942
FXUS66 KPQR 280530 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
1029 PM PDT SAT JUN 27 2026
UPDATED AVIATION DISCUSSION.
SYNOPSIS
THE NEXT SEVEN DAYS ARE HIGHLIGHTED BY BELOW
AVERAGE TEMPERATURES FOR THIS TIME OF YEAR AND A GOOD DEAL OF
CLOUD COVER. THE HEAVIEST RAIN IS EXPECTED THIS AFTERNOON WHEN
WIDESPREAD RAIN SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED
FROM THE COAST TO THE CASCADES. THE STRONGEST SHOWERS AND STORMS
WILL PRODUCE HEAVY DOWNPOURS. MAINLY DRY AND COOL SUNDAY
THROUGH FRIDAY, ASIDE FROM ISOLATED LIGHT SHOWERS MAINLY IN THE
MOUNTAINS.
DISCUSSION...SATURDAY AFTERNOON THROUGH FRIDAY NIGHT
RADAR
IMAGERY EARLY SATURDAY AFTERNOON SHOWS SHOWERS WIDESPREAD
SHOWERS HAVE FORMED ACROSS NW OR AND SW WA AS A CLOSED LOW
PUSHES SOUTH INTO THE REGION. PWAT VALUES ON SPC'S MESOSCALE
ANALYSIS PAGE ARE REACHING 0.7-0.8 INCHES, AND MODEL SOUNDINGS
STILL INDICATE THE DEPTH OF THE WARM CLOUD LAYER IS AROUND 3500
METERS. THIS MEANS SHOWERS THIS MORNING AND EARLY AFTERNOON,
EVEN ONES THAT SEEM SMALL AND BENIGN ON RADAR, ARE PRODUCING
VERY DECENT RAIN RATES. SOME SHOWERS ARE BECOMING STRONGER AS
THEY ENCOUNTER THE WESTERN SLOPES OF THE CASCADES AND COAST
RANGE DUE TO OROGRAPHIC LIFTING, AND THESE COULD PRODUCE VERY
HEAVY RAIN.
THE CLOSED UPPER LEVEL LOW WILL CONTINUE MOVING DIRECTLY
OVERHEAD THROUGH THE DAY, WHICH WILL CONTINUE TO BRING
INCREASING MOISTURE, LIFT, AND INSTABILITY. REFS ENSEMBLE MEAN
SOUNDINGS CONTINUE TO SUGGEST SURFACE-BASED CAPE VALUES WILL
INCREASE TOWARDS 250-400 J/KG FOR INLAND AREAS THIS AFTERNOON,
WHILE THE NBM MEAN SUGGESTS THE SAME. THIS MEANS ALL OF THE
INGREDIENTS ARE IN PLACE TODAY FOR ISOLATED THUNDERSTORMS ALONG
WITH THE WIDESPREAD SHOWERS. NBM PROBABILITIES FOR
THUNDERSTORMS PEAK NEAR 20-40% THIS AFTERNOON. THE MAIN IMPACT
WITH THE STRONGEST SHOWERS AND THUNDERSTORMS ARE HEAVY
DOWNPOURS. BECAUSE THE WARM CLOUD LAYER IS SO HIGH, IT WILL BE
VERY DIFFICULT FOR HAIL TO FORM. GIVEN WEAK CLOUD- LAYER
WINDS/SLOW STORM MOTION, HEAVY DOWNPOURS WILL HAVE THE POTENTIAL
TO LAST LONG ENOUGH OVER ANY GIVEN LOCATION TO PRODUCE UPWARDS
OF 0.25-0.50 INCHES OF RAIN IN ONE HOUR OR LESS. RAIN RATES OF
THIS MAGNITUDE ARE HIGH ENOUGH TO RESULT IN PONDING OF WATER IN
URBAN AREAS AND INCREASE THE RISK OF SHORT- LIVED MINOR FLOODING
IN AREAS WITH POOR DRAINAGE. HEAVY DOWNPOURS WILL ALSO POSE A
SAFETY HAZARD FOR MOTORISTS DUE TO AN INCREASED RISK OF
HYDROPLANING, AS WELL AS REDUCED VISIBILITIES. IT IS ALSO WORTH
MENTIONING THAT ISOLATED NON-MESOCYCLONIC COLD AIR FUNNEL CLOUDS ARE
OCCASIONALLY OBSERVED IN THIS TYPE OF WEATHER PATTERN, HOWEVER THE
ROTATION WITH THESE TYPICALLY FAILS TO LOWER TO THE GROUND AND THUS
DAMAGE DOES NOT OCCUR. IF ROTATION WITH ONE OF THESE WERE TO LOWER
TO THE GROUND, IT WOULD BE CONSIDERED A WEAK LANDSPOUT, AND DAMAGE
TENDS TO BE EXTREMELY ISOLATED IF ANY OCCURS AT ALL.
RAIN AMOUNTS TREND MUCH LIGHTER ON SUNDAY AS THE UPPER LEVEL LOW
SHIFTS EASTWARD INTO IDAHO AND SHOWERS BECOME LIGHTER AND MORE
ISOLATED. MOST OF THE SHOWERY ACTIVITY ON SUNDAY WILL BE CONFINED TO
THE CASCADES, CASCADE FOOTHILLS, AND COAST RANGE. SUNDAY
WILL ALSO BE ANOTHER COOL DAY WITH A GOOD DEAL OF CLOUD COVER
AND HIGHS IN THE 60S ACROSS THE LOWLANDS. GENERAL LONGWAVE
TROUGHING OVER THE WESTERN US CONTINUES MONDAY THROUGH
WEDNESDAY, KEEPING TEMPERATURES COOLER THAN AVERAGE. HOWEVER,
CONDITIONS ARE TRENDING MAINLY DRY MONDAY THROUGH WEDNESDAY, ASIDE
FROM ISOLATED LIGHT SHOWERS IN THE MOUNTAINS FROM TIME TO TIME. RAIN
CHANCES INCREASE TO 20-40% FOR BOTH THE LOWLANDS AND THE
MOUNTAINS FOR THURSDAY INTO FRIDAY WITH TEMPERATURES REMAINING
COOLER. -23/03
AVIATION
AS OF 04Z SUN, MOST OF THE RAIN SHOWERS HAVE SHIFTED
EAST OF THE INLAND TERMINALS. COOL AND MOIST ONSHORE FLOW WILL
CONTINUE TO SUPPORT CLOUD COVER AND PERIODIC RAIN SHOWERS THROUGH
MOST OF THE TAF PERIOD. RAIN SHOWERS WILL LIKELY TAPER OFF
COMPLETELY BY 00-06Z MON. EXPECT COASTAL TERMINALS TO MAINTAIN
MVFR CIGS THROUGH THE TAF PERIOD, WITH THE EXCEPTION OF BRIEF VFR
CIGS BEFORE 12Z SUN AND AFTER 00Z MON FOR KONP. INLAND TERMINALS
WILL SEE MAINLY VFR CONDITIONS THROUGH THE TAF PERIOD, HOWEVER
THERE IS A 30-60% OF MVFR CIGS FROM NOW UNTIL 19Z SUN. WHILE MOST
INLAND TERMINALS ARE VFR AS OF 04Z SUN, EXPECT A TREND TOWARDS
WIDESPREAD MVFR BY 12Z SUN. WESTERLY TO NORTHWESTERLY WINDS WILL
CONTINUE THROUGH AT LEAST 06Z MONDAY, GENERALLY RANGING FROM 5-10
KT AT INLAND TERMINALS AND 8-12 KT AT COAST TERMINALS. EXPECT THE
STRONGEST WINDS DURING THE AFTERNOON, WITH GUSTS UP TO 18 KT
POSSIBLE AT COASTAL TERMINALS AND A FEW INLAND TERMINALS.
KPDX AND APPROACHES...EXPECT VFR CONDITIONS THROUGH MOST OF THE
TAF PERIOD, WITH A 30-60% CHANCE OF MVFR CIGS FROM NOW UNTIL 19Z
SUN. GUIDANCE CURRENTLY SUGGESTS MVFR CIGS BETWEEN 12-18Z SUN.
WESTERLY WINDS WILL SHIFT MORE NORTHWESTERLY AROUND 00Z MON,
GENERALLY STAYING BETWEEN 5-10 KT THROUGH THE PERIOD. GUSTS UP TO
18 KT POSSIBLE DURING THE AFTERNOON. ~12
MARINE
WINDS AND SEAS INCREASE TODAY THROUGH SUNDAY AS A PAIR
OF FRONTS MOVE SOUTHWARD OVER THE COASTAL WATERS AND PERSISTENT
NORTHWESTERLY WINDS ALLOW FOR THE DEVELOPMENT OF A FRESH NORTHWEST
SWELL UPWARDS OF 7 TO 9 FT AT 9 SECONDS, HIGHEST OVER THE OUTER
WATERS BEYOND 10 NM OFFSHORE. MONDAY, WEAK HIGH PRESSURE BUILDS
OVER THE WATERS, HOWEVER NORTHWEST WINDS WILL CONTINUE TO BUILD
THE NORTHWEST SWELL INTO WAVE HEIGHTS AROUND 8 TO 11 FT. THERE IS
A 20 TO 40 PERCENT CHANCE SIGNIFICANT WAVE HEIGHTS WILL PEAK OVER
11 FT BEYOND 30 NM OFFSHORE ON MONDAY, MAINLY TO THE NORTH OF CAPE
FALCON. NORTHWEST WINDS AND A FRESH NORTHWEST SWELL THEN CONTINUES
TUESDAY THROUGH WEDNESDAY, MAINTAINING STEEP SEAS AND HAZARDOUS
CONDITIONS FOR SMALL CRAFT.
GIVEN STEEP SEAS AND WIND GUSTS UP TO 20 TO 25 KT OVER THE OUTER
WATERS, A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE OUTER
WATERS THROUGH MONDAY EVENING. ADDITIONALLY, A SMALL CRAFT
ADVISORY OVER THE INNER WATERS REMAINS IN EFFECT UNTIL LATE SUNDAY
FOR STEEP SEAS. ~12/23
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 PM PDT MONDAY FOR PZZ251-271>273.
SMALL CRAFT ADVISORY UNTIL 11 PM PDT SUNDAY FOR PZZ252-253.
WWW.WEATHER.GOV/PORTLAND
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