203
FXUS66 KPQR 241008
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
308 AM PDT THU APR 24 2025
SYNOPSIS
HIGH PRESSURE WILL MAINTAIN WARM TEMPERATURES AND
DRY WEATHER ACROSS MOST OF THE AREA TODAY. AN APPROACHING SYSTEM
WILL BRING A 15 TO 20 PERCENT CHANCE OF THUNDERSTORMS THIS
EVENING ACROSS THE LINN AND LANE COUNTY CASCADES AS WELL AS THE
SOUTHERN WILLAMETTE VALLEY. LINGER SHOWERS OVER THE CENTRAL
OREGON CASCADES THROUGH SATURDAY, WITH WARM AND DRY CONDITIONS
PERSISTING ACROSS THE REST OF THE AREA. COOLER WEATHER EXPECTED
FOR SUNDAY AND MONDAY.
SHORT TERM...NOW THROUGH SATURDAY NIGHT
CLEAR SKIES PERSIST
ACROSS THE REGION EARLY THIS MORNING AS HIGH PRESSURE REMAINS
OVERHEAD. EXPECT TODAY TO BE THE WARMEST DAY OF THE WEEK AS 850
MB TEMPERATURES CLIMB A FEW MORE DEGREES TO 9-10 C THIS
AFTERNOON, YIELDING HIGHS WELL INTO THE 70S ACROSS THE INTERIOR
LOWLANDS. THE WARMEST SPOT WILL BE ACROSS THE PORTLAND METRO
AREA, WHERE THE NBM SHOWS ABOUT A 60% CHANCE TO REACH 80 DEGREES
THIS AFTERNOON. MEANWHILE, COASTAL AREAS WILL REMAIN MORE MILD
TODAY AS THE MARINE LAYER MAINTAINS ITS INFLUENCE ALONG THE
COAST. ASIDE FROM THE WARM TEMPERATURES, THE PRIMARY FORECAST
CONCERN FOR TODAY REMAINS THE POTENTIAL FOR A FEW ELEVATED
THUNDERSTORMS ACROSS THE SOUTHERN PART OF OUR AREA THIS
AFTERNOON AND EVENING AS AN UPPER LEVEL TROUGH APPROACHES
OFFSHORE. THE TROUGH WILL TAKE ON A SLIGHT NEGATIVE TILT AS IT
DIGS SOUTHWARD ALONG THE COAST. THIS WILL INDUCE SOUTHERLY OR
EVEN SLIGHTLY SOUTHEASTERLY FLOW ALOFT AND DRAWING MID LEVEL
MOISTURE NORTHWARD INTO OUR AREA, CONTRIBUTING TO MUCAPE VALUES
OF 200-400 J/KG ACROSS LANE COUNTY AND VICINITY BY LATE
AFTERNOON. WILL THEREFORE MAINTAIN A SLIGHT CHANCE OF
THUNDERSTORMS ACROSS PRIMARILY THE LANE AND LINN COUNTY
CASCADES BUT ALSO PORTIONS OF THE SOUTH WILLAMETTE VALLEY AND
COAST RANGE THROUGH LATE THIS EVENING. EXPECT ANY THUNDERSTORMS
THAT DO DEVELOP TO REMAIN WELL BELOW SEVERE THRESHOLDS GIVEN
LACK OF VERTICAL WIND SHEAR, WILL FREQUENT LIGHTNING, SMALL
HAIL, AND GUSTY AND ERRATIC WINDS BEING THE PRIMARY THREATS.
WARM AND MOSTLY DRY CONDITIONS PERSIST ACROSS THE AREA FRIDAY
AND SATURDAY AS THE UPPER TROUGH EVOLVES INTO A CLOSED LOW AND
DROPS SOUTH TOWARDS THE SAN FRANCISCO BAY AREA. WRAP AROUND
MOISTURE ON THE NORTHERN PERIPHERY OF THIS FEATURE WILL MAINTAIN
A CHANCE OF SHOWERS ACROSS THE SOUTHERN EXTENT OF THE AREA INTO
THE WEEKEND, WITH THE BEST PRECIPITATION CHANCES CONFINED TO
THE LANE COUNTY CASCADES THROUGH SATURDAY. WILL NEED TO CONTINUE
TO MONITOR THUNDER POTENTIAL OVER THE NEXT FEW DAYS, BUT CHANCES
GENERALLY REMAIN BELOW 10% FOR FRIDAY AND SATURDAY AS INCREASING
CLOUD COVER HELPS TO LIMIT INSTABILITY. MEANWHILE, EXPECT AREAS
FROM SALEM NORTHWARD TO REMAIN DRY THROUGH THE WEEKEND AS THE
LOW DROPS FARTHER SOUTH. THE INCREASED CLOUD COVER AND SHOWER
POTENTIAL OVER LANE COUNTY WILL ALSO CONTRIBUTE TO A FAIRLY
SIZABLE TEMPERATURE GRADIENT FROM SOUTH TO NORTH, WITH THE
EUGEN AREA LIKELY TO BE IN THE MID 60S ON FRIDAY WHILE THE
PORTLAND AREA REMAINS IN THE MID TO UPPER 70S. /CB
LONG TERM...SUNDAY THROUGH WEDNESDAY
TEMPERATURES WILL DROP
OFF MORE SUBSTANTIALLY SUNDAY AND MONDAY AS THE UPPER LOW MOVES
INTO THE GREAT BASIN AND USHERS IN BROAD ONSHORE FLOW ACROSS
THE PACIFIC NORTHWEST. THIS WILL BRING DAYTIME HIGHS CLOSER TO
SEASONAL NORMS IN THE LOW TO MID 60S THROUGH THE EARLY PART OF
NEXT WEEK. A PASSING SHORTWAVE TROUGH MAY BRING A FEW SHOWERS
TO TO THE AREA ON TUESDAY, BUT DO NOT SEE ANY INDICATIONS OF
MEANINGFUL PRECIPITATION AT THIS TIME. BEYOND TUESDAY, WPC
ENSEMBLE CLUSTERS FAVOR A RETURN OF UPPER LEVEL RIDGING OVER THE
REGION MID TO LATE NEXT WEEK, RESULTING IN ANOTHER WARMING
TREND AS DAYTIME HIGHS POTENTIALLY CLIMB BACK UP INTO THE 70S
FOR THE LATTER HALF OF NEXT WEEK. /CB
AVIATION
EXPECT VFR CONDITIONS AT MOST TERMINALS THROUGH THE
TAF PERIOD. COASTAL TERMINALS WILL BE THE EXCEPTION, WITH A
40-50% CHANCE OF MVFR CONDITIONS, 20-30% CHANCE OF IFR CONDITIONS,
AND A 10-20% CHANCE OF LIFR CONDITIONS BETWEEN 12-17Z THURSDAY.
CONDITIONS ALONG THE COAST WILL LIKELY RETURN TO VFR THEREAFTER,
WITH THE EXCEPTION OF KONP POSSIBLY (30-50% CHANCE) STAYING MVFR
THROUGH MOST OF THE TAF PERIOD. WINDS WILL GENERALLY STAY LIGHT
AND VARIABLE FOR MOST TERMINALS. TERMINALS ALONG THE COLUMBIA
RIVER GORGE WILL SEE INCREASED EASTERLY WINDS AROUND 8-10 KT
BETWEEN 18-23Z THURSDAY.
IT'S ALSO WORTH NOTING RIGHT AROUND 21-23Z THURSDAY, THERE IS
POTENTIAL FOR ISOLATED SHOWER AND THUNDERSTORM DEVELOPMENT IN THE
LANE COUNTY CASCADES/FOOTHILLS SOUTHWARD. HAVE REFRAINED FROM
MENTIONING IN THE KEUG TAF DUE TO LOW CONFIDENCE AT THIS TIME.
PDX AND APPROACHES...VFR CONDITIONS AND CLEAR SKIES CONTINUE
THROUGH THE TAF PERIOD WITH LIGHT NORTHWEST WINDS TURNING MORE
EASTERLY AND INCREASING TO 5-8 KT AFTER 18Z THURSDAY.
~HALL
MARINE
STRONG HIGH PRESSURE OFFSHORE WILL MAINTAIN NORTHERLY TO
NORTHWESTERLY WINDS ACROSS THE COASTAL WATERS THROUGH THE
UPCOMING WEEKEND. CURRENT INCREASED WINDS CONTINUE TO EASE THIS
MORNING AS A THERMAL TROUGH BREAKS DOWN. NORTH TO NORTHWESTERLY
WINDS WILL BEGIN TO INCREASE FRIDAY NIGHT, WITH GUSTS UP TO 25 KT.
AS A RESULT, HAVE ISSUED A SMALL CRAFT ADVISORY FOR THE OUTER
COASTAL WATERS BETWEEN CAPE SHOALWATER WA AND CAPE FALCON OR.
OTHERWISE, EXPECT SEAS TO PERSIST AROUND 5 TO 7 FT AND INCREASE
TO AROUND 9 FT ON SATURDAY, WITH PERIODS AROUND 12 SECONDS
DECREASING TO 9 TO 10 SECONDS THROUGH THE WEEKEND.
~HALL/TK
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 8 PM FRIDAY TO 5 AM PDT SATURDAY FOR
PZZ271.
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