Weather Nerd

Tropical Depression 3 forms off Carolinas

[UPDATE: Welcome, InstaPundit readers! The “Weather Nerd” homepage is here; that’s the URL you’ll want to bookmark, if you’d like to follow my season-long hurricane coverage here on Pajamas Media. Meanwhile, here’s a link to my latest update.]

For nearly a week, forecasters and weatherbloggers have been anxiously watching a tropical wave — formally known as “Invest 94L” — move across the deep tropics, from off the African coast through the Lesser Antilles and into the Caribbean. This wave has been treated as the potential “next big thing” in the tropics, with the apparent the potential to steadily develop, and perhaps become a serious, land-threatening hurricane down the road. I and others even dubbed it “proto-Cristobal,” and the Houston Chronicle‘s “SciGuy,” Eric Berger, began worrying about a potential threat to the U.S. Gulf Coast.

Yet, day after day, reconnaissance flight after reconnaissance flight, Invest 94L has stubbornly refused to get its act together. The National Hurricane Center has repeatedly signaled that its development appeared imminent, and has been forced to back off each time as the system has failed to meet expectations.

Meanwhile, as 94L sputtered, a dark-horse contender for the name “Cristobal” emerged much closer to home. Off the Southeastern U.S. coast, an old frontal boundary began to acquire tropical characteristics. Now it appears poised to jump ahead of 94L in the pecking order, and seize the spotlight for itself. Ladies and gentlemen, meet Tropical Depression Three.

At 11:00 PM EDT Friday, the National Hurricane Center designated the weak low pressure area off the South Carolina coast as a tropical depression, T.D. #3. If it reaches tropical storm strength, it will be known as Tropical Storm Cristobal — assuming it does so before 94L or any other system. (The next name on the list after Cristobal is Dolly.) The official forecast says this is likely to occur within 24 hours, though the discussion suggests that forecasters aren’t too bullish about this storm’s prospects, and wouldn’t be overly surprised if it never earns a name. NHC forecaster James Franklin writes:

THE ENVIRONMENT DOES NOT SEEM CONDUCIVE TO RAPID DEVELOPMENT. THE UPPER-LEVEL WINDS ARE SOMEWHAT DIVERGENT…BUT THERE IS A LOT OF DRY AIR NEARBY OVER THE SOUTHEASTERN UNITED STATES. EXCEPT FOR THE CLIMATOLOGY AND PERSISTENCE [COMPUTER MODELS]…NONE OF THE INTENSITY GUIDANCE MAKES THE SYSTEM A TROPICAL STORM. HOWEVER…THE SHIPS [MODEL] FORECAST SEEMS TO BE BASED ON [SEA SURFACE TEMPERATURES] THAT LOOK AT LEAST 1C COOLER THAN WHAT THE COASTAL BUOYS ARE REPORTING RIGHT NOW…SO I’M GOING TO GO A LITTLE ABOVE THAT GUIDANCE AND SHOW JUST ENOUGH STRENGTHENING TO MAKE THE SYSTEM A TROPICAL STORM.

As a result of this official forecast, Tropical Storm Warnings have been issued for portions of the Carolina coast, as this map shows. T.D. 3 seems unlikely to produce terribly strong winds, however. As meteorologist and weatherblogger Bryan Woods notes, “none of the models forecast that TD 3 will intensify beyond a 50 mph tropical storm, and this is a reasonable forecast, due to the relatively cool water temperatures, moderate wind shear, and the presence of dry air nearby.”

So, it’ll be a rainy weekend in the Carolinas — particularly near the coast — but otherwise, there probably isn’t too much to worry about. That said, it’s worth noting in passing that AccuWeather’s Joe Bastardi (who, to be honest, can be a bit excitable, and has been accused at times of bordering on sensationalism) was, at least as of this morning, taking a contrarian view, declaring himself “concerned that this could be more than just a tropical storm if it reaches its full potential. I don’t see any reason for this to go ashore for 60 to perhaps even 84 hours and the water is warm, the outflow excellent and the overall pattern is such that this is a great case for development in close. The call here is for a tropical storm or perhaps hurricane to be within 50 miles of the NC coast by Sunday.”

The notion of T.D. 3 becoming a hurricane is definitely not the official view, though, and it should be taken with a grain bucket of salt at this point. Frankly, Invest 94L probably remains the greater threat to eventually rev up into a serious storm, if it can ever get its engine started.I’ll post an update tomorrow on both systems’ progress.