Tropical Development Chance up to 50%. Don’t Panic.

The Sunday afternoon view of the tropic situation is a bit different than Saturday night, but there’s still no need to head for the hills.

The National Hurricane Center now gives that I-Think-I-Can would-be tropical system currently hanging out over Tennebamassippi about a 40% chance of development once it reaches the Gulf of Mexico later this week. The Gulf waters are pretty darn warm… at least 86 degrees in spots right now… so there is a decent chance that anything that winds up there could try to spin up into a tropical depression by the end of the week.

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Sun Jul 7 2019

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

1. A trough of low pressure over the southeastern United States is
forecast to move southward toward the northeastern Gulf of Mexico,
where a broad low pressure area will likely form in a few days.
Thereafter, upper-level winds support gradual development, and a
tropical depression could form late week while the low meanders near
the northeastern Gulf of Mexico coast through Friday.  Interests
along the northern Gulf Coast and Florida peninsula should monitor
the progress of this system.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...50 percent.

So where is it going? Honestly, we’re still in “who knows” territory. The forecast models seems to agree that “something” will happen, but can’t quite get it together on “what,” “where,” or “how strong.” Here’s a sample of just how out-of-agreement the models are right now…

Note: This article contains forecast model graphics. Models do not necessarily mean an actual forecast of that result. They represent a potential result based on a specific set of available data at a single point in time, and cannot account for additional forecast variables that may occur many days into the future.

The European Model for one week from today puts a relatively well-organized tropical system at or near landfall around the Louisiana/Mississippi coasts.

Meanwhile, the American model for the same time shows it well inland by then, somewhere over South Carolina after having gone through the big Bend of Florida.

And the Canadian model puts it off the coast of North Carolina.

So why the uncertainty? The simplest description I’ve ever seen is this graphic from the National Weather Service’s Kansas City, MO office. The image is about snow forecasts, but it’s valid for any forecast that goes several days in the future.

Credit: NWS Kansas City, Missouri WFO

But make no mistake… we’re getting better. The ever-present NHC forecast cone, which represents forecast uncertainty, gets smaller every year because the overall average forecast errors get smaller every year. Take a look at how the cone for Hurricane Katrina looked in 2005 versus how small it would have been for the same storm in 2015.

Credit: NOAA

Even our non-hurricane forecasts are getting better.

Generally speaking, with each passing decade meteorologists have been able to make that claim one day farther into the future. That means a six-day forecast today is as good as a five-day forecast was a decade ago; a five-day forecast today is as good as a three-day forecast two decades ago; and, most dramatically, today’s six-day forecast is as good as a two-day forecast in the 1970s.

Andrew Blum, The Weather Machine

So our instructions to you today are the same as they were on Saturday. Don’t panic… heck, don’t even sort of worry about this thing. Just check back every few days to make sure nothing major has changed.

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