For the year, we have had a mere 7.13" of rain resulting in a deficit of -6.01", which is just 54% of normal. There is evidence that the drought is getting worse, not better. In April, we had the most of any month so far this year, with 2.36" and 115% of normal, but May was just 36% of normal and so far in June we are 0% of normal as officially we haven't had any rain yet. As cold fronts have stopped participating in our weather upper level high pressure (a huge dome of sinking air) has become quasi-stationary over the area diverting rain producing weather features around and away from South Texas. The "dry high" is scheduled to break down toward the end of next week.  Perhaps July won't start off as dry as it normally does.

STAY TUNED
DALE NELSON

In the Atlantic Basin, tropical storms are named in order to make it easier to communicate between forecasters and the general public important information about a particular storm. This process helps avoid confusion about what storm is being described when there is more than one storm in progress at a given time. In the age of more active hurricane seasons (since 1995), there have been several instances where there have been four storms in progress at one time.

During World War II, tropical storms were given women's names by the U.S. Army and Navy meteorologists (after their wives or girlfriends who appeared erratic in movement and hard to predict, just like their storm counterparts). In 1953, the U.S. Weather Bureau switched entirely to women's names. In 1979, the World Meteorological Organization (WMO) and the National Weather Service (NWS) switched to a series of six lists of names that also included men's names. The current series of names is listed in the chart above. The list of 2007 names will be reused in 2013 minus the names that were retired because they were noteworthy in size and/or destruction. Notice how the names not only alternate through the alphabet but also rotate between male and female as to who starts off each year. This format creates equality between the male and female names.

The first male named storm was "Bob" back in 1979. Some have said that was in honor of former National Hurricane Director Dr. Bob Simpson who, along with his wife, Dr. Joann Simpson, had ties to Corpus Christi. How many names we use this year remains unknown. We will continue to keep you posted.

STAY TUNED
DALE NELSON

There area several characteristics that are different about tropical showers and our tropical weather pattern. First, it normally happens in May or June but can be delayed until July or August in "El Niño" years. Tropical showers arrive from the Gulf of Mexico and tend to produce heavier rainfall ammounts than their land based counterparts. This is because they are generally moving much slower, so they stay over a specific area for a longer period of time. Another feature of a tropical weather pattern is when all the winds line up and come from the same direction the sky generally loses its hazy condition and takes on a much bluer, cleaner look, similar to what they have in Florida much of the year.

This is all good news, but there is some bad news as well. A tropical weather pattern also makes us more susceptible to tropical storm and hurricane activity. At least for the next five to ten days only good things will be happening to our weather as our overall weather pattern makes the switch to our tropical tap. Between now and Father's Day, I expect rainfall to increase dramatically over the area (compared to the below-normal levels registered over the last several months) and our winds and temperatures to settle down to more seasonal levels. The sweet smell of rain is not far off.

STAY TUNED
DALE NELSON

Preliminary reports count nearly 1200 tornadoes so far this year (see chart in Acrobat .pdf format). The record for the most tornadoes in a year is 1817 in 2004. The three year average is 1159. What really stands out this year, though, are the 30 killer tornadoes which have claimed 110 lives. We are on track to break all previous tornado counts by the end of this year.

It is unusual to see stronger tornadoes. The ones that have winds of 136 to 200 mph also seem to be hitting more populated as opposed to rural areas. There have been nearly half of the tornado deaths this year in mobile homes, exactly the wrong place to be during a severe thunderstorm.

There is currently no reasonable explanation for all of this destructive activity. Global warming cannot be blamed entirely for what's happening. Higher temperatures would cause an increase in the number of thunderstorms, which produce tornadoes, however, these storm systems would be pushed too far north to actually produce tornadoes. The good news about this increased activity is that the Storm Prediction Center has been very good at informing the public of impending danger by issuing tornado watches in a timely fashion. Of the 110 deaths this year, there was a tornado watch in effect where 101 of the deaths occurred.

We have most of our tornadoes in South Texas when we are on the northeast side of a land-falling tropical storm or hurricane. That happens during hurricane season which begins on June 1st.

STAY TUNED
DALE NELSON

The human body normally cools off by sweating which evaporates and carries heat away from the body. However, when the relative humidity is high the evaporation rate is reduced, so heat is removed from the body at a slower rate causing it to retain more heat than it would in dry air. This is why it "feels" hotter on a summer afternoon in Miami (where the temperature is around 90) compared to Phoenix (where the temperature averages about 104.) When you factor in the summer humidity coming in from the trade winds off the Atlantic Ocean, it actually "feels like" 109 degrees in Miami while the relatively dry air in Phoenix makes it feel like 99 degrees.

The Heat Index formula is HI = c1 + c2T + c3R + c4TR + c5T² + c6R² + c7T²R + c8TR² + c9T²R². It is much easier to just use the following chart by finding the intersection of the current temperature and relative humidity.

Heat Index

Here are some ways to beat the heat:

Know the first signs of heat related illness such as dizziness, nausea, headaches and muscle cramps.

If you do not have air conditoning in your home, go to places that do such as the mall library or church.

Never leave a child or pet in a closed, parked car.

Drink plenty of fluids especially water and avoid drinks with caffeine or sugar.

Wear lightweight and light-colored clothing.

Take a cold bath or shower frequently.

Check frequently on elderly friends, neighbors, and relatives.

Think cool as the next significant cold front is only about 4.5 months away!

STAY TUNED
DALE NELSON

It turns out that according to the National Weather Service (NWS) operations manual the two opposing terms are not exactly opposites. However the manual does state that "other terms may be used if they are well understood by people in the area and better describe expected conditions." I wonder how many people actually know that "partly sunny" means that clouds cover 38 to 63% of the sky. Here is a breakdown of the predominant sky condition into eighths (8ths.)

DAY TERMS                                                         SKY CONDITION
Cloudy                                                                 8/8 cloud cover
Mostly Cloudy or Considerable Cloudiness  6/8-7/8 cloud cover
Partly Sunny                                                       3/8-5/8 cloud cover
Mostly Sunny                                                      1/8-2/8 cloud cover
Sunny                                                                   0/8 cloud cover

Partly cloudy is the same as partly sunny but used more at night.
Mostly clear is the same as mostly sunny but used more at night.
Clear is the same as sunny but used more at night.

I'll always tell you what I'm forecasting for the sky condition to mostly be. When I hear the word "partly", I think someone is trying to skirt the issue even though technically it is still proper to use these "partly" terms.

STAY TUNED
DALE NELSON

As we have talked about here in the past, we are still in a La Niña weather pattern (cooler than normal water in the Pacific Ocean) which will be impacting our weather here in South Texas. Last year, we had a weakening El Niño weather pattern which produced below normal temperatures ranging from 60 to 91 degrees and also below normal rainfall which totaled only 2.23".

I’m confident that temperatures will end up above normal and be hotter than 91 this May. Forecasting rainfall is a bit trickier as it would only take one or two slow moving thundershowers to produce an entire month's worth of rain. Conventional wisdom would dictate that we would have below normal rainfall, however, I suspect that with the La Niña weakening in the Pacific that rainfall will be more than last May and approach or even exceed the average for this month.

STAY TUNED
DALE NELSON

 

Last weekend's showers produced more rain than the previous two months combined and for the first time since January rainfall for the month was above normal. Officially, 2.36" of rain fell, while rainfall amounts across the Coastal Bend ranged from 1" out west near San Diego to 5.7" to the east in Port Aransas. The rain was caused by an upper level disturbance and a cold front arriving at the same time (for a change) into warm moist unstable air near the coast. It's somewhat unusual to have above normal rainfall and above normal temperatures in the same month, but that is what happened in April. Temperatures ranged from a chilly 46 (and a record low on the 19th) to a hot 91 on the 10th and 23rd for the month. Winds were a problem, gusting as high as 54 mph and it was breezy to windy all but five days of the entire month.

The April showers that fell mainly last weekend were extremely beneficial to area farmers and ranchers. Many ranchers have had to buy hay for their cows since the rainfall recently has been sorely lacking. Farmers were particularly helped by the rain because of the timeliness of its arrival. I heard some people say we needed the rain more than anything else to help out our watershed and enhance our water supply at Lake Corpus Christi and Choke Canyon. Actually, area farmers and ranchers and homeowners needed it much more than our water supply because our two reservoirs have been at near optimum levels since the prolific rains of last summer. Today Lake Corpus Christi is over 93% full while Choke Canyon is at 94.7% full and our combined system capacity is 94.3%!  A year ago, our system capacity was 77.7% - considerably lower than it is today. It takes an extended period (6 months or more) of wet or dry weather to affect our water supply while a timely 2" rain can make or break and area farmer or rancher. Our April showers were welcomed by nearly everyone.

STAY TUNED
DALE NELSON

 

You may have noticed that it hasn’t rained much here lately. Rainfall has been sparse as most active weather systems have missed us to the north. Officially, we have had only about 3.5" for 2008, which is about 50% of normal. It is even drier out to the west (see chart above), where drought conditions are extreme to exceptional. Our current "dry spell" actually started in late September or early October, just about the same time a La Niña strengthened to moderate levels. A La Niña is essentially the opposite of an El Niño. Both represent a change to cooler or warmer than normal water in the Pacific Ocean resulting in powerful and distinct changes in global weather patterns. In the case of La Niña, there is generally less moisture in the air along the coasts of North and South America. The current La Niña is responsible for our below-normal rainfall and above-normal temperatures over the last six and a half months.

Look at the global image below. The large blue area indicates lower than normal sea level which is directly related to cold water. The current La Niña is one of the strongest in years but is also slowly weakening even though it continues to blanket the Pacific Ocean near the equator.

While a La Niña produces fairly quiet weather in the wintertime in South Texas, it tends to produce a considerable amount of tropical activity in the western Gulf of Mexico during hurricane season. We tend to get more of an easterly flow in the tropics in the mid and upper levels of the atmosphere when a La Niña is present. Going back to 1964, when there was cooler than normal weather in the Pacific, a tropical storm or hurricane has hit the Texas Coast in 8 out of 12 years - or 67% of the time! We were fortunate that most of those Texas storms either missed us or were fairly weak. However two particular storms that occurred during La Niña’s didn’t miss the Coastal Bend - one of them was "Bret", a category 4 hurricane that made landfall 75 miles south of Corpus Christi, and the other, "Celia", the strongest and most destructive hurricane that Corpus Christi has ever seen! Let’s hope the current La Niña doesn’t linger much longer.

STAY TUNED
DALE NELSON

 

This past month of March our temperatures were just barely above normal while our rainfall was promising the first half of the month but ended up slightly below normal. Overall, our temperature ended up 0.5 degrees above normal while ranging from 34 to 94. Rainfall was 1.58" with the vast majority falling during the first 10 days we ended up .16" below normal. The lack of rainfall continues a dubious trend of little rainfall that began last September. In the last seven months, only one, January, has had above normal rainfall (just barely) while combined we have a deficit of over 9 inches (see chart.)

April is the 6th wettest month of the year with 2.05 inches of rainfall normally. While it would only take one thunderstorm to produce that much rain, it appears that with "La Nina" still present in the Pacific, although weakening, our rain will end up below normal this month as well. Temperatures continue to soar this month with increasing solar radiation, and range from 33 degrees in 1987 to 102 in 1984. Overall, I expect temperatures to be above normal for April, but I wouldn't be surprised to see night-time readings dip at least into the low 50's on three or four occasions. This trend of above normal temperatures and below normal rainfall will come to an abrupt end as "La Nina" continues to weaken and we approach mid-summer. By then, we should have major increases in rainfall!

STAY TUNED
DALE NELSON