Saturday, May 7, 2011

I AM TIRED OF DOING MY RAIN DANCE




Rain in Drought Stricken Texas?

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On the heels of yesterday’s blog post (Wednesday’s, too) about the flooding and the flooding-to-come for the Mississippi and Ohio rivers, comes this: Rain in southern Texas by mid-May. No fooling.

With much of Texas experiencing extreme drought conditions and too much of Texas labeled as “exceptional drought,” the prospect of rain may very well be met with guffaws, snickers and more than a couple of “Yeah, tell me about it.” So let me tell you about it.

Better yet, let me have ImpactWeather’s StormWatch manager, Fred Schmude, tell you about it: “There may be a glimmer of hope by the middle of May as we go through a significant pattern change across North America. In the longer range, there is growing evidence that a deep upper-level trough will shift from the western U.S. to the eastern U.S. as several long-range [computer model] signals favor the shift. The resultant pattern change will more than likely shove another decent cold front to the Gulf Coast towards the middle of the month and I would not be surprised to see an increasing chance of showers and storms during the third week of the month as the flow aloft shifts northwesterly (we have not seen that in a while) displacing upper-level disturbances southeastward over the region. Remember, this is the time of year when we can get ‘southeast movers’ blasting by the region. These are associated with upper-level disturbances driven rapidly southeast from the Central Plains. These events typically occur in the latter part of spring when conditions are becoming unstable.”

In short, computer models are hinting at a pattern change which would drive storm systems father south, and as these storm systems plunge into the heat and humidity of the South, stormy weather will result and the upper flow suggests Texas will be on the receiving end of this storm activity. Springtime storms, of course, are not without hazard. However, the rain is needed and Texans will tilt their 10-gallon hats to the sky hoping to catch as much as they can.

Let’s not forget however, the current drought is deep and well-established. Though the anticipated pattern change may bring some relief, it’s only a month or so before we shift into the summer pattern which effectively locks out northern storm systems and we have to rely on tropical moisture to fill the rain gauge and stock tanks. Unfortunately, “tropical moisture” often takes the form of tropical storms and hurricanes.

To get an idea of how dry conditions have been for the past few months, here’s a summary graph depicting monthly rainfall amounts compared to normal at Houston’s Bush Intercontinental Airport.

In January we had a banner month with more than 5 inches of rain falling over the region thanks in large part to a slower flow pattern which brought several slow moving cold fronts by the area. However, since February the flow pattern has sped up and the rainfall pattern has nearly shut off for the Houston area with only a measly 1.58” of rain falling since February 1. The normal combined average for rainfall for February, March and April is 9.94”, meaning for the past three months we are averaging only 16% of normal.

Will it rain? Are you willing to bet your 10-gallon hat on it?

Cattle near Marfa run from the advancing wildfires. It's no surprise that last month's fires throughout West Texas have the drought to blame. Photo: AP


Rain in Drought Stricken Texas?

No Gravatar

On the heels of yesterday’s blog post (Wednesday’s, too) about the flooding and the flooding-to-come for the Mississippi and Ohio rivers, comes this: Rain in southern Texas by mid-May. No fooling.

With much of Texas experiencing extreme drought conditions and too much of Texas labeled as “exceptional drought,” the prospect of rain may very well be met with guffaws, snickers and more than a couple of “Yeah, tell me about it.” So let me tell you about it.

Better yet, let me have ImpactWeather’s StormWatch manager, Fred Schmude, tell you about it: “There may be a glimmer of hope by the middle of May as we go through a significant pattern change across North America. In the longer range, there is growing evidence that a deep upper-level trough will shift from the western U.S. to the eastern U.S. as several long-range [computer model] signals favor the shift. The resultant pattern change will more than likely shove another decent cold front to the Gulf Coast towards the middle of the month and I would not be surprised to see an increasing chance of showers and storms during the third week of the month as the flow aloft shifts northwesterly (we have not seen that in a while) displacing upper-level disturbances southeastward over the region. Remember, this is the time of year when we can get ‘southeast movers’ blasting by the region. These are associated with upper-level disturbances driven rapidly southeast from the Central Plains. These events typically occur in the latter part of spring when conditions are becoming unstable.”

In short, computer models are hinting at a pattern change which would drive storm systems father south, and as these storm systems plunge into the heat and humidity of the South, stormy weather will result and the upper flow suggests Texas will be on the receiving end of this storm activity. Springtime storms, of course, are not without hazard. However, the rain is needed and Texans will tilt their 10-gallon hats to the sky hoping to catch as much as they can.

Let’s not forget however, the current drought is deep and well-established. Though the anticipated pattern change may bring some relief, it’s only a month or so before we shift into the summer pattern which effectively locks out northern storm systems and we have to rely on tropical moisture to fill the rain gauge and stock tanks. Unfortunately, “tropical moisture” often takes the form of tropical storms and hurricanes.

To get an idea of how dry conditions have been for the past few months, here’s a summary graph depicting monthly rainfall amounts compared to normal at Houston’s Bush Intercontinental Airport.

In January we had a banner month with more than 5 inches of rain falling over the region thanks in large part to a slower flow pattern which brought several slow moving cold fronts by the area. However, since February the flow pattern has sped up and the rainfall pattern has nearly shut off for the Houston area with only a measly 1.58” of rain falling since February 1. The normal combined average for rainfall for February, March and April is 9.94”, meaning for the past three months we are averaging only 16% of normal.

Will it rain? Are you willing to bet your 10-gallon hat on it?

Cattle near Marfa run from the advancing wildfires. It's no surprise that last month's fires throughout West Texas have the drought to blame. Photo: AP

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