584
FXUS66 KPQR 041743 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
1043 AM PDT THU JUN 4 2026
UPDATED AVIATION DISCUSSION.
SYNOPSIS
A TRANSIENT RIDGE TODAY WILL KEEP CONDITIONS
SEASONABLE AND GENERALLY DRY. A DEEPER TROUGH AND ASSOCIATED LOW
PRESSURE SYSTEM SHIFTS SOUTHWARD INTO THE REGION FRIDAY TO
SATURDAY INCREASING ONSHORE FLOW AND RETURNING MORE WIDESPREAD
CHANCES FOR PRECIPITATION. SLIGHT CHANCES FOR THUNDERSTORMS
FRIDAY AND SATURDAY AFTERNOON. DRIER WEATHER RETURNS SUNDAY
BEFORE ANOTHER TROUGH RETURNS CHANCES FOR PRECIPITATION EARLY
NEXT WEEK.
SHORT TERM...NOW THROUGH SATURDAY NIGHT
SATELLITE IMAGERY
SHOWS WIDESPREAD CLOUD COVER OVER THE REGION WITH MOST AREAS
SITTING UNDER OVERCAST SKIES. THESE CLOUDS HAVE KEPT OVERNIGHT
TEMPERATURES ON THE WARM SIDE WITH LOWS IN THE UPPER 40S TO MID
50S FOR MANY LOCATIONS AS OF 3 AM. THROUGH THE DAY TODAY THOUGH
THOSE CLOUDS WILL THIN AS A TRANSIENT RIDGE MOVES OVER THE
REGION. WILL SEE LITTLE IN THE WAY OF SENSIBLE WEATHER AS
TEMPERATURES REMAIN SEASONABLE AND FLOW IS ZONAL. ESPECIALLY IN
THE AFTERNOON AND EARLY EVENING, THERE WILL BE A CONTRAST
BETWEEN A SURFACE HIGH OVER THE NORTHERN ROCKIES AND AN INCOMING
TROUGH OVER THE PACIFIC. BASED ON MODELS, COULD SEE BREEZY
WESTERLY WINDS NEAR SUNSET BUT WILL GENERALLY BE WITHIN EAST-
WEST ALIGNED TERRAIN LIKE THE LOWER I-5 CORRIDOR, COAST RANGE
GAPS, AND THE COLUMBIA RIVER GORGE. GUSTS AS HIGH AS 20 MPH ARE
POSSIBLE WITH A 10% CHANCE OF GUSTS UP TO 25 MPH.
THE OVERALL FORECAST ON FRIDAY AND THROUGH THE WEEKEND HAS
REMAINED UNCHANGED AND MODELS ARE IN GOOD AGREEMENT IN THE
SYNOPTIC PATTERN. A LOW ALOFT CONTINUES TO BE THE DOMINATE
FEATURE AS IT DROPS DOWN NEAR VANCOUVER ISLAND BY FRIDAY
AFTERNOON. AS THIS UPPER TROUGH MOVES IN, IT WILL PUSH A WEAK
FRONT INTO NORTHWEST OREGON AND SOUTHWEST WASHINGTON. THIS WILL
RETURN MORE WIDESPREAD CHANCES FOR PRECIPITATION, WITH THE
HIGHEST CHANCES OVER SOUTHWEST WASHINGTON AND THE NORTH OREGON
COAST, COAST RANGE, AND CASCADES. GIVEN THE SHOWERY NATURE OF
THIS SYSTEM, RAINFALL AMOUNTS WILL VARY ACROSS THE AREA AND THE
HIGHEST AMOUNTS WILL ULTIMATELY DEPEND ON WHERE SHOWERS SET-UP.
OVERALL, SHOWERS WILL BE NON-IMPACTFUL. GIVEN THE NORTHERN
TRACK OF THIS TROUGH, CHANCES FOR PRECIPITATION ARE HIGHEST AS
YOU GO FURTHER NORTH. IN ADDITION, THERE IS A 10-15% CHANCE FOR
THUNDERSTORMS ACROSS THESE AREAS AS INSTABILITY INCREASES DUE TO
COLD AIR ALOFT, A SLIGHT SOUTHWESTERLY FLOW, ALONG WITH
SUFFICIENT LIFT FROM THE TROUGH. ANY PASSING THUNDERSTORMS COULD
PRODUCE LIGHTNING, BRIEF HEAVY RAIN, ERRATIC WINDS, AND/OR
SMALL HAIL.
ONSHORE FLOW WILL ALSO INCREASE AS THIS UPPER TROUGH MOVES IN.
WEST-SOUTHWESTERLY WINDS WON'T BE TOO IMPACTFUL ACROSS MOST
AREAS WITH GUSTS UP TO 20 MPH ALONG THE I-5 CORRIDOR, HOWEVER,
TYPICAL BREEZY SPOTS DURING ONSHORE FLOW LIKE THE CENTRAL GORGE
AND UPPER HOOD RIVER VALLEY COULD GUST UP TO 35-40 MPH. THE 90TH
PERCENTILE WINDS ON FRIDAY EVENING ARE AROUND 20-25 MPH WITHIN
THE EAST-WEST ALIGNED TERRAIN, AND AROUND 30 MPH ALONG THE
HIGHER ELEVATIONS OF THE CASCADES. IF THE LOW SHIFTS ANY FURTHER
NORTH THOUGH THESE WINDS WILL BE LESS IMPACTFUL.
TRANSITIONING INTO SATURDAY THE LOW WILL SHIFT SLIGHTLY MORE
SOUTHWARD (THINK OF A REVERSE 'J' SHAPE) WHICH WILL ENHANCE
PRECIPITATION ONCE AGAIN. AT THIS TIME THERE REMAINS AMPLE
CONVECTIVE POTENTIAL FOR THUNDERSTORMS AGAIN IN THE AFTERNOON
AND PERIODS OF RAIN. MOST OF THE RAIN REMAINS CONCENTRATED TO
THE NORTH. -27/10
LONG TERM...SUNDAY THROUGH WEDNESDAY
FOR THOSE WITH SUNDAY
PLANS, THERE WILL BE A BRIEF DRIER PERIOD AS A SHORTWAVE RIDGE
PASSES OVER THE PACIFIC NORTHWEST. 500 MB ENSEMBLES ARE FALLING
INTO BETTER AGREEMENT WITH ANOTHER LONGWAVE TROUGH MOVING OVER
THE AREA. UNCERTAINTY REMAINS IN THE EXACT TRACK AS IT'S QUITE
MESSY WITH DETERMINISTIC SURFACE PLOTS SHOWING A NUMBER OF SMALL
MESOSCALE LOWS EMBEDDED WITHIN THE TROUGH. HOWEVER, THIS SYSTEM
WILL ENCOURAGE OVERALL MORE MOIST AND COOL AIR TO MOVE INTO THE
AREA. THEREFORE WILL MAINTAIN A TREND OF BELOW NORMAL HIGH
TEMPERATURES. WHEN OBSERVING THE 24-HR PRECIPITATION DIFFERENCES
BETWEEN THE ENSEMBLES, AROUND HALF OF THE SOLUTIONS ARE
TRENDING DRIER THAN THE COMPOSITE ENSEMBLE AND THE OTHER HALF
WETTER. THIS ONLY EMPHASIZES THE LEVEL OF UNCERTAINTY.
ULTIMATELY IT WILL ONCE AGAIN COME DOWN TO THE TRACK OF THE
SYSTEM. WHEN LOOKING AT INDIVIDUAL ENSEMBLE MEMBERS, THERE IS
CONSENSUS THOUGH THAT RAIN WILL START AT SOME POINT ON MONDAY
BUT HOW MUCH RAIN IS UNDETERMINED.
TUESDAY INTO WEDNESDAY IS A BIT OF A BLUR AS THE TWO DAYS RUN
SEAMLESSLY INTO ONE ANOTHER. POST FRONTAL RAIN SHOWERS EXPECTED
WITH BREEZY WESTERLY WINDS ONCE AGAIN POSSIBLE. ONE THING TO
CONSIDER IS THAT SOME OF THE MODELS ARE SUGGESTING THAT THE LOW
WILL MOVE ALMOST DIRECTLY OVER THE FORECAST AREA. IF THIS
OCCURS, THE JET STREAM WILL DIP JUST TO THE SOUTH AND WE WILL BE
IN A VERY DYNAMIC PATTERN. IN FACT, THERE ARE A FEW OF THE
MODEL RUNS THAT SUGGEST THAT WE COULD SEE GREATER THAN 1 INCH OF
RAIN ON TUESDAY INTO WEDNESDAY. AGAIN THOUGH, UNCERTAINTY IS
INCREDIBLY HIGH AND THE LARGER TREND IS TOWARDS NON-IMPACTFUL
ACCUMULATIONS. -27
AVIATION
ONSHORE FLOW WILL CONTINUE TONIGHT THROUGH TOMORROW,
BRINGING LIGHT NORTHWEST WINDS TO THE AREA AROUND 5-10 KT LATE
THIS AFTERNOON AND EVENING BEFORE WINDS BECOME LIGHT AND VARIABLE
TONIGHT. SCATTERED TO BROKEN VFR CEILINGS REMAIN IN PLACE OVER THE
AREA AS OF 1740Z THURSDAY, BUT SHOULD CLEAR OUT FOR MOST LOCATIONS
BY 00Z FRIDAY. A BROKEN VFR CLOUD DECK WILL LIKELY DEVELOP AROUND
AND AFTER 06Z FRIDAY ALONG THE CASCADE FOOTHILLS AND WILLAMETTE
VALLEY WITH CEILINGS MOST LIKELY STAYING ABOVE 4000 FT. PERIODS OF
MVFR CEILINGS ARE MORE LIKELY TO OCCUR ALONG THE COAST BETWEEN
06-18Z FRIDAY. THIS IS ALSO WHEN A WEAK FRONT WILL BEGIN MOVING
INLAND FROM THE COASTAL WATERS, WHICH WILL BRING SCATTERED LIGHT
RAIN SHOWERS TO THE COAST BY APPROXIMATELY 12Z FRIDAY.
KPDX AND APPROACHES...VFR CEILINGS ARE EXPECTED TO CONTINUE
THROUGH 18Z FRIDAY ALONG WITH DRY CONDITIONS. NORTHWEST WINDS WILL
CONTINUE AROUND 5-10 KT THROUGH THIS EVENING, WITH GUSTS AS HIGH
AS 15-18 KT TOWARDS 01-02Z FRIDAY. -23
MARINE
LOOKING AT FAIRLY BENIGN CONDITIONS OVER THE NEXT
SEVERAL DAYS DESPITE A SERIES OF FRONTAL SYSTEMS MOVING THROUGH.
WESTERLY FLOW WILL CONTINUE THROUGH SATURDAY. SEAS ARE EXPECTED
TO REMAIN AROUND 5 TO 6 FT AS A WESTERLY SWELL PERSISTS. SEAS THEN
BUILD TO 6-8 FT AT 11 TO 12 SECONDS LATE TONIGHT INTO FRIDAY
MORNING AS A WEAK FRONTAL BOUNDARY APPROACHES THE WATER. THIS
FRONT WILL ALSO BRING INCREASING WESTERLY WINDS WITH GUSTS UP TO
20 KT. THERE IS LESS THAN A 5% CHANCE OF WIND GUSTS OF 25 KT OR
GREATER.
A SECONDARY FRONT ARRIVES ON SATURDAY, BRINGING A SHIFT TO
NORTHWEST WINDS. HOWEVER, WIND SPEEDS ARE NOT EXPECTED TO
INCREASE MUCH WITH THIS FRONTAL PASSAGE. THERE IS LESS THAN A
15% CHANCE OF SMALL CRAFT ADVISORY WINDS. THE TIME PERIOD WITH
HIGHEST WIND SPEEDS WILL LIKELY OCCUR ON MONDAY AS STRONGER
SYSTEM MOVES OVER THE WATERS, BRINGING SOUTH WINDS UP TO 20-25
KT AND SEAS APPROACHING 9-10 FT. -27/23
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
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