Weather Wednesday – El Nino and the Texas Floods

KHOU via USA Today
KHOU via USA Today

What caused the recent devastating and deadly flooding in Texas, Oklahoma and other states? One thought, advanced by Accuweather and others, is that the developing El Nino played a role. As we’ve written before, an El Nino is warmer than expected waters in the Pacific Ocean. El Nino events result in a split jet stream and it the southern stream likely contributed to the flooding in the South. Typically, heavier than normal rains occur in Spring, Autumn and Winter of El Nino years in a swath from California into the Mid-South.

EPA
EPA

Historically, even weak and/or developing El Ninos can cause the extreme precipitation witnessed in May. California largely missed out although the area around San Diego picked up record rainfall. In past El Nino events California received most of its precipitation during winter months. It remains to be seen if the current event will last that long.

In the meantime drought conditions have been greatly lessened in Texas, at least in the short term. Of course that came with a terrible price…dozens of deaths and hundreds of millions of dollars in damage. The toll continues to rise and many rivers remain in flood.
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Weather Wednesday — Hurricane Season Outlook

Tropical Storm Ana earlier this month aside, June 1st marks the beginning of the “official” Atlantic Hurricane season. So what can we expect this year? Exact predictions are always iffy, but noted expert Dr. William Gray and his colleague Philip Klotzbach, both of Colorado State University, predict 7 named storms, three hurricanes and one major hurricane. If true, this would be one of the quietest hurricane seasons in the last 60-years. The long term average is for 12 named storms, six hurricanes and two major hurricanes. Some recent years have seen in excess of 20 named storms.

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NOAA

Why the smaller numbers? One factor is the development of a strong El Nino in the equatorial Pacific Ocean. Historically, El Nino years have fewer hurricanes along with other effects. The Weather Channel has created a nice page and video explaining this.

It is extremely important to note, however, that it only takes one major landfalling hurricane to cause vast damage and many casualties. Just because the long range hurricane forecast seems to be encouraging, we’re not out of the woods.

Hurricane-Sandy-stormsurgediagramIn preparation for the 2015 hurricane season, the National Hurricane Center is unveiling a new system of communicating storm surge threats and vulnerabilities. As has been seen over and over, some of the most devastating damage from hurricanes is not always from strong winds but from storm surge, the wall of water that is pushed out in advance of the center of the hurricane.

20121106-hurricane-sandy-new-jersey-shore.jpg.662x0_q100_crop-scale Hurricane Sandy is one of the more recent demonstrations of this mighty force.

This week, May 24-30, is national Hurricane Preparedness Week.  For those of you who have a role educating others about hurricanes here’s a link to FEMA’s toolkit.   And here is material from the National Hurricane Center/NOAA.

 

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National Dam Safety Awareness Day is May 31st. That date is the anniversary of the failure of the South Fork Dam which resulted in the infamous Johnstown (PA) flood. More than 2,200 lives were lost in what is considered the worst dam failure in the history of the United States according to FEMA.

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Missouri Institute of Science and Technology

The National Dam Safety Program is led by FEMA and a partnership of states, federal agencies and other stakeholders. Dams are part of an aging infrastructure and continued attention is vital in averting future catastrophic failures.

Weather Wednesday – Spring Outlook

NOAA’s Climate Center has issued its 2015 Spring Outlook covering flood potential, precipitation, temperature and drought through the April-June period. The flood outlook is for mid-March to Mid-May.

FloodRiskOutlook_2015_610
NOAA Climate Center

According to the outlook, the greatest potential for Spring flooding is in the Northeast along with a portion of the lower Missouri River and other nearby rivers and streams in parts of southern Illinois, southwest Indiana and far northern Kentucky. The near term potential is being driven by snow melt. That melt will also influence the somewhat longer term in that soil moisture will be above average to far above average in those areas.

NOAA Climate Center
NOAA Climate Center

As for temperatures, much of the eastern two-thirds of the nation will experience near-normal temperatures with the West Coast being much above normal. Only portions of Texas and New Mexico are forecast to be below normal.

The outlook calls for above-normal precipitation in the Southeast and the Four-corners area with below normal precipitation in the Pacific Northwest and parts of Minnesota and Wisconsin. The rest of the country will be near normal.

NOAA Climate Center
NOAA Climate Center

Drought conditions will continue or worsen in much of the western third of the country and drought may also spread from Minnesota into Wisconsin.  The drought will improve in eastern New Mexico and Oklahoma.  40% of California is already in an exceptional drought and the predicted hot temperatures and lack of precipitation will exacerbate that situation.

The precipitation and drought outlooks bode ill for the upcoming fire season.

As always, the long term outlook comes with a caveat that specific weather systems can always cause additional flooding and other impacts so readers should always stay alert.