904
FXUS66 KPQR 171248
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
548 AM PDT FRI APR 17 2026
SYNOPSIS
MILD SPRINGTIME CONDITIONS EXPECTED THROUGH THE
WEEKEND. SCATTERED LIGHT SHOWERS ARE POSSIBLE ON SATURDAY AS A
WEAK COLD FRONT APPROACHES, HOWEVER, TRENDS CONTINUE TO WEAKEN
THIS SYSTEM. CONFIDENCE DECREASES AS WE HEAD INTO NEXT WEEK. A
LARGE UPPER LEVEL LOW IS EXPECTED SET UP OFF THE NORTHERN
CALIFORNIA AND SOUTHERN OREGON COASTS AND SLIGHT ADJUSTMENTS IN
LOCATION WILL DETERMINE OVERALL CONDITIONS.
SHORT TERM...NOW THROUGH SATURDAY NIGHT
LIGHT AND WIDELY
SCATTERED SHOWERS CONTINUE TO SHOW UP ON RADAR AND ARE EXPECTED
TO DISSIPATE BEFORE DAWN. SKIES HAVE CLEARED OVER MOST OF THE
AREA WITH THE EXCEPTION BEING THE CENTRAL AND NORTHERN
WILLAMETTE VALLEY, INTO THE PORTLAND METRO WHERE MID LEVEL
CLOUDS HAVE THICKENED. WHERE CLOUD COVER REMAINS THIN,
TEMPERATURES HAVE DROPPED INTO THE LOW TO MID 30S WITH
EFFICIENT RADIATIVE COOLING. EXPECTING TEMPERATURES TO CONTINUE
DROPPING OVER THE NEXT FEW HOURS WITH THE MOST SHELTERED
LOCATIONS REACHING AROUND 30. FREEZE WARNINGS REMAIN IN EFFECT
THROUGH 9 AM ACROSS THE SOUTHERN WILLAMETTE VALLEY, CASCADE
FOOTHILLS IN OREGON, AND THE UPPER HOOD RIVER VALLEY WHERE TEMPS
ARE EXPECTED TO BOTTOM OUT IN THE LOW 30S. ELSEWHERE, A FROST
ADVISORY REMAINS IN EFFECT FOR LOWS EXPECTED TO DIP INTO THE MID
30S, SUPPORTING FROST DEVELOPMENT. LOCATIONS NOT UNDER A
WARNING OR ADVISORY INCLUDE THE PORTLAND/VANCOUVER METRO, THE
NORTHERN OREGON COAST, THE SOUTHERN WASHINGTON COAST, AND
COLUMBIA RIVER GORGE BELOW 1500 FEET WHERE TEMPERATURES ARE
EXPECTED TO BE A FEW DEGREES WARMER IN THE UPPER 30S TO LOW 40S.
CONDITIONS TREND WARMER TODAY WITH TEMPERATURES TOPPING OUT
NEAR NORMAL IN THE UPPER 50S TO LOW 60S INLAND AND MID TO UPPER
50S ALONG THE COAST. A WEAK THERMAL TROUGH IS EXPECTED TO
DEVELOP, LEADING TO LIGHT OFFSHORE FLOW ALONG THE EASTSIDE OF
THE COAST RANGE AND CASCADES AND LIGHT NORTHERLY FLOW WITHIN THE
WILLAMETTE VALLEY. LOWS TONIGHT ARE EXPECTED TO BE A TAD WARMER
WITH CLOUD COVER PERSISTING OVERNIGHT. THE PROBABILITY FOR
BELOW FREEZING TEMPERATURES REMAINS CONFINED TO THE HIGH
CASCADES AND THE HIGHER ELEVATIONS OF THE UPPER HOOD RIVER
VALLEY. UPPER 30S WILL BE POSSIBLE FOR MOST LOCATIONS ASIDE FROM
THE COASTAL ZONES WITH THE COOLEST TEMPERATURES EXPECTED IN THE
SOUTHERN WILLAMETTE VALLEY. PROBABILITIES FOR TEMPERATURES TO
DROP BELOW 37 ARE 40-50% IN THE SOUTHERN WILLAMETTE VALLEY AND
THE NORTHERN COAST RANGE WHILE ELSEWHERE INLAND, CHANCES TOP OUT
AT 10-30%. THE WARMING TREND CONTINUES INTO SATURDAY WITH
INLAND HIGHS EXPECTED TO REACH THE LOW 70S AND UPPER 50S TO LOW
60S ALONG THE COAST.
LONG TERM...SUNDAY THROUGH THURSDAY
THE FORECAST THROUGH THE
LONG-TERM PERIOD HINGES ON THE PROGRESSION OF AN UPPER-LEVEL LOW
TRACKING SOUTHWARD FROM THE GULF OF ALASKA OVER THE NORTHEASTERN
PACIFIC FROM SUNDAY INTO THE MIDDLE OF NEXT WEEK. CONSENSUS
REMAINS LARGELY SPLIT WITH MAYBE A SLIGHT INCREASE IN AGREEMENT
FOR MONDAY. ENSEMBLE MEMBERS SHOW SLIGHTLY LESS SPREAD IN THE
POSITION OF THE UPPER LOW OFF THE NORTHERN CALIFORNIA OR
SOUTHERN OREGON COASTS. SOME OF THESE SOLUTIONS MAINTAIN
STRONGER RIDGING OVERHEAD AND THEREFORE RESULT IN WARMER AND
DRIER CONDITIONS. IF THE PLACEMENT OF THE LOW IS CLOSE ENOUGH TO
TRANSPORT MOISTURE FROM THE SOUTH UP TOWARD THE CASCADES, THESE
WARMER TEMPERATURES COULD ALSO SUPPORT AFTERNOON/EVENING
CONVECTION MONDAY OR TUESDAY, HOWEVER THE CHANCES OF THIS REMAIN
TOO LOW TO INCLUDE IN THE FORECAST AT THIS LEAD TIME. THE OTHER
HALF OF ENSEMBLE MEMBERS PLACE THE LOW FARTHER TO THE NORTH AND
EAST, CLOSER TO THE LOCAL AREA, YIELDING HIGHER CLOUD COVER,
NEAR TO BELOW- NORMAL TEMPERATURES, AND POTENTIAL RAIN SHOWERS.
DESPITE THIS PERIOD OF HIGH UNCERTAINTY, THERE IS ACTUALLY
HIGHER CONFIDENCE TOWARD THE MIDDLE OF THE WEEK AS THE LOW
EVENTUALLY TRACKS INLAND, AND NORTHWESTERLY ONSHORE FLOW ALOFT
TENDS TO RETURN TEMPERATURES TO NEAR-NORMAL VALUES WITH CHANCES
FOR RAIN ON WEDNESDAY, THEN WARMING AND DRYING INTO THURSDAY AS
RIDGING BUILDS ANEW. -36/19
AVIATION
MAINLY VFR CONDITIONS EXPECTED ACROSS THE AREA
THROUGH THE TAF PERIOD. MID LEVEL CLOUD COVER HAS DEVELOPED OVER
THE WILLAMETTE VALLEY AROUND 4000-6000 FEET WITH GUIDANCE
SUGGESTING A 30-40% CHANCE CIGS LOWER TO 2000-3000 FEET 14-17Z.
CLEAR SKIES AND CALM WINDS WILL LEAD TO WIDESPREAD FROST
DEVELOPMENT FOR BOTH INLAND AND COASTAL TERMINALS EXCEPT KAST
AND KPDX WHERE TEMPS REMAIN SLIGHTLY WARMER. WINDS INCREASE
AFTER 18Z WITH A WEAK THERMAL TROUGH DEVELOPING. THIS WILL
SUPPORT LIGHT NORTHEASTERLY WINDS FOR COASTAL TERMINALS AND
LIGHT NORTHERLY WINDS THROUGHOUT THE WILLAMETTE VALLEY.
KPDX AND APPROACHES...MAINLY VFR CONDITIONS WITH A 20-40% CHANCE
OF CIGS DROPPING TO 2000-3000 FEET BETWEEN 14-17Z. CONFIDENCE
REMAINS LOW SO WILL NOT ADD TO THE TAF AT THIS TIME. WINDS
NORTHERLY AROUND 5 KTS EXCEPT KTTD WHERE WINDS WILL BE MORE
EASTERLY TO NORTHEASTERLY. -19
MARINE
BENIGN CONDITIONS EXPECTED TO PERSIST INTO THE
WEEKEND. SEAS CONTINUE TO TREND DOWN AND ARE EXPECTED TO DROP
BELOW 5 FEET THIS AFTERNOON. WINDS TURN NORTHEASTERLY THIS
MORNING AS A WEAK THERMAL TROUGH DEVELOPS. WINDS WILL GENERALLY
BE LIGHT AT LESS THAN 10 KT BUT COULD SEE SLIGHTLY STRONGER
WINDS UP TO 15 KT OUT TO 30 NM FROM CAPE FALCON SOUTH TO
FLORENCE. A WEAKENING COLD FRONT IS EXPECTED TO APPROACH THE
WATERS ON SATURDAY. THIS WILL VEER WINDS TO THE SOUTH ALONG
WITH POSSIBLE GUSTS TO AROUND 20 KT. THERE IS A 20-30% CHANCE
FOR SMALL CRAFT GUSTS FOR THE OUTER WATERS. SEAS INCREASE
SLIGHTLY TO 6-7 FEET. -19
PQR WATCHES/WARNINGS/ADVISORIES
OR...FROST ADVISORY UNTIL 9 AM PDT THIS MORNING FOR ORZ102>110-
112>115.
FREEZE WARNING UNTIL 9 AM PDT THIS MORNING FOR ORZ116>119-121-
123>125.
WA...FROST ADVISORY UNTIL 9 AM PDT THIS MORNING FOR WAZ203>205-207-
208.
PZ...SMALL CRAFT ADVISORY UNTIL 9 AM PDT THIS MORNING FOR PZZ210.
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