972
FXUS66 KPQR 262330
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
430 PM PDT SAT APR 26 2025
UPDATED AVIATION DISCUSSION
SYNOPSIS
SHOWERS CONTINUE TO DISSIPATE WITH NORTHEASTERLY
FLOW ALOFT. UPPER LEVEL LOW REMAINS NEARLY STATIONARY THROUGH
SUNDAY MORNING WITH THE ONLY CHANCES FOR RAIN BEING OVER THE
LANE COUNTY CASCADES AND NORTH COAST. ACCUMULATION WILL BE
MINIMAL. RIDGING ON MONDAY WILL LEAD TO DRY AND BREEZY ONSHORE
FLOW, THEN ANOTHER FRONT ARRIVES TUESDAY INTO WEDNESDAY. HIGH
CONFIDENCE IN ABOVE NORMAL TEMPERATURES FOR THURSDAY.
SHORT TERM...NOW THROUGH MONDAY NIGHT
AN UPPER LEVEL LOW
SITS OVER NORTHERN CALIFORNIA TODAY AND WILL SHIFT EASTWARD
SLOWLY OVERNIGHT INTO SUNDAY. SOUTHEASTERLY FLOW ALOFT WILL
PERSIST BRINGING LIGHT SHOWERS OVER THE REGION. THESE SHOWERS
HAVE PRODUCED VERY LITTLE ACCUMULATION AND IS GENERALLY ISOLATED
OVER LANE COUNTY AND THE CASCADES. BASED ON SATELLITE IMAGERY,
THERE ARE SOME INDICATIONS OF THUNDERSTORMS BUT SO FAR HAVE
REMAINED EAST AND SOUTH OF THE AREA. WILL CONTINUE TO WATCH AS
SKIES CLEAR AND PEAK DAYTIME HEATING ALLOWS FOR MORE VERTICAL
CONVECTION. SATELLITE ALSO SHOW CUMULUS FORMING ALONG THE
OREGON/WASHINGTON BORDER AND OVER THE WATERS AGAIN SHOWING THE
CONVECTIVE NATURE OF THE ATMOSPHERE. WINDS HAVE BEGUN TO
INCREASE ALONG THE COAST WITH GUSTS UP TO 25 MPH REPORTED AROUND
TILLAMOOK AND NEWPORT. THESE WINDS ARE DUE TO A NORTHERLY WIND
REVERSAL WHICH IS COMMONLY ASSOCIATED WITH A SUMMER PATTERN.
AS THE UPPER LOW EXITS TO THE EAST, A WEAK RIDGE BEGINS TO BUILD
SUNDAY NIGHT INTO MONDAY MORNING. DURING THE BRIDGE BETWEEN
THESE TWO SYSTEMS, CONDITIONS WILL NOT NECESSARILY BE EXCITING.
THERE IS AROUND A 10-15% CHANCE OF SHOWERS ALONG THE NORTH
OREGON AND SOUTH WASHINGTON COASTS THROUGH THE AFTERNOON.
ONSHORE FLOW WILL INTENSIFY AS THE PRESSURE AND TEMPERATURE
GRADIENT INCREASES. BASED ON THE NBM, THE UPPER HOOD RIVER
VALLEY HAS AROUND A 50-65% CHANCE OF SEEING 24 HOUR WIND GUSTS
GREATER THAN 35 MPH. HIGH RESOLUTION MODELS SHOW A LOWER
PROBABILITY (AROUND 10-15% CHANCE). OVERALL, WINDS WILL BE
DECIDED UPON BY WHERE THE LOW ENDS UP TRACKING. MOST OF THE
HIGHER WINDS WILL BE EAST OF THE CASCADES OR ALONG THE HIGHER
TERRAIN.
ON MONDAY THE RIDGE WILL BUILD WITH DRY CONDITIONS BOTH AT THE
SURFACE AND ALOFT. -MUESSLE
LONG TERM...TUESDAY NIGHT THROUGH FRIDAY
WPC ENSEMBLE
CLUSTERS CONTINUE TO ADVERTISE A RETURN OF UPPER LEVEL RIDGING
MID TO LATE NEXT WEEK, BRINGING ANOTHER WARMING TREND WITH HIGHS
BACK IN THE 70S IN THE INTERIOR LOWLANDS NEXT WEDNESDAY AND
THURSDAY. RECENT RUNS OF THE NBM ARE SHOWING EVEN HIGHER
PROBABILITY FOR TEMPERATURES GREATER THAN 80 DEGREES F ON
THURSDAY. THROUGH THE WILLAMETTE VALLEY, PROBABILITIES RANGE
FROM NEAR 90% CHANCE NEAR PORTLAND TO 50% CHANCE IN EUGENE. THIS
GRADIENT IS DRIVEN BY THE EAST TO NORTHEASTERLY FLOW ALOFT.
WARMER AIR FROM THE COLUMBIA BASIN WILL MOVE INTO THE REGION
IMPACTING THE AREAS WITHIN THE EAST-WEST ALIGNED TERRAIN OR
EXPOSURE THE MOST. SOME CLOUD COVER MAY ALSO BE PRESENT TO THE
SOUTH WHICH WOULD DAMPEN THOSE TEMPERATURES. BASED ON THE GFS,
850 MB TEMPERATURES WILL BE AROUND 8 DEG C WHICH IS WARM FOR
THIS TIME OF YEAR. INTERESTINGLY, GIVEN THE DISTANCE IN TIME,
MODELS ARE IN FAIRLY GOOD AGREEMENT IN REGARDS TO THE HIGH
TEMPERATURE FORECAST. THE AREAS WITH THE LEAST AGREEMENT, 4-6
DEGREE F SPREAD BETWEEN THE 25TH-75TH PERCENTILE, IS ALONG THE
COAST RANGE. OTHERWISE, IT'S ONLY AROUND A 2-3 DEGREE SPREAD.
AFTER THE WARM DAY, THE RIDGE WILL BREAK DOWN AND A FRONTAL
SYSTEM WILL ARRIVE ON FRIDAY MORNING. THIS FRONT AT THIS TIME IS
MORE ORGANIZED THAN PREVIOUS SYSTEMS. IT WILL ALSO HAVE THE
ADDED BENEFIT OF THESE LAST FEW DAYS OF ONSHORE FLOW TO MOISTEN
UP THE ATMOSPHERE AND MAKE IT MORE AVAILABLE TO HAVE
ACCUMULATING PRECIPITATION. THE CAVEAT TO THAT FORECAST WILL
RESIDE WITH THE EXTEND OF HOW ELONGATED THE LOW BECOMES AND HOW
FAR SOUTH IT ADVECTS. THE GFS HAS THE MOST NORTHERLY SOLUTION
WITH THE FORECAST AREA SITTING IN THE LEFT EXIT REGION OF THE
JET. IN CONTRAST, THE ECMWF AND CANADIAN ARE MUCH FURTHER SOUTH
AND EVENTUALLY MOVING INTO THE LESS ACTIVE PORTION OF THE JET
OVER THE WEEKEND. OVERALL, CONFIDENCE IN GENERAL WITH THIS
PORTION OF THE FORECAST IS LOW. -MUESSLE
AVIATION
ONGOING VFR FLYING CONDITIONS AT INLAND TERMINALS WILL
CONTINUE INTO TONIGHT. A MARINE PUSH REACHING INLAND ALONG THE
COLUMBIA AND ULTIMATELY SOUTH INTO THE WILLAMETTE VALLEY WILL SEE
INCREASING CLOUDS AND LOWERING CLOUD BASES, RESULTING IN 40-60%
CHANCES OF DEVELOPING MVFR CIGS. MVFR CONDITIONS WOULD INITIALLY
REACH PORTLAND-AREA TERMINALS (PDX, HIO, TTD) BY 12-15Z SUN, AND
THEN SOUTHWARD TO WILLAMETTE VALLEY TERMINALS (UAO, SLE, EUG) BY
14-16Z SUN. A BREAKOUT FROM MARINE STRATUS AND A RETURN TO VFR
CIGS IS FAVORED BY 17-19Z SUN. WEST TO NORTHWEST WINDS OF AROUND
5 KT WILL WEAKEN TO LESS THAN 5 KT OVERNIGHT, BEFORE INCREASING TO
5-10 KT OUT OF THE WEST TO SOUTHWEST.
ALONG THE COAST, WITH 60-80% CONFIDENCE, MVFR CIGS WITHIN MARINE
STRATUS WILL PERSIST THROUGH MUCH OF THE PERIOD. AFTER 21Z SUN,
THERE IS A 30-50% CHANCE OF SUFFICIENT CLEARING TO SEE VFR
CONDITIONS, WITH MVFR CIGS OTHERWISE FAVORED. NORTH-NORTHWEST
WINDS AT 10-15 KT GUSTING 20-25 KT WILL CONTINUE INTO THE EVENING,
THROUGH 03-06Z SUN, BEFORE WEAKENING TO 5-10 KT THROUGH THE
OVERNIGHT. NORTHWEST WINDS INCREASE TO 8-12 KT AFTER 18-21Z SUN.
PDX AND APPROACHES...VFR CONDITIONS WITH NORTHWEST WINDS OF 5-10
KT WILL CONTINUE THROUGH THIS EVENING INTO THE OVERNIGHT PERIOD. A
MARINE PUSH ARRIVING AFTER 12-14Z SUN WILL BRING 40-60% CHANCES OF
MVFR CIGS AND WINDS WEAKENING TO LESS THAN 5 KT. BREAKOUT FROM
MARINE STRATUS AND A RETURN TO VFR CONDITIONS IS FAVORED BY
19-21Z SUN, WITH NORTHWEST WINDS AROUND 5 KT. -PICARD
MARINE
HIGH PRESSURE OVER THE NORTHEAST PACIFIC ALONG WITH A
LOW IMPACTING CALIFORNIA HAS TIGHTENED THE PRESSURE GRADIENT
ACROSS OUR WATERS. THIS HAS RESULTED IN NORTHWEST WINDS GUSTING
UP TO 25-30 KT IN THE OUTER COASTAL WATERS AND UP TO 25 KT FOR
THE INNER COASTAL WATERS. WITH THESE BREEZY CONDITIONS AND A
BUILDING NORTHWESTERLY SWELL, EXPECT COMBINES SEAS TO REACH 10
TO 11 FEET THIS MORNING. AS A RESULT, THE SMALL CRAFT ADVISORY
CONTINUES ACROSS ALL WATERS INTO TONIGHT. THE OUTER COASTAL
WATERS SEE SMALL CRAFT CONDITIONS PERSIST INTO SUNDAY MORNING.
THE COLUMBIA RIVER BAR IS ALSO EXPERIENCING SMALL CRAFT ADVISORY
CONDITIONS BUT WILL DROP OFF AROUND 8 PM THIS EVENING. ANOTHER
SHORT SMALL CRAFT HAS BEEN ISSUED FOR A VERY STRONG EBB OF 6.99 KT
AT 449 AM
BY EARLY SUNDAY, BOTH WINDS AND SEASONS WILL BEGIN TO EASE AS
HIGH PRESSURE WEAKENS SLIGHTLY AND MOVES INLAND. THE START OF NEXT
WEEK LOOKS TO BE RATHER QUIET, WITH SEAS AROUND 5 TO 7 FEET AND
WIND GUSTS UNDER 20 KT. -BATZ/HALL
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 8 PM PDT THIS EVENING FOR PZZ210.
SMALL CRAFT ADVISORY FROM 2 AM TO 8 AM PDT SUNDAY FOR PZZ210.
SMALL CRAFT ADVISORY UNTIL 2 AM PDT SUNDAY FOR PZZ251>253.
SMALL CRAFT ADVISORY UNTIL 2 PM PDT SUNDAY FOR PZZ271>273.
WWW.WEATHER.GOV/PORTLAND
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