Area forecast discussion National Weather Service Portland or 243 PM PDT Wednesday Jun 19 2013 Synopsis...persistent upper level low pressure continues to bring clouds and showers to southwest Washington and northwest Oregon. Temperatures through Thursday will be well below normal. Showers will linger but probably be less numerous Thursday and Friday as the upper low meanders toward the Idaho Panhandle and northern rockies. Temperatures will climb back closer to normal Friday and Saturday with some relatively drier weather...but it appears an active Pacific jet stream will bring more wet weather Sunday into early next week. && Short term...this afternoon through Saturday...deep onshore flow continues across northwest Oregon and southwest Washington this afternoon. The morning stratocumulus deck broke apart enough for some sunbreaks...which in turn provided a little more instability than was expected earlier today. We are near the Summer solstice...so the midday sun is about as strong as it gets here. As a result The Breaks in the clouds allowed surface temperatures to push rapidly into the middle-upper 60s...and surface-based convection quickly followed. Cloud tops are pushing 20 kft in some of the stronger cells so a rumble of thunder or two is not out of the question. However for the most part there will just be scattered moderate to locally heavy rain showers...and the heaviest may produce a brief period of small hail. These showers should flatten out and decrease around sunset as surface temperatures begin to cool. Temperatures begin to warm aloft tonight as the core of cold air aloft drifts east of the Cascades. This will be another factor cutting the potential for instability. NAM bufr soundings suggest that by Thursday morning we should be under the influence of a strong capping inversion near 700 mb so any showers Thursday should be shallow. With a little more sunshine temperatures may be slightly warmer Thursday but still below normal. The upper low meanders toward the Idaho Panhandle Friday...but still remains close and broad enough to allow wraparound moisture to keep the shower threat going for our northern zones. Temperatures will continue their slow recovery as the air mass slowly warms up...with the drying and warming trend back toward normal continuing into Saturday as the upper low finally tries to move across the northern rockies. However a strong Pacific jet will be knocking on our door by then...aiming to bring a prolonged period of unseasonably wet weather to the Pacific northwest for early next week.Weagle Long term...Saturday night through Wednesday...the latest medium range model runs are showing fairly good agreement in the extended portion of the forecast. After a brief period of dry weather Sat...the models are now showing a low coming onshore Sat night into Sun morning. Although some model runs are keeping the best precipitation to our south...the ensembles solutions are showing likely probability of precipitation over much of our forecast area during the day sun. Then a deep closed upper level low is prognosticated to drop south and stall over the NE Pacific for most if not all of next week. The best chance for significant precipitation appears to be Monday night into Tuesday...when the models seem to agree that a juicy front will bring a slug of heavy precipitation to the region. Otherwise... expect that the Pacific northwest will remain in a cloudy and wet pattern through most of next week. Temperatures will also likely be running several degree below normal. Pyle && Aviation...a showery unstable airmass will lead to mainly VFR conditions across the area. The lower atmosphere should remain modestly unstable even overnight so ceilings should generally remain VFR...but MVFR ceiling development will be possible. Confidence in timing and location of any such lower ceilings is low so kept MVFR conditions limited in the tafs. Kpdx and approaches...expect VFR conditions with scattered showers into this evening. Conditions should generally remain VFR overnight into Thursday...but cannot rule out an occasional MVFR ceiling...particularly towards Thursday morning. /Neuman && Marine...expect tranquil winds and seas through Saturday as high pressure moves over the northeast Pacific. A series of weak storm systems will likely cause winds and seas to increase early next week. However...seas should remain below 10 feet and little more than small craft advisories for wind gusts of 25-30kt appear possible Monday through Wednesday. /Neuman && Pqr watches/warnings/advisories... or...none. Washington...none. Pz...none. && 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.