Midwest Drought Information
(Click maps to enlarge in a new window)
(Click maps to enlarge in a new window)
U.S. Drought Monitor
Also - see the Central Region Drought Monitor from our Central Region Maps page.
Soil temperature measured at 4” for 24-hour and 7-day periods through the previous day. Temperatures are based on data from mesonet sites in Illinois, Kentucky, Michigan, and Missouri as well as Climate Reference Network sites throughout the region and in surrounding states. These maps are updated daily at 2:30 p.m. Note: spatial resolution is limited in some states.
This experimental model does not handle snow and snowmelt well, and its performance is still being evaluated.
The soil moisture amounts for three levels (0-4", 0-20", and 0-72") are calculated using a multi-level soil model responding to daily temperature and precipitation in the counties of the region. The model is designed for the growing season when temperatures are above freezing, and does not take snow depth into account during the winter. Daily estimates of precipitation are obtained from The National Weather Service Multi-sensor Precipitation Estimate product (http://www.srh.noaa.gov/rfcshare/precip_analysis_new.php). Daily temperatures are derived from the NOAA cooperative observer network. County-level soil characteristics were derived from the State Soil Geographic (STATSGO) climate division database. If necessary, missing county temperature and precipitation data are estimated using the MRCC daily gridded data. Average values of county soil moisture are computed by week with county data from 1972 to last year.
Crop moisture indEX
The Palmer Crop Moisture Index is a very short term indicator of drought condition on a weekly time scale relevant to crop management during the growing season. Temperature and precipitation inputs are factors in a water balance model that determines whether soils have enough moisture to meet the short term needs of crops (positive value) or do not have enough moisture (negative value).
Streamflow data are reported to the USGS system in real time, with the map being a snapshot of streamflow amounts on a given day. The green dots are streamflow amounts in the normal range; orange, dark red, and red are progressively lower than normal streamflows; and turquoise, blue, and black are progressively higher than normal streamflows. Even though streamflow can respond rapidly to heavy precipitation events, it may take many months of drought conditions to cause streamflow to fall to low levels, providing a good indicator of hydrological drought that may affect water supplies.
KEETCH-BYRAM DROUGHT INDEX
Estimated Precipitation Needed
This map is based on the Palmer Drought Severity Index (PDSI) value for the current time. A calculation is made to determine the amount of precipitation above normal that would be required to return any negative PDSI value (in the drought range) to -0.5, the lowest level of the normal range and the end of the drought.
PrecipitationPrecipitation Maps for 30, 90, and 180 day periods through Today. These maps are updated by 10:30 AM Central Time.
Please click on the time periods to enlarge.
STATE DROUGHT INFORMATIONMouse over a state to see the available State Climate Office web site or state-specific drought web sites. Click your choice on the menu:
Palmer Drought Severity Index
The Palmer Drought Severity Index represents the balance between water supplied to the soil through precipitation and water lost from soil to the air (evaporation), to crops (transpiration), and to lower elevations (runoff). The PDSI accumulates the effects of many months of weather on the current state of soil moisture, and is a good indicator of long term drought status. A value of zero represents normal conditions, positive numbers indicate wetter than normal conditions, and negative numbers denote drier than normal conditions.
The Palmer Z-Index represents the change in soil moisture conditions over the last month due to the imbalance between precipitation and water lost to the air and plants and to runoff. It is a short term measure of the direction of moisture change, with positive numbers indicating wetter conditions, and negative numbers indicating drier conditions.
Standardized Precipitation Index
The Standardized Precipitation Index (SPI) is a measure of precipitation that is comparable across time and space. The index is based on the statistical distribution of rainfall amounts for a given location and period of time. An index of zero is the median value, positive numbers indicate wet conditions, and negative numbers represent dry conditions. Because the probabilities are standardized by location, one can compare places with different climates using the same scale. The 6-month SPI map on this page is designed to display intermediate length precipitation anomalies that are potentially damaging to crops. Shorter and longer period SPI values can also be examined for drought at those scales.