597
FXUS66 KPQR 242340
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
440 PM PDT THU APR 24 2025
UPDATED AVIATION DISCUSSION
SYNOPSIS
HIGH PRESSURE WILL MAINTAIN WARM TEMPERATURES AND
DRY WEATHER THROUGH THE REST OF THE DAY (THURSDAY). AN
APPROACHING SYSTEM WILL BRING A 15 TO 20 PERCENT CHANCE OF
THUNDERSTORMS THIS EVENING ACROSS LANE COUNTY. LINGERING SHOWERS
OVER THE CENTRAL OREGON CASCADES THROUGH SATURDAY, WITH WARM
AND DRY CONDITIONS PERSISTING ACROSS THE REST OF THE AREA. DRY,
COOLER WEATHER EXPECTED FOR SUNDAY AND MONDAY. PRECIPITATION
CHANCES RETURN TUESDAY.
SHORT TERM...NOW THROUGH SATURDAY NIGHT
SATELLITE IMAGERY AS
OF EARLY THURSDAY AFTERNOON DEPICTS MOSTLY CLEAR SKIES ACROSS
NORTHWEST OREGON AND SOUTHWEST WASHINGTON, EXCEPT FOR LINGERING
MARINE STRATUS ALONG THE CENTRAL OREGON COAST. TEMPERATURES ARE
EXPECTED TO PEAK IN THE MID TO UPPER 70S TODAY FOR INTERIOR
VALLEYS (WARMEST CLOSER TO THE PORTLAND-VANCOUVER METRO), AND
UPPER 50S TO UPPER 60S ALONG THE COAST (WARMEST TOWARD THE NORTH
OREGON COAST DUE TO CLEARER SKIES). RELATIVE HUMIDITIES WERE
LOWERED ACROSS THE AREA TODAY EXCEPT FOR THE COAST AS
OBSERVATIONS HAVE BEEN TRENDING MUCH DRIER THAN ORIGINALLY
FORECAST.
THE UPPER LEVEL RIDGE THAT BROUGHT US DRY WEATHER WITH CLEAR
SKIES THE LAST COUPLE DAYS IS NOW BEING PUSHED EASTWARD BY AN
INCOMING UPPER LEVEL TROUGH. THIS TROUGH HAS A SLIGHT NEGATIVE
TILT TO IT, TURNING FLOW ALOFT MORE SOUTHEASTERLY. ISOLATED
THUNDERSTORMS THAT MAY POP UP IN SOUTHWEST OREGON COULD BE
PUSHED NORTHWESTWARD DUE TO THE SOUTHEAST STEERING FLOW.
THEREFORE, A SLIGHT CHANCE (15-20%) FOR THUNDERSTORMS WAS
INCLUDED IN THE FORECAST ACROSS LANE COUNTY THIS EVENING FROM
THE CASCADES TO THE COAST. EXPECT ANY THUNDERSTORMS THAT DO
DEVELOP TO REMAIN WELL BELOW SEVERE THRESHOLDS GIVEN LACK OF
VERTICAL WIND SHEAR. MAIN IMPACTS FROM PASSING THUNDERSTORMS
INCLUDE LIGHTNING, SMALL HAIL, AND GUSTY AND ERRATIC WINDS.
WARM AND MOSTLY DRY CONDITIONS PERSIST ACROSS THE AREA FRIDAY
AND SATURDAY AS THE UPPER TROUGH EVOLVES INTO A CLOSED LOW AND
DROPS SOUTH TOWARD CENTRAL CALIFORNIA. WRAP AROUND MOISTURE ON
THE NORTHERN PERIPHERY OF THIS LOW WILL MAINTAIN A CHANCE OF
SHOWERS ACROSS THE SOUTHERN EXTENT OF THE AREA INTO THE WEEKEND,
WITH THE BEST PRECIPITATION CHANCES CONFINED TO THE LINN AND
LANE COUNTY CASCADES THROUGH SATURDAY. WILL NEED TO CONTINUE
TO MONITOR THUNDER POTENTIAL OVER THE NEXT FEW DAYS, BUT CHANCES
GENERALLY REMAIN BELOW 15% FOR FRIDAY AND SATURDAY AS INCREASING
CLOUD COVER HELPS TO LIMIT INSTABILITY. CAN'T RULE OUT SOME
CONVECTIVE DEBRIS (REMNANTS OF THUNDERSTORMS) MOVING INTO THE
AREA FROM NORTHERN CALIFORNIA AND SOUTHERN OREGON.
MEANWHILE, EXPECT AREAS WEST OF THE CASCADES TO GENERALLY
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 EUGENE AREA LIKELY TO BE IN THE
LOW TO MID 60S FROM FRIDAY TO SATURDAY WHILE THE PORTLAND AREA
REMAINS IN THE MID TO UPPER 70S. -ALVIZ/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. HIGH PRESSURE WILL RE-BUILD ACROSS THE AREA,
RETURNING PREDOMINATELY DRY CONDITIONS ON SUNDAY.
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, THE MAJORITY OF 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. -ALVIZ/CB
AVIATION
WIDESPREAD VFR FLYING CONDITIONS EXPECTED ACROSS THE
MAJORITY OF THE REGION THROUGH THE PERIOD, WITH THE EXCEPTION OF
MARINE STRATUS YIELDING MVFR/IFR CIGS ALONG THE COAST AT AST/ONP.
CONDITIONS AT AST/ONP ARE EXPECTED TO TREND DOWNWARD THROUGH
03-04Z FRI, WITH PREVAILING IFR CIGS AND RESTRICTED VIS WITHIN
MIST AT ONP, ALTHOUGH LIFR FOG CANNOT BE RULED OUT. LOW- MVFR
CIGS AT 1-1.5 KFT ARE MORE LIKELY AS MARINE STRATUS PUSHES
NORTHWARD ALONG THE COAST, WHILE IFR CIGS SIMILARLY CANNOT BE
RULED OUT AT AST.
ELSEWHERE, PREVAILING VFR CONDITIONS ARE EXPECTED AS A SURFACE
LOW PUSHES INLAND OVER NORTHERN CA. AN AREA OF ISOLATED TO
SCATTERED SHOWERS WILL TRACK WESTWARD ABOUT THE NORTHERN FLANK
OF THE LOW ACROSS SOUTHWESTERN OR, POSSIBLY REACHING SOUTHERN
TERMINALS INCLUDING ONP/EUG. CONFIDENCE IS HIGHER IN LIGHT
SHOWERS AT ONP, ALTHOUGH RAIN MAY ACTUALLY SEE CONDITIONS
BRIEFLY IMPROVE, MOST LIKELY BETWEEN 04-08Z FRI. CONFIDENCE IS
LOWER OF ANY IMPACTS AT EUG WITH ONLY A 10-15% CHANCE IN SEEING
RAIN SHOWERS AT THE TERMINAL, HOWEVER THERE REMAINS A LOW
CHANCE, AROUND 10%, THAT THUNDERSTORMS MAY DEVELOP FROM THE LANE
COUNTY CASCADE FOOTHILLS WESTWARD THROUGH 06Z FRI. IMPACTS ARE
LOW CONFIDENCE AND WOULD BE VERY ISOLATED. DRY CONDITIONS ARE
OTHERWISE EXPECTED WITH WINDS OF 10 KT OR LESS ACROSS THE REGION.
PDX AND APPROACHES...VFR CONDITIONS WILL PREVAIL THROUGHOUT THE
PERIOD. COVERAGE OF MID TO HIGH CLOUDS AT 15-25 KFT WILL INCREASE
THROUGH 06Z FRI AS A SURFACE LOW MOVES INLAND WELL TO THE SOUTH,
BEFORE SKIES TREND CLEARER AFTER 18-21Z FRI. LIGHT AND VARIABLE
WINDS THROUGH MUCH OF TONIGHT WILL TURN OUT OF THE NORTHWEST AT
AROUND 5 KT BY 18-21Z FRI. -PICARD
MARINE
STRONG HIGH PRESSURE OFFSHORE WILL MAINTAIN NORTHERLY
TO NORTHWESTERLY WINDS ACROSS THE COASTAL WATERS THROUGH THE
UPCOMING WEEKEND. NORTH TO NORTHWESTERLY WINDS WILL BEGIN TO
INCREASE FRIDAY NIGHT, WITH GUSTS UP TO 25 KT AND THESE WINDS
WILL SLOWLY SPREAD SOUTHWARD ACROSS ALL WATERS THROUGH FRIDAY
NIGHT. AT THE SAME TIME, A BUILDING WESTERLY SWELL WILL RESULT
IN SEAS BUILDING TOWARDS 7 TO 11 FT. AS A RESULT HAVE ADJUSTED
AND ADDED SMALL CRAFT ADVISORIES FOR ALL WATERS AND THESE
CONDITIONS ARE EXPECTED TO PERSIST THROUGH AT LEAST SATURDAY
EVENING. AFTERWARDS, WINDS AND SEA WILL SLOWLY SUBSIDE TO BELOW
SMALL CRAFT CONDITIONS BY THE START OF NEXT WEEK. /42
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 2 AM TO 5 PM PDT SATURDAY FOR
PZZ251>253.
SMALL CRAFT ADVISORY FROM 5 PM FRIDAY TO 5 PM PDT SATURDAY FOR
PZZ271>273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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