441
FXUS66 KPQR 282136
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
236 PM PDT TUE JUL 28 2026
SYNOPSIS
WEAK FRONT WITH LIGHT SHOWERS SHIFT EASTWARD TODAY.
ONSHORE FLOW PERSISTS THROUGH THE NEXT WEEK. HIGH PRESSURE
BEGINS TO BUILD THROUGH FRIDAY WITH FRIDAY EXPECTED TO BE THE
HOTTEST DAY THIS WEEK. ANOTHER SYSTEM ARRIVES ON SATURDAY WHICH
WILL BRING INCREASING PROBABILITIES OF PRECIPITATION AND
WESTERLY WINDS.
SHORT TERM...NOW THROUGH THURSDAY
OVERALL, LITTLE CHANGE IN
THE FORECAST. THE FRONTAL SYSTEM THAT MOVED THROUGH THIS MORNING
CONTINUES TO CHUG ALONG PRODUCING VERY LIGHT TO ALMOST NO RAIN.
THEREFORE, NO IMPACT HAS BEEN DETECTED OTHER THAN MAINTAINING
STEADY STRATUS OVER THE AREA. THIS FRONT WILL CONTINUE TO MOVE
EASTWARD OVERNIGHT WITH DRIER AND CLEARER CONDITIONS TRAILING
BEHIND IT. THESE CONDITIONS WILL BE AMPLIFIED BY A RIDGE ALOFT
FORMING OVER THE ROCKIES, AND A TROUGH OVER THE COAST STEMMING
FROM A BROAD LOW IN THE NORTHEAST PACIFIC. WHILE NOT
NECESSARILY A SIGNIFICANT PATTERN SHIFT, IT WILL MAINTAIN
WESTERLY FLOW THROUGH THURSDAY AT LEAST. TEMPERATURES WILL BE
MODERATE AND SEASONABLE ON WEDNESDAY AND THURSDAY WITH HIGHS IN
THE INTERIOR LOWLANDS IN THE LOW 80S, MID 60S ALONG THE COAST,
AND IN THE 70S ALONG THE CASCADES. -27
LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
THE TROUGH IN THE
NORTHEAST PACIFIC WILL REMAIN THROUGH MUCH OF THE WEEKEND BUT ON
THURSDAY, A BRIEF SHORTWAVE WITH AN ASSOCIATED WEAK FRONT WILL
PASS NORTH OF THE AREA, BUT STRATUS MAY FILL. ON FRIDAY, WHILE
ONSHORE FLOW PERSISTS, A WEAK RIDGE FORMS WHICH WILL USHER IN
WARMER AIR TO THE REGION. 850 MB TEMPERATURES WILL REACH AROUND
15 DEG C IN THE AFTERNOON AND THE 850-250 MB RH DIFFERENCE
REMAINS VERY DRY. THEREFORE, FRIDAY WILL LIKELY BE THE HOTTEST
DAY OF THE WEEK THOUGH NOT ANYWHERE NEAR RECORD BREAKING. WITHIN
THE WILLAMETTE VALLEY WE WILL SEE TEMPERATURES IN THE MID TO
UPPER 80S WITH SOME AREAS, ESPECIALLY URBAN ONES, REACHING 90.
THE COAST WILL BE BEAUTIFUL IN THE MID TO UPPER 60S.
THIS WARM UP WILL BE SHORT LIVED THOUGH AS THE TROUGH PREVIOUSLY
MENTIONED TRAVERSES EASTWARD. A COOLER FRONTAL SYSTEM WILL DIP
DOWN OVER THE REGION INCREASING PRECIPITATION CHANCES, AND
BRINGING IN COOLER AIR. TEMPERATURES WILL LIKELY DROP BY AROUND
10 DEGREES OR SO ON SATURDAY WITH INCREASING CHANCES FOR
PRECIPITATION. MOST MODELS ARE KEEPING THE BULK OF THE RAIN TO
THE NORTH, BUT THERE REMAINS AROUND A 30-40% CHANCE OF
MEASURABLE RAIN OVER THE TERRAIN OF SOUTHWEST WASHINGTON AND THE
COAST NORTH OF TILLAMOOK. OVERALL THOUGH, ACCUMULATIONS WILL BE
LIGHT. AS IS COMMON WITH COLD FRONTAL PASSAGES, THE ENVIRONMENT
WILL BECOME CONVECTIVE HOWEVER THUNDERSTORMS ARE NOT EXPECTED AT
THIS TIME. WE ARE MISSING A BULK OF THE INSTABILITY THAT WE
WOULD NEED TO SEE ANOTHER THUNDERSTORM OUTBREAK. ANOTHER
COMPONENT IS WIND. IN GENERALLY, WIND WILL BE TEMPERATURE AND
PRESSURE GRADIENT DRIVEN WITH THE HIGHEST WIND SPEEDS THROUGH
THE E-W ALIGNED TERRAIN LIKE THE COLUMBIA RIVER GORGE AND THE
PASSES OF THE CASCADES.
ONSHORE ZONAL FLOW REMAINS THROUGH EARLY NEXT WEEK WITH DRY
CONDITIONS EXPECTED. -27
AVIATION...THROUGH 00Z THURSDAY
VFR CONDITIONS WERE BEING
OBSERVED AT ALL TERMINALS AS OF 2130Z TUESDAY WITH CEILINGS
GENERALLY ABOVE 5000-6000 FT, EXCEPT NEAR 3500 FT AT KAST. ONGOING
CLOUD COVER IS MAINLY ASSOCIATED WITH A DECAYING COLD FRONT THAT
MOVED INLAND EARLIER TODAY. RADAR OBSERVATIONS SHOWED LIGHT RAIN
SHOWERS OCCURRING AHEAD OF THIS FRONT OVER THE NORTHERN COAST
RANGE, HOWEVER THESE SHOWERS WILL NOT IMPACT ANY OF THE TAF SITES.
THE MAIN UNCERTAINTY WITH THE AVIATION FORECAST IS EXACT CEILING
HEIGHTS LATE TONIGHT INTO TOMORROW MORNING, AS WELL AS WHETHER OR
NOT CLOUD COVER WILL BE PREDOMINATELY SCATTERED OR BROKEN. THE
LATEST GUIDANCE CURRENTLY SUGGESTS A BROKEN CLOUD DECK WILL
ATTEMPT DEVELOPING OVER THE NORTH OREGON CASCADES AND PORTIONS OF
THE WILLAMETTE VALLEY AND PORTLAND METRO BETWEEN 06-12Z WEDNESDAY.
HOWEVER, PROBABILITIES CURRENTLY FAVOR LOW-END VFR CEILINGS WITH
THIS POTENTIAL STRATUS DECK. PROBABILITIES FOR MVFR CEILINGS
BELOW 3000 FT PEAK BETWEEN 10-16Z WEDNESDAY BETWEEN 15-35% AT ALL
TAF SITES, EXCEPT 45-55% AT KAST.
KPDX AND APPROACHES...SCATTERED CLOUDS WITH CEILINGS AT OR 7000
FT ARE EXPECTED TODAY, RESULTING IN VFR CONDITIONS. VFR CONDITIONS
WILL MOST LIKELY REMAIN IN PLACE THROUGH 00Z THURSDAY, HOWEVER
THERE IS A 15% CHANCE FOR MVFR CEILINGS BELOW 3000 FT BETWEEN
10-16Z WEDNESDAY. LIGHT AND VARIABLE WINDS AROUND 5 KT ARE
EXPECTED TO BECOME NORTHWESTERLY LATE THIS AFTERNOON, WITH GUSTS
UP TO APPROXIMATELY 15 KT WITH AN INCOMING SEA BREEZE. -23
MARINE
BUOY OBSERVATIONS FROM EARLY TO MID TUESDAY AFTERNOON
SHOWED SEAS REMAINING WITHIN THE 4 TO 6 FOOT RANGE. THESE SEAS ARE
EXPECTED TO CONTINUE WITH A DOMINANT WEST TO NORTHWEST SWELL AT
7-9 SECONDS AND A SECONDARY LONG-PERIOD SOUTH-SOUTHWESTERLY SWELL
PERSISTING THROUGH MUCH OF THE WEEK. NORTHWEST WINDS WILL DEVELOP
OVER THE WATERS TUESDAY EVENING IN THE WAKE OF A COLD FRONTAL
PASSAGE. NORTH WINDS ON WEDNESDAY WILL BECOME LIGHTER AND BACK TO
THE SOUTH ON THURSDAY WITH ANOTHER WEAK FRONTAL PASSAGE.
YET ANOTHER WEAK FRONT LOOKS TO TRAVERSE THE WATERS EARLY THIS
WEEKEND, AFTER WHICH NORTHWESTERLY FLOW WILL STRENGTHEN AND VEER
OUT OF NORTH INTO EARLY NEXT WEEK AS HIGH PRESSURE BUILDS
OFFSHORE. CONFIDENCE IN WIND GUSTS OF AT LEAST 20-25 KT IS
MODERATE TO HIGH ON SUNDAY, INCREASING FROM AROUND 60% WEST OF THE
MOUTH OF THE COLUMBIA TO GREATER THAN 90% OFFSHORE OF FLORENCE.
THOSE CHANCES ARE EVEN HIGHER ON MONDAY, SOME 90-95% OR HIGHER
ACROSS THE COASTAL WATERS. THE CHANCES FOR GALE-FORCE GUSTS ON
MONDAY ARE LOW BUT NOT NEGLIGIBLE, GENERALLY 10-20% SOUTH OF CAPE
FOULWEATHER AS WELL AS WITHIN 10 NM OF THE COAST FROM CAPE FALCON
TO CAPE FOULWEATHER. -36/23
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
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