One cold spell does not disprove global warming. While Dallas might be experiencing abnormally low temps, Jacksonville's seeing uncharacteristic highs (86F today).
[0] https://www.ncdc.noaa.gov/global-warming/temperature-change
https://www.esrl.noaa.gov/gmd/ccgg/trends/
If you spend 30 seconds googling you'll see that communities in the high Canadian arctic, alaska and greenland have been setting new temperature records on a regular basis. And the subsidence and melt of coastal permafrost in some areas is increasing at a rate that will soon look like a hockey stick curve on a chart.
Certainly a decreasing average global temperature would do it. However, we are seeing a consistent upward trend in the global average[1] even if some regions have lower than normal temperatures.
[1] https://climate.nasa.gov/vital-signs/global-temperature/
To that end, what evidence of weather patterns would you have to see to believe less in the global warming model? Would years of "less extreme event days" make you believe in the global warming model any less?