Friday, August 27, 2010

The Hurricane Train Lining Up

Now that we are approaching the peak of hurricane season, the tropics are really starting to heat up.

Close to home, the Gulf of Mexico and the Caribbean Sea are quiet for the time being. However, it is a much different story further out in the Atlantic Ocean.

We have not one, but two tropical cyclones ongoing in the Atlantic, with a third area of low pressure likely to form this weekend.

Hurricane Danielle is our first major hurricane of the 2010 season, and is expected to brush Bermuda before turning northward and eventually weakening as it encounters the cooler waters of the northern Atlantic.

Behind Danielle is Tropical Storm Earl. He is expected to maintain a westward movement and could be a potential threat to the Bahamas and perhaps the east coast of the United States.

Notice that even behind Earl we have a tropical wave coming off the coast of Africa. This area of disturbed weather will more than likely become Fiona over the weekend.

I like to call the current setup you see in our satellite image "The Hurricane Train." This setup is quite common in late August through mid-September as the easterly waves coming off the coast of Africa get very active.

For now, it looks as if the Gulf of Mexico is under no threat in the foreseeable future. Hopefully we can say that another month from now.

Tuesday, August 24, 2010

Late Summer "Cold" Front

After several weeks of triple digit heat and numerous Heat Advisories, we may finally catch some relief, courtesy of a late summer cold (cool) front.

This cold front will not necessarily drop our temperatures significantly, but rather, lower the humidity.

You will feel the difference in this refreshing airmass by mid-week as dewpoints drop into the upper 50's and lower 60's.

If you watch my weathercasts, you know that I love to talk about dewpoints. It is a measure of the amount of moisture in the atmosphere and is tied into the relative humidity and air temperature.

So far this month, our dewpoints have been in the middle to upper 70's, making for very humid and sauna-like conditions.

With the passage of the front, those dewpoint values will drop into the lower 60's and upper 50's, a sign of the drier air filtering into East Texas.

Our Adonis computer model in the image above shows our dewpoint values in the upper 50's by Thursday morning. This means that when you head out the door to work or school, it will actually feel quite refreshing to take in some fresh air.

Don't get used to it, though. By the weekend, an onshore flow returns, and so does the humidity. That will give us better rain chances, which is something we could use as well.

Friday, August 13, 2010

What the Heat Index is all about

Over the past couple of weeks, you have heard us talk about the dangerous heat levels across East Texas. Even though the air temperatures have only been around 100, it is the heat index, or feels like temperature, that has made it very uncomfortable to be outdoors.

The heat index is what we call the "apparent" temperature in addition to the feels like temperature. This value is calculated by taking into account both the actual air temperature and the humidity.

When you go outside, your body is trying to cool down, not from the air temperature, but from the heat index all-together. Our heat indices have been running from 107-112° during the heating of the day.

Anyting over 105° is dangerous and anything over 110° is when it becomes a reality that heat fatigue and possible heat exhaustion could set in.

The chart above is a heat index chart, calculating the feels like temperature when taking into account the air temperature and relative humidity.

To show you just how important the humidity plays a role in our feels like temperatures, take this scenario. If we had an air temperature of 96° with 50% humidity, it would give us a heat index value of 108°. On the other hand, let's say the temperature was 100° with 40% humidity. The heat index in this case would be about the same.

The bottom line is it can be just as dangerous to have temperatures a few degrees lower, but with slightly higher humidity values than higher temperatures and lower humidity values.

That is why when we show you the heat index on the air, it is a better representation of what your body has to go through in order to cool itself down.

Tuesday, August 10, 2010

Tropical Depression #5 Takes Form in the Gulf

After a couple of days of constant shower activity just off the coast of Florida, Hurricane Reconnaisance finally found a closed low at the surface late this afternoon.

That was enough to allow our fifth depression to form this 2010 season.

This depression will move to the west-northwest in the days ahead. It will more than likely become Tropical Storm Danielle sometime during the day on Wednesday as it strengthens even furthur.

The image to your left shows our different computer model projections as to where this system will go.

The one thing that stands out is that most of them converge the storm on the Louisiana coastline on Thursday afternoon. Even if the storm track is slightly off, it should remain to our east, keeping us on the drier (cleaner) side of the system.

At this point in time, we don't expect T.D. #5 to become anything stronger than a tropical storm. Even though the sea surface temperatures are very warm in the Gulf, wind shear will remain high, keeping this system from forming into a hurricane.

This wind shear was the same thing that really destroyed Bonnie just about three weeks ago in that same position. While this system may be stronger, it will be a minimal tropical storm at best as it approaches the Gulf coast states.

Our impacts back here at home will just be a few rain showers wrapping around the counterclockwise circulation. Due to the position of the storm, it may not be big enough to allow our Heat Advisories to expire.

Thursday, August 5, 2010

NOAA Releases Updated Hurricane Forecast

After two full months in the 2010 hurricane season, things have gotten off to a fairly quiet start. We have only seen one hurricane (Alex), and two very weak tropical storms in Bonnie and Colin.

NOAA (National Oceanic and Atmospheric Adminstration) had forecasted a very active hurricane season in late May. In case you forgot, here was their official forecast.

Named Storms: 14-23
Hurricanes: 8-14
Major Hurricanes: 3-7

Earlier today, NOAA released their updated forecast for the remainder of the 2010 season. Here are the updated results.

Named Storms: 14-20
Hurricanes: 8-12
Major Hurricanes: 4-6

The one thing that stands out is that they are still calling for a very active year. The only thing that was trimmed back was the upper bound part of the range. This was due to the fact we have not seen as many storms develop early in the season.

Don't let the slow start fool you. Keep in mind that we are now beginning to enter the peak part of hurricane season. The time period from mid-August through the end of September is the most active time for tropical systems to develop, with the peak occuring around September 10th.

The combination of warmer than normal sea surface temperatures and a relaxing of the upper level winds (wind shear), leads climatologists to believe the tropics will be heating up very soon.