Watching the tropics this holiday weekend on multiple coasts

This weekend is the last weekend of the summer by many measures. Meteorologically summer ends August 31st. For everyone though Labor day weekend is the end of summer even though astronomically it ends September 23rd this year.

Labor Day is also usually a weekend with a tropical system of some kind threatening the U.S. and this year is no different. We have Katia out in the middle of the Atlantic and Lee which has yet to form but will likely down in the Gulf of Mexico by this weekend.

The forecast for both is very uncertain, though I feel much better about Katia of the two. The problem is due to a complex set-up being shown in the model guidance Katia could actually get pulled into the mess on the east coast if things go a certain way.

First Katia:

Pretty straight forward….. well kind of. Katia should be a fish storm re-curving around the big mid-Atlantic ocean ridge. Likely it will be come major hurricane north of the Caribbean. The complications start with a trough, cold front and possibility of yet to be named Lee.

Yet to be named Lee and the mess on the east coast:

There is an old front and a tropical wave that are interacting right now near the Yucatan channel. This will likely become Lee but then things get crazy based on the guidance.

GFS model:

Sunday afternoon 2pm:

Monday afternoon 2pm “Lee” I think is moving over the southeast along a strong autumn like cold front.

This is where things get funky, Lee moving over the Carolinas producing heavy rain Monday, Tuesday maybe even Wednesday. The question is does Katia move back west due to ridge to its north and the weakness on the east coast?

The European model complicates things further:

Sunday night the EURO has a huge but weaker low in the Gulf of Mexico.

Then it splits off a piece of energy to the Northeast towards the Carolinas.

So the result is 3 systems! One near the Carolinas, one in the Gulf and of course Katia near Bermuda. (Oh and 2 little waves behind Katia )

Look at this mess off the east coast on Thursday night. Looks like “Perfect Storm” part II.

So what’s going to happen?

The results are just crazy because normally you’d see Katia just re-curve but the trough might actually cause it to get too close for comfort and actually merge with the east coast system. The EURO actually shows this above then you could get into the Fujiwhara effect and all kinds of crazy possibilities. The honest answer is I just don’t know.

The only known quantities right now are Katia. So until the Lee forms and the trough enters the western U.S. we really don’t know. The one thing I can see happening is we have a great Sat-Sun start to the holiday weekend and then a big time wash out Monday into Tuesday. The worst case scenario isn’t actually a major hurricane on the east coast, it’s a stalled front and tropical system soaking already flooded areas from Irene.

Stay tuned if you live anywhere on the Gulf Coast or East Coast because for the first time in a while both could have simultaneous threats from the Tropics.