991
FXUS66 KPQR 221020
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
320 AM PDT TUE APR 22 2025
SYNOPSIS
EXPECT WARMING TEMPERATURES AND MOSTLY CLEAR SKIES THROUGH
THURSDAY. PATTERN CHANGE RETURNS LATE THURSDAY INTO FRIDAY AS
AN APPROACHING SYSTEM RETURNS COOLER TEMPERATURES AND CHANCES
FOR PRECIPITATION.
SHORT TERM...NOW THROUGH WEDNESDAY NIGHT
THIS MORNING, CLEAR SKIES, LIGHT WINDS, AND DRY AIR HAVE
SUPPORTED EFFICIENT RADIATIONAL COOLING ACROSS THE REGION.
TEMPERATURES HAVE DROPPED INTO THE 33-36 DEGREE RANGE ACROSS
MUCH OF THE INTERIOR WEST OF THE CASCADES, WITH COLDER POCKETS
IN OUTLYING VALLEYS AND SHELTERED RURAL AREAS. SHOULD SEE SOME
FROST FORMATION PARTICULARLY OVER GRASSY AND EXPOSED SURFACES.
A FROST ADVISORY REMAINS IN EFFECT UNTIL 9 AM FOR MOST LOWLAND
AREAS, EXCLUDING THE IMMEDIATE COAST AND INNER PORTLAND METRO,
WHERE URBAN HEAT ISLAND EFFECTS LIKELY HAVE KEPT TEMPERATURES
HIGHER.
IN THE UPPER HOOD RIVER VALLEY, TEMPERATURES HAVE FALLEN INTO
THE UPPER 20S TO LOW 30S, WITH THE COLDEST SPOTS ABOVE 1000 FEET
BETWEEN PARKDALE AND ODELL. A FREEZE WARNING REMAINS IN EFFECT
FOR THIS AREA THROUGH 9 AM. RESIDENTS IN THIS AREA SHOULD
ENSURE OUTDOOR PLANTS REMAIN PROTECTED UNTIL TEMPERATURES
RECOVER LATER THIS MORNING.
A PRONOUNCED WARMING TREND IS EXPECT THROUGH MIDWEEK, WITH HIGH
PRESSURE AND UPPER-LEVEL RIDGING BUILDING OVER THE REGION.
HIGHS TODAY WILL REACH THE LOW TO MID 60S ACROSS THE INTERIOR,
CLIMBING TO THE HIGH 60S TO LOW 70S BY WEDNESDAY UNDER MOSTLY
SUNNY SKIES AND DRY CONDITIONS. NO PRECIPITATION IS EXPECTED
THROUGH AT LEAST WEDNESDAY NIGHT.
~HALL
LONG TERM...THURSDAY TO SUNDAY
DRY AND MILD WEATHER CONTINUES THURSDAY AS UPPER-LEVEL RIDGING
HOLDS OVER THE REGION, KEEPING CONDITIONS STABLE. THURSDAY WILL
LIKELY BE THE WARMEST DAY OF THE WEEK, WITH INTERIOR HIGH
TEMPERATURES FORECASTED TO REACH THE MID TO UPPER 70S. THERE IS
A LOW-END CHANCE (15-35%) THAT PARTS OF THE PORTLAND/VANCOUVER
METRO COULD FLIRT WITH 80 DEGREES.
A TRANSITION BEGINS THURSDAY NIGHT INTO FRIDAY AS ENSEMBLE
GUIDANCE FROM GEFS, EPS, AND GEPS ALIGNS ON AN UPPER TROUGH
APPROACHING THE PACIFIC NORTHWEST. ALTHOUGH THERE IS STILL SOME
SPREAD IN TIMING AND EXACT PLACEMENT OF THE LOW, CONFIDENCE IS
GROWING THAT THIS SYSTEM WILL BRING A NOTICEABLE SHIFT BACK TO
COOLER TEMPERATURES AND INCREASE RAIN CHANCES. IF THE TIMING
HAPPENS TO BE EARLIER AND RAIN BEGINS THURSDAY EVENING, COULD
SEE SOME THUNDERSTORM DEVELOPMENT NEAR THE LANE COUNTY CASCADES
AND CASCADE FOOTHILLS.
BY FRIDAY, PROBABILITIES FOR 0.25 INCHES OR MORE OF RAIN IN A
24 HOUR WINDOW (5 AM FRIDAY TO 5 AM SATURDAY) RANGE FROM 20-30%
ALONG THE COAST AND WILLAMETTE VALLEY, AND CLOSER TO 40-70% IN
THE COAST RANGE AND CASCADES. PRECIPITATION CHANCES AND BELOW-
NORMAL TEMPERATURES LOOK TO PERSIST INTO THE WEEKEND AS THE
TROUGH DEEPENS AND EXPANDS ACROSS THE WESTERN US. ~HALL
AVIATION
PREDOMINATELY VFR CONDITIONS EXPECTED THROUGH THE TAF
PERIOD ACROSS NW OREGON AND SW WASHINGTON. AT 10Z TUESDAY, SATELLITE
IMAGERY SHOWS STRATUS REMAINS ALONG THE WEST SLOPES OF THE NORTH
OREGON CASCADES ALONG WITH STRATUS BUILDING OVER THE COAST RANGE,
DROPPING TO MVFR CEILINGS AT TIMES. GUIDANCE CONTINUES TO
INDICATE THE POTENTIAL OF THE STRATUS ALONG THE CASCADES
SPREADING WEST INTO THE NORTHERN AND CENTRAL WILLAMETTE VALLEY,
INCLUDING THE PORTLAND METRO AREA, AROUND 12-18Z TUESDAY WITH A
10-30% CHANCE OF MVFR CEILINGS. VFR CONDITIONS EXPECTED TO RETURN
EVERYWHERE BY 18-21Z TUESDAY. NORTHERLY WINDS GENERALLY LESS THAN
10 KTS THROUGH THE TAF PERIOD FOR MOST AREAS. WINDS TO INCREASE
ALONG THE COAST AND IN THE CENTRAL/SOUTHERN WILLAMETTE VALLEY FROM
18Z TUESDAY TO 03Z WEDNESDAY WITH GUSTS UP TO 18-25 KNOTS
POSSIBLE.
PDX AND APPROACHES...PREDOMINATELY VFR CONDITIONS OVER THE TAF
PERIOD. STRATUS BUILDING ALONG THE WEST SLOPES OF THE CASCADES
COULD DRIFT WESTWARD NEAR THE TERMINAL WHILE DISSIPATING FROM
12-18Z TUESDAY. GUIDANCE SUGGESTS A 20-40% CHANCE TO SEE AT LEAST
AN HOUR OF MVFR CIGS AT PDX DURING THIS PERIOD. NORTH WINDS LESS
THAN 10 KTS THROUGH THE TAF PERIOD. -HEC
MARINE
STRONG HIGH PRESSURE OFFSHORE ALONG WITH A SURFACE
LEVEL THERMAL TROUGH DEVELOPING AND STRENGTHENING OVER THE
SOUTHERN AND CENTRAL OREGON COAST WILL MAINTAIN NORTHERLY WINDS
ACROSS ALL WATERS THROUGH THE MIDDLE OF THE WEEK. CENTRAL OREGON
COASTAL WATERS WILL SEE INCREASING WINDS THIS EVENING INTO TUESDAY
MORNING WITH GUSTS OF 20-25 KTS AT TIMES. A SMALL CRAFT ADVISORY
REMAINS IN EFFECT FOR ZONE PZZ273. AS THE THERMAL TROUGH
STRENGTHENS OVER THE COAST, THESE WINDS ARE EXPECTED TO SPREAD
NORTH ALONG THE NORTHERN OREGON AND SOUTHERN WASHINGTON COASTAL
WATERS LATE TUESDAY INTO WEDNESDAY NIGHT, WITH GUSTS 25-30 KTS
POSSIBLE AT TIMES. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR
ZONES PZZ253, PZZ252, AND PZZ272 STARTING 2 PM TUESDAY. HAVE ALSO
ADDED A SMALL CRAFT ADVISORY FOR ZONES PZZ271 AND PZZ251 FOR THE
SAME TIME AS GUIDANCE IS INDICATING A 60-70% CHANCE OF WIND GUSTS
OVER 21 KTS IN THE SOUTHERN HALF OF THESE ZONES AS WELL AS NEAR
THE WESTERN BORDER OF ZONE PZZ271. STRONGEST WINDS ARE EXPECTED
TO EBB AND FLOW DIURNALLY, STRONGEST IN THE LATE AFTERNOON TO
OVERNIGHT HOURS, BACKING OFF IN THE MORNING HOURS. SEAS ARE
EXPECTED TO PERSIST AROUND 6 TO 8 FT AROUND 10 SECONDS THROUGH THE
MIDDLE OF THE WEEK. -HEC
PQR WATCHES/WARNINGS/ADVISORIES
OR...FROST ADVISORY UNTIL 9 AM PDT THIS MORNING FOR ORZ104>109-
113>119-123>125.
FREEZE WARNING UNTIL 9 AM PDT THIS MORNING FOR ORZ121.
WA...FROST ADVISORY UNTIL 9 AM PDT THIS MORNING FOR WAZ203>205-208.
PZ...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM PDT
WEDNESDAY FOR PZZ251>253-271-272.
SMALL CRAFT ADVISORY UNTIL 2 AM PDT WEDNESDAY FOR PZZ273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
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