Heavy Rains Alleviate Illinois Drought

Heavy rains over the weekend put a major dent in the drought in southern Illinois and neighboring states. Amounts of two to four and a half inches were common throughout the southern half of the state. Some places saw more rain in the last week than in the last three months. For example, Mt Carmel reported 5.07 inches in the last 7 days while receiving a combined total of only 4.34 inches during the months of August, September, and October.
These widespread rains should give relief to other drought-stricken areas of the Midwest as well, including Missouri, Kentucky, Indiana, and Ohio.

7 day rainfall Midwest
The 7-day rainfall total for the Midwest, ending on November 28, 2010.

Much Needed Rain Arrives in Illinois

Much needed rain arrived in Illinois over the last few days. As the map below shows, amounts of 0.50 inches or higher occurred across Illinois for the 7-day period ending November 23. And typical to these situations, the area in most need of rain misses out. In this case, that would be far southern Illinois.  There is a second opportunity for rain in the next few days.

7-day rainfall
The 7-day rainfall for Illinois, ending November 23, 2010 (courtesy NWS).

Tornadoes Strike Illinois in November

Severe weather, including   four tornado reports, struck northern Illinois on November 23, 2010. According to NOAA’s Storm Prediction Center:

  • a tornado was spotted 4 miles east of Loves Park (Boone County); power lines down and debris were reported;
  • a second tornado report from 3 miles east of Loves Park (probably the same tornado) caused 3 injuries, nearly destroyed one business, and damaged other homes and a garage;
  • a tornado was spotted on the ground 2 miles northwest of Harvard (McHenry County); no damage was reported;
  • a tornado was spotted in McHenry County, right on the Illinois-Wisconsin line, 5 miles southeast of Walworth WI; apparently all the damage occurred in Wisconsin.

Besides tornadoes, high winds caused extensive damage including tree limbs and power lines down, damage to buildings, and trucks blown over. The link to the full report is here.
The NWS offices at Davenport IA and Chicago IL are conducting damage surveys. Results will be posted here:

Average Date of First Snow in Illinois

Besides the cold temperatures, one of the initial signs of winter is that first snowfall. Parts of Iowa, Wisconsin, and Indiana have already seen their first snow. In the figure below are the median dates of the first measurable snowfall (greater than or equal to a tenth of an inch) of the season in Illinois.
Think of the median date as the date by which we have seen snow in 50 percent of the cases during the period between 1971 and 2000.
In northern Illinois, the first snowfall occurs around Thanksgiving. In far southern Illinois, you have to wait until sometime in mid-December.
In about 10 percent of the cases, the first measurable snow can occur as early as November 5 in northern Illinois to November 20 in far southern Illinois.

date of first snow
The median date of the first measurable snow of the season base on 1971-2000 data (click to enlarge).

Updated Forecast for December and Winter

NOAA’s Climate Prediction Center has come out with a new forecast for December and for December-February (winter). This is part of their routine update cycle.

December

The outlook for December in Illinois calls for an increased chance of above normal temperatures.  An increased chance of above normal temperatures translates into just a few degrees above normal. Temperatures in Illinois have run an average of 2.9 degrees above normal for every month since March of this year. Therefore, continuing with a forecast for above-normal temperatures is not surprising.
The outlook calls for equal chances of above, below, or near-normal precipitation (or equal chances as they call it) in December in Illinois.

December-February (winter)

The outlook for December-February remains the same as last month. There is an increased chance of above-normal precipitation for all of Illinois. And, there is an increased chance of above-normal temperatures for the southern two-thirds of the state. See the figure below for more details.

CPC forecast
NOAA's Climate Prediction Center forecast for December and December-February (click to enlarge).

First Half of November – Warm and Dry

First Half of November

The first half of November in Illinois has been warm and dry, according to preliminary data from November 1-15, 2010. The statewide average temperature was 47.3 degrees, 2.9 degrees above normal. The statewide average precipitation was only 0.21 inches, only 13 percent of normal for the first half of November.

Past November’s in Illinois

  • The driest November on record was 1904 with 0.28 inches.
  • November 2007 was the 25th driest with 1.75 inches.
  • November 2008 was the 20th driest with 1.48 inches.
  • November 2009 was near-normal with 2.47 inches.
  • Normal state-wide precipitation for November is 3.34 inches.

The term “normal” refers to the 1971-2000 average.

Precipitation percent of normal for first half of November 2010
Precipitation (Percent of Normal) for the First Half of November 2010.

Winter Preparedness Week

This is Winter Preparedness Week (November 14-20, 2010). As I write this, a major winter storm is moving through Minnesota and Wisconsin, so it is never too early to start preparing for winter conditions in Illinois.

Winter Storm Preparedness Guide

The Illinois Emergency Management Agency has teamed up with the National Weather Service and the American Red Cross to develop a Winter Storm Preparedness Guide (pdf). It provides information on winter storms, forecast terminology, and how to plan at home, work, school, and while on travel.
Having survived 50 winters in Missouri and Illinois, here is my short list of things to consider:

  • be alert to the current weather and forecasts – my family and I spent one Christmas Eve in a hotel in Springfield IL because I underestimated the snowfall and overestimated the ability of other drivers to drive in the snow;
  • dress appropriately – invest in a good coat, warm gloves, boots, hat, and scarf, you will be better prepared (and happier) in cold and snowy conditions;
  • be flexible in your travel plans – go early, stay later, or don’t go at all to avoid severe winter weather;
  • be prepared to be stuck at home for a few days – keep up stocks of food, water, and any medications;
  • be careful with heaters and fireplaces – many home fires and carbon monoxide poisonings have been the result of improper operation of space heaters, fireplaces, or using inappropriate devices such as barbecue grills. Trust me on this one – my father-in-law was the fire chief so I heard all the stories.

History

As a historical footnote, the concept of a winter preparedness week started at the Illinois State Water Survey in response to the severe winters of the late 1970s and early 1980s. It was done in partnership with the Illinois Department of Energy and Natural Resources and the Illinois Emergency Management Agency. Winter preparedness week was expanded through the National Weather Service, beginning around 1990.

Record High Sunshine in October

The Illinois State Water Survey has this fascinating press release.
October Solar Radiation in Illinois: Record High in 2010, Record Low Last Year
11/9/10
Source: Bob Scott, 217-333-4966, rwscott1@illinois.edu
Did it seem to you that the weather in October was quite a bit sunnier than in Octobers of the past? Do you remember last October as being rather cloudy?
If these are your impressions, you are correct, according to Bob Scott, Director of the Water and Atmospheric Resources Monitoring Program at the Illinois State Water Survey, a division of the Institute of Natural Resource Sustainability. Scott operates an array of weather sites across the state called the Illinois Climate Network, and one of the sensors on the stations measures solar radiation.
Solar radiation totals for October 2010 were higher than in any past October since sites were installed in 1989, while the solar radiation totals for 2009 were the lowest.
“Our sensors measure what we call direct solar radiation,” Scott said. “This includes pure sunshine and reflected sunshine from clouds and blue sky.”
October typically is drier than the spring and summer months that precede it, and sunshine in October is in a seasonal decline with fewer daylight hours and the sun getting progressively lower in the sky.
“But this October was much drier than normal,” Scott said. “Consequently, there were many more days with bright sunshine and fewer days with clouds and rain, as opposed to last October which had many rain events.”
During the 20-year history of the weather station in Champaign prior to last year, sunshine in October has averaged about 379 mega joules per square meter.
If you ignore the units, Scott said, the range of solar radiation values in October in Champaign through 2008 varied from a low of 328 in 2004 to a high of 414 in 1992. The very wet October of 2009 had a total of 264 units of solar radiation, while the very dry October of 2010 reported 449.
“Both prior maximum and minimum values were slammed in the past two years,” Scott reported.
The current dry conditions have now continued into November with strong indications that it too will see above normal solar radiation.
As far as a cause for these events, “There is none,” said Scott. “Our data by themselves are far too short of a record to suggest a cause, and they are on opposite sides of the scale from each other. Without more information, these data must be categorized right now as simple natural variability.”
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Satellite View of Midwestern Storm

NASA has posted low and high resolution satellite photos of the record-setting low-pressure system that rolled through the Midwest last week. They say:

The storm that swept across the center of the United States on October 26 and October 27, 2010, was memorable to those who experienced it because of its strong winds, rain, hail, and widespread tornadoes. Meteorologists get excited about the storm because it set a record for the lowest pressure (not associated with a hurricane) measured over land in the continental United States. At 5:13 p.m. CDT, the weather station in Bigfork, Minnesota recorded 955.2 millibars (28.21 inches of pressure). Pressure is one indicator of a storm’s strength, and this measurement corresponds to the pressure seen in a Category 3 hurricane.

You can read the full story and see the images here.

Satellite view of Midwest storm of late October 2010
Satellite view of Midwest storm of late October 2010 (NASA).

October Was Warm and Dry in Illinois

Precipitation

For Illinois, the statewide average rainfall for October was 1.4 inches, 1.5 inches below normal or 48 percent of normal. This ranks as the 20th driest October on record. The largest monthly rainfall total was reported at Belvidere with 3.94 inches. See map below for rainfall departures across the state.
While northern Illinois was close to normal on rainfall in October, parts of southern and eastern Illinois remained dry. The U.S. Drought Monitor lists those areas as “abnormally dry” and southeastern Illinois as”moderate drought”. At this time of year, the main impacts on agriculture would be on pasture conditions and winter wheat.

Soil Moisture

With the vegetation preparing for a long winter’s nap and lower temperatures, the demands on soil moisture are close to zero. So soil moisture should start to recover in the next few months even if precipitation remains below normal. The Illinois State Water Survey posts their latest soil moisture survey a few days after the end of the month here.

Temperature

The statewide average temperature for October was 56.2 degrees, 1.6 degrees above normal. The highest temperature for the month was reported at Fairfield with 93 degrees on October 10. The lowest temperature for the month was reported at Minonk with 22 degrees on October 29 and Sidell with 22 degrees on October 30.

Frost

During October, nearly all of Illinois has experienced temperatures down to 32 degrees and many areas have reached 28 degrees or less. See map below.

Figures

 

October rainfall Illinois
October rainfall departures from normal.

freeze Illinois
Occurrence of Frost (32F) and Freeze (28F) in Illinois at end of October 2010.

 
 
All data are preliminary.