516
FXUS66 KPQR 220510
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1010 PM PDT TUE JUL 21 2026
UPDATED AVIATION DISCUSSION AND ADDED CLIMATE DATA.
SYNOPSIS
VERY HOT TEMPERATURES TODAY WILL PERSIST OVERNIGHT
INTO WEDNESDAY. HIGHS IN THE MID TO UPPER 90S EXPECTED INLAND
WITH CHANCES OF HIGHS UP TO 100 DEGREES F ON WEDNESDAY.
MONSOONAL MOISTURE WILL MOVE IN ON WEDNESDAY WHICH WILL
COMPLICATE THE FORECAST. THUNDERSTORM AND SHOWER CHANCES
INCREASE ON WEDNESDAY, ESPECIALLY IN THE AFTERNOON WITH
ADDITIONAL DAYTIME HEATING. WIDESPREAD LIGHTNING NOT OUT OF THE
QUESTION. SHOWERS PERSIST INTO THURSDAY AND COOLER TEMPERATURES
EXPECTED THROUGH THE REMAINDER OF THE WEEK.
SHORT TERM...NOW THROUGH THURSDAY
TODAY HAS BEEN ON THE HOT
SIDE AS HIGH PRESSURE OVER THE REGION HAS BUILT. OVERNIGHT LOWS
WERE HIGHER THAN FORECAST WITH TEMPERATURES REPORTED AROUND 65
DEGREES F IN URBAN AREAS. THIS CREATED A LAUNCHING PAD FOR
TODAY'S HIGHS WHERE TEMPERATURES ARE N THE WIDESPREAD 90S INLAND
AND IN THE MID TO UPPER 50S ALONG THE COAST. EVEN ALONG THE
CASCADES, SOME SITES ARE REPORTING HIGHS OF 90-91 DEGREES AS OF
2 PM. WILL SEE A CONTINUED WARM UP MY A FEW MORE DEGREES TODAY.
ONE CAVEAT IS IN THE SOUTHERN WILLAMETTE VALLEY WHERE SOME BLEED
OVER MONSOONAL MOISTURE IS FILTERING IN. SATELLITE IS SHOWING
CLOUD COVER MOVING IN WHICH MAY INHIBIT SOME DAYTIME WARMING
AROUND EUGENE AND THE FOOTHILLS OF THE WILLAMETTE NATL FOREST.
WITH THAT SAID, STILL INCREASINGLY HOT AND THERE APPEAR TO BE
ENOUGH BREAKS WHERE THERE IS AMPLE TIME FOR WARMING. RADAR SHOWS
VIRGA ALSO IN THE REGION. OVERNIGHT TEMPERATURES WILL FALL BUT
ARE NOT EXPECTED TO SEE SIGNIFICANT RELIEF OUTSIDE OF THE COAST.
THESE OVERNIGHT TEMPERATURES COMBINED WITH TODAY'S HIGH SPARKED
THE NEED FOR ADDITIONAL HEAT ADVISORIES ALONG THE SOUTH
WASHINGTON CASCADE AND CENTRAL OREGON CASCADE FOOTHILLS THROUGH
AT LEAST TONIGHT.
MOVING INTO WEDNESDAY WE ARE GOING TO SEE A BIT OF A TRANSITION.
WHILE SOME MODELS WOULD SUGGEST THE PATTERN IS FAIRLY CUT AND
DRY, THE OVERALL PATTERN IS ACTUALLY QUITE MESSY WHICH IS
LEADING TO SOME LEVELS OF UNCERTAINTY. WHILE MODELS WANT TO
MAINTAIN THE OVERALL HIGH PRESSURE OVER THE REGION, A
COMBINATION OF MONSOONAL MOISTURE INFLUX AND A LOW PRESSURE
SYSTEM OFF OF THE OREGON/CALIFORNIA BORDER WILL DRIVE A MUCH
MORE ACTIVE WEATHER PATTERN. WILL SEE SOUTHERLY FLOW MAINTAINING
WHICH, WHEN COMBINED WITH WARM OVERNIGHT TEMPERATURES, WILL ONCE
AGAIN BRING AN INFLUX OF WARM AIR TO THE REGION. EACH MODEL RUN
HAS SHOWN THE HIGH TEMPERATURE FORECAST INCREASE STEADILY NOW
WITH MULTIPLE AREAS SEEING FORECAST HIGHS NEAR OR GREATER THAN
100 DEGREES F. HOWEVER, THAT IS NOT THE WHOLE PICTURE AS THERE
IS THAT MOISTURE TO DEAL WITH. WILL SEE HIGHER THAN NORMAL
HUMIDITY ON WEDNESDAY WHICH WILL MAKE THE AIR APPEAR HOTTER
THAN IT NORMALLY WOULD IF THE ATMOSPHERE WAS DRIER. MAJOR
HEATRISK EXISTS THROUGH MUCH OF THE WILLAMETTE VALLEY.
THIS INCOMING MOISTURE WILL NOT ONLY IMPACT HOW HOT CONDITIONS
FEEL, BUT WILL ALSO CHANGE THE SENSIBLE WEATHER. HIGH
RESOLUTION MODELS HAVE BEGUN TO SHOW MORE WIDESPREAD AND
POTENTIALLY INTENSE PRECIPITATION STARTING AS EARLY AS WEDNESDAY
MORNING WITH HIGHER CONFIDENCE ON IT STARTING WEDNESDAY
AFTERNOON. ONE THING TO NOTE THOUGH IS THAT IT LIKELY WILL NOT
BE IN THE FORM OF RAIN, BUT RATHER AS THUNDERSTORMS. CONVECTIVE
INDICES LIKE MOST UNSTABLE CAPE (MUCAPE) ARE SHOWING ELEVATED
CONVECTION AROUND 1500 J/KG OVER THE CASCADES AND EVEN SOME
INLAND SITES. THIS IS ONLY AMPLIFIED WHEN TAKING INTO ACCOUNT
DAYTIME HEATING WHICH WOULD HELP US SURPASS ANY CAPS THAT FORM
AT THE SURFACE. THEREFORE THERE IS AROUND A 15-20% CHANCE OF A
WIDESPREAD THUNDERSTORM SITUATION OVER ALL OF NORTHWEST OREGON
AND SOUTHWEST WASHINGTON. OVER THE CASCADES THOUGH THAT IS
HIGHER WITH CLOSER TO A 30-35% CHANCE. THE HIGHEST PROBABILITIES
WILL BE OVER THE WILLAMETTE NATL FOREST ON WEDNESDAY AFTERNOON
AND EVENING. SOME MODELS ARE SHOWING A FEW CELLS POPPING UP ON
WEDNESDAY MORNING ALONG THE COAST, BUT THERE IS MUCH HIGHER
CONSENSUS ON THE AFTERNOON TIME FRAME. WITH THIS IN MIND, THESE
STORMS ARE FORECAST TO BE WET WITH LIMITED WIND. HOWEVER,
WIDESPREAD LIGHTNING (SIMILAR TO LAST WEEK) CANNOT BE RULED OUT.
IT IS CRITICAL THAT IF YOU HEAR THUNDER OR SEE LIGHTNING THAT
YOU TAKE COVER IMMEDIATELY INSIDE OF A STURDY STRUCTURE, GET OFF
OF THE WATER, AND LIMIT OUTDOOR ACTIVITIES LIKE GOLFING OR
PLAYING BASEBALL.
STORMS AND SHOWERS ARE EXPECTED TO PERSIST OVERNIGHT, THOUGH
WILL BECOME LIGHTER AS WE LOSE DAYTIME HEATING. ISOLATED SHOWERS
INTO THURSDAY MORNING. -27
LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
BY THURSDAY, THE
RIDGE BEGINS TO WEAKEN AS A BROADER TROUGH MOVES TOWARD THE
PACIFIC NORTHWEST. THIS SHOULD PROMOTE A RETURN TO MORE
NOTICEABLE ONSHORE FLOW AND BEGIN A GRADUAL COOLING TREND THAT
CARRIES INTO LATE WEEK. TEMPERATURES ARE STILL LIKELY TO REMAIN
SOMEWHAT ABOVE SEASONAL NORMALS THURSDAY AND FRIDAY, BUT NOT TO
THE DEGREE SEEN EARLIER IN THE WEEK. LOOKING BEYOND FRIDAY,
FORECAST GUIDANCE CURRENTLY DOES NOT SHOW A STRONG SIGNAL FOR
MEANINGFUL PRECIPITATION, WHILE TEMPERATURES TREND TOWARD THE
LOWER 80S THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK. -12
AVIATION...THROUGH 06Z THURSDAY
VFR FLYING CONDITIONS
EXPECTED TO CONTINUE AT INLAND TERMINALS THROUGH MUCH OF THE
PERIOD BENEATH SCT/BKN HIGH CLOUDS. PERIODS OF HAZE FROM
ELEVATED SMOKE MAY RESTRICT VIS TO 5-6 SM IN THE AFTERNOON.
ALONG THE COAST, MARINE STRATUS WILL AGAIN YIELD IFR/LIFR
CIGS/VIS, WITH THE HIGHEST CONFIDENCE IN RESTRICTIONS ALONG THE
CENTRAL OR COAST (KTMK, KONP). LOW CLOUDS WILL ERODE IN THE
MORNING, RETURNING TO MVFR/VFR CONDITIONS BY 18-21Z WED. WINDS
WILL BE CALM TO LIGHT AND VARIABLE TONIGHT, BUILDING OUT OF THE
WEST TO NORTHWEST AT 5-10 KT INLAND AND 8-12 KT ALONG THE COAST
AFTER 18Z WED.
AFTERNOON TEMPERATURES ARE FORECAST TO APPROACH 100 DEGREES AT
MANY INLAND TERMINALS WEDNESDAY AFTERNOON; BE AWARE OF HIGH
DENSITY ALTITUDE WHICH MAY REDUCE AIRCRAFT PERFORMANCE. SHOWERS
AND ISOLATED THUNDERSTORMS ARE EXPECTED TO DEVELOP WEDNESDAY
AFTERNOON, TRACKING NORTHWARD THROUGH THE REMAINDER OF THE
PERIOD. CONFIDENCE IN THE OCCURRENCE OF THUNDER IS TOO LOW TO
INCLUDE IN TAFS AT THIS TIME, BUT HEAVY SHOWERS MAY BRIEFLY
RESULT IN MVFR/IFR VIS IF THEY PASS OVER A TERMINAL. SHOWERS MAY
ALSO PRODUCE GUSTY OR ERRATIC WINDS NEARBY. LATE IN THE PERIOD,
WINDS WILL BEGIN TO TURN OUT OF THE SOUTHWEST TO SOUTH AS
SHOWERS WANE.
KPDX AND APPROACHES...VFR CONDITIONS EXPECTED TO PREVAIL THROUGH
MUCH OF THE PERIOD BENEATH SCT-BKN HIGH CLOUDS. SMOKE ALOFT MAY
YIELD SURFACE VIS OF 5-6 SM WEDNESDAY AFTERNOON, ALTHOUGH VIS
ALOFT CAN OFTEN BE LOWER. CHANCES FOR SHOWERS OR AN ISOLATED
THUNDERSTORM INCREASE AFTER 00Z THU; THE MOST LIKELY TERMINAL
IMPACTS ARE GUSTY/ERRATIC WINDS AND LOCALLY HEAVY DOWNPOURS
WHICH MAY BRIEFLY RESTRICT VIS TO IFR/MVFR LEVELS. NORTHWEST
WINDS CONTINUE THROUGH THE PERIOD AT 5 KT OR LESS OVERNIGHT,
BUILDING TO 5-10 KT BY WEDNESDAY AFTERNOON. -36
MARINE
A TYPICAL SUMMERTIME PATTERN WILL CONTINUE THROUGH
THE MIDDLE OF THIS WEEK WITH PERSISTENT NORTH TO NORTHWEST WINDS
OVER THE COASTAL WATERS. WINDS THEN SHIFT SOUTHWEST TO WESTERLY
THURSDAY INTO THE WEEKEND AS WEAK LOW PRESSURE DEVELOPS OVER
THE WATERS. WINDS WILL REMAIN LIGHT LESS THAN 10-15 KTS. SEAS
WILL BE 3-6 FT AT 8-9 SECONDS THROUGH THE WEEKEND.
ON WEDNESDAY, THERE IS A CHANCE FOR SHOWERS AND THUNDERSTORMS
ACROSS ALL OF THE WATERS THROUGH THE MAJORITY OF THE DAY AND
OVERNIGHT HOURS. THERE COULD BE FREQUENT LIGHTNING AND GUSTY AND
ERRATIC WINDS WITH ANY THUNDERSTORM THAT FORMS. -03
CLIMATE
DAILY RECORD HIGH MINIMUM TEMPERATURES FOR JULY 22
ASTORIA 62 (2007)
VANCOUVER, WA 74 (2006)
PORTLAND INT'L 74 (2006)
HILLSBORO 73 (2006)
MCMINNVILLE 73 (2006)
SALEM 74 (2006)
EUGENE 71 (2006)
DAILY RECORD HIGH MAXIMUM TEMPERATURES FOR JULY 22
ASTORIA 88 (1891)
VANCOUVER, WA 98 (1928)
PORTLAND INT'L 98 (1978, 2004)
HILLSBORO103 (1938)
MCMINNVILLE102 (1928)
SALEM102 (1928, 1978)
EUGENE101 (2006)
PQR WATCHES/WARNINGS/ADVISORIES
OR...HEAT ADVISORY UNTIL 11 PM PDT WEDNESDAY FOR ORZ108>115-120>122.
WA...HEAT ADVISORY UNTIL 11 PM PDT WEDNESDAY FOR WAZ204>210.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
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