Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
677 FXUS66 KPQR 270322 AAA AFDPQR Area Forecast Discussion UPDATED National Weather Service Portland OR 820 PM PDT Fri Jul 26 2024 ...EVENING UPDATE, for aviation weather. .SYNOPSIS...Stable onshore flow will maintain fairly benign weather with seasonably warm days and cool nights through early next week. A passing system brings a chance for rain next Monday into Tuesday. Models then hint at a warming trend mid to late next week as high pressure builds back over the area. && .SHORT TERM...Tonight through Sunday Night...Typical summer weather today and through the weekend. Broad, weak troughing aloft with stable westerly flow across the region. Some light haze from nearby wildfire smoke, mainly east of I-5 will push t 5-10 kt with gusts up to 18 kt lasting until 05-06Z Saturday. back east of the Cascades tonight as another surge of onshore flow moves across the area. The main exception will be where near surface smoke is confined to the immediate vicinity of ongoing fires in the Linn and Lane County Cascades where LRAPA has issued an Air Quality Advisory through Saturday afternoon. Afternoon highs expected in the lower to mid 80s for the interior lowlands. Morning clouds from marine layer intrusions into the inland valleys each night will help moderate overnight temps a few degrees. Otherwise, mostly sunny skies continue through Sunday. Breezy conditions will continue through the central Columbia River Gorge Saturday and Sunday afternoon and evening, with a renewed onshore push perhaps allowing for slightly stronger winds gusting to around 25-35 mph in parts of Hood River County. /DH .LONG TERM...Monday through Friday...Still monitoring chances for rain early next week. Models continue to speed up the timing of the frontal system as a more well defined shortwave embedded within the large scale trough crosses the region. Rain is likely to begin as early as Monday morning for coastal areas, gradually spreading inland through Monday night. PWAT values peak Monday afternoon around 1.5 inches of precipitable water according to the ECMWF ensembles. Regardless, ensemble and probabilistic guidance continue to be rather bullish on the prospect of at least measurable rain across the area, depicting around a 70 percent chance for northern coastal areas and about a 50/50 shot for the Willamette Valley. Meanwhile, the chance for as much as a quarter inch of rain sits around 40-50 percent on the coast and 20-25 percent from Eugene to Portland. Also expect slightly cooler temps again Monday into Tuesday as this system crosses the region accompanied by increased cloud cover and highs closer tot he upper 70s in the inland valleys. WPC ensemble clusters continue depict a ridge of high pressure developing over the western CONUS and a subsequent warming trend mid to late next week. Guidance has backed off slightly for highs next Wednesday, keeping temps closer to the mid 80s for one more day before the chances to reach 90 degrees jump up to around 70-80 percent in the inland valleys by Thursday and remaining there through the end of next week. DH/CB && .AVIATION...Dry west to northwest flow aloft over the region. High pressure offshore will maintain low level onshore flow into Sat. As such, will see areas of MVFR CIGS reforming along the coast over rest of Fri evening, with that stratus pushing inland via the gaps in the coastal mtns/highlands. Should see areas of lower MVFR inland throughout the Cowlitz River Valley, and along the Columbia River upstream to the PDX/VUO/TTD area by 12Z to 13Z. But, inland stratus will gradually break up Sat am, with mostly clear skies afterwards. Stratus along the coast will persisting into the early afternoon, then gradually break apart, with scattered clouds in the afternoon. With westerly to northwest flow relaxing overnight, will maintain to see haze and smoke over and east of the Oregon Cascades. Expect some reductions to slantwise visibilities, along with smoke layers around the fires. PDX AND APPROACHES...VFR will continue, with dry air mass and mostly clear skies. But, with onshore flow, will see areas of MVFR marine stratus pushing up the Columbia River overnight, spreading across Clark County by 12Z, and into OPS area from 13Z to 17Z, mainly east of Interstate 5 to the Cascades foothills. /Rockey && .MARINE...A weak upper level trough will slowly meander eastward through the weekend. Currently, expect persistent north/northwest winds with low-end Small Craft gusts, primarily in our central and southern waters. Threat will subside late tonight (Friday) and seas will remain around 4 to 6 ft thereafter. Overall benign conditions through the weekend with a southerly wind shift expected late Sunday/early Monday. -JH && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory until 2 AM PDT Saturday for PZZ252-253-272- 273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland