMETHING TO WATCH.
SEAS WILL BUILD AGAIN INTO THE LOW TEENS LATE SUNDAY NIGHT (WIND
WAVE DRIVEN) DUE TO THE AFOREMENTIONED WEATHER SYSTEM. AFTER A
RATHER BRIEF LULL WE'LL SEE THE ARRIVAL OF A FRESH SOUTHWESTERLY
SWELL LATE MONDAY INTO TUESDAY PUSHES SEAS UP INTO THE LOW TO
MID TEENS YET AGAIN BEFORE DECREASING TUESDAY NIGHT INTO
WEDNESDAY. SEAS LEVEL OUT AROUND 5-7 FT AT 9-10 SECONDS FOR THE
MIDDLE TO END OF THE WEEK AS NORTH-NORTHWESTERLY FLOW RESIDES
ALOFT. -SCHULDT
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 4 AM TO 8 AM PDT SUNDAY FOR PZZ210.
SMALL CRAFT ADVISORY FROM 4 PM SUNDAY TO 11 AM PDT MONDAY FOR
PZZ210-251-271.
GALE WARNING FROM 1 PM SUNDAY TO 2 AM PDT MONDAY FOR PZZ252-
253-272-273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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