A blow-up of the cloud situation in Oregon shows the predicted cloud-free conditions for northern Oregon. Only the coastal zone is potentially problematic, with some low stratus clouds.





What about visibility? Moist air can result in enhanced particle sizes and precipitation is clearly bad for eclipse viewing.





Here is the visibility forecast for the U.S. at the same time from the ECMWF model (which does NOT include smoke). Degraded visibility in the southeast U.S. and central U.S. The best visibility (white color) in the Willamette Valley and SW Oregon (see blow up map for more detail)





Finally, there is wildfire smoke and unfortunately, there are a lot of fires going on right now over the western U.S. and plenty of smoke. For those viewing on the eastern slopes of the Oregon Cascades and in eastern Oregon, a veil of smoke will be present and will undermine clarity to some degree. As shown below, there are a number of fires burning over Oregon and particularly in the areas of totality (north of Bend):









The current satellite observations of smoke impacts (actually atmospheric optical depth) indicates smoke over the Northwest, particularly eastern Oregon (see blow up below). But if you look carefully, once sees that the Willamette Valley is virtually smoke free.













The Canadian Smoke model's 48h forecast for Friday at 5 PM PDT is showing plenty of smoke eastern Oregon, but not on the west side. Lots of smoke over the eclipse path of eastern Wyoming and Nebraska.









A blow-up map confirms this. Salem is 5%.





We are now close enough to the eclipse to have great confidence in the weather forecasts and the expectations regarding wildfire smoke. Computer models are in substantial agreement and forecast uncertainty is far less than a few days ago.The conclusions one draws from the predictions are clear:Clear skies and smoke-free air, resulting in exceptional viewing conditions. And it has the added benefit of being near a major interstate (I5) and several large roads (99E, 99W).Let me show you why western Oregon's Willamette Valley offers such good viewing. Let us begin by reviewing the path of totality over the U.S.--a curving path stretching from northern Oregon to south Carolina.Here is the total cloud forecast from the European Center model, one valid at 11 AM PDT on Monday, August 21st. A red line shows the path of totality. Lots of clouds in Great Plains and mixed clouds in the southeast. Only the section over Oregon is completely clear.I could you show you other models, but the answers are the same:You don't like models and want to get the predictions of my colleagues at the National Weather Service. Here is their prediction for % cloud cover at 11 AM on Monday. By far, the lowest percentage (5%) is in the Willamette Valley.So if you are in Seattle, Portland, and California,I suspect the big traffic issue won't be before the event (since folks will getting into position over several days). It is after the eclipse is over. Everyone can't leave at once. And governmental entities need to set up some major viewing locations (with bathrooms) and facilitate access to I5 and other major roads.