366 FXUS66 KPQR 030314 AFDPQR Area Forecast Discussion National Weather Service Portland OR 813 PM PDT Wed May 2 2018 .SYNOPSIS...A ridge of high pressure aloft will bring dry and warm weather to the region through Thursday. Mild weather continues into the weekend, but chances for showers also return over the weekend as an upper level trough moves into the area. Dry weather returns for the start of next week. && .SHORT TERM...Tonight through Saturday...Just cosmetic changes to the tonight and Thursday periods. Evening water vapor imagery showed an 500 mb ridge axis just inside 130W. High-level moisture continues to stream over the top of the ridge. This 500 mb ridge axis reaches the coastline around 12Z Thu and then shifts east of the Cascades in the afternoon. The 00Z Thu Hi-RES ARW run shows less boundary layer moisture compared to 24 hours ago. Thus, not expecting much, if any, morning stratus. The model does suggest the potential for some along the coastline, mainly KTMK southward, in the 12Z to 15Z time frame. The model also hints at localized stratus along the SW Washington I-5 corridor near KKLS. Included some patchy late night and morning fog in the south Willamette Valley. The Hi-RES ARW also shows the boundary layer wind becoming more W to NW along the coast by 18Z Thu, then shifting to SW to W in the afternoon. There is the potential for marine stratus to either hover near the coast through the morning then gradually spread inland during the afternoon as the onshore flow strengthens. Or, any marine stratus that is present along the coast in the morning could simply move inland sooner. Either way, max temp forecast for the west slopes of the Oregon Coast Range will be tricky. Inland areas from the east slopes of the Coast Range to the Cascades should see max temps similar to today, or a degree or two warmer. Weishaar Rest of the short term discussion unchanged...Moisture continues to increase Friday as onshore flow strengthens. Models even show some light rain or drizzle over the northern coastal areas and adjacent waters, so maintained slight chance PoPs for those areas into Friday morning. The next upper low makes its initial approach to the west coast Saturday off northern California, putting the local area in southerly to southeasterly flow, which could be favorable for Cascade thunderstorms. Have introduced a slight chance of thunder Saturday afternoon south of Mt. Hood. However, models are not in perfect agreement about the track of the low and a more southerly track would likely keep convection farther south. Bowen && .LONG TERM...Saturday night through Tuesday...A negatively tilted upper level trough approaches the coast late Sat/ early Sun. This feature will nudge the ridge that has been over the area to the east and over the Cascades. This process will cause a short period of time where S/SE mid level flow to develop, which may bring a chance for thunderstorms into the area. The best chance for thunderstorms will be along the Oregon Cascades. As the trough moves out of the area, the next upper level ridge moves into the area late Sun, and continues to set up though Mon and Tue. /42 && .AVIATION...Conditions are VFR with generally clear skies this afternoon. The models suggest the flow will turn a bit more onshore later tonight and Thu with a mixture of IFR/low MVFR conditions along the coast later tonight continuing through the day Thursday with little or no clearing Thu afternoon. There could be some patchy fog or low stratus inland around sunrise otherwise conditions inland will remain VFR through Thu. We will probably start to see some higher clouds developing Thu afternoon ahead of the next system. KPDX AND APPROACHES...VFR conditions prevailing tonight and Thu. Could see some patchy clouds around 1000 ft near sunrise. Otherwise some increasing higher clouds Thu afternoon. pt && .MARINE...There will be a little N wind along the coast but it should stay below Small Craft Advisory thresholds as the pressure gradient is not strong enough or oriented quite right for anything stronger. Pressures briefly weaken or lower along the Washington coast later tonight and Thursday which turns the winds more southwesterly but speeds will be modest. The models say the winds turn back to more northerly this weekend, possibly approaching 20 kt. Seas look to stay around 4 or 5 ft into the weekend per the most recent wave models. pt && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...None. && $$ Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland This discussion is for Northwest Oregon and Southwest Washington from the Cascade crest to 60 nautical miles offshore. This area is commonly referred to as the CWA or forecast area.