Will we be watching dancing storms?

Before the dance, there’s some good weather news here. First, we’ll be seeing a good chance of showers and storms Wednesday into Thursday with many of us getting an inch of much needed rain. Second, after the cold front clears us on Thursday night, we’ll be seeing cooler morning lows, slightly cooler afternoon highs, and noticeably less humid air for the weekend. Finally, there’s no chance of anything tropical here in the next 10 days. However, the real fascinating thing is the meteorological dance that could take place in the Atlantic where it won’t impact us.

Two tropical waves just east of the islands could develop into hurricanes over the next six days and come within 500 miles of each other. There’s a tendency for storms to rotate around each other when they get this close. That dance is called the Fujiwhara Effect, named after the Japanese meteorologist who discovered this and it’s pronounced Fuji-wa-wa, like the gas stations back east. This is real complicated stuff leading to lots of forecast uncertainty. none of which effects us along the Gulf Coast. I’ll get into why we’re safe, why meteorologists will absolutely geek out over this in my Long-Range Ramblings after a brief October outlook.

The Foreca graphic captures the temperature change and rainfall well for Slidell, but there will be some east-west differences across the region. The NWS graphic below illustrates this with much higher rain chances in Hammond and Franklinton tomorrow than in Gulfport. By “Wednesday through Thursday morning”, they mean through daybreak Thursday. So Hammond should should see more cloud cover tomorrow with temperatures staying in the upper 80s while places like the north part of Gulfport could see 92.

Showers and storms should move gradually eastward with Slidell and Gulfport seeing greater rain chances on Thursday (80%) and Hammond less chance (50%). With more clouds, all of us should stay in the mid 80s on Thursday.

The weekend should be lovely with sunny skies prevailing by Friday (though there could be a light sprinkle Friday afternoon), especially on the Northshore and Coastal MS. Highs 87-88 with Northshore lows 63-65 is a step in the right direction. Southshore lows will be closer to 70, but with a bit of breeze if you are near the water.

After the lovely weekend, temperatures should moderate just a bit by mid-week. Expect a warmer than normal first half of October with highs 87-90 and lows 66-69 on the Northshore. For what its worth, Accuweather is forecasting the first big cold front of the season about Oct. 17 with highs in 70s and lows in 50s. That seems about right.

Now, onto the Atlantic: Of the two waves east of the islands, the eastern is virtually certain to develop into a tropical storm in the next 3 days and be named Humberto. That’s shown by the red X and the hatched area shows its projected path. The one to the west has a 60% chance of developing, but it won’t develop until Saturday when it just north of Haiti or in the Eastern Bahamas IF it survives a bit of wind shear, and interaction with the mountains in Haiti.

It’s at this point, late Saturday or Sunday, that the two storms would be within about 500 miles of each other and the Fujiwhara effect would influence the storms to rotate around each other. However, an approaching dip (or trough) in the jet, though protecting us with its west winds over the Gulf (arrows in the figure below), adds another element of uncertainty. The maps shows the upper air winds and storms expected by the ECMWF model mid-day Saturday. Sometimes hurricanes grow east of these troughs because they encourage upward motion, sometimes not because of the wind shear. The bottom line is a lot of factors come into play in about 4-6 days which will make for a very uncertain forecast for these two systems. Though not likely….North Carolina and the Cape Cod area could still get hit by one of these. My hope is that something fascinating will take place, a ton of data will be captured, and forecast modeling will improve all while the systems stay offshore.

Foreca graphic for Pensacola Beach shows a nice Saturday, Sunday, and start to next week.