217
FXUS66 KPQR 241956
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1256 PM PDT WED JUN 24 2026
SYNOPSIS
TODAY WILL BE THE LAST DAY OF ABNORMALLY WARM
TEMPERATURES. CONDITIONS REMAIN DRY WHILE ONSHORE FLOW
INCREASES. A SIGNIFICANT WEATHER PATTERN CHANGE IS ON TRACK
BEGINNING THURSDAY AS A FRONTAL SYSTEM SWINGS THROUGH, BRINGING
COOLER TEMPERATURES AND WIDESPREAD CHANCES FOR RAIN BEGINNING
THURSDAY NIGHT AND THROUGH SATURDAY. THERE IS ALSO A 10-25%
CHANCE FOR THUNDERSTORMS FRIDAY AFTERNOON AND SATURDAY
AFTERNOON. CONDITIONS TREND DRIER AND SLIGHTLY WARMER SUNDAY
THROUGH EARLY NEXT WEEK, BUT WE'LL MAINTAIN SLIGHT CHANCES FOR
LIGHT RAIN SHOWERS ACROSS THE COAST RANGE AND CASCADES.
DISCUSSION...WEDNESDAY AFTERNOON THROUGH TUESDAY
THERE HAS
BEEN VERY LITTLE CHANGE IN THE LATEST FORECAST PACKAGE.
SATELLITE IMAGERY EARLY WEDNESDAY AFTERNOON SHOWS MARINE STRATUS
HAS MOSTLY DISSIPATED ALONG THE COAST, JUST CLINGING ON RIGHT
ALONG SOME BEACHES. OTHERWISE MOSTLY CLEAR SKIES WITH SCATTERED
HIGH CLOUDS ARE BEING OBSERVED ACROSS THE REST OF NW OR AND SW
WA, EXCEPT FOR CUMULUS BUILDING ALONG THE CASCADE CREST. THE
CUMULUS IS DUE TO A WEAK UPPER-LEVEL TROUGH PASSING OVER THE
PACNW TODAY. THIS TROUGH NOT EXPECTED TO BRING ANY SHOWER
ACTIVITY WEST OF THE CASCADE CREST-LINE GIVEN THE LINGERING DRY
AIRMASS OVER OUR AREA.
THE UPPER-LEVEL RIDGE THAT BROUGHT THE HEAT THE LAST COUPLE
DAYS HAS SHIFTED EAST OF OR AND WA AS THE AFOREMENTIONED TROUGH
HAS MOVED INLAND. HOWEVER, THE WARM AND DRY AIRMASS IS
LINGERING THROUGH TODAY, ALLOWING ONE LAST DAY OF VERY WARM AND
DRY CONDITIONS, THOUGH AFTERNOON HIGH TEMPERATURES WILL BE A
FEW DEGREES COOLER THAN THE LAST COUPLE DAYS (IN THE UPPER 80S
TO LOW 90S ACROSS INTERIOR VALLEYS) AS THE TROUGH IS PRODUCING
INCREASED ONSHORE FLOW. THERE REMAINS WIDESPREAD MODERATE
HEATRISK ACROSS THE WILLAMETTE VALLEY, SW WASHINGTON LOWLANDS,
AND COLUMBIA RIVER GORGE. THIS LEVEL OF HEAT WILL AFFECT THOSE
WHO ARE SENSITIVE TO HEAT, ESPECIALLY THOSE WITHOUT ADEQUATE
COOLING OR HYDRATION. MAKE SURE TO STAY HYDRATED, WEAR LIGHT-
COLORED AND LOOSE-FITTED CLOTHING, WEAR SUN PROTECTION, TAKING
FREQUENT BREAKS FROM THE HEAT, AND LIMIT STRENUOUS OUTDOOR
ACTIVITIES DURING THE HOTTEST PART OF THE DAY.
A LARGE-SCALE PATTERN CHANGE TO COOLER AND WETTER CONDITIONS
REMAINS ON TRACK FOR THURSDAY THROUGH THE WEEKEND AS ENSEMBLE
AND DETERMINISTIC GUIDANCE IS IN EXCELLENT AGREEMENT OF AN
UPPER-LEVEL LOW PRESSURE SYSTEM PROGRESSING INTO THE PACIFIC
NORTHWEST FROM THE GULF OF ALASKA. TEMPERATURES WILL COOL TO
NEAR NORMAL WITH MID 70S ACROSS THE INTERIOR LOWLANDS. MOST
ENSEMBLE MEMBERS HAVE RAINFALL VIA A COLD- FRONTAL BOUNDARY
REACHING THE COAST BY LATE THURSDAY AFTERNOON/EVENING AND THEN
SPREADING INTO THE I-5 CORRIDOR BY LATE THURSDAY NIGHT INTO
FRIDAY MORNING. WE'LL REMAIN IN THIS COOLER AND WET PATTERN
THROUGH AT LEAST SATURDAY, BUT AT LEAST TOTAL RAIN AMOUNTS AT
THIS TIME APPEAR BENEFICIAL AND GENERALLY NON-IMPACTFUL. LOOKING
AT THE LATEST NBM, CHANCES FOR 48-HOUR RAIN AMOUNTS EXCEEDING 1
INCH FROM 5 PM THURSDAY TO 5 PM SATURDAY ARE AROUND 40-70% FOR
THE COAST AND COAST RANGE, 10-30% ALONG AND EAST OF THE I-5
CORRIDOR, AND GREATER THAN 80% ACROSS THE CASCADES DUE TO
WESTERLY FLOW BRINGING OROGRAPHIC ENHANCEMENT. WILL NOTE THAT
THE WESTERN-MOST PARTS OF THE WILLAMETTE VALLEY (WEST OF I-5
INCLUDING MCMINNVILLE AND CORVALLIS) ONLY HAVE A 5-10% CHANCE OF
EXCEEDING 1 INCH DURING THIS TIMEFRAME DUE TO POTENTIAL
RAINSHADOWING FROM THE COAST RANGE.
BY FRIDAY AFTERNOON, THE UPPER-LEVEL TROUGH MOVES FURTHER SOUTH
AND EVENTUALLY CENTERS ITSELF RIGHT OVER-TOP THE PACIFIC
NORTHWEST AS A CLOSED LOW ON SATURDAY. TEMPERATURES WILL FURTHER
COOL ALOFT ALLOWING FOR INCREASING ATMOSPHERIC INSTABILITY
DURING THE DAYTIME HOURS AND FACILITATING CAPE VALUES OF 50-100
J/KG FRIDAY AFTERNOON AND 100-200 J/KG LATE SATURDAY MORNING
INTO THE AFTERNOON. THIS INSTABILITY PLUS SUFFICIENT LIFT FROM
THE LOW WILL SUPPORT A 10-20% CHANCE FOR STRONG SHOWERS AND
THUNDERSTORMS ACROSS NW OREGON AND SW WASHINGTON FRIDAY
AFTERNOON, AND A 15-25% CHANCE FOR THUNDERSTORMS SATURDAY
AFTERNOON. FOR NOW, ANY CONVECTION APPEARS RATHER WEAK AND
UNORGANIZED (OUR TYPICAL POST-FRONTAL POP-UP STORMS). LREF
GUIDANCE SUGGESTS EFFECTIVE SHEAR REMAINS BELOW 35 KT;
THEREFORE, CHANCES THESE THUNDERSTORMS BECOME SEVERE ARE
UNLIKELY (<5%). OTHERWISE, ANY STRONG SHOWER OR PASSING
THUNDERSTORMS MAY PRODUCE BRIEF HEAVY RAIN, GUSTY AND ERRATIC
WINDS, AND A FEW LIGHTNING STRIKES. ALSO CAN'T RULE OUT A COLD
AIR FUNNEL CLOUD OR TWO GIVEN THE TIME OF YEAR, ESPECIALLY ON
SATURDAY.
THE LATTER HALF OF THE WEEKEND INTO EARLY NEXT WEEK, THE
MAJORITY OF ENSEMBLE MEMBERS ARE SHOWING THE BROADER UPPER-
LEVEL LOW FEATURE SHIFTING EASTWARD AND LINGERING ALONG THE
INTERIOR MOUNTAIN WEST, RETURNING RELATIVELY DRIER CONDITIONS
AND A WARM-UP OF A FEW DEGREES TO OUR AREA. THIS WILL PUT HIGH
TEMPERATURES JUST BELOW THE SEASONAL NORMALS WITH LOW 70S FOR
THE INTERIOR LOWLANDS AND UPPER 50S TO LOW 60S FOR THE COAST).
WILL STILL MAINTAIN PRECIPITATION CHANCES ACROSS THE COAST RANGE
AND CASCADES AS WESTERLY FLOW CONTINUES TO SUPPORT OROGRAPHIC
ENHANCEMENT OF PRECIPITATION, THOUGH ANY ADDITIONAL RAIN AMOUNTS
APPEAR VERY LIGHT. STILL, WE'LL HAVE TO KEEP AN EYE ON SUBTLE
SHORTWAVE FEATURES ROTATING INTO THE REGION NORTH TO SOUTH ON
THE BACK SIDE OF THE UPPER- LEVEL LOW WHICH MAY EXPAND THE
COVERAGE OF SHOWERS TEMPORARILY - LOW CONFIDENCE ON THE
PLACEMENT/TIMING OF THESE SMALLER SHORTWAVE FEATURES. WESTERLY
WINDS THROUGHOUT THE WEEK WILL BE BREEZIEST ALONG THE CENTRAL
COLUMBIA RIVER GORGE AND ACROSS UPPER HOOD RIVER VALLEY, WITH
CHANCES FOR ISOLATED WIND GUSTS EXCEEDING 45 MPH AROUND 10-35%
FROM FRIDAY THROUGH EARLY NEXT WEEK, WITH THE HIGHEST CHANCES ON
SUNDAY AND MONDAY. -03/10/99
AVIATION
SCATTERED HIGH CLOUDS AS RELATIVELY DRY UPPER LEVEL
TROUGH MOVES ACROSS THE REGION. PREDOMINATELY VFR CONDITIONS
CONTINUE EXCEPT AT THE COAST WHERE SHALLOW MARINE STRATUS PERSISTS
WITH IFR TO LIFR CIGS NEAR KONP. STRATUS HAS SCATTERED OUT AT KAST
AS OF 19Z. LOWER CHANCES FOR CONDITIONS IMPROVING TO VFR ALONG
THE CENTRAL OREGON COAST, BASED ON A PERSISTENT PATTERN THE PAST
FEW DAYS, ALTHOUGH GUIDANCE DOES SHOW AROUND AN 80% CHANCE FOR VFR
AT KONP BETWEEN 20-00Z THIS AFTERNOON. THERE IS HIGH CONFIDENCE
THAT MARINE STRATUS FILLS BACK IN ALONG THE ENTIRE COAST THIS
EVENING AFTER 01-03Z THU. DIURNALLY DRIVEN NW WINDS CONTINUE WITH
GUSTS UP TO 20 KT EXPECTED LATER THIS AFTERNOON.
KPDX AND APPROACHES...VFR EXPECTED WITH SCATTERED HIGH CLOUDS
THROUGH THE TAF PERIOD. NORTHWEST WINDS EXPECTED TO INCREASE TO
AROUND 8-12 KT WITH GUSTS UP TO 20 KT BY 23Z THIS AFTERNOON. /DH
MARINE
HIGH PRESSURE WILL MAINTAIN NORTHWEST WINDS ACROSS THE
COASTAL WATERS THROUGH TONIGHT. WINDS ARE GENERALLY EXPECTED TO
REMAIN UNDER 20 KT. WEAKENING HIGH PRESSURE WILL GIVE WAY TO A
FRONTAL SYSTEM APPROACHING THE AREA ON THURSDAY. WINDS ARE
EXPECTED TO BACK WEST TO SOUTHWESTERLY THURSDAY AFTERNOON BEFORE
THE COLD FRONT PUSHES ACROSS THE COASTAL WATERS THURSDAY NIGHT
INTO FRIDAY. SOUTHWEST WINDS ARE EXPECTED TO BE STRONGEST ACROSS
THE INNER COASTAL WATERS NORTH OF CAPE FOULWEATHER, BUT THERE IS
ONLY AROUND A 20-30% CHANCE OF WIND GUSTS EXCEEDING 21 KT AT ANY
GIVEN HOUR THROUGH FRIDAY MORNING. WEST TO NORTHWEST WINDS WILL
PERSIST BEHIND THE FRONT LATER FRIDAY AND INTO THE WEEKEND AS WEAK
LOW PRESSURE LINGERS NEAR VANCOUVER ISLAND. HIGH PRESSURE
GRADUALLY BUILDS ACROSS THE WATERS LATE WEEKEND. SEAS AROUND 3 TO
5 FT THROUGH FRIDAY BUILD TO AROUND 6 TO 9 FT THIS WEEKEND AS A
WEST-NORTHWESTERLY SWELL MOVES THROUGH THE WATERS. /DH
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
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