week saw a major increase in drought intensity in the Central U.S. as
flash wildfires sparked across Oklahoma. Meanwhile, longer term
drought trends remained strong even as the U.S. West Coast saw breaks
in the dryness in the form of late winter precipitation.
expanded across the Central U.S. last week as precipitation deficits
there increased. Image source: Drought
return to severe to exceptional drought across the Western and
Central U.S. was one of the hallmarks of the overall warm winter of
2017-2018. Historic drought, which had been suppressed by substantial
rains during 2016-2017, appears to have returned — with threat of
worsening conditions through spring, summer and fall.
snow pack totals remain well below average despite a recent increase
in the number of storms affecting the state. Image source: CDEC.)
California, snow packs are still running well below average, despite
a recent wave of storms sweeping through the region. But it’s worth
noting that though still much diminished from typical snow depth
totals, the present range is now higher than the driest years —
2014-2015 and 1976-1977. So the situation isn’t looking quite so
bad as it was a few weeks ago.
have tended to remain above average across most of the U.S. this
winter even as abnormally dry conditions impacted the Southwest.
Image source: NOAA.)
human-caused climate change increasingly warm temperatures result in
higher rates of evaporation from lakes and soils. This increases
drought intensity for many locations around the world. In keeping
with this longer-term trend, the winter of 2018 can still be
characterized as both warmer and drier than normal for most of the
U.S. But the overall drought pattern has shifted more toward the
Central U.S. and away from the West Coast with the approach of