After several spring seasons that featured widespread flooding in the Red River Valley, the dry weather of late has been welcome by many water logged residents. As the dry pattern and record warmth continues into the spring season, drought conditions have been spreading and expanding across the region. With abundant fuels, grass fires have become an issue in many areas. Instead of flooding, the spring of 2012 has seen a marked decrease in river flows, especially when compared to recent years. Most tributaries feeding the main-stem Red River are experiencing sub-median flows, indicative of the dry conditions. On the main-stem Red, at a time when flooding is typically still ongoing, flows are generally below the median for this of year.
Reports from agricultural interests suggest that while top-soils have generally dried, some areas are still quite damp, and sub-soil conditions remain wetter than average. This is especially true in the heavier clay areas of the Red River Valley. At the present time many area growers would like some rains to replenish top-soil moisture to assist in the early growing season. Before discussing the developing drought we need to discuss how exactly drought is defined. There are essentially 4 types of drought: Meteorological, Agricultural, Hydrological and Societal Drought [Impact]. The definitions below are courtesy of the National Drought Mitigation Center.
Meteorological drought is defined usually on the basis of the degree of dryness (in comparison to some “normal” or average amount) and the duration of the dry period. Definitions of meteorological drought must be considered as region specific since the atmospheric conditions that result in deficiencies of precipitation are highly variable from region to region.`
Hydrological drought is associated with the effects of periods of precipitation (including snowfall) shortfalls on surface or subsurface water supply (i.e., stream-flow, reservoir and lake levels, groundwater). The frequency and severity of hydrological drought is often defined on a watershed or river basin scale.
Agricultural drought links various characteristics of meteorological (or hydrological) drought to agricultural impacts, focusing on precipitation shortages, differences between actual and potential evapotranspiration, soil water deficits, reduced groundwater or reservoir levels, and so forth. Plant water demand depends on prevailing weather conditions, biological characteristics of the specific plant, its stage of growth, and the physical and biological properties of the soil.
Socioeconomic definitions of drought associate the supply and demand of some economic good with elements of meteorological, hydrological, and agricultural drought. It differs from the aforementioned types of drought because its occurrence depends on the time and space processes of supply and demand to identify or classify droughts. The supply of many economic goods, such as water, forage, food grains, fish, and hydroelectric power, depends on weather. Because of the natural variability of climate, water supply is ample in some years but unable to meet human and environmental needs in other years. Socioeconomic drought occurs when the demand for an economic good exceeds supply as a result of a weather-related shortfall in water supply.
What are the current conditions across the region? The NWS partners with various agencies in measuring precipitation patterns, river flows, soil moisture and the other components that define drought. The US Drought Monitor is the official portal for all drought information, analysis and predictions. At the present time, much of the area is experiencing much below normal precipitation, leading to conditions that vary from abnormally dry to moderate drought; areas just to the south and east of the Grand Forks NWS area of responsibility are experiencing severe drought conditions. At this point conditions reflect a meteorological drought with hydrologic drought conditions developing in a few locations. Reports from the agricultural community suggest sufficient topsoil moisture exists in some areas while some areas are in need of rain to help start the 2012 growing season.
So, what of the upcoming 2012 growing season into the summer?
In the near term, conditions are expected to show improvement as precipitation impacts the region. The overall climate regime has shifted, so that cooler temperatures are forecast the next few weeks. Along with the cooler weather, there are signs that at least more "normal" precipitation is likely. At this time, it's not possible to forecast amounts of rainfall, it appears unlikely that sufficient rain will fall to end drought conditions, particularly where they are the worst. This includes the west central Minnesota Lakes Country and portions of northern Minnesota. According to the Climate Prediction Center (CPC), it would take 4 to 6 inches of rain to totally eradicate the drought in many areas.
Beyond the next few weeks, the current climate predictions suggest that the enhanced likelihood for above normal precipitation will diminish, with similar predictions for temperatures. Based upon the current ENSO forecasts, the La Nina will fade during April. To quote the CPC "...a majority of models predict ENSO-neutral conditions for March-May 2012, continuing through the Northern Hemisphere summer 2012 " end quote. (See referenced figure)
Based on the historic record, the summer seasons that follow a La Nina tend towards cooler temperatures with "normal" precipitations pattern. The images below are from the CPC, and represent the statistical variations during the June-July-August time frame over northern Minnesota. These "Box-and-Whisker" plots suggest that during the June-August period there is less variability in temperature patterns and perhaps a bit more variability to precipitation. A description of the utility of Box-and-Whisker plots may be found here.
The images above are courtesy of the CPC.
Overall, the near-term outlook calls for the drought conditions to continue with localized improvement depending on the precipitation that falls over the next several days and weeks.
The NWS will continue to monitor the situation and updates will be issued based on eventual temperature and precipitation patterns. For additional information contact the Grand Forks NWS at 701.795.5198 or email Mark Ewens at the Grand Forks NWS.