Climate change to decrease average number of mild weather days


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Residents enjoy pleasant weather at Noelridge Park in Cedar Rapids, Iowa. (Louis/flickr)
Jenna Ladd | January 24, 2017

The first of its kind, a recent study found that climate change is likely to decrease the number of “nice weather” days worldwide.

The authors of the study, scientists from the National Oceanic and Atmospheric Association and Princeton University, define “nice” or “mild” days as those days when temperatures are between 64 and 86 degrees Fahrenheit, dew points are below 68 degrees Fahrenheit and less than half of an inch of rain falls. Currently there are an average of 74 nice days globally per year, but that number is likely to drop to 70 in the next twenty years and to 64 by 2081.

Karin van der Wiel is a postdoctoral researcher at Princeton University and lead author of the study. She said,

“We used a climate model to simulate the current climate. In that simulation we counted the number of mild days. Then, we increased greenhouse gases in the climate model to simulate the future effects of climate change. This leads to increasing temperatures, changes in humidity, changes in precipitation over the whole world and with very specific patterns. In this new, future climate, we counted the number of mild days again. We could then calculate the change — increase or decrease — of mild weather days for each location globally.”

Not all corners of the Earth will be affected equally, however. Tropical regions are expected to lose the most nice days, with some areas losing up to 50 per year by the end of this century. Meanwhile, London is expected to gain 24 nice days each year.

Predictions for Cedar Rapids, Iowa mirror global averages. Eastern Iowa currently enjoys 76 nice days annually; researchers say that number is expected to drop to an average of 72 between 2016 and 2035 and to 66 each year between 2081 through 2100.

Frequent high humidity makes it tough for Iowa to meet the pleasant weather criteria outlined in the study. Absolute humidity has risen by 13 percent during the summer months in Des Moines since 1970, according to Iowa State climate scientist Gene Takle. Increased humidity also contributes to the extreme rain events that have plagued Iowa in recent years.

van der Wiel said, “Mild weather is something everyone knows, experiences, and has memories of,” she continued, “Our study shows that human-caused climate change is going to lead to changes in mild weather all over… The changes are happening now, and where people live.”

Precipitation in Iowa falls below average for first time since June


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Streamflow remains above average for much of northeastern Iowa as the state heads into the driest season of the year. (Iowa DNR)
Jenna Ladd | November 8, 2016

The Iowa Department of Natural Resources (DNR) recently released its latest Water Summary Update. Each update provides an overview of the status of Iowa’s water resources using four categories: precipitation, streamflow, drought, and shallow groundwater. The latest update provides a water resource snapshot of trends from October 10 through November 3.

As Iowa heads into the driest season of the year, stretching from November through February, October was recorded as the first month since June in which rainfall fell below normal levels. “Abnormally dry,” or drought conditions persisted for south-central Iowa, with the lowest reported October rainfall of 0.54 inches recorded in Story County. Areas of north central and northeastern Iowa, which had experienced heavy rainfall throughout much of September, saw drier conditions at last.

Temperatures throughout the month of October were warmer than they have been since 2007, averaging about 4.5 degrees above normal. This season’s first freeze is yet to occur for the Des Moines metro area, as well as far eastern and southeastern Iowa. The northwest two-thirds portion of the state experienced its first deep freeze on October 13.

Since the previous Water Summary Update, streamflow in the Chartion River Basin in south central Iowa has decreased to normal levels. However, streamflow for most of Iowa remains above average. More specifically, streamflow in the Cedar, Des Moines, and Upper Iowa River basins remain far above average. The forthcoming four months not only mark the driest season of the year, but also the most hydrologically stable. During this period of time Iowa usually receives about 15 percent of the year’s total rainfall, or 5.5 inches of precipitation. In contrast, summer months in the state bring more than 18 inches of precipitation on average.

Water Summary Updates are released every two weeks or as water resource conditions in Iowa significantly change. They are prepared by the Iowa DNR in partnership with Iowa Department of Agriculture and Land Stewardship, the U.S. Geological Survey, and The Iowa Homeland Security and Emergency Management Division. A complete record of Iowa Water Summary Updates can be found here.

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(Iowa DNR)

2016 ranks third wettest ‘water year’ since 1872


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Each bi-weekly Water Summary Update provides the current status of water resources in Iowa in terms of precipitation, stream flow, shallow groundwater, and drought monitoring. (Iowa DNR)
Jenna Ladd | October 14, 2016

Iowa Department of Natural Resources (DNR) released its most current Water Summary Update earlier this week.

DNR prepares the bi-weekly updates in collaboration with the Iowa Department of Agriculture and Land Stewardship, the U.S. Geological Survey, and The Iowa Homeland Security and Emergency Management Division. Each report provides an overview of the status of Iowa’s water resources and significant events that affect water supplies using four categories: precipitation, stream flow, shallow groundwater, and drought monitoring.

The most recent update is a snapshot of the state’s water resources from August 31st through October 10th. The report notes that different parts of Iowa experienced a wide range of rainfall totals. Heavy rains pelted the Cedar River watershed during much of September, with the largest storm-total rainfall of 10.56 inches near Nora Springs in Floyd County. In contrast, some parts of southeastern Iowa experienced a particularly dry September. Most notably, rain totals were less than one-third of the average near Fairfield and Ottumwa. Average statewide rainfall was 6.29 inches or 2.91 inches above average, making it the rainiest September since 1986.

Streamflow was also reported to be above average for much of the state. The update notes that U.S. Geological Survey employees have been taking additional streamflow measurements following heavy rain events at the end of September in the Cedar and Wapsipinicon River basins. In several locations along the Shell Rock, Cedar, and Wapsipinicon Rivers, peak stream flow was found to be the second-highest in recorded history. These values are only topped by the historic 2008 flood.

October 1st through September 30th is considered the “water year” by experts in the field. The 2016 Water Year, which ended on September 30th, 2016, is the third wettest year on record in 144 years.

Extremes characterize “normal” Iowa weather year


Photo by Katie Haugland; Flickr

Precipitation statistics could lead future cursory analysts to jump to the mistaken conclusion that 2013 was a pretty normal year.

To check out the yearly statistics and what they mean,  head over to The Gazette.

On the Radio: Warmer temperatures linked to increased rainfall


Photo by iowa_spirit_walker, Flickr.
Photo by iowa_spirit_walker, Flickr.

Listen to this week’s radio segment here or read the transcript below. This week’s segment discusses the connection between warmer temperatures and increased rainfall.

A University of Iowa study shows an increase in heavy rainfall is connected to increased temperatures in the upper Midwest.

This is the Iowa Environmental Focus.

Continue reading

Drought conditions continue to spread across Iowa


Graphic courtesy of the National Drought Mitigation Center.

An updated map by the U.S. drought monitor shows a significant expansion of drought conditions through eastern and northwest Iowa.

Rainfall totals in Iowa for the months of May and June were less than half of normal, and what little precipitation the state received has been baked from the soil by a heatwave generating temperatures of 100 degrees or more across the state.

Bryce Knorr of Farm Futures Magazine said this morning “triple digit heat will cover much of the heart of the Corn Belt again today, with only partial relief in sight. While temperatures will slowly cool from the northwest, only limited chances for rain are in sign for key states over the next week.”

For more information, read the full article at the Des Moines Register.

Several Iowa counties updated to drought status


Graphic courtesy of the National Drought Mitigation Center.

Several counties in eastern Iowa have been updated to drought status, according to U.S. Drought Monitor map issued by the National Weather Service, the U.S. Department of Agriculture, and the University of Nebraska.

The map adds the counties of Scott, Clinton, Jackson, Dubuque to the affected drought area, while also downgrading other counties from “abnormally dry” status after ample rainfall last week.

For more information, read the full article at the Des Moines Register.