695
FXUS66 KPQR 090952
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
252 AM PDT SAT AUG 9 2025
SYNOPSIS
IT'S GOING TO GET HOT! STRONG HIGH PRESSURE BUILDING
OVER THE EASTERN PACIFIC WILL USHER IN A SHARP WARMING TREND
WITH TEMPERATURES PEAKING SUNDAY AND MONDAY. EXTREME HEAT
WARNINGS AND HEAT ADVISORIES ARE IN EFFECT DURING THIS PERIOD.
CONDITIONS ARE FAVORED TO RETURN CLOSER TO NORMAL BY THE MIDDLE
OF NEXT WEEK.
SHORT TERM...NOW THROUGH MONDAY NIGHT
MOSTLY CLEAR SKIES
PREVAIL ACROSS NORTHWEST OREGON AND SOUTHWEST WASHINGTON EARLY
SATURDAY MORNING, WITH MARINE STRATUS CONFINED TO THE COASTAL
WATERS AND ONLY A FEW PATCHES OF HIGH CIRRUS DRIFTING OVER THE
AREA PER SATELLITE IMAGERY. THE WARMING TREND WILL CONTINUE
TODAY AS UPPER LEVEL HIGH PRESSURE CONTINUES TO GRADUALLY
AMPLIFY OFFSHORE BETWEEN 130W AND 140W. ALL IN ALL, SHOULD BE A
FAIRLY PLEASANT START TO THE WEEKEND AS HIGHS CLIMB INTO THE MID
TO UPPER 80S IN THE INTERIOR VALLEYS. THERE IS A 25-35% CHANCE
THAT HIGHS COULD REACH 90 DEGREES THIS AFTERNOON FROM SALEM TO
EUGENE, WITH THOSE CHANCES DWINDLING TO LESS THAN 5% IN THE
PORTLAND METRO AND SOUTHWEST WASHINGTON. COASTAL AREAS WILL
MAINTAIN A MARINE LAYER INFLUENCE, WITH HIGHS IN THE UPPER 60S
TO LOW 70S FOR THE MOST PART.
HEAT KICKS INTO HIGH GEAR SUNDAY AND MONDAY AS THE RIDGE
CONTINUES TO STRENGTHEN OFFSHORE AND 850 MB TEMPS SOAR INTO THE
21-23 C RANGE, WELL ABOVE THE 90TH PERCENTILE OF EARLY AUGUST
KSLE SOUNDING CLIMATOLOGY. THIS WILL CORRESPOND TO TEMPERATURES
SPIKING WELL INTO THE 90S IN THE INTERIOR VALLEYS, WITH CHANCES
FOR THE FIRST TRIPLE DIGIT READINGS OF THE SEASON RANGING FROM 15-25%
IN THE COWLITZ VALLEY TO 50% ACROSS THE PORTLAND/VANCOUVER
METRO TO ABOUT 90% IN THE CENTRAL/SOUTH WILLAMETTE VALLEY. THIS,
ALONG WITH OVERNIGHT LOWS RUNNING IN THE UPPER 60S TO PERHAPS 70
DEGREES IN SOME URBAN AREAS, WILL DRIVE NWS HEATRISK INTO THE
MAJOR CATEGORY ACROSS A WIDE SWATH OF THE AREA. MONDAY LOOKS TO
PLAY OUT SIMILAR TO SUNDAY IN TERMS OF HIGH TEMPERATURES, WITH
THE WILD CARD BEING A SHORTWAVE FEATURE EMBEDDED IN THE EASTERN
PERIPHERY OF THE RIDGE THAT COULD PROVIDE A MINOR BOOST IN
ONSHORE FLOW. THIS IS REFLECTED IN A SLIGHTLY LARGER RANGE OF
TEMPERATURE OUTCOMES IN THE NBM, ALTHOUGH MOST OF THE GUIDANCE
CONTINUES TO SUGGEST ANY SENSIBLE WEATHER IMPACTS ASSOCIATED
WITH THIS FEATURE WOULD BE MINIMAL. THAT SAID, A SLIGHTLY
STRONGER SHORTWAVE FEATURE COULD BE THE DIFFERENCE BETWEEN
HIGHS IN THE MID 90S VS THE LOW TRIPLE DIGITS FROM THE
PORTLAND/VANCOUVER METRO TO PARTS OF SOUTHWEST WASHINGTON,
PRODUCING A SMALL BUT NON TRIVIAL DIFFERENCE IN TERMS OF
HEATRISK IMPACTS IN SOME LOCATIONS ON MONDAY. IN TERMS OF
PROBABILITIES, THE CHANCE TO REACH 100 DEGREES INCREASES
SLIGHTLY IN MOST LOCATIONS MONDAY, RANGING FROM 40-60% IN THE
PORTLAND/VANCOUVER METRO TO OVER 90% IN THE CENTRAL/SOUTH
WILLAMETTE VALLEY. MEANWHILE, COASTAL LOCATIONS WILL ALSO SEE A
BIT OF A WARMUP FROM SUNDAY INTO MONDAY, WITH HIGH TEMPERATURES
COMMONLY IN THE 70S AND A 15-30% CHANCE TO REACH 80 DEGREES IN
THE COASTAL COMMUNITIES. NO CHANGES TO THE EXISTING HEAT
HEADLINES WITH THIS FORECAST PACKAGE. /CB
LONG TERM...TUESDAY THROUGH FRIDAY
TUESDAY REPRESENTS A
TRANSITION DAY OUT OF THIS COMING STRETCH OF HOT WEATHER AS THE
RIDGE BEGINS TO RETROGRADE WESTWARD INTO THE PACIFIC, OPENING
THE DOOR TO A WELCOME COOLING TREND ACROSS THE PACIFIC
NORTHWEST. THERE REMAINS SOME UNCERTAINTY IN THE DEGREE OF UPPER
LEVEL TROUGHING DEVELOPING ACROSS WESTERN CANADA IN THIS
TIMEFRAME, ALTHOUGH ABOUT 70% OF WPC ENSEMBLE CLUSTER MEMBERS
HAVE STARTED TO FAVOR A WEAKER SOLUTION. AS SUCH, TEMPERATURE
GUIDANCE IS LOWER THAN SUNDAY AND MONDAY BUT STILL RESIDES
MOSTLY IN THE 90S IN THE INTERIOR VALLEYS ON TUESDAY AFTERNOON,
WITH A LINGERING 20-30% CHANCE TO REACH 100 DEGREES FROM
PORTLAND TO SALEM AND CLOSER TO A 60% CHANCE IN EUGENE. THIS
WILL YIELD MODERATE HEATRISK FOR MOST INLAND LOCATIONS ON
TUESDAY, AIDED BY ANOTHER NIGHT OF WARM LOWS MONDAY NIGHT INTO
TUESDAY MORNING.
THE AREA SHOULD TRANSITION FULLY BACK INTO AN ONSHORE FLOW
REGIME BY WEDNESDAY, WITH A RELATIVELY HIGH DEGREE OF
CONFIDENCE IN TEMPS CLOSER TO OR EVEN SLIGHTLY BELOW SEASONAL
NORMS IN THE UPPER 70S TO LOW 80S FROM WEDNESDAY THROUGH THE
END OF THE WEEK. THERE IS NO PRECIPITATION IN THE FORECAST FOR
THE NEXT SEVEN DAYS, WITH THE EXCEPTION OF A SLIGHT CHANCE ALONG
THE SOUTH WASHINGTON COAST LATE IN THE WEEK AS ONSHORE FLOW
RETURNS. /CB
AVIATION
HIGH PRESSURE WILL MAINTAIN PREDOMINATELY VFR
CONDITIONS ACROSS THE REGION WITH HIGH CLOUDS. AN EXCEPTION WOULD
BE KAST WHERE MOISTENING CONDITIONS WILL LIKELY (>80% CHANCE)
RETURN IFR/MVFR MARINE STRATUS THIS MORNING. STRATUS ALONG THE
COAST IS EXPECTED TO BREAK OUT BY 17-18Z SAT AS DAYTIME HEATING
PROGRESSES, IMPROVING CONDITIONS TO VFR. THERE IS A 40-60% CHANCE
THAT MARINE STRATUS RETURNS ALONG THE ENTIRE COAST BY AROUND
00-03Z SUN, WITH THE HIGHEST CHANCES ALONG THE NORTH OREGON COAST.
EXPECT NORTHERLY TO NORTHWESTERLY WINDS ACROSS THE AREA TODAY,
STRONGEST IN THE AFTERNOON WITH GUSTS TO 20-25 KT.
PDX AND APPROACHES...VFR WITH HIGH CLOUDS. NORTHWESTERLY WINDS
UNDER 10 KT THROUGH 21-23Z SAT, THEN INCREASING TO 10-15 KT WITH
GUSTS UP TO 20 KT IN THE EVENING. -ALVIZ
MARINE
HIGH PRESSURE ACROSS THE WATERS WILL MAINTAIN NORTHERLY
WINDS ACROSS THE WATERS THROUGH AT LEAST WEDNESDAY NEXT WEEK.
PRESSURE GRADIENTS WILL TIGHTEN THIS WEEKEND AS HIGH PRESSURE
BUILDS OVER THE NE PACIFIC, LEADING TO INCREASED WINDS. THE WINDS
WILL BE STRONGEST IN THE AFTERNOON AND EVENINGS AND WILL BE
HAZARDOUS TO SMALL CRAFTS FROM THIS AFTERNOON THROUGH AT LEAST
MONDAY. THE WIND GUSTS WILL RELAX IN THE MORNINGS, ESPECIALLY
CLOSER TO SHORE. IN THE LATEST UPDATE, THE SMALL CRAFT ADVISORY
WAS EXTENDED INTO THE NORTHERN OUTER WATERS (NORTH OF CAPE FALCON
BEYOND 10 NM).
SEAS WILL BE MOSTLY WIND-DRIVEN AND AROUND 3-5 FT AT 10-11 SEC
TODAY. A FRESH NW SWELL BUILDS SEAS TO 6 TO 7 FT AT 10-11 SEC
SUNDAY, AND CLOSE TO 10 FT ON MONDAY. THERE IS A 60-80% CHANCE OF
WAVE HEIGHTS EXCEEDING 8 FT BY MONDAY, WITH THE HIGHEST CHANCES
OVER THE OUTER WATERS. -ALVIZ/TJ
FIRE WEATHER
ANOTHER FACTOR TO MONITOR ON SUNDAY WILL BE THE
POTENTIAL FOR ENHANCED FIRE WEATHER CONCERNS AS THE POSITION OF
THE THERMAL TROUGH ALONG THE WEST SLOPES OF THE CASCADES YIELDS
BREEZY NORTH WINDS IN THE WILLAMETTE VALLEY. DO NOT ANTICIPATE
WIDESPREAD CRITICAL FIRE WEATHER CONDITIONS BEING MET AT THIS
TIME, BUT THE COMBINATION OF MINIMUM RH VALUES IN THE 20S AND
NORTH WINDS GUSTING TO 15-20 MPH DOES RAISE THE POSSIBILITY THAT
CONDITIONS WILL FLIRT WITH RED FLAG CRITERIA IN THE CENTRAL AND
SOUTH WILLAMETTE VALLEY FOR A TIME ON SUNDAY AFTERNOON. LIGHTER
WINDS WILL HELP TO LIMIT FIRE WEATHER CONCERNS ON MONDAY. /CB
PQR WATCHES/WARNINGS/ADVISORIES
OR...HEAT ADVISORY FROM NOON SUNDAY TO 11 PM PDT MONDAY FOR ORZ104-
105-108.
EXTREME HEAT WARNING FROM NOON SUNDAY TO 5 AM PDT TUESDAY FOR
ORZ109>125.
WA...HEAT ADVISORY FROM NOON SUNDAY TO 11 PM PDT MONDAY FOR WAZ202-
204-208.
EXTREME HEAT WARNING FROM NOON SUNDAY TO 5 AM PDT TUESDAY FOR
WAZ205>207-209-210.
PZ...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 8 AM PDT MONDAY
FOR PZZ252-253-272-273.
SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 AM PDT SUNDAY
FOR PZZ271.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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