Downpours and Droughts: Timing is Everything
Videos, Mon, Sep 10th, 2012
Deke Arndt of NOAA’s National Climatic Data Center reports that heavy rains from Hurricane Isaac in late August fell too late–and mostly in the wrong places–to provide much relief from U.S. drought.
Deke Arndt, Chief of the Climate Monitoring Branch, National Climatic Data Center.
Tropical Storm Isaac reached hurricane force for three days at the end of August and dropped almost a foot of rain in some areas. It devastated homes and communities as it hovered over the Coastal Plain before it moved up into the Ohio River valley. People in the middle of the United States, who have been plagued by drought for much of the year—they wanted rain, and they needed rain. But how much did Isaac alleviate the drought in this part of the country?
Where rain falls and when it falls determines whether drought will persist or diminish. Areas that show up in darker colors here needed a lot of rain, but Isaac didn’t deliver it when or where many farmers needed it.
This map shows the percent of normal rainfall that fell across the United States this summer in June, July, and August. The greener colors show that more rain fell in coastal Louisiana, Alabama and throughout the surrounding Coastal Plain. And that’s exactly where Isaac dumped most of its rain. Areas that were already soggy, they got inundated. And that’s why there was additional flooding and damage along the coast.
On the other end of the spectrum, dry areas stayed mostly dry. My home state of Oklahoma is in the western part of the worst-hit drought region, and it didn’t get any relief from Isaac. Nor did many of the communities stretching east and north from there.
Most of the areas in deep drought remained at the same level they were at the beginning of summer. Arkansas, Missouri, Iowa and Illinois all needed about a foot of rain to mitigate their drought. And even though Illinois got about that much–and much more than its neighbors—the timing wasn’t that good. According to Jim Angel, the Illinois state climatologist, the rain was too late in the season to reverse the damage that had already been done to the corn crops.
The Central U.S. needed about a foot of rain to make up from the summer deficit and much of the Gulf Coast got just that from Isaac. Drought is all about when and where… And depending on your livelihood, the timing can be just as important as the amount of rainfall.
For Climate.gov, I’m Deke Arndt.Downpours and Droughts: Timing is Everything,
Spring 2013 has brought something fairly unusual in recent years—colder-than-average temperature for the nation as a whole. NOAA’s Deke Arndt talks about how spring temperatures in three U.S. climate divisions compare to the local long-term trend.
During late winter, Texas, Oklahoma, and Kansas received sorely needed rain which helped reduce short-term impacts, like wildfire and dry topsoil. But it has taken months to develop deep and severe drought in the region, and a few wet weeks won’t erase that situation. It can take months of ideal conditions to bring soil, rivers, and vegetation back to health.
On any given day or any given month, somebody somewhere experiences colder-than-average temperature, even though the globe as a whole is warmer than average. We know this through climate monitoring, which entails measuring temperature on land and across the ocean.