005
FXUS66 KPQR 271940
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1240 PM PDT SAT JUN 27 2026
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
COOL AND MOIST ONSHORE FLOW WILL CONTINUE TO BRING
WIDESPREAD CLOUD COVER AND PERIODIC RAIN SHOWERS ACROSS THE
AIRSPACE THROUGH AT LEAST 18Z SUN. SHOWERS WILL BE MOST
WIDESPREAD AND HEAVY UNTIL 00Z SUN. FROM NOW UNTIL 21Z SAT, THERE
IS A 25-45% CHANCE OF THUNDERSTORMS AT ANY GIVEN HOUR THEN HIGHER
CONFIDENCE FOR PREVAILING THUNDERSTORMS FROM 21Z SAT TO 00Z SUN
FOR INLAND TAF SITES. PROBABILITIES ARE A BIT LOWER AT THE COAST
AT 15-30%. CHANCES FOR THUNDERSTORMS THEN LOWER TO 15-20% FOR ALL
TERMINALS BETWEEN 00-03Z SUN. STRONGER SHOWERS AND THUNDERSTORMS
TODAY WILL BRING THE POTENTIAL FOR HEAVY DOWNPOURS WITH SURFACE
VISIBILITIES AS LOW AS 2 SM FOR BRIEF PERIODS OF TIME. WITH
CONVECTION TODAY, OUTFLOW WINDS ARE NOT EXPECTED TO BE
PARTICULARLY STRONG BUT MAY CAUSE ABRUPT SHIFTS IN WIND DIRECTION
AS SHOWERS AND/OR STORMS PASS BY.
EXPECT A MIXTURE OF MVFR/VFR CIGS AT ALL TERMINALS THROUGHOUT THE
TAF PERIOD, WITH MVFR CIGS MAINLY OCCURRING WITH PASSING SHOWERS
OR THUNDERSTORMS. AFTER 06-12Z SUN, GUIDANCE SUGGESTS THE
POSSIBILITY (20-40% CHANCE INLAND, 60-80% CHANCE AT THE COAST) OF
PREVAILING MVFR CIGS THROUGH AT LEAST 18Z SUN.
KPDX AND APPROACHES...MAINLY VFR CIGS THROUGH AT LEAST 18Z SUN.
OCCASIONAL DROPS TO MVFR CIGS POSSIBLE WITH PASSING SHOWERS OR
THUNDERSTORMS. THUNDERSTORM PROBABILITIES PEAK NEAR 45% BETWEEN
18Z SATURDAY AND 00Z SUNDAY, WITH THE HIGHEST CONFIDENCE FOR
PREVAILING THUNDERSTORMS BETWEEN 21Z SAT AND 00Z SUN. CHANCES FOR
THUNDERSTORMS LOWER TO 15-20% BETWEEN 00-03Z SUN, THEN LESS THAN
15% THEREAFTER. STRONGER SHOWERS AND STORMS WILL BRING HEAVY
DOWNPOURS WITH SURFACE VISIBILITIES BRIEFLY FALLING AS LOW AS 2
SM. OUTFLOW WINDS ARE NOT EXPECTED TO BE STRONG WITH PASSING
SHOWERS AND STORMS, HOWEVER ABRUPT SHIFTS IN THE WIND DIRECTION
ARE LIKELY. ~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.
SMALL CRAFT ADVISORY UNTIL 11 PM PDT SUNDAY FOR PZZ252-253.
SMALL CRAFT ADVISORY UNTIL 5 PM PDT MONDAY FOR PZZ271>273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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