There are three regions within the Plains, (1) the northern region, (2) the central region and (3) the southern region. How these regions are made and how we define the 14-day extreme precipitation periods can be found in ************
- There are 145 periods in the Plains from 1915 to 2018, with 48 periods in the northern region, 49 periods in the central region and 56 periods in the southern region.
- The typical wet season for the Plains occurs from April to October.
- Precipitation periods have occurred all year, with a minimum within the winter months (DJF) for northern and central region.
- Typical storm reports include convective reports such as Flash Flood, Flood, Hail, and Thunderstorm Wind; as well as cold period storm reports such as: Heavy Snow and Blizzard.
When do Plains Extreme Periods occur?
Seen to the left, 14-Day periods within all Plains regions are counted, based on month, from 1915 to 2018.
The typical wet season within the Plains occurs from April to October. Yet, 14-day extreme precipitation periods can happen throughout the year.
What are typical storm reports of Plains Extreme Periods?
Using NCEI storm reports typical impacts of our 14-day extreme periods, past 1996, can be estimated. Beginning in 1996, 48 event types were recorded into the storm events database. Every report was recorded based on the county of occurrence by a National Weather Service forecast office (WFO) and then passed onto NCEI. Therefore, reports within 14-day extreme periods from 1996-2018 within North Dakota, South Dakota, Nebraska, Kansas, Oklahoma or Texas are counted as Plains 14-day extreme periods reports. Definitions of all storm reports can be found within the NWSI, Appendix A.
The average number of storm reports during a wet season or a dry season extreme period, within both regions in the Plains, from 1996 to 2018 are seen to the right. “Hail”, “Thunderstorm Wind” and “Flash Flood” are the most frequent reports seen during periods.
Wet season 14-day extreme periods have larger averages of storm reports for a period, compared to dry season periods. However, similar storm reports are seen in both wet and dry season periods. Common reports during a wet season period are “Hail”, average of 237, “Thunderstorm Wind”, average of 152, and “Flash Flood”, average of 78. While common reports during a dry season period are “Hail”, average of 99, “Thunderstorm Wind”, average of 50, and “Winter Storm”, average of 63. Therefore, dry season periods tend to have more frozen precipitation, while wet season periods are more convective in nature.