042
FXUS66 KPQR 201045
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
345 AM PDT SUN JUL 20 2025
SYNOPSIS
SEASONABLE TEMPERATURES CONTINUE THROUGH EARLY THIS WEEK, WITH A
SLIGHT CHANCE (10-20%) FOR SHOWERS FROM TONIGHT INTO MONDAY AS
A WEAK UPPER LOW MOVES ACROSS THE REGION. A WARMING TREND
RETURNS MIDWEEK, BRINGING ABOVE NORMAL TEMPERATURES BY
WEDNESDAY.
DISCUSSION...NOW THROUGH FRIDAY
A MODEST SHORTWAVE ALOFT
CONTINUES TO SLIDE ACROSS THE PACIFIC NORTHWEST THIS MORNING. AS
THIS DISTURBANCE DROPS SOUTHWARD OVER THE NEXT 24 HOURS,
ENSEMBLES SHOW A GRADUAL LOWERING OF 500 MB HEIGHTS ACROSS THE
REGION. THIS PATTERN WILL HELP REINFORCE THE MARINE LAYER,
POTENTIALLY LEADING TO GREATER INLAND CLOUD COVER THIS MORNING
COMPARED TO YESTERDAY. HOWEVER, HIGH RES ENSEMBLE GUIDANCE
SUGGESTS THAT MAY NOT MATERIALIZE FOR ALL AREAS.
THIS AFTERNOONS HIGH TEMPERATURES WILL REMAIN NEAR SEASONAL
AVERAGES, WITH INLAND VALLEYS REACHING THE MID TO UPPER 70S. AS
THE UPPER TROUGH TRANSITIONS INTO A CLOSED LOW SUNDAY NIGHT
INTO MONDAY, SOME MOISTURE AND WEAK LIFT WILL ACCOMPANY IT,
OPENING THE DOOR TO LIGHT SHOWER ACTIVITY, MAINLY ACROSS THE
CASCADES. WHILE SOME ENSEMBLE MEMBERS SUPPORT ISOLATED
PRECIPITATION, MOST KEEP CONDITIONS LARGELY DRY ELSEWHERE. THIS
ALIGNS WELL WITH NBM PROBABILITIES, WHICH MAINTAIN 10-20%
CHANCES FOR SHOWERS, HIGHEST OVER THE HIGHER TERRAIN AND
ESPECIALLY ACROSS THE LANE AND LINN COUNTY CASCADES. OVERALL,
MONDAY WILL BRING ANOTHER ROUND OF MILD TEMPERATURES AND
VARIABLE CLOUD COVER, WITH NO SIGNIFICANT IMPACTS EXPECTED
OUTSIDE OF LOCALIZED SPRINKLES IN ELEVATED TERRAIN.
THE PATTERN UNDERGOES A MORE NOTABLE SHIFT MIDWEEK, AS ENSEMBLE
SOLUTIONS INCREASINGLY FAVOR RISING HEIGHTS AND RIDGING ALOFT
BEGINNING TUESDAY. THIS TRANSLATES INTO A WARMING TREND, WITH
INLAND AREAS CLIMBING BACK INTO THE UPPER 80S TO LOW 90S BY
WEDNESDAY. ENSEMBLE PROBABILITIES SUGGEST MODERATE CONFIDENCE
IN THE WARM UP, WITH A 60-80% CHANCE OF THE WILLAMETTE VALLEY
REACHING AT LEAST 90 DEGREES OR HIGHER. THE MOST LIKELY RANGE
FOR THE WILLAMETTE VALLEY MIDWEEK APPEARS TO BE 88-93 DEGREES.
ONSHORE FLOW WILL PERSIST, KEEPING THE COAST MILD AND STABLE,
WITH HIGHS HOLDING NEAR AVERAGE VALUES.
TOWARD THE LATTER HALF OF THE WEEK, THERE IS GROWING ENSEMBLE
SUPPORT FOR A SECONDARY DISTURBANCE BREAKING OFF FROM THE
EARLIER TROUGH AND RETROGRADING OFF THE CALIFORNIA COAST. IF IT
LIFTS NORTHEAST LATER THURSDAY OR FRIDAY, THERE IS POTENTIAL FOR
ELEVATED INSTABILITY AND ISOLATED THUNDERSTORM DEVELOPMENT,
PARTICULARLY IN THE LANE LINN COUNTY CASCADES. CURRENT GUIDANCE
PLACES THE 48 HOUR THUNDERSTORM POTENTIAL IN THE 10-30% RANGE,
THOUGH EXACT TIMING AND TRACK REMAIN UNCERTAIN. NORTH AND WEST
OF THIS AREA, STORM PROBABILITIES DECREASE QUICKLY. GIVEN THE
CURRENT SPREAD IN TIMING, 12 HOUR THUNDERSTORM PROBABILITIES
REMAIN TOO LOW TO INCLUDE IN THE OFFICIAL FORECAST, THOUGH THIS
WILL BE MONITORED CLOSELY AS MODEL SPREAD NARROWS.
~HALL
AVIATION
SATELLITE IMAGERY AS OF EARLY SUNDAY MORNING DEPICTS
MARINE STRATUS ALONG THE NORTH OREGON COAST AS WELL AS HIGH LEVEL
CLOUDS AS AN UPPER LEVEL TROUGH MOVES OVER THE REGION. EXPECT
MVFR CIGS AT KAST TO CONTINUE THROUGH 18-20Z SUN; HOWEVER, THERE
IS LOW TO MODERATE CONFIDENCE (30-50% CHANCE) THAT MARINE STRATUS
MAKES IT TO KONP BETWEEN 12-18Z SUN. LOW STRATUS ALONG THE COAST
SHOULD SCATTER OUT AND RETURN VFR CONDITIONS BY EARLY AFTERNOON
AS DAYTIME HEATING PROGRESSES. VFR PREVAILS ACROSS THE WILLAMETTE
VALLEY WITH SCT-BKN HIGH CLOUDS. EXPECT NORTHERLY TO NORTHWESTERLY
WINDS UNDER 10 KT ACROSS THE AREA.
PDX AND APPROACHES...PREDOMINATELY VFR THROUGH THE TAF PERIOD WITH
HIGH CLOUDS. 10% CHANCE FOR MVFR STRATUS BETWEEN 13-16Z SUN.
EXPECT NORTHWESTERLY WINDS AROUND 5-7 KT. -ALVIZ
MARINE
BENIGN WEATHER EXPECTED ACROSS THE WATERS THIS WEEKEND
INTO EARLY NEXT WEEK. HIGH PRESSURE WILL MAINTAIN NORTHERLY TO
NORTHWESTERLY WINDS, GENERALLY LESS THAN 10 KTS. EXPECT WAVE
HEIGHTS OF 2-4 FEET. THESE WIND AND WAVE CONDITIONS ARE FORECAST
TO CONTINUE THROUGH AT LEAST MID-WEEK. -ALVIZ/HEC
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
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