Area forecast discussion National Weather Service Portland or 234 PM PDT Sat may 18 2013 Synopsis...plenty of clouds and occasional rain today as a weak low pressure system slowly moves into Oregon and Washington. Showers will slowly decrease tonight and Sunday as the system moves into the Great Basin and falls apart. More sunbreaks Sunday should lead to more seasonable temperatures. Monday is shaping up to be a pleasant sunny and warm day under high pressure with temperatures in the lower to middle 70s. High clouds will begin to increase from the northwest later in the day in advance of our next system...which will bring a dramatic change back to chilly and unsettled weather Tuesday through Friday. && Short term...today through Tuesday night...visible satellite imagery shows solid cloud cover across the district this afternoon. Krtx radar shows an area of light rain spreading across Washington County and entering the greater Portland and eventually Vancouver metropolitan area. Additionally areas of light rain persist along the coast and much of the rest of our forecast area. Snow levels remain rather high...odot pass cams show occasional rain and it appears to be raining at timberline as well. Weak and poorly defined low pressure circulation just offshore from Astoria will drag a weak cold front onshore over the next few hours with decreasing showers thereafter. What is left of the front will finally lumber east across the Cascades tonight with decreasing showers behind the front. By Sunday morning showers will be mainly confined to the higher terrain...though a stray shower is still possible elsewhere due to weak shallow instability. Made very few changes for Monday and Tuesday. The move the midnight shift made to bump up Monday temperatures into the 70s appears to be a good one. The air mass looks rather dry throughout Monday on NAM bufr soundings...from Eugene all the way up to Portland. With 850 mb temperatures pushing +10 degree c in the Willamette Valley...highs could get well into the 70s some areas with plenty of sunshine. Onshore gradients will keep the coast from warming up too much. Models showing good agreement on rain from our next system holding off until Tuesday morning. As Tuesday progresses it appears an unseasonably deep and cold upper low will sink southeast into Washington/or spreading rain across the region. Rain appears likely a good portion of the day Tuesday...with snow levels lowering to the Cascade passes Tuesday night. There is an outside chance we may need to eventually consider snow advisories for the Cascades as early as Tuesday night. Weagle Long term...Tuesday evening through Saturday...few changes. Closed low pressure system will linger over the Pacific northwest through the week. With the cold nature of the low...record low maximum temperatures are possible on Wednesday...with snow down to pass level likely in the Cascades. Thursday and beyond models begin to disagree on where the low will propagate...however the overall trend will remain...with showery and cool conditions persisting through at least Saturday. Burgess && Aviation...mix of VFR and MVFR ceilings across the region. A weakening front is pushing across the region...but back edge of the front is still offshore and not likely to clear the Cascades until this evening. Not much change...with scattered showers and mostly low VFR and pockets of MVFR through tonight. Cascades and passes will frequently be obscured in clouds. Showers should diminish overnight behind the front...with MVFR ceilings at the coast and mostly VFR inland. Some patchy fog possible tomorrow morning in the southern Willamette Valley if any clearing occurs...possibly affecting keug. Kpdx and approaches...expect a mix of VFR and MVFR in scattered showers through this afternoon as a cold works its way through. Shower activity should decrease later this evening behind the frontal passage. Mostly VFR conditions overnight. Pyle Expect light rain or showers off and on through the day. Predominantly VFR conditions may drop to MVFR at times during heavier showers. Shower activity should taper off somewhat this evening... with mainly VFR conditions during the evening and overnight hours. Pyle && Marine...a cold front is pushing through the coastal waters this afternoon. The front has been slower than expected...so decided to extend the Small Craft Advisory for winds into the early evening hours. Expect winds to decrease and turn northwest later this evening behind the front. High pressure will build over the NE Pacific sun into early next week. It appears that there will be a few chances for small craft advisories for winds over the next few days. Sunday and Monday may see wind gusts into the 20 to 25 knots range during the late afternoon and early evening hours. Seas remain at 5 to 6 feet through the weekend. Seas may bump up a bit during the periods of gusty winds on sun and Monday. A large low pressure system may bring another small craft for winds on Wednesday...along with seas above 10 feet. Pyle && Pqr watches/warnings/advisories... or...none. Washington...none. Pz...Small Craft Advisory for winds until 7 PM PDT this evening for coastal waters from Cape Shoalwater Washington to Florence or out 60 nm. && $$ More weather information online at... http://weather.Gov/Portland 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.