THE FUJIWHARA EFFECT...

There's been no shortage of sunshine across the region as we've gone through the month of September. This has led to a lack of precipitation and above normal temperatures. The sunny, warm weather continues on Thursday:

The warm, dry conditions persist through the end of the week and weekend despite the remnants of Hurricane Helene moving into the region. Helene, projected to be a powerful major hurricane (category 3 or 4) will make landfall in Florida on Thursday night:

The remnants of Helene will interact with an upper level low pressure system in a unique phenomenon known as the Fujiwhara effect. Watch here as the two low pressure systems dance around each other and then merge:

The Fujiwhara effect is commonly seen with tropical systems, when they get close to each other they'll spin around a common center. This can happen on different scales, as seen here with a non-tropical upper low. The two are expected to merge and linger in the Mid-South, leading to our area largely missing out on rain. This is due to high pressure at the surface and a strong ridge in the upper levels:

When the Fujiwhara effect happens, models can have a difficult time resolving. However, it seems that the systems will merge and produce heavy rain in portions of the southeast through the weekend:

Much of the Midwest sits high and dry with just some clouds passing through on Friday and Saturday. There may be some light rain in northwestern Illinois, but not anything impactful.

These dry conditions are unfortunately expected to continue through the end of the month and start of October:

More on the dry stretch in my next post...

Rebecca Kopelman