Drought status is calculated using several indices that measure how much precipitation for a given period of time has deviated from historically established norms. Different indices result in different levels of drought warning depending on the time scale of the indices. The Palmer Drought Severity Index is used by the U.S. Department of Agriculture to determine when to grant emergency drought assistance. The Palmer index results in better predictions when working with large areas of uniform topography. When monitoring droughts in New Mexico with complex regional microclimates, other information is used to supplement Palmer information. A newer index, the Standardized Precipitation Index identifies emerging droughts months sooner than the Palmer Index and is computed on various time scales.

Droughts have occurred on an average every 10 years in New Mexico. All drought status monitoring requires information from climate stations, surface flow and reservoir level measuring sites, and ground water level monitoring sites. The Surface Water Supply Index (SWSI) in conjunction with the Palmer and Standardized Precipitation index are the main indices used to define a drought status.  The table below present the Palmer Index for each climate division for those years when the Palmer Drourght Index was less than -3.0

New Mexico has numerous climate networks that can be used in calculating the Palmer Drought Severity Index and the Standardized Precipitation Index. Currently the Palmer Index is calculated only using the cooperator climate network maintained by the National Weather Service (NWS). Around 25 stations report daily by phone to the NWS and this data is used to calculate a weekly Palmer Index. The state is divided into 8 climate divisions and the Palmer Index calculated for these divisions. In some cases only data from two climate stations are used to calculate the Palmer Index. At the end of the month the rest of the 180 stations in the state send in a paper form and these data are used to calculate the monthly Palmer Index.

The climate divisions are large and in many cases the drought will occur only over part of the division. The need exits to increase the number of cooperator stations that report daily to NWS and to include data from the other climate networks maintained in the State in the calculation of the Palmer and Standardized Precipitation Index. In addition, the Palmer Index needs to be calculated weekly for sub-climate divisions of the 8 climate divisions. Currently this can not be accomplished because the NWS that does the calculations, does not access the other climate networks in the state and does not have sufficient data from the cooperator network to calculate the Palmer Index for sub-climate divisions. The job needs to be accomplished by the New Mexico State Climate center, but they currently do not have the resources needed to accomplish this task. The data from the different climate networks in the state are maintained or are available from the State Climate Center but the Palmer computer program must be rewritten to use these additional data bases.

Because snow pack monitoring is an important part of predicting droughts and the effect of droughts on the state, it is imperative that the number of Snotel sites maintain and monitored by the Natural Resource and Conservation Service (NRCS) be increased. Currently, no Snotel sites exist in the south-east portion of the state, and only 43 snowfall measuring stations exist throughout New Mexico.

The U.S. Geological Survey (USGS) maintains, operates and analyzes a network of over 200 stream flow measuring stations throughout the State of New Mexico. Many of these gauging stations have been automated, thus providing real-time access to stream flow data but the effort of automating all the sites needs to be continued. The irrigation districts also monitor stream flow diversions and these data bases need to be automated and the data made available and use to monitor drought impacts on agriculture.