https://droughtmonitor.unl.edu/About/AbouttheData/DroughtCla...

Drought Classification
The U.S. Drought Monitor (USDM) identifies areas in drought and labels them by intensity. The map uses four categories of drought, from D1—the least intense—to D4, the most. It also highlights areas with no drought and uses the D0 category to indicate abnormally dry areas that could be entering or recovering from drought.

Category Description Example Percentile Range for Most Indicators Values for Standard Precipitation Index and Standardized Precipitation-Evapotranspiration Index
None Normal or wet conditions 31 or above -0.49 or above
D0 Abnormally Dry 21 to 30 -0.5 to -0.79
D1 Moderate Drought 11 to 20.99 -0.8 to -1.29
D2 Severe Drought 6 to 10.99 -1.3 to -1.59
D3 Extreme Drought 3 to 5.99 -1.6 to -1.99
D4 Exceptional Drought 0 to 2.99 -2.0 or less
The USDM differentiates between short- and long-term drought. Short-term drought can have impacts on agriculture and grasslands, and the drought classification can rapidly change. Long-term drought, in contrast, has deeper impacts on hydrology and ecology and can persist even with short-term gains in precipitation.

It’s the highest level of drought. There is the exceptional one, but it is too specialized to be used here.

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Note added at 16 mins (2023-07-16 14:40:18 GMT)
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When we say
مدقع،
We mean the highest level of a negative condition.

Indeed, your discernment is accurate. The Arabic expression "الجفاف المدقع" can be rendered into English as "parching desiccation" or "pernicious aridity," alternatively as "exceedingly arid circumstances." In the soldier's training context, it conveys that they underwent rigorous preparation amidst diverse meteorological elements, encompassing frigid cold, torrential rain, and the relentless severity of dryness.

https://www.collinsdictionary.com/dictionary/english/extreme...