Tropical Depression 9 – We’re Watching It

The kiss of death for a TV meteorologist is guaranteeing sunshine, low humidity, and comfortable temperatures for a holiday weekend. Something always seems to go wrong. This year Tropical Depression 9 is threatening to ruin the party.

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Tropical Depression 9 is looking better organized this evening and has a decent shot of becoming a strong tropical storm or even a hurricane before making landfall in Florida. What happens after that is much less certain. Here’s the forecast from the National Hurricane Center which brings the storm along the Carolina coast and then slows it down and begins to hook it left in the general direction of New England.

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So what the heck is going on? Why the stall and left hook? Many of our computer models show a somewhat odd evolution including most of the GFS ensemble members and some of the European ensemble members. When this thing gets to our latitude there’s a whole lot of weirdness going on.

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The reason why we’re seeing a bit of a stall/bend back to the west is that TD9 appears will miss it’s one way ticket out to the Atlantic Ocean. The westerlies/jet stream may avoid picking this storm up causing it to meander around our latitude. That allows all sorts of funky things to happen including loop-de-loops, total stalls, movement in odd directions (due west), etc.

The jet stream effectively retreats to the north here with a building ridge to our north and east. This closes the escape hatch most storms love to take.

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It’s important to note that getting a direct hit from a major tropical storm or hurricane with this kind of setup is tough to do. A large blocking downstream ridge helped Sandy get flung west (but more importantly a large cut-off low to the west effectively sucked the storm in). Hurricane Esther in 1961 has a fun looking path from a funky weather pattern.

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But it’s really hard to come up with examples of storms that stalled or had such an odd evolution off the coast that had a major impact here. Sure it’s possible but it’s definitely not likely.

The most likely scenario is a miss or little/no impact in Connecticut. This is still 5 days away and the storm isn’t even a storm yet – just a depression. There’s a small risk (say less than 1 in 4) that these closer to the coast or nearby stall scenarios will verify which would give us a more moderate impact storm (think out of season nor’easter with rain instead of snow). It’s extremely unlikely that we’d see a serious/major impact at this point from a more powerful tropical cyclone- though I can’t rule it out entirely.

So there you have it. We’ll watch this storm every step of the way and keep you posted. The good news is (for the time being) that the most likely scenario is still a sunny and warm Labor Day weekend. Let’s hope it doesn’t change – although we do need the rain!