PENNSYLVANIA, USA — It's Friday, and that means it's time for another Weather Rewind, where we take a look at some of the best weather video from the past week, with a twist.
This week, we're talking about the stubborn low clouds and fog that often slowed up our morning travels.
LET’S REWIND
Stalled moisture off the Mid-Atlantic coast made for several days of damp and dreary conditions earlier this week.
Low clouds, stubborn fog, drizzle and light showers hung around until Wednesday morning.
Fall is around the time Central Pa. can get stuck in these ruts.
You may recall earlier in the month when the moisture from former-hurricane Ian stalled and brought a similar, dreary stretch.
So why does this happen?
WHAT’S HAPPENING?
There are many ways to get fog, but in these two particular cases this month, inversion fog was the culprit.
Moisture settles in from a system near or off the Atlantic coast, and it’s usually weak and slow-moving—or even stalled.
Light winds, normally with an easterly component, help to draw in more moisture.
The combination often brings more low clouds, fog, and drizzle.
This helps to keep the lowest part of the atmosphere cooler and denser than the milder and less dense air above it.
This forms an "inversion" layer, where temperatures increase with height.
This can often turn into a feedback cycle where the low clouds and light precipitation keeps the cool, dense air in place.
The lowering sun angle in late fall often struggles to clear out the moisture, unlike what we usually see during the summer months.
Often what's needed to finally break these stagnant setups is a strong storm system from the west, like we saw on Wednesday.
Depending on how long that takes, you could be waiting several days for some sunshine!
Stay tuned every Friday for the "whys" behind the weather wonders that grab our attention each week!