992
FXUS66 KPQR 172148
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
248 PM PDT FRI APR 17 2026
SYNOPSIS
A WARMING TREND CONTINUES INTO SATURDAY WITH MILD
SPRING CONDITIONS EXPECTED. ATTENTION THEN TURNS TO EARLY NEXT
WEEK, WHERE MODERATE TO HIGH CONFIDENCE EXISTS IN A DEVELOPING
UPPER- LEVEL-LOW OFFSHORE INFLUENCING TEMPERATURES AND
PRECIPITATION CHANCES. A WEAK FRONTAL SYSTEM MAY BRING A FEW
LIGHT SHOWERS LATE SATURDAY, THOUGH IMPACTS APPEAR MINIMAL.
SHORT TERM...NOW THROUGH SUNDAY NIGHT
A WARMING TREND IS
UNDERWAY THIS AFTERNOON, WITH TEMPERATURES RISING INTO THE UPPER
50S TO LOW 60S INLAND AND MID TO UPPER 50S ALONG THE COAST
UNDER PARTLY TO MOSTLY CLEAR SKIES. A WEAK THERMAL TROUGH
REMAINS IN PLACE THROUGH SATURDAY, SUPPORTING LIGHT OFFSHORE
FLOW ALONG THE EAST SLOPES OF THE COAST RANGE AND CASCADES AND
GENERALLY LIGHT NORTHERLY FLOW THROUGH THE WILLAMETTE VALLEY.
THIS PATTERN WILL MAINTAIN MOSTLY DRY CONDITIONS ASIDE FROM THE
LIMITED LATE-DAY SHOWER POTENTIAL.
CONDITIONS TONIGHT WILL BE MORE MARGINAL FOR WIDESPREAD FROST
DEVELOPMENT COMPARED TO RECENT MORNINGS, THOUGH LOCALIZED
IMPACTS REMAIN POSSIBLE IN FAVORED VALLEY LOCATIONS. A FROST
ADVISORY HAS BEEN ISSUED FOR THE SOUTHERN WILLAMETTE VALLEY AND
UPPER HOOD RIVER VALLEY FOR TONIGHT INTO SATURDAY MORNING. WHILE
OVERALL CONDITIONS ARE MARGINAL, VARIABILITY IN CLOUD COVER
WILL PLAY A KEY ROLE IN OVERNIGHT COOLING, WITH MORE PERSISTENT
BREAKS POTENTIALLY ALLOWING FOR LOCALIZED FROST DEVELOPMENT IN
SHELTERED AREAS. WHILE MOST INLAND LOCATIONS ARE EXPECTED TO
FALL INTO THE UPPER 30S TO LOW 40S, THE SOUTHERN WILLAMETTE
VALLEY AND UPPER HOOD RIVER VALLEY MAY DROP INTO THE MID 30S.
PROBABILITIES FOR TEMPERATURES DROPPING BELOW 37 DEGREES REMAIN
AROUND 40-50% IN THE SOUTHERN WILLAMETTE VALLEY, 50-70% IN THE
UPPER HOOD RIVER VALLEY ABOVE 1500 FT, AND 10-30% ELSEWHERE
INLAND.
ON SATURDAY, WEAK RIDGING SUPPORTS CONTINUED MILD CONDITIONS,
WITH INLAND HIGHS REACHING THE LOW 70S AND COASTAL AREAS
REMAINING IN THE UPPER 50S TO LOW 60S. A WEAK FRONTAL BOUNDARY
APPROACHING FROM THE NORTHWEST MAY BRING INCREASING CLOUD COVER
AND A SLIGHT CHANCE OF LIGHT SHOWERS LATE IN THE DAY, THOUGH
RECENT TRENDS CONTINUE TO WEAKEN THIS SYSTEM WITH MINIMAL
EXPECTED IMPACTS.
AN UPPER-LEVEL LOW DEVELOPS OFFSHORE ON SUNDAY, INTRODUCING
INCREASING UNCERTAINTY. CURRENT GUIDANCE FAVORS THE SYSTEM
REMAINING OFFSHORE, THOUGH THIS WILL SUPPORT INCREASED CLOUD
COVER ACROSS THE REGION AND LIMITED PRECIPITATION CHANCES
PRIMARILY ALONG THE COAST. MOST INLAND AREAS REMAIN DRY, THOUGH
SKIES MAY TREND MOSTLY CLOUDY AT TIMES. DESPITE THIS,
TEMPERATURES REMAIN UNSEASONABLY WARM, WITH HIGHS IN THE LOW TO
MID 70S EXPECTED AS A RESULT OF SOUTHERLY FLOW.
LONG TERM...MONDAY THROUGH THURSDAY
THE PRIMARY FORECAST
CONCERN EARLY NEXT WEEK CENTERS ON THE EVOLUTION OF A
DEVELOPING UPPER-LEVEL LOW OFFSHORE, WHICH WILL INTRODUCE
INCREASING UNCERTAINTY IN TEMPERATURE TRENDS AND PRECIPITATION
CHANCES.
ON MONDAY, A RANGE OF OUTCOMES REMAINS POSSIBLE DEPENDING ON
THE POSITION OF THIS LOW. A FARTHER OFFSHORE TRACK WOULD SUPPORT
RELATIVELY MILD AND DRIER CONDITIONS, WHILE A CLOSER OR MORE
NORTHERLY SOLUTION WOULD FAVOR INCREASED CLOUD COVER AND A
HIGHER LIKELIHOOD OF SHOWERS. AT THIS TIME, LOW-END PRECIPITATION
CHANCES INCREASE AND BECOME MORE WIDESPREAD BY LATE IN THE DAY,
WITH TEMPERATURES GENERALLY ABOVE SEASONAL AVERAGES.
TUESDAY, ATTENTION TURNS TO A MORE ORGANIZED PACIFIC FRONTAL
SYSTEM APPROACHING THE REGION. CONFIDENCE INCREASES THAT THIS
SYSTEM WILL BRING A RETURN TO MORE WIDESPREAD PRECIPITATION LATE
TUESDAY INTO WEDNESDAY, THOUGH SOME TIMING DIFFERENCES REMAIN
AMONG ENSEMBLE MEMBERS. SPECIFICALLY, CURRENT GUIDANCE SUGGESTS
THE START TIME OF PRECIPITATION REACHING INLAND WILL VARY FROM
ANY TIME BETWEEN TUESDAY EVENING AND WEDNESDAY AFTERNOON. FROM 5
PM MONDAY TO 5 PM TUESDAY, PRECIPITATION TOTALS IN THE LOWLANDS
WILL VARY FROM 0 TO 0.6 INCHES (HIGHEST ALONG THE COAST) UNDER
BEST AND WORST SCENARIOS, WHICH CONTINUES TO REFLECT THE POOR
AGREEMENT BETWEEN MODELS AT THIS TIME.
THE MOST IMPACTFUL PERIOD LOOKS TO BE EARLY WEDNESDAY, WITH
WIDESPREAD RAIN EXPECTED ACROSS THE REGION AS THE FRONT MOVES
THROUGH, BRINGING UP TO 0.6 TO 0.9 INCHES TO THE LOWLANDS FROM
5 PM TUESDAY TO 5 PM WEDNESDAY IN A WORST-CASE SCENARIO. WHILE
EXACT RAINFALL TOTALS REMAIN SOMEWHAT UNCERTAIN (A BEST CASE
SCENARIO COULD STILL RESULT IN 0 INCHES OF RAINFALL TOTALS),
THIS SYSTEM REPRESENTS A MORE NOTABLE SHIFT BACK TO WETTER
CONDITIONS COMPARED TO EARLIER THIS WEEK. INTO THURSDAY, THE
PATTERN BEGINS TO TRANSITION ONCE AGAIN AS THE UPPER-LEVEL
SYSTEM SHIFTS INLAND AND HEIGHTS START TO RISE. THIS WILL
SUPPORT A TREND TOWARD DECREASING PRECIPITATION AND A GRADUAL
RETURN TO DRIER CONDITIONS. ~12
AVIATION
VFR CONDITIONS EXPECTED THROUGHOUT THE TAF PERIOD
BENEATH FEW-SCT LOW CLOUDS AT 3-5 KFT AND SCT HIGH CLOUDS AT OR
ABOVE 25 KFT. DIURNAL NORTH TO NORTHWEST WINDS AROUND 5 KT AT
INLAND TERMINALS AND 8-12 KT ALONG THE COAST WILL EASE TO 3 KT OR
LESS TONIGHT, WITH CALM TO LIGHT AND VARIABLE CONDITIONS ALONG
THE WILLAMETTE VALLEY AND LIGHT EAST FLOW WEST OF THE COLUMBIA
RIVER GORGE (KTTD) AND WEST OF GAPS IN THE COASTAL TERRAIN (KAST,
KONP). THERE ARE LOW CHANCES (10-15%) FOR MVFR CIGS AT COASTAL
TERMINALS 12-18Z SAT, BUT OFFSHORE FLOW WILL LIKELY INHIBIT
MARINE STRATUS FORMATION.
KPDX AND APPROACHES...VFR CONDITIONS EXPECTED THROUGHOUT THE
PERIOD BENEATH FEW-SCT LOW CLOUDS AT 3-5 KT AND SCT HIGH CLOUDS AT
OR ABOVE 25 KFT. DIURNAL WINDS OUT OF THE NORTH TO NORTHWEST
AROUND 5 KT WILL EASE TO LIGHT AND VARIABLE OVERNIGHT AFTER 08Z
SAT. LIGHT EAST FLOW IS EXPECTED TO DEVELOP WEST OF THE COLUMBIA
RIVER GORGE AS HIGH PRESSURE BUILDS INLAND, BUT EAST WINDS ARE NOT
EXPECTED TO REACH KPDX. -36
MARINE
RELATIVELY BENIGN MARINE CONDITIONS CONTINUE THROUGH
THIS WEEKEND. NORTHERLY WINDS AROUND 10 KT CONTINUE INTO TONIGHT,
THEN TURN SOUTHERLY AHEAD OF A WEAKENING COLD FRONT ON SATURDAY.
GUSTS UP TO 20 KT MAY CONTINUE THIS AFTERNOON SOUTH OF CAPE FALCON
WITHIN 20 NM, BEFORE EASING THIS EVENING. SEAS WILL CONTINUE TO
FALL TO 3-5 FT BY TONIGHT, BUILDING ONLY SLIGHTLY TO 4-6 FT AS THE
WEAK FRONT APPROACHES.
THERE IS HIGHER FORECAST UNCERTAINTY FOR WINDS AND SEAS EARLY
NEXT WEEK AS AN AREA OF LOW PRESSURE OFFSHORE APPROACHES THE
COAST. THE PLACEMENT OF THE LOW WILL DETERMINE THE CONDITIONS
ACROSS THE WATERS, WITH THE FORECAST AT THIS LEAD TIME FAVORING
INCREASING ONSHORE FLOW THROUGH WEDNESDAY, WHEN WNW GUSTS MAY
REACH 20-25 KT BEYOND 30 NM. HIGHER WINDS AND A FRESHLY ARRIVING
NW SWELL MAY PUSH SEAS TO 10-12 FT WEDNESDAY INTO THURSDAY.
VERY STRONG EBB CURRENTS WILL CONTINUE ACROSS THE COLUMBIA RIVER
BAR EACH MORNING THROUGH TUESDAY. WITH SEAS EXPECTED TO BUILD
SLIGHTLY BY EARLY NEXT WEEK, A STEEP EBB CHOP MAY NECESSITATE
SMALL CRAFT ADVISORIES IN THE HOURS AROUND PEAK FLOW EACH DAY.
-36
PQR WATCHES/WARNINGS/ADVISORIES
OR...FROST ADVISORY FROM 1 AM TO 8 AM PDT SATURDAY FOR ORZ116>118-121.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
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