351
FXUS66 KPQR 170522
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1022 PM PDT THU APR 16 2026
UPDATED AVIATION DISCUSSION AND HAZARD SECTION.
SYNOPSIS
VERY ISOLATED RAIN SHOWERS WILL CONTINUE TO DIMINISH
IN COVERAGE AS THE REGION TRENDS DRIER INTO THE BEGINNING OF THE
WEEKEND. CLEAR SKIES WILL SEE WARM DAYTIME HIGHS AND COOL
OVERNIGHT LOWS, WITH WIDESPREAD FROST OR FREEZE CONDITIONS
EXPECTED TONIGHT. CHANCES FOR ADDITIONAL RAIN RETURNS SUNDAY
INTO EARLY NEXT WEEK, BUT LONG-TERM FORECAST CONFIDENCE REMAINS
RELATIVELY LOW.
SHORT TERM...NOW THROUGH SATURDAY NIGHT
LIGHT, ISOLATED RAIN
SHOWERS CONTINUE TO DWINDLE IN COVERAGE THIS AFTERNOON AS THE
UPPER TROUGH AXIS AND COLDEST AIR ALOFT TRACKS AWAY TO THE EAST.
CHANCES FOR THESE SHOWERS REMAIN 10-15% OR LESS, DECREASING TO
5% OR LESS ON FRIDAY. BUILDING UPPER-LEVEL RIDGING AND SURFACE
HIGH PRESSURE OVER THE NORTHEAST PACIFIC WILL SEE A WARMING AND
DRYING TREND PERSIST INTO AT LEAST THE START OF THE WEEKEND.
AS HIGH PRESSURE BUILDS OVERHEAD TONIGHT, WEAK SURFACE PRESSURE
GRADIENTS WILL ALLOW WINDS TO GO LARGELY CALM, WHICH COMBINED
WITH CLEAR SKIES WILL YIELD EFFICIENT RADIATIVE COOLING.
TEMPERATURES WILL THEREFORE COOL QUICKLY OVERNIGHT, REACHING
FRIDAY MORNING LOWS IN THE UPPER 20S TO UPPER 30S ACROSS THE
REGION. THE COLDEST LOCALES EXPECTED TO FALL BELOW FREEZING ARE
THE UPPER HOOD RIVER VALLEY, FOOTHILLS OF THE OREGON CASCADES,
AND THE SOUTHERN WILLAMETTE VALLEY. A FREEZE WARNING HAS BEEN
ISSUED FOR THESE LOCATIONS FROM 1-9 AM PDT FRIDAY; AGRICULTURAL
INTEREST OR THOSE WITH SENSITIVE OUTDOOR PLANTS SHOULD TAKE
ACTION TO PREVENT DAMAGE. ELSEWHERE, TEMPERATURES IN THE MID-30S
WILL FAVOR FROST DEVELOPMENT ACROSS MUCH OF THE REGION, AND A
FROST ADVISORY IS ALSO IN EFFECT FOR MOST FROM 1-9 AM FRIDAY.
THE WARMEST SPOTS, INCLUDING THE IMMEDIATE PORTLAND/VANCOUVER
METRO, SOUTH WASHINGTON AND FAR NORTH OREGON COASTS, AND WITHIN
THE COLUMBIA GORGE BELOW 1500 FT ELEVATION, ARE MORE LIKELY TO
REMAIN IN THE UPPER 30S TO NEAR 40 DEGREES EARLY FRIDAY MORNING,
LIMITING THE RISK FOR FROST DAMAGE TO PLANTS.
BENEATH MODERATING MID-LEVEL TEMPERATURES AND PARTLY SUNNY
SKIES, SURFACE TEMPERATURES WILL TREND UPWARD TO NEAR-NORMAL ON
FRIDAY AND NEARLY 10 DEGREES ABOVE NORMAL ON SATURDAY. DRY AND
CALM CONDITIONS MAY AGAIN ALLOW FOR COOL TEMPERATURES EARLY
SATURDAY MORNING, HOWEVER THE WARMING TREND WILL GREATLY REDUCE
THE CHANCES FOR BELOW-FREEZING TEMPERATURES OUTSIDE OF THE HIGH
CASCADES. ADDITIONAL FROST ADVISORIES MAY BE NEEDED FOR MORNING
LOW TEMPERATURES IN THE MID-30S, WITH 30-80% CHANCES IN THE
UPPER HOOD RIVER VALLEY, CENTRAL AND SOUTHERN WILLAMETTE VALLEY,
COWLITZ VALLEY, NORTHERN OREGON COAST RANGE, WILLAPA HILLS, AND
CASCADE FOOTHILLS. -36
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. THERE REMAINS
NO FIRM CONSENSUS IN LONG-RANGE GUIDANCE, AND RESULTANT FORECAST
CONFIDENCE THEREFORE ALSO REMAINS LOW. BY MONDAY, ABOUT HALF OF
ENSEMBLE MEMBERS POSITION THE LOW WELL TO THE SOUTHWEST, 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. IN TOTAL, THE FORECAST CURRENTLY
RUNS DOWN THE MIDDLE OF THESE SCENARIOS, BUT THIS COULD CHANGE
SUBSTANTIALLY AS GUIDANCE EVOLVES TOWARD A HIGHER-CONFIDENCE
CONSENSUS IN THE COMING DAYS. 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
AVIATION
PREDOMINATELY VFR CONDITIONS EXPECTED THROUGH FRIDAY
AS HIGH PRESSURE BEGINS BUILDING OVER THE PACNW. A FEW SHOWERS WILL
CONTINUE OVER PORTIONS OF NW OR AND SW WA NORTH OF KTMK THROUGH 12Z
FRI. HIGH CLOUDS HAVE MOSTLY DISSIPATED LEADING TO SCATTERED OR
BROKEN MID LEVEL CLOUDS, MUCH MORE CLEAR THAN EARLIER TODAY. WITH
THE CLEARING SKIES, LATEST GUIDANCE INDICATES A 45-50% CHANCE FOR
FOG AND/OR LOW STRATUS BELOW 500 FEET AT KHIO BEGINNING AROUND 14-
15Z FRI, AND A 35-40% CHANCE FOR CIGS BELOW 2000-3000 FT AT KPDX
BETWEEN 12-18Z FRI. GIVEN THE CLEARING SKIES AND CALM WINDS IN PLACE
TONIGHT, WIDESPREAD FROST IS EXPECTED BOTH INLAND AND AT THE COAST.
ONE EXCEPTION IS AT KAST AND KPDX WHERE TEMPERATURES WILL MOST
LIKELY STAY ABOVE 36 DEGREES, THUS LIMITING THE POTENTIAL FOR FROST
DEVELOPMENT. WINDS REMAIN CALM THROUGH THE TAF PERIOD, EXCEPT FOR
ALONG THE COAST WHERE THEY WILL BECOME NORTHERLY AND INCREASE TO
AROUND 8-10 KTS AFTER 18-20Z FRI.
KPDX AND APPROACHES...MAINLY VFR CONDITIONS EXPECTED OVER THE NEXT
24 HOURS. HOWEVER, THERE IS A 35-40% CHANCE FOR LOW STRATUS WITH
CIGS BELOW 2000-3000 FT BETWEEN 12-18Z FRI. CONFIDENCE IN LOW
STRATUS DEVELOPING OVER THE TERMINAL IS NOT HIGH ENOUGH TO REFLECT
IN THE TAF. -03
MARINE
WEAK NORTHWESTERLY FLOW CONTINUES TODAY WITH LINGERING
SHOWERS DECREASING THIS EVENING. SMALL CRAFT ADVISORY SEAS OF
8-11 FEET AT 10-11 SECONDS PERSIST THIS AFTERNOON, MAINLY DUE
TO A NORTHWESTERLY SWELL AS WIND SPEEDS AND WIND WAVES ARE NOW
MINIMAL. EXPECT WAVE HEIGHTS TO SLOWLY WANE THIS EVENING INTO
SATURDAY ACROSS BOTH THE INNER AND OUTER WATERS, FALLING BELOW
10 FT. NOTE A VERY STRONG EBB CURRENT WILL BRING STEEP SEAS OF 7
TO 8 FT WITHIN THE MAIN CHANNEL OF THE COLUMBIA RIVER BAR EARLY
TO MID FRIDAY MORNING. A SMALL CRAFT ADVISORY HAS BEEN ISSUED
FOR THE COLUMBIA RIVER BAR TO COVER THE STRONG EBB CURRENT.
THE ONGOING NORTHWESTERLY WINDS WILL BECOME NORTHEASTERLY FRIDAY
MORNING. WINDS WILL THEN VEER TO THE SOUTH THIS WEEKEND AHEAD OF
A WEAK FRONT. WITH THE APPROACHING FRONT, GUIDANCE NOW SUGGESTS
A 50-75% CHANCE FOR MAX WIND GUSTS OVER 21 KT ACROSS THE OUTER
WATERS SATURDAY EVENING/NIGHT. CHANCES DECREASE TO 15-40% OVER
THE INNER WATERS, WITH THE LOWEST CHANCES ALONG THE COAST. SEAS
ARE EXPECTED TO INCREASE BY 2-3 FT WITH THE INCREASE IN WINDS,
BUT WILL MOST LIKELY STAY UNDER 10 FT. -23
PQR WATCHES/WARNINGS/ADVISORIES
OR...FROST ADVISORY UNTIL 9 AM PDT FRIDAY FOR ORZ102>110-112>115.
FREEZE WARNING UNTIL 9 AM PDT FRIDAY FOR ORZ116>119-121-123>125.
WA...FROST ADVISORY UNTIL 9 AM PDT FRIDAY FOR WAZ203>205-207-208.
PZ...SMALL CRAFT ADVISORY FROM 3 AM TO 9 AM PDT FRIDAY FOR PZZ210.
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