523
FXUS66 KPQR 231012
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
312 AM PDT WED APR 23 2025
SYNOPSIS
A STRETCH OF DRY, SUNNY WEATHER CONTINUES TODAY AND THURSDAY AS
HIGH PRESSURE REMAINS OVER THE REGION. HOWEVER, A SHIFT IN THE
WEATHER PATTERN IS EXPECTED LATE THURSDAY INTO FRIDAY, BRINGING
INCREASING CLOUDS, COOLER TEMPERATURES, AND A CHANCE OF RAIN AS
A NEW SYSTEM APPROACHES FROM THE PACIFIC.
SHORT TERM...NOW THROUGH THURSDAY NIGHT
EXPECT DRY AND MOSTLY
CLEAR WEATHER THROUGH THURSDAY AS HIGH PRESSURE MAINTAINS SUNNY
SKIES AND LIGHT WINDS. A RIDGE ALOFT IS GRADUALLY BUILDING
INLAND, WITH UPPER-LEVEL WINDS BEGINNING TO SHIFT MORE NORTHERLY
LATER TODAY. TEMPERATURES WILL CONTINUE A WARMING TREND, WITH
INTERIOR VALLEYS REACHING THE UPPER 60S TO LOW 70S TODAY, THEN
RISING INTO THE LOW TO UPPER 70S ON THURSDAY. A FEW SPOTS,
ESPECIALLY AROUND THE PORTLAND AND VANCOUVER METRO, COULD
BRIEFLY HIT 80 DEGREES, WITH PROBABILITIES IN THE 30-60% RANGE.
OVERNIGHT LOWS REMAIN SEASONABLY COOL, GENERALLY IN THE 40S
ACROSS THE LOWLANDS. ALONG THE COAST, EXPECT SOME GUSTY
NORTHWESTERLY WINDS THIS AFTERNOON, TOPPING OUT AROUND 20-25
MPH.
THURSDAY NIGHT, A BROAD UPPER-LEVEL TROUGH BEGINS TO APPROACH
FROM THE PACIFIC, SHIFTING THE FLOW ALOFT MORE SOUTHERLY. THIS
PATTERN FAVORS INCREASING MOISTURE AND ELEVATED INSTABILITY,
PARTICULARLY OVER THE CASCADES. WHILE THUNDERSTORMS POTENTIAL
REMAINS LIMITED, SOME MODELS SUGGEST A SMALL WINDOW FOR ELEVATED
CONVECTION OVER THE LINN AND LANE COUNTY CASCADES THURSDAY
EVENING. THE NAM INDICATES MODEST INSTABILITY (MUCAPE ~300-400
J/KG), THOUGH OTHER GUIDANCE IS LESS SUPPORTIVE. AS A RESULT,
THUNDERSTORM CHANCES HAVE BEEN NUDGED SLIGHTLY HIGHER TO AROUND
10-15% IN THAT AREA. WILL NEED TO KEEP AN EYE ON HOW MODELS
TREND TODAY. OTHERWISE, CONDITIONS BEGIN TO TREND COOLER AND
CLOUDIER LATE THURSDAY NIGHT INTO FRIDAY AS THE SYSTEM MOVES
INLAND.
~HALL
LONG TERM...FRIDAY TO MONDAY
A MORE ACTIVE PATTERN SETS IN
FRIDAY AS A LARGE UPPER LEVEL TROUGH DROPS INTO NORTHERN
CALIFORNIA. THIS WILL PULL MOISTURE NORTHWARD INTO NORTHWEST
OREGON AND SOUTHWEST WASHINGTON, INCREASING THE CHANCE FOR RAIN
BY FRIDAY AFTERNOON. RAINFALL TOTALS BETWEEN FRIDAY MORNING
AND EARLY SATURDAY WILL VARY BY LOCATION. CURRENT MODEL
GUIDANCE SHOWS A 10-30% CHANCE OF OVER 0.25 INCHES ALONG THE
COAST AND WILLAMETTE VALLEY, WITH 30-60% PROBABILITIES IN THE
COAST RANGE AND CASCADES. BEHIND THE FRONT, COOLER AIR SETTLES
IN, BRINGING DAYTIME HIGHS DOWN TO THE UPPER 50S TO LOW 60S
ACROSS MUCH OF THE AREA WEST OF THE CASCADES. SATURDAY LOOKS TO
REMAIN UNSETTLED, WITH INTERMITTENT SHOWERS PERSISTING AS THE
SYSTEM EXITS EAST INTO THE INTERMOUNTAIN WEST.
CONDITIONS BEGIN DRYING OUT BY LATE SUNDAY INTO MONDAY, AS
ENSEMBLE GUIDANCE SUPPORTS HIGH PRESSURE REBUILDING ACROSS THE
REGION, FAVORING A RETURN TO QUIETER AND DRIER WEATHER INTO
EARLY NEXT WEEK.
~HALL
AVIATION
EXPECT VFR CONDITIONS TO PREVAIL THROUGH THE PERIOD AT
MOST TERMINAL ACROSS NW OREGON AND SW WASHINGTON. MOSTLY CLEAR
SKIES WILL BE MAINTAINED WEDNESDAY. HOWEVER, THERE IS A 10-30%
CHANCE OF COASTAL STRATUS FORMING AROUND 13-16Z WEDNESDAY IF
NORTHERLY WINDS ALONG THE COAST TAKE ON MORE OF A NORTHWESTERLY
COMPONENT, WHICH COULD PRODUCE MVFR OR HIGH END IFR CEILINGS.
HOWEVER, MOST GUIDANCE INDICATES COASTAL WINDS WILL REMAIN
NORTHEASTERLY WHICH IS WHY PROBABILITY OF THIS OCCURRENCE IS LOW.
WINDS REMAIN NORTHERLY AND GENERALLY LESS THAN 10 KTS FOR INLAND
AREAS. ALONG THE COAST, NORTH WINDS INCREASE AFTER 18-20Z
WEDNESDAY WITH GUSTS 20-25 KTS POSSIBLE ALONG THE CENTRAL OREGON
COAST, INCLUDING KONP. COASTAL WINDS WILL DECREASE AFTER 02-04Z
THURSDAY. -HEC
PDX AND APPROACHES...VFR CONDITIONS CONTINUE THROUGH THE TAF
PERIOD. NORTHWESTERLY WINDS BECOME NORTH-NORTHEAST AFTER 19-21Z
WEDNESDAY, GENERALLY AROUND 5-10 KTS THROUGH THE PERIOD. -HEC
MARINE
STRONG HIGH PRESSURE OFFSHORE ALONG WILL MAINTAIN
NORTHERLY WINDS ACROSS ALL WATERS THROUGH THE END OF THE WEEK. A
SURFACE LEVEL THERMAL TROUGH REMAINS OVER THE SOUTHERN AND
CENTRAL OREGON COAST THROUGH TODAY, WHICH COMBINED WITH THE HIGH
PRESSURE OFFSHORE WILL CONTINUE INCREASED WINDS ACROSS THE WATERS
WITH GUSTS UP TO 25-30 KTS AT TIMES. A SMALL CRAFT ADVISORY
REMAINS IN EFFECT FOR ALL ZONES (EXCEPT THE COLUMBIA RIVER BAR)
UNTIL 11 PM TONIGHT. STRONGEST WINDS ARE EXPECTED IN THE LATE
AFTERNOON TO OVERNIGHT HOURS, AS WELL AS FOR THE CENTRAL OREGON
COASTAL WATERS. THE THERMAL TROUGH WILL BREAK DOWN TONIGHT,
ALLOWING WINDS TO EASE THURSDAY INTO FRIDAY. SEAS ARE EXPECTED TO
PERSIST AROUND 5 TO 8 FT AROUND 10 SECONDS THROUGH THE MIDDLE OF
THE WEEK. -HEC
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR PZZ251>253-
271>273.
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