outlook+water: December 2018

outlook+water: December 2018

SUMMARY:

  • Drought is affecting less than 1 percent of the state.
  • This year’s hurricane season affected Portugal more than Texas.
  • The Pacific is warm enough for El Niño, but has not yet shown an effect on the atmosphere; so no Niño yet.

We landed at Louis Armstrong New Orleans International Airport about 9:30 am before Thanksgiving. After dropping our bags off at a BagBnB, my bride asked “Where next?” Without hesitation, I answered: “Lower 9th Ward.”

As we all know, Hurricane Katrina delivered devastation upon New Orleans, and no neighborhood took it harder than the Lower 9th. After Brad Pitt saw so little rebuilding in the area by 2007, he created the Make It Right Foundation to help rebuild the neighborhood with sustainable homes and progressive architecture, including one by Thomas Mayne of Morphosis that floats during severe floods.

And as we all also know, Hurricane Harvey delivered devastation upon southeast Texas, prompting discussions on what Texas needs to do better on floods. A couple reports recently came out, one by the Texas Water Development Board (The State Flood Assessment) and one by The Governor’s Commission to Rebuild Texas (Eye  of the Storm). As far as I know, neither report recommends floating homes…

Speaking of hurricanes, hurricane season ended on November 30th. Texas escaped without a direct hit unlike Portugal who suffered through two tropical depressions (Figure 1a)! Nevertheless, Texas has had its share of flooding rainfalls this year. Fortunately, the big-big rains stopped over the past 30 days although southeast Texas still received more than 8 inches (Figure 1b).

 

 

Figure 1a: Tracks of tropical cyclones in the Atlantic in 2018 (source).
Figure 1a: Tracks of tropical cyclones in the Atlantic in 2018 (source).
Figure 1b: Inches of rain that fell in Texas in the 30 days before December 14, 2018 (source).
Figure 1b: Inches of rain that fell in Texas in the 30 days before December 14, 2018 (source).

The amount of drought in Texas (D1-D4) over the past month decreased from 1.15 percent to 0.8 percent with moderate drought in the Panhandle and in Far West Texas (Figure 2a). Abnormally dry conditions have developed in Presidio County and the Lower Rio Grande Valley (Figure 2b).

Figure 2a: Drought conditions in Texas according to the U.S. Drought Monitor (as of December 11, 2018; source).
Figure 2a: Drought conditions in Texas according to the U.S. Drought Monitor (as of December 11, 2018; source).
Figure 2b: Changes in the U.S. Drought Monitor for Texas between October 9, 2018, and November 6, 2018 (source).
Figure 2b: Changes in the U.S. Drought Monitor for Texas between October 9, 2018, and November 6, 2018 (source).

With the drier past 30 days, 90-day rainfall amounts are closer to normal but still two to three times higher than normal for the Edwards-Plateau area (Figure 3). The reason for the drought and dry areas in the Drought Monitor become clear after seeing the areas with less than normal 90-day rainfall.

Figure 3: Rainfall as a percent of normal for the past 90 days (as of December 14, 2018; source).
Figure 3: Rainfall as a percent of normal for the past 90 days (as of December 14, 2018; source).

The North American Drought Monitor for the end of October shows continuing drought in the headwaters of the Rio Grande in southern Colorado, the primary source of water for Elephant Butte Reservoir, and no drought in North-Central Mexico, the primary source of water for lakes Amistad and Falcon (Figure 4a). Parts of southern Colorado in the Rio Grande watershed have received less than 5 percent of normal precipitation for the past 90 days (Figure 4b).

Figure 4a: The North American Drought Monitor for October 31, 2018 (source).
Figure 4a: The North American Drought Monitor for October 31, 2018 (source).
Figure 4b: Percent of normal rainfall for the past 90 days for Colorado and New Mexico as of December 12, 2018 (source). I use this map to see check precipitation trends in the headwaters of the Rio Grande in southern Colorado, the main source of water to Elephant Butte Reservoir downstream.
Figure 4b: Percent of normal rainfall for the past 90 days for Colorado and New Mexico as of December 12, 2018 (source). I use this map to see check precipitation trends in the headwaters of the Rio Grande in southern Colorado, the main source of water to Elephant Butte Reservoir downstream.

Statewide reservoir storage has continued to rise from 88.0 percent full on November 12th to 89.7 percent on December 14th (Figure 5a), nearly the highest level for this time of year since 1990. Percent full status for individual reservoirs this month is (Figure 5b) about the same as last month (Figure 5c).

Figure 5a: Statewide reservoir storage since 2016 compared to statistics (median, min, and max) for state-wide storage since 1990 (source).
Figure 5a: Statewide reservoir storage since 2016 compared to statistics (median, min, and max) for statewide storage since 1990 (source).
Figure 5b: Reservoir storage as December 14, 2018, in the major reservoirs of the state. (source).
Figure 5b: Reservoir storage as December 14, 2018, in the major reservoirs of the state (source).
Figure 5c: Reservoir storage as November 12, 2018, in the major reservoirs of the state. (source).
Figure 5c: Reservoir storage as November 12, 2018, in the major reservoirs of the state (source).

Despite sea surface temperatures achieving El Niño levels (Figure 6), we remain under an El Niño Watch. The reason is that in addition to achieving temperatures above 0.5 degrees Celsius in a particular patch of the Pacific, the El Niño designation also requires a clear coupling with the atmosphere. In other words, those warm waters need to start affecting the atmosphere, and we aren’t there yet. So up from the ~80 percent chance last month we are now at ~90 percent for El Niño forming this winter with a 60 percent chance of continuing through the spring. El Niños generally result in wetter-than-normal and cooler-than-normal conditions for Texas and act as a tropical storm suppressor.

Figure 6. Forecasts of sea surface temperatures anomalies for the Niño 3.4 Region as of December 13, 2018 (modified from source).
Figure 6. Forecasts of sea surface temperatures anomalies for the Niño 3.4 Region as of December 13, 2018 (modified from source).

The U.S. Seasonal Drought Outlook through February 2019 suggests drought improvements in southern Colorado, something that would be welcome for Elephant Butte Reservoir, and drought removal for Texas (Figure 7).

Figure 7: The U.S. Seasonal Drought Outlook for November 15, 2018, through February 28, 2019 (source).
Figure 7: The U.S. Seasonal Drought Outlook for November 15, 2018, through February 28, 2019 (source).

 

Author

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Robert Mace,
Deputy Executive Director & Chief Water Policy Officer at The Meadows Center for Water and the Environment
Robert Mace is  a Professor of Practice in the Department of Geography at Texas State University. Robert has over 30 years of experience in hydrology, hydrogeology, stakeholder processes, and water policy, mostly in Texas. 

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