Area Forecast Discussion National Weather Service Portland OR 904 PM PDT Fri Apr 28 2017 .SYNOPSIS...Mild and dry weather will continue into Saturday, though there will be a chill to the air tonight and Saturday morning. A front dropping southeastward Saturday evening will spread rain across the area, followed by decreasing showers Sunday. Another system ejecting northeast from Hawaii brings a small chance for rain late Monday into Monday night, then high pressure is expected to dominate for dry and warm weather midweek. && .SHORT TERM...Today through Monday...No changes were made to the forecast this evening other than a couple minor tweaks to the wind grids. Inherited forecast appears to be in very good shape, and showers have ended across the forecast area as expected. Low temps Sat morning will be similar to this morning, so there could be some patches of frost in the outlying valleys. Decided to leave it out of the forecast though, since there is a fair chance that high clouds over the NE Pacific will spread into the forecast area by daybreak. Forecast discussion from earlier this afternoon (below) remains valid.Weagle Previous discussion issued 307 PM Fri Apr 28 2017 below: Water vapor satellite imagery shows a large trough digging southward into the Great Basin and Great Plain states. Shortwave ridging building into the northeast Pacific has placed the Pacific Northwest under large scale north to northwesterly flow aloft. High clouds rounding the top of a shortwave ridge are pushing into the northeast Pacific and will arrive later tonight. Doppler radar and surface observations continue to indicate a few light showers over the higher terrain of the Coast Range and Cascades. Expect these showers to decrease rapidly this evening as shortwave ridging builds overhead and surface heating wanes. Expect a mostly clear and cool night tonight before clouds thicken from northwest to southeast across the area on Saturday. Valley high temperatures should climb into the 60s Saturday despite the increasing cloud cover. A front dropping southeastward across the area late Saturday should spread rain onto the south Washington coast as early as mid-late afternoon and into the Willamette Valley, especially the northern half, during the mid to late evening hours on Saturday. Some lingering low level instability may allow for a few showers to persist into Sunday afternoon, but overall Sunday looks considerably more dry than wet as shortwave ridging slowly redevelops. Another shortwave trough riding up and over the ridge could bring rain back on Monday, but the operational EC and many GEFS members shunt most of the moisture north of the CWA. Did raise PoPs, but still kept them generally below climo since it appears Monday stands a better chance of staying dry than turning wet. /Neuman .LONG TERM...Monday night through Friday...A weak disturbance will continue to bring a few showers to the forecast area late Monday. Models continue to keep the bulk of the moisture to our north so expect minimal accumulations. Conditions will then become warmer and drier for a few days starting Tuesday as an upper level ridge builds across the Pac NW. Today`s 12Z runs show a slightly dirtier ridge over the region next week, but given the forecasted 500 mb heights and 850 mb temps, Wednesday is expected to be the warmest day of the year thus far, with afternoon highs climbing into the low to mid 70s across the Willamette Valley. The ridge starts to breakdown Thursday as a weak frontal system approaches the region. Expect mostly cloudy conditions to return by Thursday, with a slight chance of showers, mainly over the Cascades. Could also see a few thunderstorms over the Cascades on Thursday, but confidence is not high enough to add it to the forecast. Conditions become a lot more uncertain late next week due to model difference so will stick close to climo and keep partly cloudy skies and a slight chance of showers in the forecast. /64 && .AVIATION...VFR conditions overnight. Expect high clouds moving in to preclude any chances for fog or low stratus. Brief ridging will drift across the region tomorrow for VFR conditions with increasing high clouds. Low pressure will approach the coast tomorrow afternoon and could bring light rain and cigs 030-050 to KAST by 29/22z. PORTLAND AND APPROACHES...VFR conditions and light winds through the period. /Bentley && .MARINE...No Changes. Previous Discussion Follows. A front will pass across the region late Sat and Sat evening with south to southwesterly winds of 15 to 25 kt across the north and slightly weaker winds for the central coastal waters. Seas will get a minor bump, but stay under 10 ft. Once the front passes, winds will ease back and turn more northwesterly. High pressure aloft returns early next week with northerly winds for the bulk of the time. However, the strength of the upper ridge looks to be considerably weaker than 24 hours ago. This may open the door for a brief southerly wind reversal monday night and early Tuesday. Seas appear to remain 7 ft or less through that time. /JBonk && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory for winds from 11 AM to 9 PM PDT Saturday for Coastal Waters from Cape Shoalwater WA to Cascade Head OR out 60 nm. Small Craft Advisory for winds from 2 PM Saturday to 1 AM PDT Sunday for Coastal Waters from Cascade Head OR to Florence OR out 60 nm. && $$ This discussion is for Northwest Oregon and Southwest Washington from the Cascade crest to 60 nautical miles offshore. The area is commonly referred to as the forecast area.