It's not at all uncommon for us to see fog in these parts this time of year. However, the regularity with which we've contended with fog this month has been quite atypical. Fog has been reported in the Stateline on exactly half of March's first 24 days, and it's nearly certain that a 13th March day with fog lies ahead Wednesday.
Already as of 11pm Tuesday, visibility was reported to have been dropping over much of the Stateline, with further reductions set to occur in a rather favorably environment for fog development presently in place. There are three principle factors we look for when forecasting fog potential. We first look at the moisture content present in the air. From there, attention is paid to the amount of cloud cover present, or the lack thereof, as well as the magnitude of the wind blowing. Let's address where we stand with regard to each of these criteria.
As moisture supply goes, frankly stated, there's not a ton of it present, though there's some, enough so that it's at least a bit of a player. Dew points are only in the lower 30s in most spots. However, as temperatures fall closer to the dew point overnight, the atmosphere will become increasingly saturated, which increases the specter for fog. That's where the other two ingredients come in.
Skies are mainly clear across the Stateline right now. This will allow our temperatures to more expeditiously fall closer and closer to the dew point in the hours ahead, further adding to the fog potential. On top of that, winds continue to die down, and will continue to do so overnight. This limits the ability for our atmosphere to be stirred around, so any fog that does develop will likely just hover around the rest of the night. Without any wind to stir up the atmosphere until at least the early or middle portions of Wednesday Morning, it's plausible the fog may stick around well past sunrise.
As of the writing and publishing of this story, no advisories have been posted for the Stateline with regards to the dense fog potential. That said, I would not be surprised to see at least part of the area under an advisory at some point in the night or early morning hours of Wednesday.
With visibility expected to drop well under one mile over much of the Stateline through at least early Wednesday, it will be prudent to exercise caution if any travel is necessary through mid-morning. As winds pick up later in the morning, the fog should slowly lift.