549
FXUS66 KPQR 270940
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
240 AM PDT MON JUL 27 2026
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 06Z TUESDAY
A DYING FRONTAL BOUNDARY
WILL STALL NEAR THE OREGON COAST AND ACROSS WESTERN WASHINGTON
TONIGHT. THIS WILL MAINTAIN SOUTHWESTERLY FLOW ALOFT ACROSS THE
REGION WITH A GREATER THAN 80% CHANCE THAT CONDITIONS DETERIORATE
INTO A MIX OF MVFR AND IFR CONDITIONS ALONG THE COAST WHILE
CONDITIONS PRIMARILY REMAIN VFR FOR INLAND TAF SITES. WITH THAT
SAID, MARINE STRATUS IS ANTICIPATED TO DEVELOP OVER THE CASCADE
FOOTHILLS OVERNIGHT AND BACK BUILD WESTWARD INTO THE WILLAMETTE
VALLEY. THERE IS UNCERTAINTY WHETHER CEILINGS WILL FORM AROUND 4-
5KFT OR END UP BEING LOWER IF THEY DEVELOP. AROUND 30-40% OF THE
HIGH RESOLUTION MODELS SUGGEST MVFR CEILINGS WILL OCCUR AT MOST OF
OUR INLAND TAF SITES DURING THE 09-15Z TIMEFRAME. WITH THAT SAID,
OUR BEST STATISTICAL MODEL SUGGESTS THE PROBABILITY FOR MVFR
CEILINGS AT ANY GIVEN HOUR ONLY TOPS OUT AROUND 10-20% FOR OUR
INLAND TAF SITES DURING THAT TIME. IF MVFR CEILINGS DO DEVELOP, THEY
APPEAR MOST LIKELY TO DISSIPATE BETWEEN 17-19Z MONDAY.
KPDX AND APPROACHES...ONSHORE FLOW WILL MAINTAIN PREDOMINANTLY VFR
CONDITIONS THROUGH 06Z TUESDAY WITH AROUND A 20% CHANCE FOR MVFR
CEILINGS AT ANY GIVEN HOUR BETWEEN 12-18Z MONDAY.
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
INTERACT WITH US VIA SOCIAL MEDIA:
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X.COM/NWSPORTLAND
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