655 FXUS66 KPQR 210455 AAA AFDPQR Area Forecast Discussion...UPDATED National Weather Service Portland OR 953 PM PDT Fri May 20 2022 Updated short term, aviation, and marine sections. .SYNOPSIS...A dry and mild weather pattern is expected across southwest Washington and northwest Oregon through Wednesday except for a few thunderstorms over the Cascades on Saturday. A return to a cooler and wetter pattern appears likely to return late next week. && .SHORT TERM...Tonight through Monday...The 00z iteration of high resolution, convective-allowing model guidance suggested some isolated showers will be possible within the Coast Range, so a slight chance of precipitation was added there. Any showers that do form are expected to be relatively sparse in nature, but still the chance seemed high enough to warrant a slight mention in the forecast. The previous discussion remains relevant, and follows. Water vapor satellite imagery this evening reveals a shortwave trough entrenched across much of the western US and an upstream shortwave ridge over the eastern Pacific. Models and their ensembles are in good agreement the aforementioned shortwave trough will slowly shift eastward and allow a more subdued version of the offshore shortwave ridge to traverse the region this weekend. This will produce dry weather for most of us and the first extended stretch of near to above average temperatures in literally a couple months. With that said, a subtle vort max currently over north-central British Columbia will drop south-southeastward across WA/OR Saturday and help to initiate some convection across our higher terrain Saturday afternoon into Saturday evening. At this point, most model and ensemble guidance suggests any showers and thunderstorms will most likely remain over the Cascades with the highest probabilities of rain and thunder being over the south Washington Cascades and adjacent Columbia River Gorge. The low to mid level flow will generally be out of the north, but there may be just enough north-northeasterly flow to allow a storm or two to try and push into the east Portland/Vancouver metro between 4-8 pm Saturday. Bumgardner/Neuman .LONG TERM...Monday night through Friday...The GEFS, EPS and CMCE systems suggest shortwave ridging will shift across the Pacific Northwest Tuesday into Wednesday. This will keep temperatures near to above average for the middle part of next week. Since KPDX still has not hit 80F this year, NBM4.0 does suggest the probability of KPDX hitting 80F on Wednesday is 30% so while not likely, there's certainly a reasonable chance it could occur midweek. A 500mb height cluster analysis does show that most members of the GEFS, EPS and CMCE ensemble systems shift a shortwave trough either towards the Pacific Northwest or through the Pacific Northwest towards next Thursday and Friday. Given this, the NBM forecast of cooling temperatures and increasing PoPs into at least chance category wording seems entirely reasonable for late Thursday into Friday. /Neuman && .AVIATION...06z TAFs: Skies have largely cleared across the area as the solar mixing has diminished. Weak offshore flow will continue to bring drier air aloft further breaking up ceilings into the night. Clearer skies and radiative cooling will likely result in some shallow fog development between 09-12z Saturday. VFR continues Saturday as high pressure over the NE Pacific moves closer to the coast.There is some indication that convection off the Cascades will drift westward. If so, it most likely impacts KTTD and KPDX with light showers and a 040 cig. For detailed regional Pac NW aviation weather information, go online to: https://weather.gov/zse KPDX AND APPROACHES...Ceilings are slow to break up but the capping inversion around 4500 ft will break by these evening producing clear skies across the terminal. Shallow fog is possible between 09-15z. Expect VFR conditions to reestablish if fog develops by 18z. Cigs at 040 are possible Saturday afternoon and early evening if the aforementioned convection builds and drifts westward off the Cascades. Regardless, the distant east RWY 28 approaches could encounter thunderstorms. JBonk/BMuhlestein && .MARINE...Northerly wind regime across the coastal waters as high pressure builds aloft which will allow the thermal low to build over California. Breezy north winds across the central Oregon waters will likely strengthen this evening with gusts up to 25 kt. Seas up to 8 ft are possible within the stronger wind fields with periods around 8 seconds. Winds and seas will subside with light to moderate northerly breezes prevailing through Saturday as a modest 4-5 ft NW swell continues to move through the waters. Winds will drop below 10 kt on Sunday as the ridge shifts closer to the coast and weakens the gradient. No major systems on the horizon through the next seven days. -BMuhlestein/CB && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory until midnight PDT tonight for coastal waters from Cascade Head OR to Florence OR out 60 nm. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland