How warm and dry is it, really?

Use MSU’s Enviro-weather tools to quickly compare seasonal heat (degree-day) and moisture (precipitation) accumulations with previous and “normal” years.

Though we can’t change the weather, we still want to know where we stand. How does this year’s weather compare with previous years’? Is it hotter than normal? Is it drier than normal? Is the growing season more advanced than it was this time last year? These questions and more can be quickly answered by using Enviro-weather’s online tools.

We can use a measure of accumulated heat (“degree-days” or “growing degree-days”) to answer the questions “are we warmer than normal?” and “is the growing season more advanced?” Temperature drives the growth of most living things (everything except the warm-blooded mammals and birds), and that includes crops, diseases and pests. That is why, in warmer years like 2012, the season comes earlier and crops grow faster and mature quicker. Flowers that usually bloom the first of July may flower in mid-June. The opposite occurs in cooler years, crop growth is delayed and so is pest development. Degree-day accumulation mirrors development of crops and pests.

To see an overview of seasonal degree-day accumulation (base 50) across Michigan, Enviro-weather provides a “current degree day maps” tool that is accessible from any station or commodity page (Photo 1).

Degree-day tools
Photo 1. Envir
o-weather degree-day tools.
This menu can be found on
any station or
commodity page.

Clicking on the “current degree day maps” link will show you the current degree-day map that lists the degree-day accumulations (base 50) throughout Michigan. You can choose to change the dates on the pull-down menus above the map and view accumulated degree-days past dates.

If you scroll down from the current degree-day map you will see two more maps that depict how far ahead or behind “normal” the season is in terms of heat (degree-days). For example, through June 26, 2012, most of Michigan is one to two weeks ahead of “normal” and parts are more than two weeks ahead (Photo 2).

Heat accumulation
Photo 2. Map of Michigan showing heat accumulation (degree-days base 50)
for March 1 through June 26, 2012, compared with “normal.” Number of days
and weeks ahead of or behind normal is shown.

In contrast, on June 26, 2011, the growing season was progressing normally in most of Michigan; some areas in northern Michigan were behind normal (Photo 3).

Heat accumulation
Photo 3. Map of Michigan showing heat accumulation (degree-days base 50)
for March 1 through June 26, 2011, compared with “normal.” Number of days
and weeks ahead of or behind normal is shown.

Enviro-weather users can choose to view these maps for any date from 2008 to present.

If you’d like to see more details and precipitation information, Enviro-weather has additional tools available. To see a listing of degree-day accumulations over the past five years at one of the Enviro-weather station locations, select “Degree-day comparisons: last 5 years at this station” (Photo 1). A table will display the accumulated degree-days from March 1 through the present date for the current year and the previous five years. The “average” or normal for those past five years is also displayed. Photo 4 shows this table for Emmett, Mich.

Degree-day accumulations
Photo 4. Degree-day accumulations March 1 through June 26 for 2007
though 2012 at the Emmett, Mich., Enviro-weather station.

Similarly, to see a comparison of accumulated rainfall for the past five years, select “Rainfall comparisons last five years at this station” (Photo 5). This tool is available from any station or commodity page on Enviro-weather.

List of weather observations and summaries
Photo 5. List of weather observations and
summaries on Enviro-weather. This menu
can be found on all station and commodity pages.

Clicking on this option will display a table listing total rainfall to date for the current growing season (both total inches of rain and number of hours with rain) and for the same time period the previous five years. Here, for example, is a table for Emmett, Mich., that shows total rainfall in inches and number of hours with rain for March 1 through June 27 of each year from 2007 to 2012 (Photo 6).

Rainfall totals
Photo 6. Rainfall totals March 1 through June 26 for 2007 though 2012
at the Emmett, Mich., Enviro-weather station.

I’ve used these Enviro-weather tools to put together a table comparing the degree-day (base 50) accumulations from March 1 through June 26 for 2007 through 2012, plus the “average” degree-day for that time period over the past five years, for four different locations in Michigan. Included are degree-days from the Commerce Township Enviro-weather station (southeast Michigan), Clarksville Enviro-weather station (west central Michigan), Traverse City Enviro-weather station (northwest Michigan) and the Escanaba Enviro-weather station (Upper Peninsula) (Table 1).

Table 1. Degree-day accumulations (50) from March 1 through June 26 for 2007-2012 at four Enviro-weather stations

Degree-days Base 50

Commerce Township

Clarksville

Traverse City

Escanaba

Southeast MI

West Central MI

Northwest MI

Upper Peninsula MI

2007

1011

1040

940

691

2008

842

817

669

503

2009

815

788

651

477

2010

1068

1036

919

718

2011

843

814

654

489

2012

1073

1090

1002

704

Average (2007 through 2011)

916

899

766

575

This table shows clearly the variation in degree-day accumulations from year-to-year. It also shows that, although 2012 is the warmest of the past six years (so far) in all locations except for Escanaba, we’ve experienced some pretty warm springs during the past five years (for example, 2007 and 2010). Also note that how much warmer than normal we are depends a lot on location.

I also put together a table of rainfall totals over the past six years for the same four locations using Enviro-weather (Table 2). Please note that these numbers reflect rainfall totals at the station. Since rainfall amounts can vary widely in a small geographical area, these numbers may not be reflective of the rainfall totals throughout the area. Nevertheless, the table shows we are drier than normal for many locations in south Michigan and wetter than normal for many locations in the north.

Table 2. Total rainfall (inches) from March 1 through June 26 for 2007-2012 at four Enviro-weather stations.

Total Rainfall   (inches)

Commerce Township

Clarksville

Traverse City

Escanaba

Southeast MI

West Central MI

Northwest MI

Upper Peninsula MI

2007

9.9

10.6

6.4

4.8

2008

10.1

10.7

10.4

5.8

2009

14.5

14.3

6.8

8.8

2010

16.5

13.0

11.0

10.0

2011

16.4

15.0

11.1

13.0

2012

8.0

9.4

12.6

9.3

Average (2007 through 2011)

12.9

12.7

9.1

8.5

We hope you are using these and other Enviro-weather tools and applications and that you find them useful. If you have questions, comments or suggestions, please contact .(JavaScript must be enabled to view this email address), Enviro-weather coordinator, at 517 432-6520. If you’d like to contribute to Enviro-weather, please visit the MSU gift cart.

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