637
FXUS66 KPQR 291015
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
315 AM PDT SUN JUN 29 2025
SYNOPSIS
WARM AND DRY WEATHER WILL PERSIST THROUGH THE REMAINDER OF THE
WEEKEND, WITH TEMPERATURES CONTINUING TO RISE INTO EARLY NEXT
WEEK. THE HOTTEST DAY IS EXPECTED TO BE MONDAY, WITH WIDESPREAD
HIGHS IN THE LOW TO MID 90S ACROSS INTERIOR VALLEYS. SLIGHT
COOLING FOLLOWS MIDWEEK, BUT TEMPERATURES WILL REMAIN ABOVE
SEASONAL NORMS. THERE IS ALSO A LOW-END POTENTIAL FOR ISOLATED
THUNDERSTORMS OVER THE CENTRAL OREGON CASCADES MONDAY AND
TUESDAY.
DISCUSSION...NOW THROUGH SATURDAY
THE REGION REMAINS UNDER THE INFLUENCE OF DRY AND WARMING
CONDITIONS THIS MORNING, WITH TEMPERATURES ON TRACK TO CLIMB
FURTHER THROUGH MONDAY. A BROAD ZONAL FLOW PATTERN ACROSS THE
PACIFIC NORTHWEST IS EVOLVING INTO A MORE AMPLIFIED REGIME AS A
RIDGE OF HIGH PRESSURE - ROOTED OVER THE DESERT SOUTHWEST -
BUILDS NORTHWARD ALONG ITS WESTERN EDGE. THIS WILL REINFORCE
WARMING ACROSS THE AREA, PARTICULARLY FOR INLAND VALLEYS.
HIGH TEMPERATURES TODAY WILL REACH THE UPPER 80S TO NEAR 90
ACROSS THE INTERIOR LOWLANDS. MEANWHILE, COOLER MARINE INFLUENCE
AND PERSISTENT ONSHORE FLOW WILL KEEP COASTAL ZONES AND HIGHER
ELEVATIONS IN THE UPPER 60S TO MID 70S, OFFERING MORE
COMFORTABLE CONDITIONS.
MONDAY WILL LIKELY BE THE HOTTEST DAY OF THE PERIOD. INLAND
VALLEYS ARE FORECAST TO SEE HIGHS IN THE LOW TO MID 90S, WITH
LOCALIZED DOWNSLOPE EASTERLY FLOW ENHANCING WARMTH ON THE
WESTERN SLOPES OF THE CASCADES. HOWEVER, THIS DOWNSLOPE
INFLUENCE SHOULD REMAIN SHALLOW AND NOT SIGNIFICANTLY IMPACT
COASTAL TEMPERATURES, WHICH ARE EXPECTED TO HOLD IN THE LOW TO
MID 70S. CURRENT PROBABILISTIC GUIDANCE INDICATES A 40-70%
CHANCE FOR TEMPERATURES EXCEEDING 95 DEGREES IN THE WILLAMETTE
VALLEY, PARTICULARLY SOUTH OF PORTLAND. SIMILARLY, THERE IS
ABOUT A 50-70% CHANCE THAT THE UPPER HOOD RIVER VALLEY WILL ALSO
REACH 95 DEGREES ON MONDAY. ALTHOUGH THIS HEAT EVENT IS BRIEF
AND DOES NOT CURRENTLY MEET CRITERIA FOR EXCESSIVE HEAT
HEADLINES, SENSITIVE POPULATIONS - ESPECIALLY THOSE WITHOUT
ACCESS TO COOLING - MAY EXPERIENCE DISCOMFORT.
THERE IS ALSO A SLIGHT CHANCE (15-25%) OF ISOLATED
THUNDERSTORMS MONDAY AFTERNOON AND EVENING ACROSS THE OREGON
CASCADES, MAINLY FROM LANE COUNTY SOUTHWARD. A WEAK DISTURBANCE
OFF THE NORTHERN CALIFORNIA COAST IS HELPING TO ADVECT MID-LEVEL
MOISTURE INTO THE REGION. COMBINED WITH MODEST INSTABILITY -
MOST NOTABLE OVER THE CENTRAL OREGON CASCADES - THIS MAY BE
SUFFICIENT FOR THUNDERSTORM INITIATION OVER HIGHER TERRAIN.
SHOULD MOISTURE TRENDS SHIFT NORTHWARD, ISOLATED STORM ACTIVITY
COULD APPROACH AREAS CLOSER TO MOUNT HOOD, THOUGH CONFIDENCE
REMAINS RATHER LOW AT THIS TIME. A SIMILAR PATTERN HOLDS FOR
TUESDAY, THOUGH STORM COVERAGE AND ORGANIZATION APPEAR TO
DIMINISH SOMEWHAT. WITH SOUTHWESTERLY UPPER LEVEL FLOW EXPECTED,
CONFIDENCE FOR THUNDERSTORM DEVELOPMENT IS MUCH LOWER AS THE
FLOW WILL LIKELY KEEP THUNDERSTORMS TO THE EAST OF THE CASCADES.
TEMPERATURES WILL MODERATE SLIGHTLY BEGINNING TUESDAY, THOUGH
STILL REMAINING ABOVE NORMAL. HIGHS THROUGH MIDWEEK SHOULD
SETTLE INTO THE LOW TO MID 80S ACROSS THE WILLAMETTE VALLEY,
WITH OVERNIGHT LOWS GENERALLY IN THE 50S. ENSEMBLE GUIDANCE
CONTINUES TO SUPPORT A WARM AND DRY PATTERN THROUGH AT LEAST
SATURDAY, WITH LITTLE SIGNAL FOR SIGNIFICANT COOLING DURING
THAT TIME FRAME. ~HALL
AVIATION
WIDESPREAD VFR CONDITIONS EXPECTED TO PERSIST ACROSS
THE AIRSPACE, AS AN UPPER LEVEL HIGH PRESSURE SYSTEM REMAINS
ANCHORED OVER THE PAC NW. CURRENT SATELLITE OBSERVATIONS AS OF 09Z
SUNDAY, SHOW SOME MARINE CLOUDS ABOUT 30NM OFFSHORE. THESE CLOUDS
ARE NOT EXPECTED TO SPREAD INLAND. NORTHERLY WINDS LESS THAN 10
KT EXPECTED THROUGH AT LEAST 17Z SUNDAY. AFTERWARDS, EXPECT
NORTHERLY WINDS TO INCREASE ACROSS THE AIRSPACE, WITH GUSTS UP TO
30 KT ALONG THE COAST AND GUSTS UP TO 20 KT FOR INLAND LOCATIONS.
THESE GUSTS ARE EXPECTED TO PERSIST THROUGH AROUND 04Z-08Z MONDAY.
PDX AND APPROACHES...WIDESPREAD VFR WITH NORTHERLY WINDS THROUGH
THE PERIOD. WINDS CURRENTLY LESS THAN 10 KT; WINDS INCREASE
AROUND 18Z-20Z SUNDAY WITH GUSTS UP TO 20 KT THROUGH 03Z-05Z
SUNDAY. /42
MARINE
HIGH PRESSURE OVER THE PACIFIC WILL MAINTAIN NORTHERLY
WINDS ACROSS ALL WATERS THROUGH THE WEEK. TODAY, WINDS WILL
GRADUALLY STRENGTHEN FROM SOUTH TO NORTH AS PRESSURE GRADIENTS
TIGHTEN. EXPECT NORTHERLY WINDS AROUND 15-20 KT WITH GUSTS TO
UP TO 30 KT, THROUGH AT LEAST EARLY MONDAY MORNING. BREEZY
NORTHERLY WINDS ARE EXPECTED TO PERSIST GIVEN THE OVERALL PATTERN
IS NOT EXPECTED TO CHANGE MUCH. THEREFORE, HAVE EXTENDED THE
CURRENT SUITE OF SMALL CRAFT ADVISORIES THROUGH AT LEAST MONDAY
MORNING.
SEAS 5 TO 8 FT AT 9 TO 10 SECONDS THROUGH TUESDAY. GIVEN THAT
SEAS WILL MAINLY BE WIND-DRIVEN, COMBINING THAT WITH WESTERLY
SWELLS, EXPECT CONDITIONS TO BE STEEP AND CHOPPY AT TIMES. OVERALL
CONDITIONS EXPECTED TO SLOWLY SUBSIDE THROUGH THE MIDDLE OF THE
WEEK AS THE AFOREMENTIONED HIGH PRESSURE IS PUSHED EASTWARD. /42
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 11 AM PDT
MONDAY FOR PZZ210.
SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 11 AM PDT MONDAY
FOR PZZ251-271.
SMALL CRAFT ADVISORY UNTIL 11 AM PDT MONDAY FOR PZZ252-253-272-
273.
WWW.WEATHER.GOV/PORTLAND
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