459 FXUS66 KPQR 062257 AFDPQR Area Forecast Discussion National Weather Service Portland OR 257 PM PST Tue Mar 6 2018 .SYNOPSIS...Weak high pressure aloft will bring dry weather and warmer temperatures through Wednesday. Another weather system will bring rain with higher Cascades snow Wednesday night and Thursday. That system will also bring a short period of gusty winds to the coast Thursday afternoon. Cooler weather, lowering snow levels, and plenty of showers continue Friday. Saturday through Monday may have more dry periods than wet as high pressure builds over the Rockies and low pressure re-establishes a fair distance offshore. The pattern shifts east Monday night and Tuesday returning us to a more dominant wet weather pattern. && .SHORT TERM...Tonight through Friday: Short wave high pressure over the region has brought a seasonably fine day. Temperatures will likely end up a little above 30 year normals after the chilly start. Low pressure centered well offshore is starting to stream a band of high clouds overhead to likely limit significant warming for the later half of the afternoon but do expect a few degrees above current temps. The upper low well offshore will track toward the PacNW, increasing offshore flow. Winds through the Gorge will increase with 25 to 35 mph gusts tonight and Wednesday. The upper low weakens as it arrives Wednesday night but will appear to have plenty of moisture still attached to a warm front. Snow levels will stay 5500 feet as the low opens up in to a short wave and moves across western WA early Thursday. The now open trough axis, will approach the coast Thursday morning and bring potential for gusty and marginal warning level winds along the central coast headlands for a few hours Thursday afternoon and evening. Opted to sit tight for now and see how the details evolve over the next 24 hours. Cooler air moves across the region and could bring about an 18-hour period Thursday afternoon and night where several inches of snow fall near the 4500-5000 foot level. Looks like the South Washington Cascades are most likely to reach the lower tier of Winter Weather Advisory amounts. Fortunately, the northerly track will not lend toward significant orographic lift, nor much of a threat of prolonged heavy lower elevation rains. The upper low remnants move inland early Friday with deep flow taking on a greater westerly component. Decent wind speeds will keep the orographic shower threat in place with snow level running 3500- 4500 feet. However, low level moisture will continually be decreasing to limit overall rain/snow accumulations. Still would expect a few inches of fresh heavy, wet snow across the Cascades The track of the upper low/wave will generally keep the CWA on the warmer side of the jet stream. Thus, daytime temperatures across the area will remain near or slightly above normals for the short-term period. /JBonk .LONG TERM...Friday Night through Tuesday: An upper-level ridge builds up over the area Friday night into Saturday, which will dry us out and bring temperatures back up into the upper 50s to near 60 on Saturday. As the ridge migrates farther inland, though, we end up with a shortwave clipping the southernmost part of our area late Saturday into Sunday. This means a chance for some showers, mainly in Lane County in the mountains and along the coast. As the ridge builds and becomes almost stationary to our east, we end up with a persistent trough off the coast of Washington and Oregon through at least the first half of next week. Depending on the exact position of this trough; as well as timing and the track of shortwaves rotating around the east side of the trough, we will probably see chances of rain on and off through at least the first half of next week. Snow levels will come up to around 6000-7000 feet and stay fairly high with at least the first wave Sunday night into Monday. Forecast becomes much more uncertain as we get into Tuesday. -McCoy && .AVIATION...VFR conditions with clear skies this evening. High clouds will gradually increase this evening and tonight. The thickness of these clouds will determine if IFR fog will develop in the interior valleys tonight into Wednesday. If they are thick enough to limit radiation cooling, do not think fog will form. If they are thin fog may result in brief IFR conditions, but a more likely possibility is for frost. PDX AND APPROACHES...VFR conditions under dry NE flow. East winds and high clouds should prevent fog formation tonight. However, but if the winds are calm and the clouds thin, then brief fog and IFR is possible early Wednesday. ~TJ && .MARINE...Offshore winds increase this afternoon and will have marginal Small Craft Advisory gusts through tonight. A strong low pres system will approach Wed night into Thu, and likely produce Gales over the waters. Have updated the forecast this morning to issue a Gale Watch. The low is modeled to move onshore somewhere along the WA coast Thursday afternoon. The seas will increase in response to these winds and expect seas in the mid to upper teens Thursday morning. A weak cold front will move through the waters Thursday night into Fri keeping a chance for Small Craft Advisory conditions. Then weak high pressure moves into the waters later Fri into the weekend for more benign ocean conditions and a return to offshore winds. ~TJ && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Gale Watch from Wednesday evening through Thursday afternoon for Waters from Cape Shoalwater WA to Florence OR from 10 to 60 NM. Small Craft Advisory for winds until midnight PST tonight for Waters from Cape Shoalwater WA to Florence OR from 10 to 60 NM. Gale Watch from Thursday morning through Thursday afternoon for Coastal Waters from Cape Shoalwater WA to Florence OR out 10 NM. && $$ 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.