627
FXUS66 KPQR 301818
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1118 AM PDT SUN MAR 30 2025
UPDATED AVIATION DISCUSSION
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
SHORTWAVE RIDGING
CONTINUES TO BUILD OVER THE REGION TODAY. THIS WILL BRING ABOUT
A BRIEF REPRIEVE IN PRECIPITATION ALONG WITH A SLIGHT WARMING
TREND ACROSS THE CWA. HOWEVER, THIS WILL BE SHORT LIVED AS A
BROAD AREA OF LOW PRESSURE WILL BRING A RETURN TO COOL AND WET
CONDITIONS STARTING THIS EVENING. COOL AND WET CONDITIONS WILL
REMAIN IN THE FORECAST THROUGH THE MAJORITY OF THE UPCOMING WEEK
WITH ANOTHER SHORTWAVE RIDGE BRINGING WARM AND DRIER CONDITIONS
BY THURSDAY.
THE NEXT SYSTEM WHICH ARRIVES TONIGHT LOOKS TO BE A DETACHED LOW
OF WHICH THE PARENT LOW LOOKS TO BE AROUND 43.82N/137.28W ON
MONDAY. LOOKING AT CAMS, THE DETACHED LOW WILL MOVE RATHER
SWIFTLY NORTHWARD AS IT PARALLELS THE OR/WA COAST. THIS LOW
WILL BRING THE FIRST SLUG OF MOISTURE AND COOL AIR TO THE
REGION. WARM MOIST AIR OVER RELATIVELY COOLER OCEAN WATER, WILL
ALSO RESULT IN A 10-15% PROBABILITY FOR THUNDERSTORMS OVER OUR
COASTAL WATERS IN ADDITION TO ISOLATED, GUSTY WINDS (UP TO 35
MPH) FOR INLAND LOCATIONS AS THE PRESSURE GRADIENT OPENS UP.
AS THE DISTENDED LOW MARCHES NORTHWARD, THE LARGER PARENT LOW
WILL CONTINUE TO TRAVERSE SOUTHEASTWARD TOWARDS SOUTHERN OREGON
AS IT SLOWLY WEAKENS. MODELS HAVE NARROWED DOWN THE POTENTIAL
LANDFALL AREA CLOSER TO THE OR/CA BORDER ON TUESDAY. AS THIS LOW
CONTINUES TO MOVE SOUTHEASTWARD, IT WILL SEND MULTIPLE FRONTS
ACROSS THE REGION AND 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 STARTING MONDAY AFTERNOON AND CONTINUING THROUGH
LATE MONDAY EVENING.
COOL AND MOIST CONDITIONS WILL PERSIST ON TUESDAY, BUT BY THIS
TIME THE LOW LOOKS TO BE WELL SOUTH OF OUR FORECAST AREA. NOW,
WHILE COOL TEMPERATURES ALONG WITH SHOWERS WILL CONTINUE, THIS
PATTERN IS NOT FAVORABLE FOR THUNDERSTORM DEVELOPMENT. AS THE
LOW CONTINUES TO MOVE SOUTHEASTWARD. 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.
AT THIS TIME, DO TO THE SHOWERY NATURE OF THE PRECIPITATION 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, WHICH WILL
HINDER SNOWFALL ACCUMULATIONS AROUND PASS-LEVEL. OVERALL, 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. HOWEVER, WE WILL CONTINUE TO MONITOR THE SITUATION AS
IT MORE INFORMATION COMES IN. WEDNESDAY LOOKS TO BE VERY SIMILAR
IN COMPARISON TO TUESDAY.
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. /42
AVIATION
GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH MUCH OF
THE FORECAST PERIOD. HIGH CLOUDS CONTINUE TO SPREAD OVER THE
REGION FROM THE SOUTH DUE TO OUR NEXT APPROACHING WEATHER
DISTURBANCE WITH RAIN SLATED TO ARRIVE AT KEUG AND KONP OVER THE
NEXT HOUR OR TWO. THIS FRONTAL BOUNDARY CONTINUE TO PROGRESS
NORTHWARD THE REST OF THE AFTERNOON SPREADING LOW-VFR CIGS AND
RAIN/RAIN SHOWERS ACROSS THE REGION. HOWEVER, MVFR CIGS/VIS
CANNOT BE RULED OUT AT THIS POINT, ESPECIALLY ALONG THE COAST
INCLUDING AST/ONP WHERE MVFR CIGS BECOME MORE LIKELY AFTER 22-24Z
SUN. INLAND, COULD SEE BRIEF MVFR CIGS AND VIS IN HEAVIER RAIN
SHOWERS. EXPECT EASTERLY WINDS, CURRENTLY BREEZY AT SOME LOCATIONS
LIKE KPDX, KTTD, AND KHIO, TO TURN MORE SOUTHERLY LATE THIS
AFTERNOON AND EVENING AFTER THE FRONTAL PASSAGE, ALTHOUGH DUE TO A
PERSISTENT OFFSHORE PRESSURE GRADIENT KTTD MAY NOT SEE MUCH OF A
CHANGE IN WIND DIRECTION GOING FORWARD.
PDX AND APPROACHES...VFR CONDITIONS ARE ANTICIPATED TO PREVAIL
THE NEXT 24 HOURS. A FRONTAL BOUNDARY IS APPROACHING FROM THE
SOUTH LATE THIS MORNING, LIKELY ARRIVING BY 21-23Z SUNDAY,
BRINGING RAIN/RAIN SHOWERS. BUT, LOW-END VFR CIGS AT 4-7 KFT AND
UNRESTRICTED VIS ARE EXPECTED TO PREVAIL WITHIN LIGHT RAIN SHOWERS
WITH A SMALL CHANCE OF MVFR CIGS IN HEAVIER SHOWERS TONIGHT INTO
MONDAY. WHILE WINDS ARE EASTERLY GUSTING TO 20-30 KNOTS CURRENTLY,
BEHIND THE FRONTAL BOUNDARY, WINDS LIKELY SHIFT SOUTHERLY BY
23-24Z SUNDAY WITH GUSTS UP TO 20-25 KTS CONTINUING THROUGH AROUND
06Z MONDAY. -SCHULDT/HEC
MARINE
OFFSHORE WINDS THIS MORNING ARE LOCALLY BREEZY
THROUGH COASTAL GAPS. OCCASIONAL WIND GUSTS UP TO 20-25 KTS ARE
POSSIBLE, THOUGH NOT WIDESPREAD ENOUGH FOR A SMALL CRAFT
ADVISORY. WINDS THEN TURN SOUTHERLY BY THIS AFTERNOON AND
INCREASE THROUGH TONIGHT AS ANOTHER FRONTAL SYSTEM APPROACHES
FROM THE SOUTHWEST. HIGH RESOLUTION GUIDANCE INDICATES A 75-90%
CHANCE FOR LOW END GALE FORCE WINDS LATER THIS AFTERNOON INTO
TONIGHT ACROSS THE INNER AND OUTER WATERS SOUTH OF OCEAN PARK,
WA, INCLUDING THE COLUMBIA RIVER BAR. A GALE WARNING HAS BEEN
ISSUED FOR ALL COASTAL WATERS. WINDS DECREASE SOMEWHAT BY EARLY
MONDAY MORNING, THOUGH REMAIN ELEVATED WITH GUSTS UP TO 30 KTS,
OCCASIONALLY UP TO 35 KTS, THROUGH MONDAY AFTERNOON AS ANOTHER
LOW PRESSURE SYSTEM APPROACHES THE WATERS. A SMALL CRAFT
ADVISORY HAS BEEN ISSUED FOR ALL WATERS.
SEAS WILL BUILD AGAIN INTO THE LOW TEENS LATE TONIGHT DRIVEN BY
THE STRONG WINDS. WINDS WILL REMAIN ELEVATED THROUGH MONDAY INTO
TUESDAY AS A FRESH SOUTHWESTERLY SWELL ARRIVES, KEEPING SEAS UP
INTO THE LOW TO MID TEENS. SEAS DECREASE TUESDAY NIGHT INTO
WEDNESDAY, LEVELING OUT AROUND 5 TO 7 FT AT 9 TO 10 SECONDS BY
WEDNESDAY AFTERNOON, REMAINING FOR THE MIDDLE TO END OF THE WEEK
AS NORTH TO NORTHWESTERLY FLOW RESIDES ALOFT, KEEPING WINDS FAIRLY
LOW, AND THE PREVAILING SWELL REMAINS LOW. -SCHULDT/HEC
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...GALE WARNING FROM 4 PM THIS AFTERNOON TO 2 AM PDT MONDAY FOR
PZZ210-251-271.
SMALL CRAFT ADVISORY FROM 2 AM TO 11 AM PDT MONDAY FOR PZZ210-
251>253-271>273.
GALE WARNING UNTIL 2 AM PDT MONDAY FOR PZZ252-253-272-273.
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