016
FXUS66 KPQR 271952
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1252 PM PDT THU AUG 27 2026
SYNOPSIS
A COOL AND SOMEWHAT UNSETTLED PATTERN WILL PERSIST
THROUGH THE WEEKEND AS UPPER-LEVEL TROUGHING REMAINS OVER THE
PACIFIC NORTHWEST. PERIODIC MARINE PUSHES WILL CONTINUE TO BRING
MORNING CLOUD COVER INLAND, WHILE WEAK DISTURBANCES MAY PRODUCE
OCCASIONAL LIGHT PRECIPITATION ALONG THE COAST AND AT HIGHER
TERRAIN. FORECAST UNCERTAINTY INCREASES INTO EARLY NEXT WEEK AS
ENSEMBLE SOLUTIONS DIVERGE ON THE PATTERN.
DISCUSSION...NOW THROUGH WEDNESDAY
UPPER-LEVEL TROUGHING REMAINS
THE DOMINANT FEATURE OVER THE NORTHEAST PACIFIC, MAINTAINING A
COOL AIR MASS AND PERSISTENT ONSHORE FLOW ACROSS THE REGION.
ANOTHER PUSH OF MARINE STRATUS IS EXPECTED TONIGHT INTO FRIDAY
MORNING, WITH CLOUDS LIKELY REACHING WELL INTO THE INTERIOR
LOWLANDS. DESPITE THE CLOUD COVER, PRECIPITATION CHANCES REMAIN
LOW, WITH MOST LOCATIONS STAYING DRY. TEMPERATURES FRIDAY SHOULD
REMAIN IN THE UPPER 70S ACROSS THE INTERIOR AND 60S ALONG THE
COAST.
THE BROADER TROUGH WILL REMAIN IN PLACE THROUGH SATURDAY, ALTHOUGH
ANOTHER WEAK DISTURBANCE MAY ENHANCE PRECIPITATION CHANCES,
PARTICULARLY NORTH OF A LINE FROM MCMINNVILLE AND MOLLALA.
ENSEMBLE GUIDANCE CURRENTLY GIVES A 15-40% CHANCE OF MEASURABLE
RAINFALL ACROSS THESE AREAS. ANY PRECIPITATION THAT DEVELOPS IS
EXPECTED TO BE LIGHT, WITH THE COAST, COAST RANGE, AND CASCADE
FOOTHILLS FAVORED FOR THE HIGHEST CHANCES. CONTINUED ONSHORE
FLOW WILL ALSO MAINTAIN THE POTENTIAL FOR MORNING MARINE STRATUS
ACROSS THE INTERIOR. BY SUNDAY, THE UPPER-LEVEL LOW SHIFTS EAST
AND A SHORTWAVE RIDGE FORMS, ALLOWING TEMPERATURES TO INCREASE
1 TO 3 DEGREES INTO THE UPPER 70S ACROSS INTERIOR.
LOOKING INTO EARLY NEXT WEEK, ENSEMBLE GUIDANCE CONTINUES TO
FAVOR A COOLER AND POTENTIALLY WETTER PATTERN, BUT CONFIDENCE
REMAINS LIMITED. AN INCREASING NUMBER OF ENSEMBLE MEMBERS
SUPPORT MEASURABLE PRECIPITATION ACROSS A LARGER PORTION OF THE
FORECAST AREA, THOUGH THERE REMAINS SUBSTANTIAL SPREAD IN THE
TIMING, AMPLITUDE, AND EVENTUAL POSITION OF THE UPPER-LEVEL
TROUGH. FURTHER REFINEMENT WILL BE POSSIBLE AS THE PATTERN
BECOMES BETTER RESOLVED. LASTLY, TO GIVE A ROUGH APPROXIMATION
OF EXPECTED PRECIPITATION EARLY NEXT WEEK, PROBABILISTIC
GUIDANCE SUGGESTS CHANCES FOR AT LEAST 0.01 INCHES OF RAIN
OVER 48 HOURS FROM EARLY TUESDAY TO LATE WEDNESDAY RANGES FROM
70-90%. AS FOR CHANCES OF HIGHER AMOUNTS OF RAIN, THERE IS A
40-70% CHANCE FOR 0.25 INCHES, 25-50% CHANCE FOR 0.50 INCHES,
AND A 5-30% CHANCE FOR 1 INCH.
~12
AVIATION...THROUGH 18Z FRIDAY
SOUTHWEST FLOW ALOFT CONTINUES AS
AN UPPER LEVEL TROUGH PERSISTS OVER THE REGION. LIGHT RAIN SHOWERS
CONTINUE NEAR KAST AS A WEAK FRONT PUSHES ONSHORE TODAY. THIS IS
PRODUCING PREDOMINATELY MVFR CONDITIONS AT THE COAST, WITH
PERIODS OF REDUCED VIS. A FEW LOW CLOUDS ARE ALSO EXPECTED TO PUSH
INLAND, GENERALLY REMAINING VFR. GUIDANCE SUGGESTS INCREASING
CHANCES (AROUND 50% NEAR KONP) FOR LIFR CONDITIONS DEVELOPING
ALONG THE CENTRAL OREGON COAST AFTER 02Z FRIDAY. THE BEST CHANCES
FOR MVFR STRATUS DEVELOPING INLAND FRIDAY MORNING (12-14Z) WILL BE
ALONG THE COLUMBIA RIVER (INCLUDING KTTD AND KPDX) AS WELL AS IN
THE SOUTHERN WILLAMETTE VALLEY (KEUG). SOUTH TO SOUTHWEST WINDS
TODAY ARE EXPECTED TO BECOME MORE WESTERLY LATER THIS AFTERNOON.
KPDX AND APPROACHES...PREDOMINATELY VFR CONDITIONS ARE EXPECTED
THROUGH THE PERIOD. A WEAK FRONT PUSHING INLAND BRINGS LOW CHANCES
FOR BROKEN MVFR CIGS THROUGH THIS AFTERNOON. THERE IS ALSO A
20-30% CHANCE FOR MVFR STRATUS DEVELOPING NEAR THE TERMINALS AFTER
12Z FRIDAY. RELATIVELY LIGHT SSW WINDS ARE EXPECTED TO VEER
WESTERLY THIS AFTERNOON, BECOMING NORTHWEST 6-8 KT BY 00Z FRIDAY.
/DH
MARINE
AS LOW PRESSURE NEAR VANCOUVER ISLAND WEAKENS, HIGH
PRESSURE CONTINUES TO BUILD IN ACROSS THE NE PACIFIC. LIGHT
SOUTHERLY WINDS VEER WESTERLY LATER THIS AFTERNOON, BECOMING
NORTH-NORTHWESTERLY BY EARLY FRIDAY. WINDS ARE EXPECTED TO REMAIN
AROUND 10-15 KT OR LESS. A WEAK FRONT DROPS INTO THE NORTHERN
COASTAL WATERS LATE FRIDAY INTO SATURDAY WITH LITTLE TO NO IMPACT
EXPECTED. NORTHERLIES PERSIST THROUGH THE WEEKEND WHILE
PREDOMINATELY WIND DRIVEN SEAS REMAIN AT AROUND 3 TO 5 FT. THE
PATTERN MAY BECOME A BIT MORE ACTIVE EARLY TO THE MIDDLE OF NEXT
WEEK AS THERE IS POTENTIAL FOR MULTIPLE FRONTAL SYSTEMS TO MOVE
INTO THE COASTAL WATERS.
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
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