092
FXUS66 KPQR 171016
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
316 AM PDT TUE MAR 17 2026
SYNOPSIS
UPPER LEVEL RIDGING WILL BRING WARMER SPRING-LIKE
TEMPERATURES AND LIGHT WINDS THROUGH AT LEAST THURSDAY WITH HIGH
TEMPERATURES MAINLY IN THE 60S AND LOWER 70S WITH COOLER
TEMPERATURES IN THE CASCADES AND ALONG THE COAST. MAINLY DRY
CONDITIONS FOR THE REGION, BUT AREAS ALONG THE COAST AND NORTH
OF SALEM, OR COULD SEE OCCASIONAL LIGHT RAIN THROUGH THURSDAY,
ESPECIALLY IN PACIFIC COUNTY AND ALONG THE NORTH OREGON COAST.
AS THE END OF THE WEEK APPROACHES, THE AREA IS TRENDING A TOUCH
COOLER AS A PATTERN CHANGE IS EXPECTED. LOOKING INTO THE
WEEKEND, THE FORECAST BECOMES MORE UNCERTAIN IN REGARDS TO
TEMPERATURES AND PRECIPITATION AMOUNTS.
DISCUSSION...NOW THROUGH MONDAY
BENIGN WEATHER IS EXPECTED
ACROSS THE FORECAST AREA AS AN UPPER LEVEL HIGH BRINGS WARM,
DARE WE SAY, SPRING-LIKE TEMPERATURES, LIGHT WINDS, AND MAINLY
DRY CONDITIONS THROUGH AT LEAST THURSDAY. HOWEVER, RAIN IS
LIKELY AT TIMES (60%-80% CHANCE) THROUGH THURSDAY OVER NORTHERN
PORTIONS OF THE FORECAST AREA, PARTICULARLY FOR LOCATIONS TO
THE NORTH OF SALEM, OR AND ALONG THE COAST. THE CAUSE OF THE
LIGHT RAIN IS THE INTERACTION OF A RIDGE OF HIGH PRESSURE IN
CALIFORNIA AND A ATMOSPHERIC RIVER (AR) TAKING AIM AT THE
OLYMPIC PENINSULA AND VANCOUVER ISLAND. THE PUSH AND PULL OF
THESE TWO SYSTEM IS RESULTING IN THE HIGH POP/ LOW-MODERATE QPF
SCENARIO. OVERALL, RAIN WILL BE MOST PERSISTENT OVER PACIFIC
COUNTY AND THE FAR NORTH OREGON COAST; THESE AREAS HAVE FORECAST
RAIN TOTALS RANGING BETWEEN 0.60-2.50 INCHES FROM 5 AM PDT
TUESDAY THROUGH 5 AM PDT FRIDAY. SINCE THESE RAIN AMOUNTS ARE
EXTENDED OVER A PROLONGED PERIOD OF TIME (96 HOURS) WITH
UNIMPRESSIVE HOURLY RAIN RATES, FLOODING IS NOT A CONCERN.
CONFIDENCE IS ALSO HIGH THAT FLOODING WILL NOT BE A CONCERN EVEN
IF THE WORST CASE SCENARIO VERIFIED, AS THE NBM 90TH PERCENTILE
FOR 72-HOUR RAIN AMOUNTS ENDING AT 5 AM PDT FRIDAY IS NOT HIGH
ENOUGH TO SUGGEST FLOODING WILL OCCUR AS PRECIPITATION MAXES
OUT AROUND 3.5 INCHES.
EXPECT HIGH TEMPERATURES MAINLY IN THE MID TO UPPER 60S ACROSS
THE LOWLANDS, LOWER 70S FOR INLAND VALLEYS IN LANE COUNTY AND
MID 50S TO LOWER 60S OVER SOUTHWEST WA AND THE NORTH OREGON
COAST EACH DAY THROUGH THURSDAY. SLIGHTLY COOLER TEMPERATURES
ON FRIDAY AS A PATTERN CHANGE IS EXPECTED.
HOWEVER, THE FORECAST DOES BECOME A BIT MORE UNCERTAIN FOR THE
WEEKEND AS MODEL ENSEMBLE GUIDANCE BEGINS TO DIFFER AS TO HOW
THE CALIFORNIA LOW WILL RELEASE ITS CONTROL OVER THE PACIFIC
NW. WPC CLUSTER ANALYSIS CONTINUES TO SHOW THE HIGH PRESSURE
PERSISTING AND THUS MAINTAINING WEAK SOUTHWESTERLY FLOW AS IT
MOVES EASTWARD. NOW, WHILE THIS SOUTHWESTERLY FLOW SOLUTION IS
MORE FAVORED (75% CHANCE), THERE IS ANOTHER SOLUTION THAT COULD
OCCUR (25% CHANCE). THE LESS LIKELY SOLUTION HAS THE RIDGE
DE-AMPLIFYING ENOUGH TO RESULT IN A TRANSITION FROM SOUTHWEST
FLOW ALOFT TO NEARLY ZONAL FLOW. EITHER SOLUTION WILL BRING
RELATIVELY COOLER TEMPERATURES TO THE REGION, BUT THE FAVORED
ONE WILL MAINTAIN A DRY PATTERN, WITH THE LESS LIKELY ONE BRINGING
PRECIPITATION BACK INTO THE FORECAST. TO QUANTIFY THE UNCERTAINTY,
LETS LOOK AT THE NBM 10-90TH PERCENTILE FOR TEMPERATURES. FOR
SATURDAY, DAYTIME HIGHS RANGE FROM THE UPPER 50S TO LOW 70S AND
FOR SUNDAY, DAYTIME HIGHS RANGE FROM THE LOW 50S TO MID 60S. A
SIMILAR SPREAD CAN ALSO BE OBSERVED IN THE OVERNIGHT LOWS. FOR
SATURDAY, OVERNIGHT LOWS RANGE FROM THE UPPER 20S TO LOW 50S AND
FOR SUNDAY, DAYTIME HIGHS RANGE FROM FROM THE UPPER 20S TO
UPPER 40S.
REGARDLESS OF THE OUTCOME, CONFIDENCE IS HIGH THERE WILL BE NO
HIGH IMPACT WEATHER FOR THE REMAINDER OF THE WEEK AND INTO THE
WEEKEND. /42
AVIATION
A BROAD UPPER LEVEL RIDGE WITH AN ATMOSPHERIC RIVER
RIDING THE NORTHERN EDGE OF THE RIDGE WILL KEEP MOISTURE AND
CLOUDS STREAMING INTO THE REGION. THIS WILL BRING GENERALLY VFR
CONDITIONS WITH MID-HIGH LEVEL CLOUDS AND INTERMITTENT, LIGHT
RAIN FOR THE NORTH OREGON AND SOUTHWEST WASHINGTON COAST. THIS
PRECIPITATION WILL IMPACT THE COAST AROUND 12Z-15Z TUESDAY, THEN
SPREAD INLAND FOR LOCATIONS GENERALLY NORTH OF KEUG FROM 15Z-18Z
TUESDAY. THIS INCOMING PRECIPITATION WILL ALSO RESULT IN PREDOMINATELY
MVFR CONDITIONS AND A 30-40% PROBABILITY OF IFR CONDITIONS ALONG
THE COAST THROUGH THE TAF PERIOD. AS FOR INLAND LOCATIONS, EXPECT
PREDOMINATELY VFR CONDITIONS A 25% CHANCE FOR MVFR CONDITIONS
THROUGH THE TAF PERIOD. GENERALLY SOUTHERLY WINDS ACROSS THE
AIRSPACE, WITH LESS THAN 5 KT EXPECTED FOR INLAND LOCATIONS AND
5-10 KT ALONG THE COAST WITH GUSTS UP TO 25 KT. EXPECT THESE WINDS
THROUGH THE TAF PERIOD.
KPDX AND APPROACHES...MAINLY VFR CONDITIONS THROUGH THE TAF
PERIOD. LIGHT PRECIPITATION WILL BE POSSIBLE FROM 15Z-23Z AND
THE LIGHT PRECIPITATION WILL RESULT IN A 25% CHANCE FOR MVFR
CONDITIONS. ALSO, SOUTHERLY WINDS LESS THAN 5 KT. /42
MARINE
SOUTHERLY WINDS ACROSS ALL WATERS EXPECTED THROUGH THE
MIDDLE OF THE WEEK. WIND GUSTS UP TO 25 KT WILL BE POSSIBLE
THROUGH TODAY AS A COLD FRONT SAGS SOUTHWARD TOWARD THE NORTHERN
OREGON AND SOUTHERN WASHINGTON COASTS. AS SUCH, WILL MAINTAIN THE
CURRENT SUITE OF SMALL CRAFT ADVISORIES FOR ZONES PZZ251,252,271,272
AND THE COLUMBIA RIVER BAR UNTIL 5 AM WEDNESDAY. SEAS OF 8 AND 11
FEET AT 10 TO 13 SECONDS AS WINDS INCREASE AND A SOUTHWESTERLY TO
WESTERLY SWELL MOVES INTO THE WATERS. CONDITIONS SUBSIDE BELOW
SMALL CRAFT CONDITIONS AS THE MIDDLE OF THE WEEK APPROACHES.
ANOTHER WEAK FRONT MAY PASS THROUGH THE REGION THURSDAY, BRINGING
A 20-30% CHANCE FOR LOW END SMALL CRAFT GUSTS. /42
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT WEDNESDAY FOR PZZ210-251-252-
271-272.
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