June 1st marks the beginning of hurricane season. However, in rare cases, you can get a tropical system before then. Take for example tropical depression #1 that formed off the east coast the last week in May. It seems like in the past few years, Texas has seen its fair share of hurricanes, including Rita and Ike. But what is a hurricane, how do they form, and what drives them?

Most tropical systems will form from tropical waves coming off of the west coast of Africa. Sometimes, a circulation can form on the tail end of a cold front that pushes off the east coast. You need certain atmospheric conditions for development.

• Warm ocean water, over 80 degrees
• Low wind shear, which are winds changing with height
• Very moist air; dry air can hinder development

Once a storm begins producing winds over 38 mph, it will be classified as a tropical storm and given a name. The reason for the naming is to keep better records. In the past, when hurricanes were just numbered, it would get confusing referring to past storms. The names start with A and go through W, alternating between boy and girl names. There are no names that start with Q, U, X, Y, or Z. Names are reused after about 5 years unless the storm causes widespread damage. Then the name is retired and never used again.

A tropical storm will become a hurricane when winds reach 74 mph. Then we use the Saffir Simpson Scale to determine strength. The scale goes from 1-5 with 5 being the strongest. The scale is based on a combination of wind speed, storm surge, and pressure. In recent year, the scale has questioned on its accuracy. Many meteorologist, including myself, like to use pressure as an indication of strength. Usually, pressure will fall first, followed by an increase in winds. So pressure can tell you sooner how strong the hurricane could get. In the next few years, we may even see an “enhanced” scale like the Enhanced Fujita Scale used for tornadoes.

So what steers hurricanes across the ocean? The biggest influence is what we call the Bermuda high. It is an area of high pressure that sets up over the Atlantic Ocean during tropical season. The basic idea is that the flow is clock wise around the high so a weak Bermuda high leads to hurricanes turning north quicker and either missing the U.S. or hitting the east coast. A strong Bermuda high will keep the hurricanes farther south in the Caribbean and hitting Mexico. The 2007 season was a good example of that. So depending on the position of this Bermuda high makes a big difference in who sees the hurricanes.

What about the 2009 season? Well, I feel the east coast, especially the Carolina’s, are way over due for a major storm. It is really impossible to pinpoint where hurricanes will strike. Computer models struggle in their handling of tropical systems and many times, the track will change even 24 hours before a landfall. As TV meteorologist, our job is to portray the uncertainty, which can be difficult since we want to be as accurate as possible. The best advice is the be ready no matter what. Of course, Central Texas does not really get the brunt of hurricanes, but we are still impacted with rain, evacuees, and severe weather. So when a hurricane threatens the Texas coast, trust your First Alert weather team for the latest info and forecast. — First Alert 25 Meteorologist Conley Isom

U.S. Energy Secretary Steven Chu proposes we paint all flat roofs white on commercial and residential buildings. The white color will reflect more sunshine, thus cooling the temperature of the Earth. The science is right, but I don’t think this would work. It would take a lot of white paint to achieve this goal and who would pay for the it? The government? That sounds like a lot of money. What do you think? Leave your comments below. – First Alert 25 Meteorologist Conley Isom

The severe thunderstorm watch has been expired. However, numerous severe storms continue effecting parts of Central Texas. One storm is moving into Bosque county and it has had a history of producing golf ball size hail and strong winds. This storm was tracking east at about 15 mph. At its current path, it will pass just north of Waco.

More storms are developing farther west and along the cold front in the Texas panhandle. So we may be dealing with these storms into the morning hours. — First Alert 25 Meteorologist Conley Isom

Severe thunderstorm warnings are out for Bosque and Hill counties until 10:30 PM. Storms south of Fort Worth are putting out outflow boundaries, or cold air rushing out of the storms, which will cause new storms to develop. These storms will be capable of producing large hail, gusty winds, and frequent lightning. Heavy rain is also a threat.

We are also tracking storms moving into the western parts of Central Texas. This complex may gain some strength as it moves into more unstable air. Expect this complex to approach the I-35 corridor later this evening around midnight or so.

You can email us photos to weatherpics@kxxv.com. Also, follow us on Twitter at www.twitter.com/FirstAlert25WX for instant updates on warnings and storm info. — First Alert 25 Meteorologist Conley Isom

June 1st marks the beginning of hurricane season and the forecast for this year can be found in the post below. This week, May 24th-30th, is National Hurricane Preparedness Week. Each day covers a specific topic about tropical systems. Here in Central Texas, inland flooding is our main concern with any hurricane that heads towards the Texas coast. We came close with hurricane Ike but luckily it stayed mainly across East Texas.

For more information, click here!

Satellite Imagery of Hurricane Ike

The National Hurricane Center is calling for a normal year in the tropics. Here is the break down of their forecast:

• 9-14 Named Storms
• 4-7 Hurricanes
• 1-3 Major Hurricanes

No matter what the forecast calls for, more than likely there will be several tropical systems effecting the United States coast line. The more important question is where will they strike? That is something we cannot answer accurately. Of course, here in Central Texas, we do not get directly effected from a tropical system except for the rain and the influx of evacuees. But many of us have friends and family along the Texas coast so tropical events become more important. As we get deeper into hurricane season, we will have many updates here in the Weather Blog, so check back often. — First Alert 25 Meteorologist Conley Isom

The Saffir-Simpson Hurricane Wind Scale is a 1 to 5 categorization based on the hurricane’s intensity at the indicated time. The scale provides examples of the type of damages and impacts in the United States associated with winds of the indicated intensity. In general, damages rise by about a factor of four for every category increase. The maximum sustained surface wind speed (peak 1-minute wind at 10 m [33 ft]) is the determining factor in the scale. The historical examples (one for the U.S. Gulf Coast and one for the U.S. Atlantic Coast) provided in each of the categories correspond with the intensity of the hurricane at the time of landfall in the location experiencing the strongest winds, which does not necessarily correspond with the peak intensity reached by the system during its lifetime. The scale does not address the potential for such other hurricane-related impacts, as storm surge, rainfall-induced floods, and tornadoes. These wind-caused impacts are to apply to the worst winds reaching the coast and the damage would be less elsewhere. It should also be noted that the general wind-caused damage descriptions are to some degree dependent upon the local building codes in effect and how well and how long they have been enforced.  For example, recently enacted building codes in Florida, North Carolina and South Carolina are likely to somewhat reduce the damage to newer structures from that described below. However, for a long time to come, the majority of the building stock in existence on the coast will not have been built to higher code. Hurricane wind damage is also dependent upon such other factors as duration of high winds, change of wind direction, amount of accompanying rainfall, and age of structures.

Click here to read more!

Computer model showing an area of low pressure in the eastern Gulf of Mexico.

Typically, the tropics stay quiet until we get more towards August and September. However, this year, we could get an early start to the tropical season. For the past few days now, many of the computer models have shown an area of low pressure developing near Cuba and heading into the eastern Gulf of Mexico by midweek. The question is whether or not this thing will be tropical or subtropical. What is the difference? A tropical low has a warm core and a normal low that we see across Texas, has a cold core. The subtropical low happens when it starts off as a cold core, then transitions into a warm core. If you remember back to 2007, we had subtropical storm Andrea off the east coast, so it happens. However, getting something tropical before hurricane season starts is rare. Only 26 storms have ever develop before June 1st between 1851 to 2008. If something does develop, the first name on the list is Ana.

So what will happen. My current thinking is it will remain a cold core low and never take on tropical characteristics. However, there is a very small window next week if it can emerge into the Gulf of Mexico that it could transition into a subtropical low. Even so, this will be a heavy rain maker for Florida and parts of the southeast. The only impact we will see here in Central Texas will be more of an east/northeast wind by the end of the week. However, we will be tracking it closely and will have more updates as needed. — First Alert 25 Meteorologist Conley Isom

Courtesy of the NWS in Fort Worth

We are about to get a break from the heat and humidity that has been with us for the past couple of weeks. A cold front will be sweeping through Central Texas on Saturday afternoon, bringing some much needed rain and cooler temperatures. There may be a few strong storms mixed in but the severe weather threat will be very isolated. Rainfall totals could add up to an inch or two because of the slow movement of the rain. That will help out our drought conditions. The other part of the story is the cooler weather heading our way. Overnight lows are going to drop into the 50s so you might want to have those jackets ready. If we clear out fast enough Sunday evening, it could get even colder than that! The weather turns quiet by next week. — First Alert 25 Meteorologist Conley Isom