Large tropical wave in the eastern Atlantic

A large cluster of showers has developed off the west coast of Africa and its drifting toward the west. Wind shear is currently keeping the storm from organizing and there's a lot of dry air to the north and west of the disturbance.

Only one of the forecast models is showing some development from this system as it moves across the Atlantic, and it's very weak development at that.

Where will it go?

There's a large area of high pressure north of the wave now, so it will move westward throughout the week.  By the time it reaches the western Atlantic it should turn toward the north, around the edge of the high pressure.  A strong trough of low pressure developing on the east coast this weekend should also help pull this storm north before it gets close to the U.S.

It's kind of early for a storm to develop in the eastern Atlantic, what we call the "deep tropics."  But tropical weather systems don't follow any rules.  I'll let you know if anything develops from this.

New this year: we're tracking hurricanes on Twitter. Follow "abc13weather" for real-time updates on tropical activity and your daily forecast.

When storms develop you'll find the position and forecast track here.

Quiet start to 2009 hurricane season

The first month of hurricane season passed with just one little tropical depression developing off the east coast. There were no named storms in June, which is not at all unusual.

Based on historic data from the National Hurricane Center the first named storm of the season usually develops around July 10. The first hurricane develops about August 14.  The most active time of the season is from mid-August through mid-October.

During the month of July, tropical cyclones tend to develop in the Gulf of Mexico and along the east Coast. Decaying frontal systems that stall in these areas can spawn tropical systems. That leaves little time for coastal residents to respond, another reason to have your hurricane plan in place before a storm develops.

Even though our air temperatures have topped out over 100° ten times over the past few weeks, the water temperatures in the Gulf of Mexico are just slightly warmer than normal.  As I pointed out here on the Houston Weather Blog two months ago, there's not a lot of deep, warm water in the Gulf. That's still true today.

Meanwhile, water temperatures in the Pacific Ocean are about 1°C above normal...but that's a good thing! This phenomena, called El Nino, tends to increase upper air west-to-east wind speeds which can hamper tropical development in the Atlantic basin.

There's still five months left in the hurricane season. While it might be starting off quiet, I expect things to start to pick up later this summer. Still, all current indications continue to suggest this year won't be active as previous years.  Here's a link to all the hurricane season outlooks issued for this year.

New this year: we're tracking hurricanes on Twitter. Follow "abc13weather" for real-time updates on tropical activity and your daily forecast.

When storms develop you'll find the position and forecast track here.

Tropical wave develops in the Caribbean

Updated Saturday Evening: The tropical wave over the western Caribbean is still very weak and disorganized. But there is still a chance of this developing once it moves into the Gulf of Mexico on Sunday.

The late computer model runs Saturday night showed a change in the forecast track, which is not unusual. The forecast now moves the system northwest, not toward Florida but into the southern Gulf of Mexico.  The intensity forecast, which is always difficult, shows it developing into a tropical storm...but not a hurricane. At least not now.

Even if this thing does track farther north, it probably won't make it to Houston/Galveston. The upper high pressure responsible for our heatwave is still very strong.  The clockwise windflow around the high would cause the storm to move westward into Mexico or far south Texas. 

Check back for another update Sunday afternoon.

New this season: Track the tropics with "abc13weather" on Twitter.

Previous Discussion follows:

We're watching a big flare-up of clouds over the central Caribbean. The tropical wave quickly intensified Friday afternoon.

The National Hurricane Center put the hurricane hunters on stand-by for a possible flight into the storm on Saturday if it continues to show signs of organization.

The GFDL computer model develops the disturbance into a tropical storm within 24 hours, tracks it through the Yucatan Channel and then dissipates the storm as it moves northeast toward Florida.  The HWRF also develops the storm very quickly but holds it together as it tracks toward southern Florida early next week.

The big player in the forecast is a trough of low pressure that is forecast to move across the country over the weekend.  We think this trough could help generate a few showers around hereon Monday and Tuesday.  If the trough doesn't pick up the storm in the Caribbean, it could make it into the Gulf of Mexico. And depending on where the storm tracks it could quickly strenthen into a hurricane as it moves northward.

 

NHC Director responds to my blog post

A few weeks ago I wrote about changes the National Hurricane Center is making to the Saffir-Simpson Scale. Starting this year, the Scale will no longer include references to storm surge.

You shared your comments here on the Houston Weather Blog and, as promised, I emailed them to Bill Read, Director of the National Hurricane Center (shown to the right.)  Bill and I swapped emails back and forth several times this past week and he gave me permission to share his comments with you.

First of all, Bill appreciates a “good healthy dialog" which benefits all of us. He wrote, "The tables as shown in your blog and carried on NOAA/NHC web sites and preparedness pamphlets have been a bad addition since day one. You know my ideal world view would be to not have a scale."

Rather than getting rid of the scale or changing it, I suggested NHC should separate the wind and surge levels, but ultimately rank the storm based on whichever poses the greatest threat. During Hurricane Ike, for example, NHC was expecting a 15-20' surge. Using my method, statements would have read, "Hurricane Ike is a dangerous category four hurricane based on storm surge." 

Bill explained that very few people know the surge values assigned to the different categories. However, I responded, most people do know a category 3 storm is a major hurricane, 4 is bigger, and 5 is the worst.

Let me be clear: NHC will not be withholding storm surge information from the public. (Based on a few comments to my original blog post, I'm afraid some people misunderstood.) Instead of a storm surge category rank which I propose, NHC meteorologists will be providing specific water levels for locations along the coast, like that shown to the left.  Storm surge probabilities will also be issued for coastal communities.  The information is complicated and requires people living in surge zones to spend a lot of time deciphering their personal risk which is why, in addition to that mountain of information, we should also offer a simple category that (1) ranks the intensity of the storm and (2) emphasizes the greatest threat.

"Social Science studies consistently say people need specific information (how strong the winds, how much rain, how deep flooding) to elicit the best response." Bill explained. 

I'm all for giving people as much information as possible, that's why I show things on-air like the forecast computer models.  But in reality, the public is making decisions based on the category ranking. Many folks in Bolivar waited because Ike was "only a category 2 hurricane."

In conclusion Bill wrote, "The message scientists have given me loud and clear is that (a) Saffir Simpson scale, which was developed solely on the basis of maximum wind, cannot be used as an index for surge, and (b) the range of possibilities based on maximum wind, size of wind field, and bathymetry preclude any meaningful universally applicable range of values. A scale will only work if the information is correct and universally applicable.”

Even though NHC says the revised "Saffir-Simpson Hurricane Wind Scale" is an experiment, the changes are most likely permanent.  The category of a hurricane has always and will always be based only on the wind speed. It gives no indication of how bad the storm surge will be at landfall.

 

Watch "Hurricane Ike: His Story" online

<

"Tiny Tim" tropical storms

Have more hurricanes been developing in the last few years or are we just getting better at finding them?

The most active hurricane season on record was 2005 during which 28 tropical storms developed.  This broke the old record of 21 storms in 1933. But is that a fair comparison? 

Satellites, which we didn't have in 1933, now allow us to identify storms we might otherwise miss.  Eight of the storms that developed in 2005 were found by satellites over the open water of the Atlantic Ocean and never made landfall.   And a few were "Tiny Tim" storms.

I swear I'm not making up that term. Tiny Tims are small, meaningless, short-lived tropical systems.

We had one off the east coast a couple of weeks ago.  It's not that these are new types of storms, but we probably didn't know many of them existed before 1963, before weather satellites started monitoring the ocean.  Steve McIntyre wrote on his blog back in 2007, Tiny Tims are "so minimal that the NHC end-of-season reports do not report a single ship or single shore report of storm-force winds."  Yet they get named because they look like tropical storms on satellite data.

Hurricane records are used in climate research and help set insurance rates. But not every little clump of clouds in the Atlantic will develop into a full-strength hurricane. The problem is we still don't know which ones will strengthen and which storms will fizzle out.

Save the Saffir-Simpson Scale

The National Hurricane Center is making a big mistake. This year, they are removing the storm surge levels from the Saffir-Simpson Scale. The problem is not the Scale, but how we use it.

When Herbert Saffir and Bob Simpson introduced their hurricane intensity scale to the public in 1975 it ranked storms based on wind speed, with air pressure and storm surge values assigned to each category. A simple scale ranging from one to five, it took a complicated storm and made it easy for the public to understand.

Most of the time it worked, however, there were a few exceptions. Last year, Hurricane Ike had category two winds when it made landfall in Galveston, but Bolivar Peninsula was swamped a storm surge usually seen with a category four hurricane. Despite frequent warnings of a deadly storm surge, some folks assumed the storm wouldn't be "that bad" because it was "only a category two storm."

To eliminate any confusion in future storms, this season the National Hurricane Center has removed all references to storm surge from the Saffir-Simpson Scale.  It's an experiment and if it's approved the change will be permanent.  There is also talk of creating a second scale just for storm surge.  Others want to get rid of the current scale entirely and create something completely different that would rank the total destructive power of a hurricane.

I think this is a big mistake. The Saffir-Simpson Scale works. Leave the scale alone but rank storms based on wind speed OR storm surge, whichever is the greater threat.

For example, in Hurricane Ike we had 100 mph winds but a 15-20' storm surge.  In this case, surge trumps wind, therefore it would have been ranked a category four storm. Not one person would have stayed on Bolivar Peninsula if they had heard a massive category four hurricane was going to make a direct hit.

Exploring other options

Completely eliminating the Saffir-Simpson Scale destroys all our hurricane records and forces the public to learn a new scale. We have more than 30 years of experience using the old scale. Furthermore, we wouldn't be able to compare today's storms with past storms. Most people can quickly recall that Alicia was a category three, Carla was a four, Ike was a two but should have been a four, etc.

Adding yet another scale only adds to the noise. Think about how many numbers we throw out now during hurricane coverage. There's the latitude/longitude location, the wind speed, the gusts, the pressure, the forward speed and the direction. Then there's the tropical storm force wind speed probabilities, the hurricane force wind speed probabilities and coming soon, the storm surge probabilities. Each of these is different for every location along the coast...and all of this changes continuously every few hours over a period of several days! Do we really need another number to add to the mix?

Every year I attend work sessions and discussion groups at the National Hurricane Conference and we always talk about what didn't work the season before. Inevitably it comes down to the public not understanding the threat. To that end, every year the National Hurricane Center throws us more data, more numbers and therefore more noise.

I'm all for data, but at some point we have to consolidate this mountain of information into something a little more digestible. It might not be perfect, but we know the public understands the Saffir-Simpson Scale: category one is a small storm, three is big and five is the worst. These simple numbers prompt people to take action. Nobody is going to make a decision on whether to board up their windows based on the wind speed probabilities.

That's why I believe we need to keep the Saffir-Simpson Scale and rethink how we use it: rank storms based on wind speed OR storm surge, whichever is the greater threat.

What do you think?

Two weeks after originally posting this blog article, I sent an email to Bill Read, Director of the National Hurricane Center so he could read your comments below.

While the comments section on this blog post is now closed, you can email your ideas directly to the National Hurricane Center using the link toward the bottom of this webpage.

Hurricane season begins today

June 1 marks the official beginning of hurricane season.

However, as we've seen in years past, hurricanes don't always follow the calendar. Last year the first storm of the season formed on May 31. The year before both Andrea and Barry developed before the season started.  The last time we used this year's list of names in 2003, Ana developed in April!

Most long-range forecasting companies are expecting a few more storms than normal this season.

Hurricane season officially ends November 30.

"Hurricane Ike: His Story" airs tonight on ABC13

Every hurricane has its own personality. Ike hit Texas with category two winds and category four waves, a combination that has since caused the National Hurricane Center to drop all mention of storm surge from the Saffir-Simpson Scale. 

It was a deadly hurricane, killing almost twice as many people as Hurricane Alicia. And at least a dozen people are still missing.

Tonight after our late news at 10:35 PM, the 13 Eyewitness Weather team presents "Hurricane Ike: His Story."  We'll take you back to the moment this monster storm first developed. You'll relive landfall as the hurricane rushed ashore during the dark of night.  We'll take you down the Road to Recovery and show you where almost nothing has changed since the day Ike made landfall.

Hurricane Ike is now the benchmark by which all future storms will be compared. This is "His Story."

Houston's Hurricane Workshop scheduled for today

Ready or not, here come the hurricanes. And now is the time to prepare. 

To get started, join us today at the 2009 Hurricane Workshop at the George R. Brown Convention Center in downtown Houston.  Doors open at 9 AM.

Bill Read, Director of the National Hurricane Center, will speak at 10 AM.  I'll be participating in a panel discussion at 11 AM and 1 PM called "Ask Your Local TV Meteorologist."  There are interactive demonstrations planned by CenterPoint Energy, Home Depot, Wal-Mart and the American Red Cross.

There's also a Kids Zone with fun activities for the kiddos. 

And it's all FREE!