FXUS66 KPQR 192227 AFDPQR Area Forecast Discussion National Weather Service Portland OR 327 PM PDT Fri Jul 19 2024 .SYNOPSIS...Above-average temperatures continue as high pressure strengthens through Saturday. Chance of light showers and thunderstorms late Saturday night through Sunday afternoon with best chances along the coast. Then, broad upper level troughing brings cooling trend early next week, with temperatures around seasonable normals through next week. && .SHORT TERM...Friday afternoon through Sunday...Visible satellite imagery Friday afternoon shows mostly clear skies across NW Oregon and SW Washington with the exception of low stratus and fog right along the coast north of Newport. Smoke plumes from wildfires in the central Oregon Cascades are also visible this afternoon, and haze and smoke from these fires are expected into the weekend. Inland temperatures are on track to peak in the upper 80s today with 60s to low 70s along the coast. Marine stratus and fog will build along the coast again this evening into Saturday morning under upper level ridging. The upper level ridge will amplify over the region on Saturday while 850 mb temperatures warm to around 22- 24 deg C. Inland highs are expected to reach the mid to upper 90s (60-95% probability of reaching or exceeding 95 degrees), while highs near Hood River will push triple digits (50-60% probability). This will create widespread high-end Moderate HeatRisk across the inland lowlands to to localized areas of Major HeatRisk from the Portland metro through the Columbia River Gorge. A Heat Advisory has been issued for the eastern Willamette Valley, Portland Metro area, Clark County, Columbia River Gorge, and Hood River Valley on Saturday. Upper level ridge begins to shift eastward on Sunday. Models continue to indicate a negatively tilted shortwave trough lifting north over the coastal waters Saturday night through Sunday, albeit rather weak. Chances are increasing for scattered showers with light rain through Sunday afternoon across most of the area (15-20%), though best chances are along the coast (20-30%). Elevated convection potential has increased to around 15%, so have introduced thunderstorm chances to the forecast. Temperatures Sunday afternoon expected to be around 10 degrees cooler than Saturday, along with stronger onshore winds. -DH/HEC .LONG TERM...Monday through Thursday...Temperatures are very likely to trend cooler near seasonable normals early next week. Upper level troughing nudges into the Pacific NW on Monday with strong onshore flow. Marine stratus more likely to push inland Monday morning with highs topping out around 80 degrees. WPC cluster analysis remains in good agreement with model ensembles showing upper level low centered near Haida Gwaii on Tuesday, slowly shifting east into British Columbia by mid-week. NBM guidance suggests temps will likely trend closer to the mid-80s as near seasonal normals and dry weather persists next week. /DH && .AVIATION...High pressure remains over the region, along with mild southwest flow aloft, will maintain VFR conditions under clear skies for inland areas. Currently VFR and clear skies along the coast, but conditions will return to IFR beginning 00-03Z Saturday, as the stratus will once again surge back onshore. Conditions will remain at least IFR until around 20Z Saturday, with chances of conditions lowering to LIFR around 50-60%. Around 19-20Z Saturday, northwesterly winds will increase along the coast, with sustained winds around 10-15 kt and gusts up to 20-25 kt. PDX AND APPROACHES...Little change, with VFR conditions and clear skies under high pressure and mild southwest flow aloft. -JH && .MARINE...High pressure offshore will gradually strengthen today into this weekend, and with thermal low pressure on south Oregon coast, will see return of north winds on the waters. As pressure gradients tighten on Saturday, will see gusts to 25 kt at for Sat and Sun, mainly in the afternoons/evenings from Cascade Head southward. Seas mostly stay in the 3 to 5 ft range, with a mix of variable period swell, but with gusty winds, will have locally choppy steep seas to 6 or 7 ft. Again, this mainly for areas south of Newport. /Rockey && .FIRE WEATHER...An upper level disturbance moving through NW Oregon and SW Washington late Saturday night through Sunday will bring an influx of mid level moisture to the region. This moisture will produce a 10-15% chance of elevated thunderstorms. Since the majority of the moisture is in the mid levels, rainfall at the surface is expected to be limited, less than a wetting rain. Therefore, a Fire Weather Watch has been issued for most fire weather zones in the region excluding along the coast, the northern Oregon Coast Range, and Willapa hills as fuel conditions are not primed for rapid fire spread potential in these areas. The main threat will be fires started by lightning strikes as well as the potential for spread of new and existing fires due to gusty outflow winds from thunderstorms. Thunderstorm chances will spread from the south to north with best chances 11 PM PT Saturday through 5 PM PT Sunday. -HEC && .PQR WATCHES/WARNINGS/ADVISORIES... OR...Heat Advisory from 11 AM to 11 PM PDT Saturday for ORZ111-112- 115-117-118-120>122. WA...Heat Advisory from 11 AM to 11 PM PDT Saturday for WAZ205>207- 209-210. PZ...Small Craft Advisory from noon Saturday to midnight PDT Saturday night for PZZ251>253. Small Craft Advisory from noon Saturday to midnight PDT Sunday night for PZZ271>273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland