Missouri's Driest Era

[donsutherland1]

Based on climate reconstructions, Missouri suffered a prolonged dry period during the 1597-1611 timeframe. During that period, 11 of the 15 years saw below normal rainfall. None saw much more than moderate rainfall.

At least two years had exceptionally extreme drought conditions. There was a six year dry period and later a four-year dry period. Both dry periods saw at least one year with extreme drought conditions.

The reconstructed data was derived from tree ring analyses performed by Dr. D.W. Stahle and Dr. M. K. Cleaveland at the University of Arkansas-Fayetteville and Mr. D.N. Duvick of Iowa State University.

Their study reconstructed the July Palmer Index readings for Missouri. Briefly, the Palmer Index is effective in helping assess long-term droughts or wet periods.

Several points of its scale are relevant for comparative purposes:

+2=Moderate Rainfall
0=Normal Rainfall
-2=Moderate Drought
-3=Severe Drought
-4=Extreme Drought

This index is particularly useful, as it is standardized for local climates. Therefore, it can be used across the nation.

The reconstructed Palmer Index data for Missouri follows:

1597-10.41
1598 -8.47
1599 -1.75
1600 -1.31
1601 -2.38
1602 -1.99
1603 1.54
1604 1.58
1605 -0.32
1606 2.31
1607 2.31
1608 -5.26
1609 -1.74
1610 -0.16
1611 -0.52

Key Statistics:
15-Year Average: -1.77
1597-1602 Average: -2.92
1608-1611 Average: -1.92
Most Severe Two-Years (1597-1598): -9.44
Most Severe Year (1597): -10.41

To put things into further perspective, the following are the driest periods in each century:

2-Year Periods:
1597-1598: -9.44
1608-1609 and 1642-1643: -3.50
1708-1709: -3.28
1870-1871: -2.35
1901-1902: -3.44

5-Year Periods:
1597-1601: -4.86
1640-1644: -2.97
1734-1738: -1.71
1868-1872: -1.89
1930-1934: -1.93

10-Year Periods:
1596-1605: -2.12
1639-1648: -1.65
1696-1705: -1.32
1865-1874: -1.05
1925-1934: -0.82