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Will El Niño return with even more wet, cool weather?

From feast to famine and drought to floods, it seems like the state of Texas is constantly cycling between weather extremes. Wet weather that has recently blanketed much of the Brazos River basin, based on forecasts, could continue well into winter.

After the dry spell that parched much of Texas – including the vast majority of the Brazos River basin – the rainfall that dramatically changed the state’s weather could be just a sample of what is expected for the coming months.

Those September and October rains set the stage for more of the same this fall and winter, said John Nielsen-Gammon, the state’s climatologist.

“By September 9, Texas had already received its normal rainfall for the entire month, according to data from the Northeast Regional Climate Center,” he said. By the middle of that month, he added, September 2018 had already registered as one of the 10 wettest months on record (dating back to 1895). That meant exceptional drought levels across the state had been almost entirely eliminated.

But that was only the beginning. “Based on preliminary numbers of total accumulated precipitation for the Lone Star State,” Nielsen-Gammon said, September 2018 was one of the three wettest months on record, trailing only May 2015 and August 2017.

The rainfall continued to soak much of the basin through October. Significant releases were being made from both Possum Kingdom Lake and Lake Granbury in mid-October, a dramatic change from what those reservoirs experienced just two months earlier when drought had resulted in lower lake levels.

The recent trend toward abundant moisture is not expected to change any time soon, with El Nino weather conditions likely returning to drench the state through the fall, winter and beyond.

“It looks like wet tropical patterns will contribute more moisture,” Nielsen-Gammon said. “Texas can expect more consistent rain through spring as the El Niño patterns strengthen.” He added that it is likely the El Niño pattern will stay in place well into 2019.

For those who had seen lake levels drop and can now expect reservoirs to fill back up, the trend toward more rainfall is welcome news. For those living in flood-prone areas, it’s a warning to be cautious, monitor weather conditions closely and prepare for high water again.

Still, considering where the entire basin was in late August, vast improvements had been made in reservoir levels basinwide. All reservoirs in BRA’s water supply system are either nearing capacity or are at capacity and releasing runoff due to the widespread rains. All of the U.S. Army Corps of Engineers flood control reservoirs have reached levels within their flood pools and are slowly releasing water downstream. A major factor that could continue to impact the basin and bring even more rainfall is an El Niño weather pattern.

While El Niño is not a certainty, the National Oceanic and Atmospheric Administration predicts a 60 percent chance of the weather pattern developing. In addition to wetter weather, this usually means cooler than average weather as well, but Nielsen-Gammon pointed out that isn’t always the case. NOAA says Texans can expect temperatures to be average or slightly below average in November for the northern part of the state, and below average for the central and southern portions of the state. NOAA also reports that the jet stream should result in moisture from the Pacific Ocean and storm systems bringing rainfall to Texas, and extended cloudy conditions should contribute to a cooling trend across the state – but nothing dramatically different than usual.

“There’s about a two in three chance of El Niño developing this fall or winter,” Nielsen-Gammon said. “If it does develop, the jet stream will tend to be farther south during the winter and spring enhancing our chances for above-normal precipitation. Temperatures are unlikely to be unusual, as the coolness associated with stormy weather will be at least partly compensated by the long-term warming trend presently underway.”

December weather forecasts call for near or slightly below average temperatures for most of Texas, including all of the Brazos River basin, according to NOAA.

The Weather Company, which owns The Weather Channel, forecasts near average or slightly below average temperatures for northern and western Texas, and below average temperatures for southern Texas for November.

“The coldest conditions relative to average are expected to be found in south-central and southeastern Texas,” The Weather Channel predicts.

The December forecast by The Weather Channel forecasts near or slightly below average temperatures for nearly all of Texas, with the exception of a northwestern corner of the Panhandle, which could experience slightly above average temperatures.

Nielsen-Gammon said while there may be the usual winter cold snaps, “El Niño makes super-cold freezes less likely, but does enhance other types of winter weather, such as ice and snow.”

Are there any other factors that are expected to play a significant role in the climate outlook in the next few months?

“Scientists are still trying to figure out the influence of changes in Arctic Sea ice coverage,” Nielsen-Gammon said. “If it does have a direct impact, it probably involves snow in Asia and cold temperatures in Europe, but not so much of an effect in Texas,” he said.