Weather Around The World, 5/26: Action In The Tropics And Flooding In Texas

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Water causes 80% of Atlantic hurricane fatalities, wind less than 10%. Graphic courtesy of National Hurricane Center.

Summer is approaching, and with it a hurricane season. But the immediate concern is flooding in Texas, where eight people have been killed and several more are missing. Let’s go Around The World.

Hurricane Preparedness Week:  5/24-30/2015

The National Hurricane Center has designated this week as Hurricane Preparedness Week.

Their main point is: Be prepared.

The Hurricane Center urges everyone who lives in a zone that might be impacted by a hurricane to have an evacuation plan, and to have a supply of things that will be needed if the power goes off: battery-powered lights (don’t forget the batteries); canned food; a place to store vehicles; arrangements for boats; and some plan for what to do with pets should it be necessary to go to a shelter (some shelters have become pet-friendly).

Contrary to popular belief, most fatalities in a hurricane are a result of water, not wind. In fact, wind causes less than 10% of all hurricane-related deaths. Water causes 80% of fatalities: Storm surge, 50%; Rain-induced flooding, 25%; Surf, 5%.

Staring down a hurricane is not a good idea. Everyone in the danger zone should have an evacuation plan, keeping in mind that street lights may go out, bridges may not open, and others will be evacuating at the same time. Know where a shelter will be located should you need one.

The water temperature chart for May 25

The water temperature chart for May 25 presents conflicting indicators for the upcoming Atlantic hurricane season. El Niño, represented by warm water in the equatorial Pacific tends to discourage hurricane formation. Warm water in the western Atlantic, Gulf of Mexico, and northern Caribbean would encourage hurricane formation. Graphic courtesy of NOAA.

Hurricanes In The Atlantic Basin

The Atlantic Basin hurricane season officially begins on June first, though we have already had the first named storm this year. All of the forecasting teams with any track record are predicting a season with below average activity due to the blossoming El Niño. Decoded Science remains an outlier, with a forecast of an average season.

Though El Niño is strengthening, and El Niños are correlated with subdued Atlantic hurricane activity, the water temperatures in the western Atlantic, the northern Caribbean Sea, and the Gulf of Mexico remain elevated. Above-average water temperatures are correlated with above-average hurricane activity.

Pacific Ocean Tropical Systems

The tropical cyclone season in the western Pacific, where hurricane-intensity storms are called typhoons, literally never ends: A new one starts every January One and ends on December Thirty-one. Though there have already been three Super-Typhoons with winds over 150 miles per hour, an extraordinarily robust beginning to the season, the waters are quiet for now.

The National Hurricane Center estimates that the disturbance south of Mexico has an 80% chance to become a tropical storm within five days. Graphic courtesy of NOAA.

The National Hurricane Center estimates that the disturbance south of Mexico has an 80% chance to become a tropical storm within five days. Graphic courtesy of NOAA.

In the eastern Pacific, where storms are called hurricanes, the season officially began on May 15. And right on cue, there is a disturbance which reminds us of last year’s pattern in the region.

The water south of Mexico is warmer than normal, and an area of low pressure in the area is expected to become a named storm by late in the week.

El Niño years tend to see more hurricanes hit the coast of Mexico, but this storm is well offshore and will probably blow itself out over colder water as it moves to the northwest.

Weather Pattern Government Continues To Cause Flooding Rain And Tornadoes

The floods of the last few days are the culmination of a stagnant weather pattern which Decoded Science has named Government. The pattern is characterized by a deep and wide trough of low pressure in the jet stream over the western United States.

Within this trough, shorter waves ripple by, each bringing a new round of rainfall and severe weather. With an unlimited source of moisture in the Gulf of Mexico, Government has the potential to produce torrential rains in the eastern part of the US.

Normally rain comes and goes, but when the weather pattern persists, there can be much more coming than going. When the ground becomes saturated and the accumulated water overwhelms river and storm drain capacity, flooding results.

All flooding, like politics, is local. Local flooding can depend on the efficiency of the drainage systems and the capacity of the ground to absorb moisture. Sand is more porous than compacted soil. Concrete and asphalt have no capacity to absorb moisture at all.

Flooding depends critically on the rate of rainfall. In Houston yesterday, two months’ worth of rain fell in a single day. In Oklahoma this month, more rain has fallen than in any single month. Both of these situations created flooding scenarios.

Government Will Slowly Relax Its Grip

As the latest ripple moves through the western trough and into the southeast and midwest, more severe weather is likely in a wide area. However, as the energy of the trough is dispersed, there should not be as much local damage.

The large-scale trough will gradually weaken over the next few days, and the severe weather will slowly become more intermittent and spread out.

Summer Is Almost Here

Longer range forecasts for the US indicate that a decidedly summer-like weather pattern is setting up, with daily afternoon showers and thunderstorms almost anywhere in the country. Meteorologists will look towards the tropics for the next incident of extreme weather. What evidence do you see of the transition to summer weather where you are?

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