049
FXUS66 KPQR 161811 AAB
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
1111 AM PDT THU APR 16 2026
UPDATED AVIATION DISCUSSION AND PQR WATCHES/WARNINGS/ADVISORIES.
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
AT 18Z THURSDAY, SATELLITE AND SURFACE WEATHER
OBSERVATIONS SHOWED SCATTERED TO BROKEN CUMULUS CLOUDS ACROSS
NORTHWEST OR AND SOUTHWEST WA WITH ISOLATED LIGHT
SHOWERS/SPRINKLES OVER THE CASCADE FOOTHILLS AND COAST RANGE. CIGS
WERE GENERALLY VFR, ASIDE FROM BRIEF PERIODS OF HIGH-END MVFR CIGS
AT KTTD, KUAO, AND KSLE. EXPECT THIS TREND TO CONTINUE TODAY
BEFORE CLOUDS DECREASE IN COVERAGE THIS EVENING INTO TONIGHT.
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. NOTE THERE IS A 45% CHANCE FOR FOG AND/OR LOW
STRATUS BELOW 500 FEET AT KHIO BEGINNING AROUND 15Z FRIDAY, AND A
30-40% CHANCE AT KPDX.
KPDX AND APPROACHES...EXPECT MAINLY VFR CONDITIONS TODAY AND
TONIGHT WITH LIGHT AND VARIABLE WINDS AROUND 5 KT OR LESS. BETWEEN
15-18Z FRIDAY, THERE IS A 30-40% CHANCE FOR LOW STRATUS WITH CIGS
BELOW 1000 FT. CONFIDENCE IN THIS STRATUS DECK DEVELOPING OVER THE
TERMINAL IS CURRENTLY NOT HIGH ENOUGH TO REFLECT IN THE TAF. -23
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 FROM 1 AM TO 9 AM PDT FRIDAY FOR ORZ102>110-
112>115.
FREEZE WARNING FROM 1 AM TO 9 AM PDT FRIDAY FOR ORZ116>119-121-
123>125.
WA...FROST ADVISORY FROM 1 AM TO 9 AM PDT FRIDAY FOR WAZ203>205-207-
208.
PZ...SMALL CRAFT ADVISORY UNTIL 5 PM PDT THIS AFTERNOON FOR
PZZ251>253-271>273.
WWW.WEATHER.GOV/PORTLAND
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