801
FXUS66 KPQR 271041
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
340 AM 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 SATURDAY 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
WEDNESDAY, ASIDE FROM ISOLATED LIGHT SHOWERS MAINLY IN THE MOUNTAINS.
DISCUSSION...FRIDAY AFTERNOON THROUGH THURSDAY NIGHT
COOL AND
MOIST ONSHORE FLOW REMAINS IN PLACE TODAY, WITH RADAR OBSERVATIONS
FROM EARLY SATURDAY MORNING DEPICTING SCATTERED RAIN SHOWERS ACROSS
NORTHWEST OREGON AND SOUTHWEST WASHINGTON. A BAND OF HEAVY SHOWERS
MOVED ACROSS THE GREATER PORTLAND/VANCOUVER METRO AREA BETWEEN
1:00-3:15 AM PDT SATURDAY, WITH SOME LOCATIONS OBSERVING HEAVY
DOWNPOURS. IN FACT, HEAVY DOWNPOURS HIT THE NWS PORTLAND OFFICE
BETWEEN 2:00-2:45 AM PDT AND PRODUCED 0.33 INCHES OF RAIN WITHIN 45
MINUTES. SINCE RADAR OBSERVATIONS SHOWED EVEN HEAVIER CELLS NEARBY
THE OFFICE, SOME LOCATIONS INEVITABLY PICKED UP EVEN MORE THAN THAT.
GIVEN THE SHOWERY HIT-OR-MISS NATURE OF THIS PRECIPITATION, OBSERVED
RAIN AMOUNTS VARY SIGNIFICANTLY FROM LOCATION TO LOCATION WITH SOME
LOCATIONS PICKING UP ONLY A TRACE TO FEW HUNDREDTHS OF AN INCH THUS
FAR THIS MORNING.
THESE EARLY MORNING DOWNPOURS ARE A TASTE OF WHAT IS TO COME LATER
TODAY, PARTICULARLY THIS AFTERNOON ONCE DAYTIME HEATING BEGINS. THIS
IS WHEN MODELS AND THEIR ENSEMBLES CONTINUE TO SHOW THE CENTER OF A
CLOSED UPPER LEVEL LOW MOVING DIRECTLY OVERHEAD, WHICH WILL 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. PWAT VALUES ARE FORECAST TO REACH 0.7-0.8
INCHES WITH THE DEPTH OF THE WARM CLOUD LAYER REACHING AN IMPRESSIVE
3500 METERS. THIS MEANS ALL OF THE INGREDIENTS ARE IN PLACE TODAY FOR
WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS WITH HEAVY DOWNPOURS
EXPECTED WITH THE STRONGEST SHOWERS AND STORMS. NBM PROBABILITIES FOR
THUNDERSTORMS PEAK NEAR 20-30% FOR INLAND AREAS AND 15-20% AT THE
COAST THIS AFTERNOON. 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. IN
FACT, HEAVIER SHOWERS THAT MOVED DIRECTLY OVER THE PORTLAND
INTERNATIONAL AIRPORT AROUND 2:15 AM PDT SATURDAY LOWERED
VISIBILITIES DOWN TO 1.75 MILES, WHICH IS A GOOD PROXY TO WORK WITH.
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 30-40% FOR BOTH THE LOWLANDS AND THE MOUNTAINS ON
THURSDAY WITH TEMPERATURES REMAINING COOL. -23
AVIATION
COOL AND MOIST ONSHORE FLOW WILL PERSIST ACROSS THE
AIRSPACE THROUGH THE TAF PERIOD, BRINGING WIDESPREAD CLOUD COVER
AND PERIODIC RAIN SHOWERS FROM THE COAST TO THE CASCADES. SHOWERS
WILL BE MOST WIDESPREAD AND HEAVIEST BETWEEN 18Z SATURDAY AND 00Z
SUNDAY, WHICH IS ALSO WHEN THERE IS A 20-30% CHANCE OF
THUNDERSTORMS AT ANY GIVEN HOUR FOR INLAND TAF SITES.
PROBABILITIES ARE RELATIVELY LOWER AT THE COAST AT 15-20%.
STRONGER SHOWERS AND THUNDERSTORMS TODAY WILL BRING THE POTENTIAL
FOR HEAVY DOWNPOURS WITH SURFACE VISIBILITIES AS LOW AS 1 1/2 TO
2 SM FOR BRIEF PERIODS OF TIME. OUTFLOW WINDS ASSOCIATED WITH
CONVECTION ARE NOT EXPECTED TO BE PARTICULARLY STRONG, HOWEVER
ABRUPT SHIFTS IN THE WIND DIRECTION ARE LIKELY NEAR PASSING
SHOWERS AND STORMS.
EXPECT A MIXTURE OF MVFR TO VFR CEILINGS THROUGHOUT THE TAF PERIOD
BOTH INLAND AND AT THE COAST, WITH MVFR CEILINGS MAINLY OCCURRING
WITH PASSING SHOWERS OR THUNDERSTORMS.
KPDX AND APPROACHES...EXPECT MAINLY VFR CEILINGS THROUGHOUT THE
TAF PERIOD, ASIDE FROM OCCASIONAL DROPS TO MVFR CEILINGS WITH
PASSING SHOWERS OR THUNDERSTORMS. THUNDERSTORM PROBABILITIES PEAK
NEAR 30% BETWEEN 18Z SATURDAY AND 00Z SUNDAY. STRONGER SHOWERS AND
STORMS WILL BRING HEAVY DOWNPOURS WITH SURFACE VISIBILITIES
BRIEFLY FALLING AS LOW AS 1 1/2 TO 2 SM. OUTFLOW WINDS ARE NOT
EXPECTED TO BE STRONG WITH PASSING SHOWERS AND STORMS, HOWEVER
ABRUPT SHIFTS IN THE WIND DIRECTION ARE LIKELY. -23
MARINE
WINDS AND SEAS WILL INCREASE SATURDAY INTO 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 7-9 FT AT 9 SECONDS, HIGHEST
OVER THE OUTER WATERS BEYOND 10 NM OFFSHORE. GIVEN SEAS WILL
BECOME STEEPER AND WINDS WILL GUSTS UP TO 20-25 KT OVER THE OUTER
WATERS, A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE OUTER
WATERS FROM SATURDAY MORNING THROUGH SUNDAY NIGHT. ALTHOUGH WINDS
ARE A BIT WEAKER OVER THE INNER WATERS, SEAS WILL STILL BECOME
STEEP ENOUGH TO POSE A HAZARD FOR SMALL CRAFT SATURDAY AFTERNOON
INTO SUNDAY. THEREFORE, THE SMALL CRAFT ADVISORY HAS BEEN EXPANDED
TO INCLUDE THE INNER WATERS.
ALTHOUGH WEAK HIGH PRESSURE BUILDS OVER THE WATERS ON MONDAY,
NORTHWEST WINDS WILL PERSIST AND WILL MAINTAIN A FRESH NORTHWEST
SWELL WITH SIGNIFICANT WAVE HEIGHTS PEAKING NEAR AT LEAST 8-11 FT.
THERE IS A 20-40% 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. -23
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 11 PM PDT
SUNDAY FOR PZZ251>253.
SMALL CRAFT ADVISORY FROM 5 AM EARLY THIS MORNING TO 11 PM PDT
SUNDAY FOR PZZ271>273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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