Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
278 FXUS66 KPQR 161633 AAA AFDPQR Area Forecast Discussion...UPDATED National Weather Service Portland OR 933 AM PDT Sun Jun 16 2024 Aviation Discussion Updated... .SYNOPSIS...Low pressure maintains cool and showery conditions today, with a chance of thunderstorms across much of the area this afternoon and evening. A few showers linger into Monday then much warmer and drier weather returns Tuesday through the end of next week. && .SHORT TERM...Now through Monday Night...An elongated upper level trough has shifted southward from British Columbia to Washington and remains the dominant feature over the Pacific Northwest this morning. Latest satellite imagery shows broken cloud cover lingering across northwest Oregon and southwest Washington, with a lull in shower activity as radar echos are mainly confined to northern coastal areas and parts of the Cascades as of 2 AM Sunday. Expect a similar day to Saturday as unseasonably cold air aloft yields another day of highs topping out in the mid 60s. Shower activity will increase in coverage with daytime heating as the trough axis shifts southeast across the area, with steep mid level lapse rates and modest instability again contributing to a chance of thunderstorms. The best thunderstorm potential will reside from roughly Salem north through early evening, but can`t rule out a few lightning strikes with southward extent towards Eugene as well. Shower activity will trend downward through Monday with temperatures remaining in the 60s as northwest flow takes hold in the wake of the departing trough. Showers will remain light and mostly be confined to the higher terrain through Monday afternoon, then wind down through Monday night and set the stage for the next stretch of warmer and drier weather beginning Tuesday. /CB .LONG TERM...Tuesday through Saturday...More summerlike weather returns to the region on Tuesday as WPC ensemble clusters continue to show broad agreement on the weakening of the trough over the western CONUS and subsequent increasing 500 mb heights across the Pacific Northwest. This will send temps back above seasonal norms as highs climb into the mid to upper 70s across the interior lowlands on Tuesday afternoon. Wednesday through Friday looks to be the hottest stretch for the coming week as most ensemble and deterministic solutions continue to depict a weak Rex Block characterized by a low amplitude ridge over western Canada and an open trough over northern California. Ensemble temperature spreads have nudged slightly upward for the latter half of the week, with probabilistic guidance now peaking with around a 50 percent chance to reach 90 degrees in the Portland area on Thursday and a 25-35 percent chance both Wednesday and Friday. Notably, the probability to reach 95 degrees on any of these days is less than 10 percent from Portland to Salem and closer to one percent in other locations, serving to underscore the relatively high confidence in the range of temperature outcomes for the coming week. The bulk of the guidance then suggests that temperatures will begin to trend back down next weekend with the approach of another trough. /CB && .AVIATION...Rain showers will return between 18Z Sunday and 06Z Monday as the low moves southeast into our region. Most of the airspace will be VFR between these times, with the only concern of possible MVFR CIGs in KAST (10-20% probability). Additionally, scattered thunderstorms throughout the region remain a possibility (20-30%) today, until 03Z Monday. With ongoing clearing this morning expected to improve warming in the afternoon, instability should increase enough to maintain thunderstorm development through the afternoon. Could see some hail and brief gusty winds with these thunderstorms. After the showers dissipate around 05-06Z Monday, northwesterly to westerly winds will weaken to below 10 kt and potential for MVFR CIGs will increase. Most terminals will have a 10-20% chance of MVFR CIGs from 06-18Z Monday, with probabilities as high as 40-50% for coastal terminals, primarily north of KTMK. PDX AND APPROACHES...Showers between 18Z Sunday and 03-06Z Monday, with predominantly VFR conditions through the TAF period. A 20-30% chance of scattered thunderstorms is possible until 03Z Monday, with potential to see hail and brief gusty winds. After 06Z Monday, northwesterly winds will weaken and chances of MVFR CIGs will increase to 10-20% until 18Z Monday. -JH && .MARINE...Seas around 5 to 7 ft at 9 to 11 seconds for the near future. Winds are currently negligible, but will increase following the weak frontal passage up to just under Small Craft Advisory level Sunday evening. A stray gust of two above SCA criteria may be possible Sunday night, but by and large the majority of waters will remain under, with only a 10% chance of SCA level winds. Next chance at more impactful conditions will be Tuesday night, though uncertainty is still relatively high. Marginal SCA winds look possible from Tuesday evening onwards, with breezier marginal winds possible until at least the weekend. /JLiu && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...None. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland