409
FXUS66 KPQR 271130
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
430 AM PDT MON JUL 27 2026
UPDATED AVIATION DISCUSSION.
SYNOPSIS
PERSISTENT ONSHORE FLOW WILL BRING NEAR-AVERAGE
TEMPERATURES WITH VARYING DEGREES OF MORNING CLOUDS AND
AFTERNOON SUNSHINE FOR MUCH OF THE NEXT WEEK. A SERIES OF WEAK
FRONTS WILL BRING NOTABLE CHANCES FOR LIGHT RAIN AND DRIZZLE TO
PORTIONS OF THE WASHINGTON AND NORTH OREGON COASTS TUESDAY AND
NEXT WEEKEND, WHILE FRIDAY IS LIKELY TO BE THE WARMEST DAY.
DISCUSSION...NOW THROUGH SUNDAY
THE LARGE-SCALE PATTERN
REMAINS FAIRLY STEADY THROUGH THE NEXT WEEK WITH THE REGION
WEDGED BETWEEN UPPER-LEVEL TROUGHING OVER THE GULF OF ALASKA AND
UPPER-LEVEL RIDGING OVER THE ROCKIES AND CENTRAL PLAINS. IN
GENERAL, THE WEATHER LOCALLY WILL BE TYPICAL FOR THE MID-SUMMER:
MORNING CLOUDS FOLLOWED BY INCREASING AFTERNOON SUNSHINE,
SEASONABLE TEMPERATURES, AND LARGELY DRY CONDITIONS, BUT WITH
SOME VARIATIONS AS THE STRENGTHS OF THESE TWO DOMINANT
FEATURES CHANGE RELATIVE TO ONE ANOTHER.
TODAY, UPPER RIDGING WINS OUT AS HEIGHTS ALOFT RISE MARGINALLY,
YIELDING CLOUDS CLEARING ALL THE WAY TO THE COAST BY THE EARLY
AFTERNOON WITH SEASONABLY WARM HIGH TEMPERATURES IN THE 60S ON
THE COAST AND MID 80S WITHIN THE WILLAMETTE VALLEY. ON TUESDAY,
AN UPPER SHORTWAVE PASSING TO THE NORTH WILL TILT THE SCALES IN
FAVOR OF UPPER TROUGHING, SENDING A WEAK FRONT TOWARD THE COAST
RESULTING IN COOLER TEMPERATURES ACROSS THE REGION AND CHANCES
FOR LIGHT RAIN OR DRIZZLE ALONG THE COAST AND COAST RANGE,
INCREASING FROM 40% AT FLORENCE TO 60% AT NEWPORT, 75% AT
TILLAMOOK, 95% AT ASTORIA, AND NEARLY 100% ON THE LONG BEACH
PENINSULA. CHANCES FOR ACCUMULATING RAINFALL ARE LOWER ALONG
THE I-5 CORRIDOR, RANGING FROM 20% AT SALEM TO 30% AT PORTLAND,
60% AT WOODLAND, AND 75% AT KELSO/LONGVIEW.
THROUGH THE LATTER HALF OF THE WORKWEEK, THE UPPER-LEVEL RIDGE
WILL STRENGTHEN AND RETROGRADE WESTWARD INTO THE GREAT BASIN,
INCREASING HEIGHTS ALOFT LOCALLY AND AGAIN TIPPING THE BALANCE
TOWARD WARM AND DRY WEATHER. AS SUCH, TEMPERATURES WILL TREND
UPWARD EACH AFTERNOON, PEAKING ON FRIDAY IN THE UPPER 60S TO
AROUND 70 DEGREES ON THE COAST AND IN THE MID TO UPPER 80S
WITHIN INLAND VALLEYS. DESPITE THIS TREND, ONSHORE FLOW WILL
CONTINUE, LIMITING THE RISK FOR HAZARDOUS HEAT. MINOR HEATRISK
IS FAVORED FOR THE ENTIRE REGION ON FRIDAY, WITH 20-40% CHANCES
FOR MODERATE HEATRISK IN URBAN AND SUBURBAN AREAS FROM SALEM
NORTH TO VANCOUVER, WA. BY NEXT WEEKEND, THERE CONTINUES TO BE
HIGHER UNCERTAINTY IN THE EVOLUTION OF THE UPPER-LEVEL PATTERN,
BUT MANY ENSEMBLE MEMBERS DEPICT MORE PRONOUNCED TROUGHING
RETURNING TO THE PACIFIC NORTHWEST, FAVORING COOLER TEMPERATURES
AND FURTHER CHANCES FOR RAINFALL. THE DETAILS OF TIMING AND
POTENTIAL RAINFALL AMOUNTS REMAIN FUZZY AT THIS LEAD TIME, BUT
THOSE NEAR THE COAST OR WITHIN COASTAL TERRAIN WILL BE THE MOST
LIKELY BENEFICIARIES OF ANY RAINFALL, WITH CHANCES INCREASING TO
THE NORTH. -36
AVIATION...THROUGH 12Z TUESDAY
A DYING FRONT REMAINS STALLED
OFF THE OREGON COAST AND OVER WESTERN WASHINGTON EARLY THIS
MORNING, SUPPORTING MIXED IFR/MVFR CIGS AT COASTAL TERMINALS.
THESE CONDITIONS ARE FAVORED (60-80% CHANCE) TO PERSIST UNTIL
CLOUD COVER DECREASES BY 17-19Z MON. LIGHT OFFSHORE DRAINAGE
FLOW EARLY THIS MORNING WILL VEER OUT OF THE SOUTHWEST AND BUILD
TO NEAR 10 KT WITH GUSTS OF 15-20 KT BY MIDDAY, BEFORE EASING
BELOW 5 KT AND BACKING OUT OF THE SOUTH THIS EVENING. FURTHER
LOW CLOUD COVERAGE IS LIKELY AFTER 03Z TUE AS THE STALLED FRONT
PUSHES INTO THE COAST LATE IN THE PERIOD.
INLAND, CONDITIONS REMAIN LARGELY VFR EARLY THIS MORNING AS
MARINE STRATUS COVER HAS BEEN LIMITED TO THE SOUTH WASHINGTON
CASCADE FOOTHILLS AND THE TUALATIN VALLEY IN NORTHWEST OREGON,
WHERE MVFR CIGS WILL LIKELY (60-70% CHANCE) CONTINUE UNTIL
CLOUDS MIX OUT BY 16-18Z MON. ELSEWHERE, FEW-SCT LOW CLOUDS AT
2-3 KFT MAY DEVELOP THROUGH 15-16Z MON, BUT CHANCES FOR MORE
WIDESPREAD MVFR CIGS ARE ONLY 25-35% BEFORE SKIES TREND CLEARER
BY MIDDAY. CALM TO LIGHT SOUTHERLY WINDS EARLY THIS MORNING WILL
BUILD TO 5-10 KT AND VEER OUT OF THE WEST TO NORTHWEST AT
PORTLAND-AREA TERMINALS AND WEST TO SOUTHWEST AT WILLAMETTE
VALLEY TERMINALS BY THIS AFTERNOON, BEFORE EASING BELOW 5 KT AND
BACKING OUT OF THE SOUTH THIS EVENING. ADDITIONAL LOW CLOUDS
MAY DEVELOP LATE IN THE PERIOD.
KPDX AND APPROACHES...VFR CONDITIONS FAVORED THROUGH MUCH OF THE
PERIOD. LOW STRATUS HAS BEEN SLOW TO DEVELOP EARLY THIS MORNING,
BUT THERE REMAINS A 35% CHANCE CLOUD COVERAGE INCREASES,
YIELDING HIGH-END MVFR CIGS BEFORE SKIES TREND CLEARER MIDDAY.
LIGHT WINDS EARLY THIS MORNING WILL BUILD TO 5-10 KT, VEERING
THROUGH SOUTHWEST FLOW THIS MORNING AND ULTIMATELY TO WEST-
NORTHWEST FLOW BY THIS AFTERNOON, BEFORE EASING BELOW 5 KT AND
BACKING OUT OF THE SOUTH THIS EVENING. CHANCES FOR FURTHER MVFR
CIGS INCREASE LATE IN THE PERIOD, AFTER 06Z TUE, AS A FRONT
APPROACHES FROM THE NORTHWEST. -36
MARINE
A WEAK FRONT OFFSHORE WILL FINALLY RETREAT NORTHWARD
TODAY, BRINGING AN END TO LIGHT RAIN OR DRIZZLE CHANCES OFF THE
SOUTH WA AND FOR NORTH OR COASTS BY THIS AFTERNOON. DIURNAL
SOUTHERLY WINDS AROUND 10-15 KT AND CONTINUE INTO TUESDAY
MORNING. BUILDING HIGH PRESSURE BEHIND ANOTHER PASSING FRONTAL
BOUNDARY WILL SEE A WIND SHIFT TO MORE SEASONABLE NORTHERLY FLOW
ON TUESDAY. STRENGTHENING NORTHERLY FLOW THROUGH THE LATTER
HALF OF THE WORKWEEK WILL SEE 25-50% CHANCES FOR PEAK WIND GUSTS
TO REACH 20-25 KT WEDNESDAY THROUGH FRIDAY AFTERNOONS,
ESPECIALLY WITHIN 10 NM OF THE COAST.
SEAS CONTINUE AT 4-6 FT THROUGH THE NEXT WEEK WITH A DOMINANT
WEST TO NORTHWEST SWELL AT 8-9 SECONDS. -36
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
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