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The Atlantic tropics have been eerily quiet over the last couple of weeks. Indeed, the big headline has been that we turned the calendar to September without having a hurricane, the first time since 2002 that’s happened. Overall, August was remarkably quiet, despite the fact that conditions broadly favor development:

August 2013 had one of the lowest Accumulated Cyclone Energy (ACE) totals on record for an August in the Atlantic. … This year’s combination of no El Niño, warm [sea surface temperatures], and an exceptionally low August ACE is an event unparalleled in the historical record, going back to 1966. … The main reason for the quiet August has been the large amount of dry, stable air over the Atlantic. This dry air has two sources: the Sahara desert of Africa, and sinking air from aloft, which warms and dries as it sinks. Even so, I find it highly perplexing that activity has been so low when all of the other factors–lack of an El Niño, low wind shear, an active African Monsoon spitting out plenty of tropical waves, and above average ocean temperatures–have favored development.

But we may now finally have a candidate for significant tropical development. “Invest 97L” near the Lesser Antilles, a wave that emerged from Africa a week ago (and was written off by computer models days ago), seized the attention of the weather community Sunday as it took advantage of favorable conditions caused by a split-in-half upper low system (which Jonathan Belles explains further), and started looking unexpectedly robust:

97Lrgb0

As the convection fired up, 97L also started producing some attention-grabbing long-range computer model forecasts:

Now, let’s not get carried away here. “97L” isn’t even a tropical depression yet, let alone the major hurricane that some models are predicting it will eventually become. It may very well fizzle entirely, or become another Chantal/Dorian/Erin — a minor storm that develops, but never becomes a significant threat. Notably: “Several of the models indicate that this tropical wave will, in fact, become a hurricane. However, the advanced global models, such as the GFS, show next to nothing at all happening.”

The smart money is that, at a minimum, those bullish intensity models are developing 97L too quickly, for the reasons Dr. Jeff Masters notes:

The main factor keeping the disturbance from developing over the next two days would appear to be the fact that 97L is quite large, and is stretched out from east to west over a wide expanse. Large, elongated systems like 97L usually take several days to consolidate and spin up. Another factor that will likely retard development is the presence of strong surface trade winds over the Eastern Caribbean ahead of 97L, south of the Dominican Republic. These strong trade winds are a common feature of the Eastern Caribbean, and make the region something of a hurricane graveyard. As the surface wind flow to the west of 97L accelerates into this wind max, air will be sucked from aloft downward towards the surface, creating sinking air, interfering with the formation of thunderstorm updrafts. The best chance for development of 97L would appear to be on Wednesday or Thursday, when the disturbance reaches the Central Caribbean.

Here’s a graphical representation of that concept:

By the way, that video update by Levi Cowan really is very helpful and informative. If you want to understand what’s going on with 97L, I recommend taking 8 minutes to watch it:

Another important caveat: if this system does become “Gabrielle,” we cannot even begin to know where, specifically, it will go, because any continental landfall would be many days away — plus, storms that don’t exist yet are very difficult to accurately forecast! So there’s no cause for #PANIC or hype. It bears watching for anyone in Florida or anywhere on the Gulf Coast, but guidance more specific than that is impossible. As Brian McNoldy writes:

We will clearly have to watch this closely, as model solutions range from near-nothing to a Category 3 hurricane in 5 days near Jamaica. Right now, it’s too soon to get concerned, but not too soon to pay attention.

I’ll certainly be paying attention. Stay tuned to this blog and my Twitter account for the latest.

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All Comments   (9)
All Comments   (9)
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The most significant news in tropical storm forecasting in the last 10 years or so came from 2004, in which a Tropcial Prediction Center official admitted that, "We don't forecast on the basis of where we think the storm will go but rather on the basis of what we want people to do."

A meteorologist I know (and who, unlike the TPS, correctly predicted the path of Hurricane Charley in 2004) explained a concept called "The Forecast of Least Regret." For example, if there is a drought and you think there is a good chance of rain tomorrow, you publically admit that there is a chance of rain but discount it as being unlikely. That way, if it rains, people will be pleased. If you say it will but it does not rain they will come after you with pitchforks and torches.

If you fail to tell people a hurricane is going to hit them and one does, they'll hunt through the debris afterwards and find their pitchforks and torches (reference: Hurricane Charley in 2004). If you tell then a storm is going to hit them and it passes by 60 miles away they'll be relieved. That's how the TPS makes predictions. And if they are off by only 60 miles they'll throw a party to celebrate how they hit the track dead nuts, according to their standards. The fact that 10 million people evacuated needlessly is of no consequence to them; in fact, they'll call that a victory.

Conclusion: Listen to what they say but make your own decisions.
51 weeks ago
51 weeks ago Link To Comment
Most of the the hyping is just BS global warming warming window dressing. Sometimes it's just stir crazy professionals with nothing to do. Dorian gray etc. Or this: a get to the 1st-snowflake-of-the-season commercial.

www.tvspots.tv/video/14203/DUNKIN-DONUTS--PLOW
51 weeks ago
51 weeks ago Link To Comment
This goes right along with their Global Warming theories and hypotheticals--none of them are worth a feculent flatulent expulsion of greenhouse gas! Talk about minor gov't functionaries trying to justify their pathetic excuses for jobs!
51 weeks ago
51 weeks ago Link To Comment
The over-hyping of every tropical rain cloud notwithstanding, sooner or later we WILL get a hurricane. Maybe this year. Maybe next. But by then who will listen to the warnings?

The last time we got hit with a major hurricane was 2005. Remember 2005?
51 weeks ago
51 weeks ago Link To Comment
I don't normally make predictions about the weather, especially this far out, but I will break my own rule in this case. I have an outdoor event next Saturday on the beach in St. Augustine, Florida. It cannot be moved. It cannot be rescheduled. Chance of hurricane? 100%
51 weeks ago
51 weeks ago Link To Comment
That's the most accurate forecast modeling I can think of! ;) If I was scheduled to go to the condo that weekend I would heartily concur. Good luck with your outdoor plans....

Remember BENGHAZI!
51 weeks ago
51 weeks ago Link To Comment
The weather clowns are pathetic, They're so desperate for a really bad "weather event" they have to start inventing them now.

I can just hear the whole lot of them in the background, murmuring, "Please be a hurricane, please be a hurricane ...."
51 weeks ago
51 weeks ago Link To Comment
It only takes one hurricane to make the doomsayers' narrative continue. They're like terrorists. They only have to be "right" once to bear out all their predictions.
51 weeks ago
51 weeks ago Link To Comment
I suppose if the weather reporters can't have a real hurricane they'll have to make the best of almost-hurricanes. Next step will be to give the almost-hurricanes a catchy new name. Protocane? ImpedingDoomicane?
51 weeks ago
51 weeks ago Link To Comment
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