This swirl in the northern Pacific south of Alaska isn’t going very far anytime soon. This large low-pressure vortex may even drift a little more south or southeast toward the Northwest U.S. And as long as it’s there, the chances of extreme Arctic air anywhere in the U.S. and for major storm systems east of the Mississippi is just about nil. The low, rotating counterclockwise, will hurl some disturbances into the Pacific Northwest, leading to rounds of rain and wind, with snow in the high mountains. Farther east, it will lead to a west -southwest flow of air through many layers of the atmosphere that will sweep in mild Pacific air over much of the U.S., deterring the southward advance of large Arctic air masses. We call this pattern of low-pressure in the northwest dominating the weather the Pacific-North American negative phase (PNA-) — these charts track the PNA index, and the line staying below the middle mark shows the PNA- pattern holding for the next several days. Some of the U.S. east of the Appalachians, however, will remain outside the main part of the Pacific mild thrush, and will continue to be affected by cold high pressure systems in southeast Canada and the northeast U.S. nosing in some colder surface air, with near to below normal temperatures hanging on in the mid-Atlantic and Southeast, including Virginia, for much of the next 10 days. This will be augmented some by the counterclockwise rotation of an offshore low-pressure system early next week, now projected by nearly all forecast models to be well offshore and not a great threat to cause inclement weather over any portion of the East (except perhaps the coast of the Carolinas) during Thanksgiving week. It appears that whatever fronts that do push through will be mostly dry, with no sign of any strong low-pressure systems forming that would cause more widespread precipitation in the East (except maybe scraping some of the Southeast U.S. coast early next week) through at least Thanksgiving Day and perhaps beyond. The resulting weather for Southwest Virginia will be a long period of mostly dry weather (some drizzle/light rain may develop with “wedge” effects of easterly winds blowing against the mountains by late weekend or early next week) with 50s highs, 20s/30s lows, gradually working toward perhaps some low-mid 60s highs and 30s/40s lows by Thanksgiving itself. This does not look to be a troublesome or turbulent Thanksgiving for travel in most of the U.S. aside from the Pacific Northwest.
Beyond Thanksgiving, there are just too many mixed signals to say too much right now.