December 29, 2007
The Mild Winters of Indiana & Illinois 1785-1796
Due to the lack of knowledge of the climate west of the Appalachians when the colonies were first organized along the east coast, there was a certain danger to the few weary settlers that ventured over this spine of mountains at the time via sparse, mainly Native American, trails. Due to a lack of knowledge of the rigors of the Wabash & Ohio Valley climate, early settlers were quite vulnerable. Thus, early colonial scientists sought to study the "Old Northwest's" flora, fauna, soils, geomorphology, geology & especially, its climate. Thomas Jefferson & even George Washington, were two who spearheaded this effort.
http://memory.loc.gov/ammem/gwhtml/5gwintro.html
http://wiki.monticello.org/mediawiki/index.php/Weather_Observations
It just so happened that as the earliest settlers began to arrive into the bottomlands of the Wabash & Ohio, the Midwest was amidst a warm, rather wet period. There were rather significant spring floods on the Ohio River in the mid 1780s & there is evidence of a good deal of tornadic activity in the Ohio Valley during this period. One date of note is that of June 19, 1794, when a tornado outbreak, including major tornadoes at Poughkeepsie, New York, Milford, Connecticut & near Toledo, Ohio ("Battle of Fallen Timbers" named for the great fall of trees in the forest at the battle site due to a tornado) on June 19.
Constantin Francois de Chasseboeuf, Comte de Volney, spent time at Vincennes from 1795 to 1798 & mentioned the early farming of cotton around Cincinnati & Vincennes during this period. He also explained that the climate was a good 3 degrees warmer in winter in our area, as compared to the Mid-Atlantic coast. He had mentioned in his writings, according to Ludlum, that there was "a much greater prevalence of southerly winds in the Mississippi & Ohio Valleys than along the Atlantic seaboard where.................northeasterly currents dominating." According to early scientists at Cincinnati:
"Our climate is much more mild in the same degree of latitude, than eastward of the Alleghany Mountains. This is caused by the winds which are mostly up the river, or from southward or westward. I have rarely known a northeast storm here; that unfriendly wind seems to know that its bounds are the mighty Alleghany Mountains."
Further, in Ludlum's Early American Winters 1604-1820, he states,
"The group of settlers organized by the Ohio Company of New England, arriving at Marietta on 8 April 1788 (Marietta is in eastern Ohio), found the fields green with verdure and the season well advanced. Not considering their change in altitude and perhaps the recent arrival of the new air mass, they were much impressed by the contrast of these conditions with the harshness of the weather in the highlands of western Pennsylvania which they had just departed. From this they derived an erroneous view of the softness of the Ohio Valley climate which was to affect the climatological thinking for many years to come."
It is very interesting to note that opinions about the climate of the Ohio Valley & mid-Atlantic began to change after 1800 (some shock after a sharp cold wave in 1796, the worst in early Illinois/Indiana since the cold winter of 1780-81). William Darby referred to Volney's claims about the mild Ohio Valley climate as "innoxious vulgar error", but this followed many severe winters & the famous "Year Without a Summer" of 1816, when these criticizing words were revealed in his writings in 1818. In my opinion, Volney was not wrong, as the Wabash & Ohio Valleys were in an exceptionally mild period when the very first settlers arrived following the Revolution. There was a lack of long-term, widespread climate data & this mild period gave these scientists & settlers an unclear view of the seemingly endless waxes & wanes, if you will, of the Wabash & Ohio Valley climate. In fact in 1857 in the new publication Climatology of the United States, author Lorin Blodget explained:
"The early distinction between the Atlantic States and the Mississippi............has shown them to be essentially that same, or differ only in unimportant particulars."
This statement followed the horrendous winters of 1852, 1856 & 1857 when bitter cold & snow was rather uniform across the eastern half of the United States, which led to the coldest winters since the early 1800s.
This wasn't the first time that misconceptions were made about the climate of Indiana & Illinois with the flood of new European settlers. In the mid 1820s, a series of exceptionally mild winters led to the false impression of early pioneers settling on the prairies of central & east-central Illinois that the growing seasons were sufficiently long enough for the cultivation of cotton. Following the construction of a cotton gin near Springfield by 1827, rigorous & debilitating winters from 1830 to 1836 proved to be strong enough to cause the collapse of the short-lived cotton industry in central Illinois & a large migration of pioneers out of the area, following the especially tough winters of 1830-31, ‘31-32 & ‘33-34.
During this mild period, only one snowstorm was of significant note in these early records. Vincennes to Cincinnati (11") to Marietta, Ohio (12") were blanketed in this 10-14" of snow February 17-18, 1791. It wasn't until March 31, 1807 that a snow of equal depth fell at Vincennes with a late 11" after the trees had commenced budding during this onset of astronomical springtime. The February 17-18, 1791 snowfall of 11" witnessed at Fort Washington, at Cincinnati, was regarded by General Josiah Harmar as ".......the most that has fallen.......................since the settlement of this place." The area was founded in 1788 & there were no permanent settlers in the area prior to 1788.
Dr. Hugh Williamson stated in his papers to the American Philosophical Society at that time (late 1700s at Cincinnati), that (according to Ludlum): "the winters were now less severe and the summers warmer than the earlier part of the century (1700s). This he ascribed to the cutting down of the forests and the multiplication of open fields since bare ground would absorb and retain more heat than forested terrain. This, in turn ameliorated the cold of the northwest wind which was an instigator in cooling the climate. No attempt at statistical analysis was made since such data did not exist."
President Thomas Jefferson, the one whom I consider the father of American meteorology, agreed & stated (in referring to central Virginia):
"A change in our climate, however is taking place very sensibly. Both heats & colds are become much more moderate within the memory even of the middle-aged. Snows are less frequent and less deep. They do not often lie, below the mountains, more than one, two, or three days, and very rarely a week. They are remembered to have been formerly frequent, deep, and of long continuance. The elderly inform me that earth used to be covered with snow about three months every year. The rivers, which then seldom failed to freeze over in the course of the winter, scarcely ever do now. This change has produced an unfortunate fluctuation between heat and cold in the spring of the year, which is fatal to the fruits. From the year 1741 to 1769, an interval of 28 years, there was no instance of fruit killed by frost in the neighborhood of Monticello. An intense cold, produced by constant snows, kept the buds locked up till the sun could obtain, in the spring of the year, so fixed ascendancy as to dissolve those snows, and protect the buds, during their development, from every danger of returning cold. The accumulated snows of the winter remaining to be dissolved all together in the spring, produced those overflowings of our rivers, so frequent then, and so rare now."
David Ramsay explained in the History of South Carolina that "remarkable that oranges, though plentiful forty or fifty years ago, are now raised with great difficulty. Once every eight or ten years a severe winter destroys the trees on which they grow." This is likely referring to the mild years of the late 1700s, as this book was published in the 1800s.
General William Dunbar wrote this letter to Thomas Jefferson in 1801, after the cold winters set in by early 1797, after the "mild years" of 1785-1796.
"It is with us a general remark, that of the late years the summers have become hotter & the winters colder than formerly. Orange trees and other tender exotics have suffered much more in the neighborhood of New Orleans within the past 4 or 5 years than before that period; the sugar cane also has been so much injured by the severity of the frosts of the two last winters, as greatly to discourage the planters, whose crops, in many instances, have fallen to one third or less of their expectations. In former years I have observed the mercury of the thermometer not to fall lower than 26 or 27, but for the few years past, it has generally once or twice in the winter fallen as low from 17 to 20 and on the 12th of December 1800 as above noticed it was found sunken to 12, which has hithero no parallel in this climate, indicating a degree of cold, which in any country would be considered considerable, and probably may never be again produced by natural means in lat. 31.5.
As this apparent alteration of climate has been remarked only for a few years and cannot be traced up to any visible natural or artificial change of sufficient magnitude, it would be in vain to search for its physical cause. Doctor Williamson and others have endeavoured to show that clearing, draining and cultivation, extended over the face of the continent, must produce the double effect of a relaxation of the rigors of winter, and an abatement of the heats of the summer; the former is probably more evident than the latter, but admitting the demonstration to be conclusive, I would enquire whether a partial clearing extending 30 or 40 miles square, may not be expected to produce a contrary effect by admitting with full liberty, the sunbeams upon the discovered surface of the earth in summer, and promoting during winter a free circulation of cold northern air."
Tree rings, river sediment cores, lake cores & early pieces of data have been analyzed & reconstructions of the Drought Palmer Index, which measures the severity of drought on a number scale. This scale is converted into categories. This modern day scale has been used to reconstruct precipitation pattern over areas of the U.S. where tree ring & early settler data is available. These reconstructions date back to 0 A.D., as corings on 2000 year-old trees in the west provide an avenue to reconstruct our ancient drought & floods. River sediment cores can help reconstruct floods & lake sediment cores can help to develop a timeline of increased aridity by examining particle sizes & specific mineral contents at each layer.
Here are the reconstructed maps based on 1000s of units of data from this mild period in the Valleys weather history:
NOTICE THE WARM PERIOD CONSPICUOUS IN THIS GRAPH FROM 1750-1800 from a southern New England climate reconstruction from W.R. Baron at the University of Arizona & David Smith of the Climate Change Institute & Department of Earth Science at the University of MaineUniversity of Northern Arizona, and David C. Smith, of the Climate Change Institute
http://www.climatechange.umaine.edu/Research/MaineClimate/Weather.html
KEY TO MAPS BELOW:
DROUGHT:
Yellow = Abnormally Dry
Orange = Drought
Slightly Darker Orange = Moderate Drought
Red = Severe Drought
Dark Red = Extreme Drought
Darkest Red = Exceptional (Worst) Drought
NORMAL PRECIP. = Gray Background
WETNESS:
Green = Wetter-Than-Normal
Sky Blue = Wet
Blue = Very Wet......Some Flooding
Dark Blue = Well-Above Normal Precipitation, Flood Events
Purple = Extremely Wet Year.........Major Floods
JUST ENTER THE YEARS OF 1785, 1786, 1787, 1788, 1789, 1790, 1791, 1792, 1793, 1794. 1795 & 1796 INTO THE DATABASE AT THE ADDRESS BELOW & HIT RETURN.
http://www.ncdc.noaa.gov/cgi-bin/paleo/pd04plot.pl
Email Chad Evans about this entry at cevans@wthitv.com.
