345
FXUS66 KPQR 291859
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1159 AM PDT WED JUL 29 2026
SYNOPSIS
ONSHORE FLOW PERSISTS THROUGH MUCH OF THE NEXT
WEEK, WHILE HIGH PRESSURE BUILDING OFFSHORE WILL SEE
TEMPERATURES TREND WARMER THROUGH FRIDAY. A FRONTAL SYSTEM
SATURDAY WILL BRING THE NEXT CHANCES FOR LIGHT RAIN AND USHER IN
A BROAD PATTERN CHANGE THIS WEEKEND INTO NEXT WEEK.
SHORT TERM...NOW THROUGH FRIDAY NIGHT
BROAD UPPER-LEVEL
RIDGING CURRENTLY CENTERED OVER THE ROCKIES WILL BUILD AND
RETROGRADE WESTWARD OVER THE GREAT BASIN THROUGH FRIDAY,
INCREASING HEIGHTS ALOFT LOCALLY AND SUPPORTING A WARMING TREND
ACROSS THE REGION. A WEAK SHORTWAVE IS MOVING OVER THE REGION
THIS AFTERNOON WHICH IS INCREASING INSTABILITY OVER THE HIGH
CASCADES. CAPE VALUES ARE EXCEEDING 150 J/KG WHICH IS NOT
NECESSARILY ENOUGH TO PRODUCE WIDESPREAD THUNDERSTORMS, BUT MAY
PRODUCE SOME TOWERING CUMULUS OVER THE CASCADES. TEMPERATURES
NEAR NORMAL IN THE MID 60S ON THE COAST AND LOW 80S WITHIN
INLAND VALLEYS ARE EXPECTED THROUGH THURSDAY AS WEAK WAVES
WITHIN THE SOUTHWESTERLY FLOW ALOFT WILL KEEP HEAT FROM RISING
TO HAZARDOUS LEVELS. EVEN ON FRIDAY, WHILE STILL GOING TO BE THE
WARMEST DAY OF THE WEEK, TEMPERATURES WILL MOST LIKELY PEAK IN
THE MID 60S TO LOW 70S AT THE COAST AND MID TO UPPER 80S INLAND.
THESE CONDITIONS ARE FAIRLY TYPICAL FOR THIS TIME OF YEAR.
OTHERWISE, A TYPICAL SUMMERTIME PATTERN WILL SEE DRY WEATHER AND
MORNING CLOUDS, ESPECIALLY ALONG THE COAST, CLEARING TO MOSTLY
SUNNY SKIES EACH AFTERNOON. -27/36
LONG TERM...THURSDAY THROUGH WEDNESDAY
A MORE SUBSTANTIAL
PATTERN SHIFT WILL BEGIN FRIDAY NIGHT INTO SATURDAY AS AN UPPER
TROUGH MOVES FROM THE GULF OF ALASKA INLAND OVER THE PACIFIC
NORTHWEST. THIS SYSTEM WILL BRING A COLD FRONT INTO THE COAST ON
SATURDAY. RAINFALL IS EXPECTED WITH AROUND A 50% CHANCE OF
ACCUMULATING RAIN ALONG THE COAST AND SOUTHWEST WASHINGTON IN
THE AFTERNOON. ACCUMULATION WILL VARY GREATLY, AND WILL BE
OROGRAPHICALLY IMPACTED. ANY RAINFALL WILL MOST LIKELY BE VERY
LIGHT, AMOUNTING TO NO MORE THAN 0.05-0.10 INCHES. THE 90TH
PERCENTILE SHOWS SOME AREAS OF AROUND 0.25 INCH ALONG THE COAST
NORTH OF TILLAMOOK, BUT IN ORDER FOR THAT TO OCCUR, THE SYSTEM
WILL HAVE TO DROP FURTHER SOUTH THAN CURRENT MODELS ARE
SUGGESTING. NEAR TO SLIGHTLY BELOW NORMAL HIGH TEMPERATURES IN
THE 60S AND 70S ARE EXPECTED THROUGH THE WEEKEND IN THE WAKE OF
THE FRONTAL PASSAGE.
AS THE PROGRESSIVE UPPER TROUGH EXITS EASTWARD, THERE IS
INCREASED UNCERTAINTY IN THE EVOLUTION OF THE PATTERN BY EARLY
NEXT WEEK. LONG-RANGE ENSEMBLES DEPICT A HIGH PROBABILITY OF
STRONG UPPER-LEVEL RIDGING DEVELOPING OVER THE FOUR CORNERS, BUT
WHETHER THAT WILL TRANSLATE TO HOT WEATHER LOCALLY IS MORE
UNCERTAIN. 500 MB ENSEMBLE HEIGHTS SHOW AROUND HALF OF THE
OUTPUTS WITH A TROUGH OVER THE COAST EARLY NEXT WEEK, WHILE THE
OTHER HALF SHOW SUBSTANTIAL RIDGING. IN THE CASE THAT WE SEE
TROUGHING, WE CANNOT RULE OUT ANOTHER COOL START TO THE WEEK,
WHILE IF THE ECMWF RINGS TRUE, MORE HEATING WOULD BE IN THE
FORECAST AND A THERMAL TROUGH WOULD FORM AT THE COAST. WHILE
WARMER TEMPERATURES COMPARED TO THE WEEKEND ARE ALL BUT CERTAIN,
THE SPREAD OF POTENTIAL SOLUTIONS REMAINS WIDE. THE "BEST
FORECAST" (MEAN) AT THIS LEAD TIME SHOWS TUESDAY WITH THE
WARMEST DAYTIME HIGHS; IN THE 70S ALONG THE COAST AND UPPER 80S
TO LOW 90S INLAND. HOWEVER, THERE IS A 10% CHANCE THAT WE COULD
SEE HIGHS INLAND AROUND 95-100 DEG F, AND IN THE LOW 80S ALONG
THE COAST. THERE ARE EQUAL CHANCES FOR HIGHS IN THE UPPER 60S
ALONG THE COAST, AND MID 80S INLAND. THIS WIDE SPREAD LEADS TO
QUESTIONS REGARDING WHETHER OR NOT THE THERMAL TROUGH FORMS ON
MONDAY AND TUESDAY. IF IT DOES SO ON MONDAY, NORTHERLY WINDS
WILL INCREASE WITH GUSTY CONDITIONS UP TO 25 MPH POSSIBLE.
-27/36
AVIATION...THROUGH 18Z THURSDAY
SATELLITE IMAGERY AS OF LATE
WEDNESDAY MORNING SHOWS STRATUS QUICKLY DISSIPATING ACROSS THE
WILLAMETTE VALLEY AS MIXING INCREASES FROM DAYTIME HEATING. EXPECT
PREDOMINATELY VFR CONDITIONS THROUGH THE TAF PERIOD FOR VALLEY
TERMINALS WITH FEW/SCT HIGH CLOUDS (>25 KFT) AT TIMES. THERE IS A
20-30% CHANCE FOR MVFR STRATUS RE-DEVELOPING ACROSS VALLEY
TERMINALS AT ANY GIVEN HOUR BETWEEN 10-17Z THU AS THE LOW LEVEL
ATMOSPHERE MOISTENS OVERNIGHT. ALONG THE COAST, WILL ALSO SEE
STRATUS BREAKING UP AND CONDITIONS IMPROVING TO VFR THIS
AFTERNOON. AFTER 06-07Z THU, THERE IS HIGH CONFIDENCE FOR LOW-END
MVFR STRATUS (1-2 KFT) RETURNING ALONG THE COAST AND PERSISTING
THROUGH THURSDAY MORNING. NORTHWESTERLY WINDS 5-10 KT TODAY,
STRONGEST IN THE AFTERNOON WITH GUSTS UP TO 20 KT ALONG THE COAST.
WINDS EASE OVERNIGHT.
KPDX AND APPROACHES...VFR CONDITIONS THROUGH THE TAF PERIOD WITH
HIGH CLOUDS. 20-30% CHANCE FOR MVFR CIGS AT ANY GIVEN HOUR BETWEEN
10-17Z THU. NORTHWESTERLY WINDS 6-8 KT TODAY, WEAKENING UNDER 5 KT
TONIGHT. -10
MARINE
BUOY OBSERVATIONS FROM LATE WEDNESDAY MORNING SHOW SEAS
CONTINUING AT 4-5 FT, WHICH ARE EXPECTED TO PERSIST THROUGH MUCH
OF THE WEEK WITH A DOMINANT WEST TO NORTHWEST SWELL AT 7-9 SECONDS
AND A SECONDARY LONG-PERIOD SOUTH-SOUTHWESTERLY SWELL. A FRONTAL
SYSTEM APPROACHING THE WATERS LATE THIS WEEK WILL RESULT IN
NORTHERLY WINDS TURNING MORE SOUTHWESTERLY AHEAD OF THE WEAK
SURFACE FRONT BEGINNING THURSDAY, MAINLY FOR THE WATERS NORTH OF
CAPE FALCON AND THE WATERS BEYOND 30 NM SOUTH OF CAPE FALCON DOWN
TO CAPE FOULWEATHER. CHANCES FOR LIGHT RAIN PEAK LATE FRIDAY
NIGHT INTO SATURDAY MORNING DURING THE FRONTAL PASSAGE.
BEHIND THE BOUNDARY, INITIAL WESTERLY FLOW WILL VEER OUT OF THE
NORTH THROUGH THE WEEKEND AS SURFACE HIGH PRESSURE BUILDS
OFFSHORE. CHANCES FOR MAXIMUM WIND GUSTS OF AT LEAST 20-25 KT
ARE GREATER THAN 90% ACROSS THE WATERS FROM SUNDAY THROUGH AT
LEAST TUESDAY. CHANCES THAT PEAK AFTERNOON GUSTS REACH GALE-FORCE
IS THE HIGHEST ON MONDAY AFTERNOON BUT HAVE GONE DOWN SINCE THE
LAST FORECAST PACKAGE, WITH SOME 25-35% WITHIN 10 NM SOUTH OF CAPE
FALCON AND 15-25% BEYOND 10 NM. CHANCES FOR GALE-FORCE GUSTS NORTH
OF CAPE FALCON ARE LOWER, ONLY 1-5%. -10/36
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
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