215
FXUS66 KPQR 311025
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
325 AM PDT SUN MAY 31 2026
SYNOPSIS
HIGH PRESSURE PERSISTS THROUGH TUESDAY WITH RISING
TEMPERATURES EACH DAY. MODERATE HEATRISK WITHIN THE
PORTLAND/VANCOUVER METRO AND LOWER I-5 CORRIDOR ON MONDAY AND
TUESDAY. WEAK SHORTWAVE AND MESOSCALE LOW PRESSURE TODAY WILL
CAUSE WINDS TO INCREASE OVER THE WATERS AND ALONG THE COAST.
FILLING LOW PRESSURE MOVES NEAR THE COAST STARTING WEDNESDAY.
ZONAL FLOW THROUGH FRIDAY. LOW PRESSURE INTENSIFIES ON SATURDAY
WITH INCREASING CHANCES FOR RAIN.
SHORT TERM...NOW THROUGH TUESDAY NIGHT
HIGH PRESSURE OVER THE
NORTHEAST PACIFIC PERSISTS THROUGH TUESDAY. WITH PLENTY OF
SUNSHINE TODAY, EXPECT AFTERNOON TEMPERATURES TO INCREASE TO
SEASONABLE AVERAGES. A WEAK MESOSCALE LOW PRESSURE SYSTEM FORMS
ALONG THE COAST THIS MORNING. THIS PATTERN COMPOSITION COMBINED
WITH DIURNALLY DRIVEN TEMPERATURE RISES WILL INDUCE BREEZY
NORTHERLY WINDS. GUSTS ALONG THE COAST WILL RISE TO 25-30 MPH
AND INLAND CLOSER TO 20-25 MPH. OVERNIGHT, TEMPERATURES WILL
RECOVER WITH LOWS IN THE MID TO UPPER 40S.
BY MONDAY, UPPER LEVEL RIDGING ATTEMPTS TO AMPLIFY JUST
OFFSHORE THOUGH IT WILL NOT REACH IT'S PINNACLE UNTIL TUESDAY.
THIS SHOULD KEEP THE POTENTIAL FOR THE HOTTEST TEMPERATURES AT
BAY ON MONDAY, BUT THE WARMING TREND IS EXPECTED TO CONTINUE
INTO TUESDAY. A SLIGHT SURFACE ONSHORE FLOW PERSISTS ON MONDAY
WHICH WILL AID IN KEEPING TEMPERATURES BELOW 90 DEGREES.
HOWEVER, FLOW ALOFT WILL BE EASTERLY AND THUS WARMING FROM
COMPRESSION IS LIKELY WITHIN THE LOWLANDS. IN THE HOTTEST
LOCATIONS, LIKE THE PORTLAND/VANCOUVER METRO AREA, THERE IS
AROUND A 10% CHANCE OF HIGH TEMPERATURES ON MONDAY OF 88 DEG F
OR GREATER, WITH SIMILAR PROBABILITIES FOR 80-85 DEG F ELSEWHERE
IN THE INTERIOR LOWLANDS. OVER THE LAST SEVERAL DAYS, THERE HAVE
BEEN MINOR SHIFTS IN THE FORECAST IN REGARDS TO ACTUALLY
EXPECTED HIGHS AND THUS, THE HEATRISK HAS WAVERED ON THE
THRESHOLD OF MODERATE AND MINOR HEATRISK. A FEW DEGREE RISE WILL
PUT MORE AREAS INTO MODERATE HEATRISK ON MONDAY. IN ADDITION,
OVERNIGHT TEMPERATURES WILL INCREASE INTO THE MID TO UPPER 50S
MONDAY NIGHT INTO TUESDAY SETTING A LAUNCHING PAD IN PLACE FOR A
TUESDAY WARM UP.
THE RIDGE AMPLIFIES FURTHER AND REACHING IT'S PEAK ON TUESDAY.
850 MB TEMPERATURES WILL BE IN THE 13-15 DEG C RANGE WHICH, WHEN
COMBINED WITH THE EASTERLY FLOW ALOFT WILL MIX DOWN THIS WARMER
AIR. LATEST PROBS SUGGEST THERE IS AROUND A 40-60% CHANCE OF
EXCEEDING 90 DEGREES ALONG THE I-5 CORRIDOR FROM CASTLE ROCK, WA
SOUTH TO SALEM, WITH HIGHEST PROBABILITIES LYING WITHIN THE
GREATER PORTLAND/VANCOUVER METRO. MUCH LOWER PROBABILITIES EXIST
IN THE SOUTHERN WILLAMETTE VALLEY WHERE THOSE CHANCES ARE AROUND
5-10%. THERE IS LESS THAN A 10% CHANCE OF HIGHS OF 95 DEG F OR
GREATER THROUGHOUT THE FORECAST AREA. A MODERATE HEATRISK IS
LIKELY (60- 80% CHANCE) FOR TUESDAY WITHIN THE GREATER
PORTLAND/VANCOUVER METRO AREA, WHICH MEANS THOSE WITHOUT ACCESS
TO SUFFICIENT COOLING AND HYDRATION MAY BE IMPACTED BY THE HEAT.
THEREFORE, TAKE PRECAUTIONS ON TUESDAY IF PARTICIPATING IN
OUTDOOR ACTIVITIES, ESPECIALLY DURING PEAK AFTERNOON HEATING.
THE HEAT IS NOT EXPECTED TO LAST LONG, THOUGH AS A DECENT MARINE
PUSH IS EXPECTED BY LATER TUE EVENING AHEAD OF AN UPPER
SHORTWAVE TROUGH. -27/DH
LONG TERM...WEDNESDAY THROUGH SATURDAY
THERE IS RELATIVELY HIGH
CONFIDENCE THAT TEMPERATURES COOL BACK INTO THE 70S ON WEDNESDAY AND
PERSIST THROUGH THE END OF THE WEEK, REMAINING NEAR TO SLIGHTLY
ABOVE AVERAGE TEMPERATURES FOR EARLY JUNE. MODELS AND THEIR
ENSEMBLES ARE IN FAIRLY GOOD AGREEMENT THAT A LOW PRESSURE
SYSTEM IN THE NE PACIFIC WEAKENS AS IT MOVES TOWARD THE GULF OF
ALASKA ON WEDNESDAY. AN ASSOCIATED FRONTAL BAND WELL AHEAD OF
THE SURFACE LOW WILL APPROACH THE COAST, BUT GUIDANCE CONTINUES
TO TREND DOWN WITH MINIMAL, IF ANY, PRECIPITATION SPREADING
INLAND. IN FACT, NBM GUIDANCE GENERALLY SHOWS LESS THAN A 10%
CHANCE OF RAIN THROUGH THURSDAY. BUT, THERE REMAIN A HANDFUL OF
ENSEMBLE MEMBERS THAT DO SHOW SOME QPF, SO WE CANNOT RULE OUT
SOME PRECIPITATION YET.
WITHIN THE LONG-TERM FORECAST, THERE IS GREAT UNCERTAINTY
REGARDING A POTENTIAL LOW PRESSURE SYSTEM. BASED ON THE ENSEMBLE
LOW PRESSURE CENTER OUTPUTS, SEVERAL MEMBERS ARE BRINGING A COOL
AIR WRAPPED LOW PRESSURE SYSTEM DOWN FROM THE GULF OF ALASKA AND
IT SKIRTS THE WASHINGTON COASTLINE. AT THIS POINT, THE NUMBER OF
MODELS THAT SHOW SOME KIND OF AN ADVECTING TROUGH LESS LESS THAN
40% AND THEREFORE, CONFIDENCE IS LOW. DESPITE THE POTENTIAL
PATTERN SHIFT, ONSHORE FLOW IS LIKELY WHICH WILL USHER IN COOLER
MARINE AIR AND THUS TEMPERATURES WILL BE LOWER. THE OVERALL
SPREAD BETWEEN THE 10TH TO 90TH PERCENTILE (ESSENTIALLY THE
COOLEST AND WARMEST SCENARIO) IS ONLY 10 DEG F RANGING FROM
AROUND 65-75 DEG F IN THE LOWLANDS WITH LITTLE TO NO CHANGE
ALONG THE COAST. THE BIG QUESTION IS IN REGARDS TO PRECIPITATION
ACCUMULATION WHERE THE SPREAD IS MUCH GREATER. FOR EXAMPLE, IN
TILLAMOOK, THE 10TH PERCENTILE (DRY SCENARIO) SHOWS 0.00 INCH OF
RAIN, WHERE THE 90TH PERCENTILE (WET SCENARIO) IS CLOSE TO 1.0
INCH. THEREFORE AGAIN CONFIDENCE IS LOW. -27/DH
AVIATION
VFR CONDITIONS GENERALLY PERSIST TONIGHT INTO SUNDAY
MORNING AT ALL TERMINALS AS THE FLOW ALOFT TURNS NORTHERLY.
HOWEVER, WE'LL HAVE TO WATCH SOME LOW CLOUDS SHOWN BY SATELLITE
(AS OF 05-06Z) BUILDING ALONG THE WEST FLANKS OF THE CASCADES.
THESE HAVE TO POTENTIAL TO SHIFT TOWARDS I-5/THE PORTLAND METRO
DURING THE 12-17Z PERIOD SUNDAY MORNING BEFORE DISSIPATING WITH A
15-25% CHANCE FOR MVFR CONDITIONS AT KPDX/KUAO AND A 30-40%
CHANCE A KTTD. OTHERWISE, HIGHER CONFIDENCE IN VFR CONDITIONS THE
REMAINDER OF THE FORECAST PERIOD. WINDS ALONG THE COAST AND IN THE
CENTRAL/SOUTHERN WILLAMETTE VALLEY INCREASE AS SUNDAY PROGRESSES
WITH GUSTS AROUND 20-25 KNOTS POSSIBLE.
KPDX AND APPROACHES...VFR CONDITIONS ARE FAVORED THROUGH THE TAF
PERIOD WITH PERSISTENT NORTHWESTERLY WINDS. THESE WINDS LIKELY
INCREASE AROUND 17-19Z SUNDAY WITH OCCASIONAL GUSTS AROUND 18-20
KNOTS IN THE AFTERNOON. IT'S WORTH NOTING THERE IS A 15-20%
CHANCE FOR MVFR CIGS BETWEEN 12-17Z SUNDAY MORNING AS CLOUDS SLOSH
TOWARDS THE TERMINAL FROM THE EAST - SOMETHING TO WATCH. -99
MARINE
HIGH PRESSURE BUILDS THROUGH TUESDAY WHICH WILL LEAD TO A
TYPICAL SUMMER LIKE PATTERN. HIGH PRESSURE WILL START TO MOVE
EASTWARD WHICH WILL RESULT IN INCREASING NORTH/NORTHWESTERLY
WINDS ACROSS ALL WATERS. AT THE SURFACE THERE IS ALSO AN
ADDITIONAL SHORTWAVE TROUGH WHICH, WHEN COMBINED WITH THE
OVERARCHING PATTERN, WILL INCREASE WINDS OVER ALL OF THE WATERS.
NORTHWESTERLY WINDS WILL BE HIGHEST IN PZZ253/273 WHERE WE WILL
SEE GUSTS UP TO 30 KT. SMALL CRAFT ADVISORY SPEEDS ARE STILL
EXPECTED OVER ALL OF THE WATERS THOUGH THEY WILL INCREASE
GRADUALLY FROM SOUTH TO NORTH. THE NORTHERN WATERS WILL SIT
RIGHT ALONG THE THRESHOLDS SO THE SPREAD OF GUSTS UP TO 25 KT
WILL BE INCONSISTENT. THESE WINDS ARE ALREADY BEGINNING TO PICK
UP IN THE SOUTHERN WATERS AND WILL PEAK THIS AFTERNOON. SEAS
WILL BE COMPRISED OF A NORTHWESTERLY PRIMARY SWELL AND THE
NORTHERLY WIND WAVE. SOME AREAS MAY SEE SEAS OF 10 FT BUT MOST
MODELS ARE SUGGESTING COMBINED WAVE HEIGHTS BELOW THAT
THRESHOLDS.
THE RIDGE CONTINUES TO SHIFT EASTWARD AND INTENSIFY THROUGH
TUESDAY BUT OVERALL WILL HAVE MINIMAL IMPACT TO THE MARINE
ENVIRONMENT. A PATTERN CHANGE EXPECTED ON WEDNESDAY AS A SERIES
OF SYSTEMS LOOK TO DIVE DOWN OUT OF THE NORTHEASTERN PACIFIC
THROUGH THE LATTER PART OF NEXT WEEK, BUT MINIMAL IMPACTS ARE
EXPECTED WITH THESE SYSTEMS AT THIS TIME. -27
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 8 AM PDT THIS MORNING FOR PZZ210.
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM PDT
MONDAY FOR PZZ251-271.
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 5 PM PDT
MONDAY FOR PZZ252-272.
SMALL CRAFT ADVISORY UNTIL 5 PM PDT MONDAY FOR PZZ253-273.
WWW.WEATHER.GOV/PORTLAND
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