454
FXUS66 KPQR 180447 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
946 PM PDT THU JUL 17 2025
UPDATED MARINE AND AVIATION DISCUSSIONS.
SYNOPSIS
INCREASING ONSHORE FLOW WILL SEE TEMPERATURES
CONTINUE TO TREND COOLER TOWARD BELOW-NORMAL VALUES BY THE
BEGINNING OF NEXT WEEK. AN UPPER-LEVEL TROUGH MAY PROVIDE THE
BEST RAINFALL CHANCES IN A MONTH ON MONDAY, ALTHOUGH ODDS
REMAIN LOW FOR ACCUMULATING PRECIPITATION. FORECAST CONFIDENCE
THEN DECREASES RAPIDLY THROUGH THE WORKWEEK.
SHORT TERM...NOW THROUGH SUNDAY
AN INITIAL UPPER SHORTWAVE
CONTINUES TO WEAKEN AS IT PUSHES EASTWARD TOWARD THE NORTHERN
ROCKIES THIS AFTERNOON. WESTERLY TO NORTHWESTERLY ONSHORE FLOW
WHICH DEVELOPED OVERNIGHT AND INTO THIS MORNING IN TANDEM WITH
THE SHORTWAVE PASSAGE HAS COOLED TEMPERATURES COMPARED TO THE
PEAK OF THE HEAT YESTERDAY, YIELDING AFTERNOON HIGHS SOME 10
DEGREES COOLER THROUGHOUT INLAND VALLEYS, AND ABOUT 5 DEGREES
COOLER ALONG THE COAST. SIMILAR CONDITIONS TO TODAY ARE EXPECTED
TO END THE WORKWEEK, NAMELY 60S WITH MORNING LOW CLOUDS AND FOG
ALONG THE COAST AND MID AND UPPER 80S TO AROUND 90F INLAND.
ANOTHER MORE ENERGETIC SHORTWAVE WILL APPROACH THE REGION LATE
FRIDAY, USHERING IN FURTHER ONSHORE FLOW AND ADDITIONAL COOLING.
SLIGHTLY CLOUDIER AND BREEZIER CONDITIONS MAY DEVELOP AS SOON
AS FRIDAY AFTERNOON, MOST EVIDENTLY THROUGH THE COLUMBIA GORGE
WHERE GUSTS MAY REACH 25-30 MPH. MID-LEVEL TEMPERATURES WILL
FALL FROM AROUND 15C ON FRIDAY TO 10-11C ON SATURDAY, PUSHING
SURFACE TEMPERATURES TO BELOW-NORMAL VALUES. AFTERNOON HIGHS
THROUGH THE WEEKEND ARE EXPECTED IN THE LOW 60S ALONG THE COAST
AND MID 70S TO LOW 80S WITHIN INLAND VALLEYS. INCREASED MARINE
STRATUS COVERAGE MAY SEE AREAS OF PATCHY COASTAL FOG AND MIST,
MOST LIKELY OVERNIGHT AND INTO THE MORNING BOTH DAYS THIS
WEEKEND, ALTHOUGH CHANCES FOR JUST 0.01" OF ACCUMULATING
RAINFALL REMAIN ONLY 15-25% SOUTH OF TILLAMOOK, AND 25-40% FROM
TILLAMOOK NORTH TO PACIFIC COUNTY, WASHINGTON. -PICARD
LONG TERM...SUNDAY NIGHT THROUGH THURSDAY
THE FORECAST
THROUGH THE LONG TERM PERIOD REMAINS LOWER CONFIDENCE AS
NUMERICAL GUIDANCE DIVERGES BEYOND MONDAY. TROUGHING INITIALLY
PRESENT OVER THE PACIFIC NORTHWEST LOOKS TO BECOME MORE
ELONGATED AS A SHORTWAVE DIVES SOUTH ON ITS WESTERN FLANK. WHILE
THIS WAVE MAY SUPPORT LIGHT RAIN REACHING INTO THE REGION SUNDAY
NIGHT INTO MONDAY, CHANCES REMAIN LOW, ONLY 10-20% ALONG THE
COAST AND IN THE HIGHER TERRAIN OF THE CASCADES AND COAST RANGE
WHILE THE LOWLANDS SEE LESS THAN A 10% CHANCE. ENSEMBLE MEMBERS
THEN SHOW A WIDE VARIETY OF POSSIBLE SCENARIOS INCLUDING A
CUTOFF LOW DEVELOPING OVER THE PACIFIC OR A DEAMPLIFICATION OF
THE TROUGH WITH AN ASSOCIATED WARMING TREND AS COOLER AIR IN
THE MID-LEVELS MODERATES. AT THIS POINT, THE MAJORITY OF MEMBERS
FAVOR THE TREND BACK TOWARD A MORE ZONAL PATTERN AND THE
FORECAST THEREFORE WARMS BACK ABOVE SEASONAL NORMS. -PICARD
AVIATION
INLAND TAF SITES WILL MAINTAIN CLEAR SKIES AND
RELATIVELY LIGHT WINDS UNDER 10 KT THROUGHOUT THE 06Z TAF PERIOD.
LIFR CIGS WITH LOW MARINE STRATUS WILL IMPACT THE COAST THROUGH AT
LEAST 18-21Z FRIDAY, INCLUDING KONP AND KAST.
PDX AND APPROACHES...VFR CONDITIONS UNDER CLEAR SKIES. LIGHT
AND VARIABLE WINDS UNDER 5 KT TONIGHT WILL BECOME NORTHWESTERLY
AROUND 7-10 KT TOWARDS 22Z FRIDAY. -TK
MARINE
NORTHWEST WINDS AROUND 5-10 KT ARE BEING OBSERVED OVER
THE COASTAL WATERS THURSDAY EVENING AS HIGH PRESSURE REBUILDS. THE
INCOMING NORTHWESTERLY SWELL HAS BEEN OVER-PERFORMING MODEL
OUTPUT, AND SEAS REMAIN AROUND 9-10 FT AT 10 SECONDS THURSDAY
EVENING. A SMALL CRAFT ADVISORY HAS BEEN ISSUED THROUGH 11 AM
FRIDAY DUE TO STEEP SEAS. A MARINE DENSE FOG ADVISORY IS ALSO IN
EFFECT FROM 10 PM THURSDAY THROUGH 2 PM FRIDAY FOR VISIBILITIES OF
1 NM OR LESS. SEAS WILL SUBSIDE HEADING INTO THE WEEKEND WITH
MINIMAL IMPACTS EXPECTED. -TK/JLIU
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 11 AM PDT FRIDAY FOR PZZ210-251>253-
271>273.
DENSE FOG ADVISORY UNTIL 2 PM PDT FRIDAY FOR PZZ251>253-271>273.
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