Spinning

[updates follow original entry; latest as of Sunday evening]

[Radar images: GRLevelX]

Tropical Storm Cristobal continues spinning with its center just offshore, but it has not become any better organized since Saturday afternoon, in fact winds on the North Carolina and South Carolina coast at this hour (midnight) are quite light. Cristobal will brush the coast on Sunday with only minor impacts expected on land (locally heavy showers and breezy weather, but watch out for rip currents).

Cristobal, however, brings back memories of Alex in 2004, which was in a similar position, sliding parallel to the coast and not expected to be as bad as it turned out to be. The storm suddenly became a Category 2 hurricane, its center hooked close to shore, its western eyewall raked the Outer Banks, and Ocracoke Island was particularly hard hit. I hope I don't wake up in the morning and see that something similar is starting to happen!

Meanwhile, yet another cluster of big thunderstorms is hitting Iowa.

And not only does it have a spectacular signature on radar (much more impressive than that of the tropical storm), it resembles the hurricane symbol!

The middle of the system was even rotating, and the bowed line of storms (known as a bow echo) produced wind damage.

Lastly, the next disturbance over Africa, which in my Saturday afternoon update to my previous entry on the active tropics I mentioned was the next potential Cape Verde-type development, looks like it'll head into the tropical Atlantic during the next couple of days as a spinning low pressure system, not just a tropical wave. At least temporarily it too has an impressive signature on the imagery -- looking like something typically more likely to be seen there in mid-August than mid-July ...

UPDATE 1PM EDT SUNDAY JULY 20

Well, I could have rested easy. Cristobal has behaved itself, having not significantly strengthened.

Here's more on the Cristobal - Alex comparison I referenced above.

This NASA MODIS image from the afternoon of August 2, 2004 shows Tropical Storm Alex. It's a little hard to see the boundary between ocean and land, but the center of the storm is a short distance off the coast of South Carolina.

Tropical Storm Cristobal yesterday (Saturday) afternoon, looking similar in structure, with its center also just offshore of the South Carolina coast:

Now, Alex the following day!

Compare that, an intensifying hurricane, with Cristobal this Sunday morning, with much of its inner core devoid of deep convection (rain and thunderstorms), and its center within an "exposed" low-level swirl of clouds and shallow showers:

Happiness for coastal residents and visitors is dry, sinking air, shown by the black and dark red shades, swooping into the storm and inhibiting its development!

So the effects on the NC coast will be much more minor than from Alex -- just some brisk winds and locally heavy showes, not the kind of storm surge which inundated Ocracoke in 2004.

Even if the storm continues to hold steady in intensity or only increases a little, though, there will be one life-threatening effect: rip currents as a result of waves generated by the storm. Waves in general tend to be feistier on the Outer Banks than many other places, and with this being a weekend in the midst of the peak of the summer beach season, and a tropical storm coming through, be careful in the water!

Meanwhile ...

DOLLY

In the Caribbean, aircraft reconnaissance found that the tropical wave became a spinning "closed circulation" (the center of which is where I've put a circle below); deep convection continues to be very persistent; and the National Hurricane Center has named the system Tropical Storm Dolly.

Skipping over the tropical depression stage can happen when a tropical wave is very vigorous, with tropical storm force winds, just awaiting the flow of surface winds to become a complete circle rather than merely bending like a wave.

Dolly will head across the Yucatan, which will inhibit development, and then move over the southwestern Gulf of Mexico, where intensification is likely, with a midweek second landfall expected somewhere on the coast of Mexico or South Texas. The latest TWC forecast "cone of uncertainty" for the track of the center of circulation can be found here.

SUNDAY EVENING UPDATE

Although convection is flaring more than it has in awhile with Cristobal, it's on the south and east side of the center, which has now passed the Outer Banks and is starting to move away from the coast.

A statement issued by Hyde County emergency management included this: "As everyone in Hyde already knows, this was total non-event, even in Ocracoke. We barely had even a few sprinkles and no wind to speak of and not a single squall."

That's what we like to hear!

Dolly, though, continues to organize ... and in regard to that disturbance I mentioned over Africa, this isn't something you see every day in the National Hurricane Center's tropical weather outlook:

A VIGOROUS AND WELL-DEFINED TROPICAL WAVE IS LOCATED OVER WESTERN AFRICA A FEW HUNDRED MILES EAST OF DAKAR SENEGAL. THIS SYSTEM HAS THE POTENTIAL TO BECOME A TROPICAL CYCLONE VERY QUICKLY AFTER IT EMERGES INTO THE EASTERN ATLANTIC ON TUESDAY.