science – Illinois State Climatologist

April 10, 2014

Thursday Highlights – Drought Monitor and El Nino Forecast

Here are two highlights for today:

U.S. Drought Monitor

After some concerns of dryness over the last several months in parts of Illinois, the conditions across Illinois were much wetter in the last two weeks. Rainfall totals were especially heavy south of Interstate 72 and ranged from 3 to 8 inches or more (see map below).

The U.S. Drought Monitor has removed all areas of drought in Illinois and greatly reduced the region of “abnormally dry” conditions.

Climate Prediction Center El Niño Forecast

The NOAA Climate Prediction Center issued a new El Niño Watch today, saying …

While ENSO-neutral is favored for Northern Hemisphere spring, the chances of El Niño increase during the remainder of the year, exceeding 50% by summer.

This reflects a slightly stronger chance of El Niño arriving this summer than mentioned in their post a month ago. However, they caution that there is still a great deal of uncertainty in the timing and strength of the El Niño and recognize that the skill in forecasting El Niño this early in spring is low. This is a less certain forecast than the one issued by the Australian Bureau of Meteorology earlier this week, indicating that there was a greater than 70 percent of an El Niño event by June.

March 27, 2012

Searching for March Records

If you are interested in daily and monthly weather records, there are a few excellent web sites that can help.

NOAA National Climatic Data Center

The NCDC site http://www.ncdc.noaa.gov/extremes/records/ allows you to look at daily, monthly, and all-time records for sites in a selected state. Records include temperature (highest high, lowest low, etc.), precipitation, and snowfall. The report for March is especially interesting with 352 broken records and 52 tied records for sites in Illinois as of March 27. See the link to the PDF below:
Report from NCDC on record highs set in March 2012

Weather Underground

The folks at weatherunderground.com has a similar page as the NCDC site with slightly different interface and output at http://www.wunderground.com/climate/extremes.asp.

February 29, 2012

Deadly Tornado Strikes Harrisburg IL

Based on preliminary reports, six people were killed in Harrisburg (southeastern Illinois), when a tornado struck late last night. The NWS is surveying the damage today. I will post more information when it becomes available.
Update 9:30 pm, March 1. I have updated the numbers below to reflect the addition of 2011 data.
Update 8:30 am, March 1. The Paducah NWS office has released a preliminary report on the tornado outbreak in southern Illinois, Indiana, and Kentucky.
Update 3:45 pm, February 29. According to a news conference aired on WSIL-TV, the NWS has identified this as an EF-4 tornado with wind speeds up to 170 mph. Wind speeds are estimated from the level of devastation at the scene in Harrisburg. EF-4 tornadoes are relatively rare in Illinois. Out of ~~2244~~ 2322 tornadoes reported in Illinois between 1950 and ~~2010~~ 2011, only 40 were in this category. However, they are very deadly. Of the 203 deaths related from tornadoes between 1950-~~2010~~2011, 100 of these came from EF-4 tornadoes. That is 49 percent of the data with an average rate of 2.5 deaths per EF-4 event.
Tornadoes are more common in spring and summer, but they can occur in February. A total of 29 39 tornadoes occurred in February from 1950 to ~~2010~~ 2011, causing 6 deaths and 28 serious injuries. We have a complete analysis of Illinois tornadoes here, including plots and maps. As the map below shows, many of our February tornadoes occur in the southern part of the state.

February 16, 2012

New Spring Outlook – Warmer and Wetter for Illinois

The NWS Climate Prediction Center has released the new outlooks for March as well as March-May.
One of the key things to come into play is the status of La Niña in the Pacific Ocean. A La Niña event occurs when ocean temperatures are colder-than-normal along the eastern part of the Pacific Ocean basin. The associated ocean and atmospheric pattern tends to give us a wet spring in states along the Ohio River Valley. CPC states that “La Niña is likely to transition to ENSO-neutral conditions during March-May 2012.” That’s government-talk for saying that the La Niña event is fading fast and will be gone before the end of spring.
The outlook for March in Illinois calls for an increased chance of above-normal temperatures and above-normal precipitation. The outlook for March-May calls for an increased chance of above-normal temperatures throughout the state. However, it shows an increased chance of above-normal precipitation in the eastern half of the state while the western half has “equal chances” of above-, below-, near-normal precipitation.
The new outlook for June-August (maps below), the heart of the growing season, is for an increased chance of above-normal temperatures in southern Illinois and “equal chances” for the rest of the state. The entire state is in “equal chances” with respect to precipitation.
Just a note on “equal chances”. That’s the NWS way of saying that none of their forecasting techniques are indicating a higher risk of unusual temperature or precipitation patterns.