![]() However, because the jet aloft dips south so quickly therefore reducing the residence time of atmospheric river over the area it'll likely be categorized as a moderate to strong atmospheric river when it's all said and done. Putting this easily into the strong category with some ensemble members reaching into the extreme threshold. There is very good agreement between the ECMWF and GFS ensemble model suites that integrated vapor transport will reach 750-1000 kg/ms over the NW Oregon, SW Washington area Friday afternoon, early evening. The bulk of the guidance continues to point to a significant precipitation event taking shape as a strong, possibly extreme, atmospheric river impacts the region beginning along the WA Coast on Friday afternoon and shifting southward to the OR Coast Friday night into early Saturday morning. This will set the stage for the next system to impact the region from Friday into Saturday as a 160-170 kt jet streak takes aim on the Washington and Oregon coasts. Thursday looks to be a mostly dry day between systems, though rain chances may return across the northern coastal areas and the Lower Columbia Valley by Thursday evening as the ridge is quickly flattened out by the next upstream trough emerging from the Gulf of Alaska. This will result in a chilly start to the day on Thursday, with partial clearing overnight allowing temperatures to dip well into the 30s across the Willamette Valley and into the 20s in the higher terrain. Shower activity will quickly wind down from north to south this evening as the trough departs into the Great Basin, giving way to dry northerly flow as transient shortwave ridging builds in tonight. The winter weather advisory across the Lane County Cascades has been cancelled a few hours early as showers in this area have all but ceased. Snow levels will continue right around 2500-3000 ft through the night with diminishing shower activity. KRTX and KLGX shows scattered thunderstorms across the coastal waters with most losing their structure a few miles after coming ashore. Cold air advection aloft is producing enhanced instability across most of the area. An upper level trough has moved onshore and is currently over the Puget Sound as of 130 PM. Cool and showery weather then expected to continue into early next week.ĭISCUSSION. Atmospheric river sets up Friday afternoon into Saturday morning, bringing heavy rain and rising snow levels. Expect a brief dry period tonight into Thursday, with near freezing temperatures in the valleys on Thursday morning. ![]() Cool and showery weather with mountain snow diminishing this evening. Updated aviation discussion and PQR WATCHES/WARNINGS/ADVISORIES. UPDATED National Weather Service Portland OR 952 PM PDT Wed Nov 2 2022 ![]() Area Discussion for - Portland, OR (on/off) Help NOTE: mouseover dotted underlined text for definitionĪrea Forecast Discussion. ![]()
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