769
FXUS66 KPQR 311725
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1025 AM PDT SUN MAY 31 2026
UPDATED AVIATION DISCUSSION.
SYNOPSIS
HIGH PRESSURE PERSISTS THROUGH TUESDAY WITH RISING
TEMPERATURES EACH DAY. MODERATE HEATRISK ALONG THE I-5 CORRIDOR
NORTH OF SALEM INCLUDING THE PORTLAND/VANCOUVER METRO 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 ITS 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 ITS 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
SURFACE HIGH PRESSURE CENTERED OFFSHORE WILL
MAINTAIN VFR CONDITIONS ACROSS THE AIRSPACE. PATCHY REMAINING
LOW CLOUDS THIS MORNING WILL ERODE BY 19-20Z SUN, YIELDING CLEAR
SKIES INTO TONIGHT. RISING DIURNAL WINDS WILL BECOME GUSTY BY
20-22Z SUN, REACHING 15-20 KT WITH GUSTS TO 30 KT ALONG THE
COAST AND 10-15 KT WITH GUSTS TO 20-25 KT INLAND OUT OF THE
NORTH TO NORTHWEST. TERRAIN WILL SHIELD EAST-WEST ORIENTED GAPS
FROM THE WIND, SO THE COLUMBIA GORGE INCLUDING KTTD WILL SEE
LIGHTER FLOW BELOW 10 KT OUT OF THE NORTHWEST. WINDS ALOFT WILL
TURN OFFSHORE TONIGHT, WHILE SURFACE WINDS EASE TO 5 KT OR LESS
OUT OF THE NORTH TO NORTHEAST. MARINE STRATUS IS FAVORED TO
REMAIN WEST OF COASTAL TERMINALS GIVEN INCIPIENT OFFSHORE FLOW.
KPDX AND APPROACHES...VFR CONDITIONS BENEATH LARGELY CLEAR SKIES
EXPECTED THROUGHOUT THE PERIOD. DIURNAL NORTHWEST WINDS WILL
RISE TO 10-15 KT WITH GUSTS OF 20 KT AFTER 20-21Z SUN, THEN EASE
BELOW 5 KT LATE THIS EVENING, AFTER 06Z MON. -36
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 NORTHERLY TO
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 SOUTH OF CAPE
FOULWEATHER OR WHERE GUSTS WILL REACH 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 SOUTH OF CAPE FOULWEATHER 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 GUIDANCE SUGGESTS 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 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
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page