742
FXUS66 KPQR 161442
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
742 AM PDT THU APR 16 2026
SYNOPSIS
RAIN AND MOUNTAIN SNOW SHOWERS WILL BE ON THE
DECREASE TODAY AS THE OVERALL PATTERN TRENDS DRIER AND WARMER
HEADED INTO THE WEEKEND. HOWEVER, AS THIS TRANSITION OCCURS, A
LINGERING COOLER AIRMASS FAVORS AT LEAST ONE MORE NIGHT OF
FROST/FREEZE CONCERNS TONIGHT INTO FRIDAY MORNING. SHOWER
CHANCES RETURN SUNDAY INTO EARLY NEXT WEEK ALTHOUGH FORECAST
UNCERTAINTY INCREASES SIGNIFICANTLY FROM THIS POINT ONWARD.
SHORT TERM...NOW THROUGH SATURDAY
EARLY THIS MORNING
SATELLITE AND RADAR OBSERVATIONS DEPICT CONTINUED SHOWER
ACTIVITY ACROSS THE REGION AS THE TILTED AXIS OF A BROAD UPPER-
LEVEL TROUGH PASSES OVERHEAD. MODELS ARE IN EXCELLENT AGREEMENT
THIS UPPER-LEVEL LOW EXITING EASTWARD THROUGH THE DAY TODAY
ALLOWS FOR BUILDING HEIGHTS AND A SWITCH DRIER NORTHERLY FLOW
ALOFT. RAIN SHOWERS GRADUALLY DWINDLE IN COVERAGE AS A RESULT BY
MIDDAY WITH MOST DRY CONDITIONS RETURNING TO THE ENTIRE REGION
BY THE MID TO LATE AFTERNOON HOURS EXCLUDING THE CASCADES WHERE
SLIGHT CHANCE (15-25%) FOR SHOWERS STILL HOLDS ON DUE TO TERRAIN
FORCING.
WE'RE ANTICIPATING ANOTHER ROUND OF COOL TEMPERATURES TONIGHT
INTO FRIDAY MORNING. CONDITIONS APPEAR EVEN MORE SUPPORTIVE OF
EFFECTIVE RADIATIONAL COOLING COMPARED TO THE NIGHT PRIOR WITH
ADDITIONAL CLEARING AND LIGHTER WINDS, ALBEIT WITH AN AIRMASS
THAT'LL BE SLOWLY MODERATING. A FREEZE WATCH REMAINS IN EFFECT
FROM 1-9 AM FRIDAY FOR THE AREAS MOST LIKELY TO SEE TEMPERATURES
FALL BELOW FREEZING, NAMELY THE UPPER HOOD RIVER VALLEY AND THE
CASCADE FOOTHILLS OF MARION, LINN, AND LANE COUNTIES. SHOULD
MODEL GUIDANCE CONTINUE TO SUPPORT THE OVERALL SET-UP AND
FORECAST LOW TEMPERATURES IN THE 30S ACROSS OTHER PORTIONS OF
THE INLAND/COAST RANGE VALLEYS, WIDESPREAD FROST ADVISORIES MAY
ONCE AGAIN BE NEEDED. THE SOUTHERN WILLAMETTE VALLEY IS AN AREA
OF PARTICULAR CONCERN BEYOND THOSE MENTIONED ABOVE FOR
FROST/FREEZE IMPACTS. AGRICULTURAL INTERESTS AND THOSE WITH
SENSITIVE OUTDOOR PLANTS SHOULD PLAN TO TAKE PROTECTIVE ACTION
TO PREVENT PLANT DAMAGE.
CONFIDENCE IS HIGH UPPER-LEVEL RIDGING BUILDS FURTHER ON
FRIDAY INTO SATURDAY, USHERING IN DRIER AND WARMER WEATHER
ACROSS THE REGION, ALTHOUGH THERE REMAINS SOME UNCERTAINTY IN
THE PROGRESSION OF YET ANOTHER UPPER LOW OVER THE NORTHEAST
PACIFIC. THIS LOW OR OPEN TROUGH MAY MOVE NEARER TO THE REGION
AND BRING CLOUDS AND SHOWERS, THE CHANCES FOR THE LATTER ONLY
REACH AROUND 15-25% ALONG THE COAST COME SATURDAY AFTERNOON,
INCREASING FURTHER SATURDAY EVENING. IT SHOULD BE QUICKLY NOTED
BEYOND SOME ISOLATED POCKETS OF COOLER TEMPERATURES IN THE
UPPER HOOD RIVER VALLEY, FAR SOUTHERN WILLAMETTE VALLEY, AND
OTHER COAST RANGE/CASCADE VALLEYS, THE THREAT FOR FROST WILL BE
RATHER LIMITED FRIDAY NIGHT INTO SATURDAY MORNING -99/36
LONG TERM...SUNDAY THROUGH WEDNESDAY
ALL EYE ARE ON THE
PROGRESSION OF AN UPPER-LEVEL LOW OR OPEN TROUGH TRACKING
SOUTHWARD FROM THE GULF OF ALASKA OVER THE NORTHEAST PACIFIC
EARLY NEXT WEEK AS IT WILL BE THE DRIVER OF SENSIBLE WEATHER
GOING FORWARD. THE FORECAST AND POTENTIAL IMPACTS REMAIN
EXTREMELY SENSITIVE TO THIS FEATURE'S EVOLUTION. AN UPPER LOW
LOCATED NEARBY WILL FAVOR CLOUDY SKIES AND RAINFALL CHANCES,
WHILE A POSITION WELL TO THE WEST WOULD SEE CONTINUED WARM AND
DRY WEATHER. THE CURRENT FORECAST AS FAR AS TEMPERATURES IS
CONCERNED IS SOMEWHERE IN-BETWEEN. IF THE UPPER-LEVEL LOW
LOCATED OFF THE NORTHERN CA OR SOUTHERN OR COAST, THE PATTERN
COULD ALLOW SUFFICIENT MOISTURE TO MOVE NORTHWARD ON ITS EASTERN
FLANK TO SUPPORT CONVECTION ALONG THE CASCADES EARLY NEXT WEEK.
TO HELP HIGHLIGHT THIS FORECAST UNCERTAINTY, THE PROJECTED HIGH
TEMPERATURE SPREAD IN THE NBM ENSEMBLE RANGES FROM 83 DEGREES
(90TH PERCENTILE) TO 57 DEGREES (10TH PERCENTILE) ON MONDAY, A
26 DEGREE SPREAD. TT'S NOT OFTEN WE SEE THAT MUCH UNCERTAINTY
ON DAY 4-5 OF THE FORECAST. AT LEAST THERE IS A DECENT CONSENSUS
THIS UPPER-LEVEL LOW OR TROUGH FEATURE KICKS EASTWARD BY THE
MIDDLE OF THE WEEK LEAVING US IN A MORE TYPICAL ONSHORE FLOW
PATTERN. THAT SAID, THE EXACT TRANSITION AND THUS POTENTIAL
IMPACTS REMAIN NEBULOUS AT THIS TIME. -99/36
AVIATION
SHOWERS CONTINUE ACROSS THE REGION EARLY THIS
MORNING WITH GENERALLY VFR CONDITIONS OVERHEAD. ESPECIALLY
OVER THE NEXT FEW HOURS (THROUGH 15-16Z), ANY ACTIVITY WHEN
PASSING OVER A TERMINAL MAY BRIEFLY DROP CIGS/VIS TO MVFR.
FORTUNATELY, LINGERING SHOWERS AND THUS CHANCES FOR MVFR FLIGHT
CONDITIONS DECREASE BY THE MIDDAY HOURS BEFORE REMAINING RATHER
ISOLATED DURING THE AFTERNOON HOURS. BOTH EARLY THIS MORNING
NEAR SUNRISE, AND TONIGHT INTO FRIDAY MORNING, TEMPERATURES
COULD BE COLD ENOUGH FOR FROST FORMATION OVER EXPOSED SURFACES,
ALTHOUGH FOR THE FORMER PERIOD IT WILL BE HIGHLY DEPENDENT ON
PARTIAL CLEARING. WINDS REMAIN FAIRLY LIGHT, GENERALLY LESS THAN
5 TO 10 KNOTS AT ALL SITES.
KPDX AND APPROACHES...EXPECT MAINLY VFR CONDITIONS, FALLING TO
MVFR BRIEFLY NEAR SHOWERS THIS MORNING BEFORE ~15Z. HIGH
CONFIDENCE IN PREVAILING DRY WEATHER AND VFR CONDITIONS AFTER
THIS POINT THROUGH THE AFTERNOON AND EVENING. -99
MARINE
BROAD NORTHWESTERLY FLOW CONTINUES TODAY WITH
LINGERING SHOWERS DECREASING THROUGH THE DAY. WE'LL SEE SMALL
CRAFT SEAS AT 8-11 FEET AT 9-10 SECONDS PERSIST AS WELL DUE TO A
FRESH WNW SWELL COMBINED WITH A WNW WIND WAVE. IN ADDITION,
THERE WILL ALSO BE A STRONG EBB THIS MORNING FOR THE COLUMBIA
RIVER BAR HELPING TO KEEP WAVES STEEP. EXPECT WAVE HEIGHTS TO
SLOWLY WANE THROUGH THE DAY ACROSS BOTH THE INNER AND OUTER
WATERS. WINDS WILL REMAIN W-WNW THROUGH FRIDAY MORNING, THEN
SHIFT TO THE NORTH AS A HIGH PRESSURE RIDGE SETS UP OVERHEAD.
THIS SUMMER-LIKE WEATHER PATTERN IS FAIRLY SHORT-LIVED HOWEVER,
SWITCHING SOUTHERLY ON SATURDAY AND INCREASING ACROSS THE OUTER
WATERS. GUIDANCE SUGGEST A 40-60% CHANCE FOR GUSTS ABOVE 21+
KNOTS ACROSS THE OUTER WATERS SATURDAY EVENING/NIGHT. FAIRLY
BENIGN CONDITIONS CONTINUE DURING THE EARLY TO MIDDLE PORTION OF
NEXT WEEK WITH WAVE HEIGHTS HOLDING IN THE 4 TO 7 FEET. -99/27
PQR WATCHES/WARNINGS/ADVISORIES
OR...FROST ADVISORY UNTIL 9 AM PDT THIS MORNING FOR ORZ104>110-
114>118.
FREEZE WARNING UNTIL 9 AM PDT THIS MORNING FOR ORZ121-123>125.
FREEZE WATCH FROM LATE TONIGHT THROUGH FRIDAY MORNING FOR
ORZ121-124-125.
WA...FROST ADVISORY UNTIL 9 AM PDT THIS MORNING FOR WAZ203>205-208.
PZ...SMALL CRAFT ADVISORY UNTIL 11 AM PDT THIS MORNING FOR PZZ210.
SMALL CRAFT ADVISORY UNTIL 5 PM PDT THIS AFTERNOON FOR
PZZ251>253-271>273.
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