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1988 and 2007 drought patterns - 04.19.07


The upcoming summer contains the potential for a repeat of the 1988 Midwest drought. Learn why in this article.


To climatologists the period in North America from April to late July 1988 is known as the "Great Dry". This was a severe placement of a set of blocks or ridges starting in spring and continuing into late summer that prevented the onset of moisture currents from the Gulf of Mexico that are the source of much of the summer thunderstorm activity in the Corn Belt and the wheat growing regions of the United States.

The causes of drought in the Midwest and high Plains of the United States are many. Much research has gone into understanding the climate patterns that periodically parch the growing sections of the country. In general the most fundamental climate pattern is the presence of blocking high-pressure area over the Western US during the spring and summer months.

Climatologists recognize that a nineteen- year rhythm is often linked to the presence of drought and crop failure in the High Plains. This is not so closely linked to Midwest drought cycles. However, even the Midwest, central states and Corn Belt droughts more often than not have their origin in some form of blocking pattern over the High Plains. The drought then spreads eastward during the season as the dome of blocking air or ridge builds with each day that the rains fail to cool the earth.


Fig.1


Fig.1

1 blocking patterns in summer 1988

Figure 1 shows this blocking pattern in the context of the three major high-pressure areas that contributed to what is known to climatologists as the Great Dry of 1988. In the chart, a large dome of high-pressure sits over the Mountain States and the High Plains. The circulation around this area is clockwise. This means that on the leading edge of the dome the air is moving from north to south. The smaller blue arrow depicts this motion. The main cause of rain in the Midwest during the summer is moisture moving from south to north out of the Gulf of Mexico. In rainy years this moisture forms a low level jet of moist air flowing northward that acts as the source for thunderstorms that bring life to the soybeans, corn and other crops grown in the Corn Belt. When a strong high-pressure area establishes itself over the High Plains the north to south circulation diminishes the monsoon flow from the Gulf of Mexico bringing drought. Often, in the most serious drought conditions there are two more high-pressure areas in the vicinity of the United States. One is over the eastern Pacific and the other is over the Mid Atlantic Ocean. These can be seen in figure 1.The linkage of these highs creates a narrow trough over the East Coast where wet conditions prevail. More will be said about these other highs as we go along.


Fig.2


Fig.2

2 teleconnections

In figure 2 an expanded chart shows a more comprehensive view of what climatologists call a teleconnection. We can see that the three highs that are implicated in serious drought are actually part of a whole series of highs and lows that are connected over vast distances. These super remote linkages of air masses are teleconnected to each other like waves in the ocean. In the chart we see that the highs over the United States have an origin near Asia. The green snake like arrow is the jet stream that winds its way around the highs forming lows or troughs in the breaks between the high-pressure masses. This pattern of highs and lows stretching across the Pacific is known to climatologists as the North Pacific Index or NPI pattern. The rhythm of the flow across the Pacific in the NPI pattern is a consistent sequence of lows and highs following one another, except for the area between Hawaii and the Aleutian Islands. Geometrically, by following the sequences of highs and lows we would expect a trough or low to form there if the spacing of the waves of air masses was consistent. Indeed, normally there would be such a trough forming there and the result would be rain for the West Coast as a low would form off of the coast to guide storms into the coast. If this pattern were unfolding in winter then the high over the eastern Pacific would normally be much weaker and the saddle shape between the high in the mid Pacific and the high over the inter Mountain areas would dissolve to allow a low to dig south along the west coast.

But this is a chart of the late winter and the pattern is forming for the emergence of high-pressure in the eastern Pacific. In the early spring, this pattern has the Hawaii high beginning to expand and move northward keeping the jet stream from dropping to the south. This is the first element in the formation of this drought in 1988. The summer regime is supportive of a stronger east Pacific high. However there is no major drought each summer when the Hawaii high strengthens, so there must be more to this than just this element. Indeed there is. But the position of the Hawaii high in the spring is significant in this particular case, as we shall see later. We could say that the growth of the Hawaii high in the summer is the fundamental of the drought sequence of 1988 in the Midwest


Fig.3


Fig.3

3 North Pacific Index (NPI) pattern

The next image shows the same chart for the North Pacific Index (NPI) pattern across the Pacific, superimposed on a chart for the eclipse grid patterns used in Doc Weather. In this chart we can see the eclipse grid http://www.docweather.com/2/show/5/ positioned over the Pacific. In this year the eclipse grid stretches from the east coast of the United States all the way out to the East China sea. It is interesting to note that the teleconnection http://www.docweather.com/index.php?sec=2&act=show&enid=30#teleconnections between the inter-Mountain states and Indochina is a perfect image of the whole of the eclipse grid. In Doc Weather this geometry of the eclipse grid is the source of the trans-Pacific teleconnection between Indo-China and the east coast of the United States. It can be seen from figure three that the thicker lines representing the eclipse lines from the two points straddle the highs over both Korea and the western Atlantic. The solar and lunar points and their reflex points project into mid -latitude high pressure areas contained within the eclipse lines. In figure 3 a low-pressure area sits to the east and west of the western Pacific high over Korea and a low sits to the west of the Bermuda high placed to the east of the east coast of America in the western Atlantic. These lows are linked in the wave train as fluctuations in the amplitude of the major motions of the jet stream across the Pacific and the N. American continent.


Fig.4


Fig.4

4 disturbance diamond

In the next chart, figure 4, the 72 degree jet curve lines are accentuated by thicker lines. The disturbance diamond http://www.docweather.com/2/show/5/
that is the main feature in the eclipse grid is accentuated with thick lines. The patterns of high-pressure around this diamond of lines supports the maintenance of high-pressure in the saddle between the highs in the eastern Pacific and the inter-Mountain states in the summer of 1988. When these 72 degree jet curves are stimulated to high-pressure the most predictable result is that high-pressure dominates high latitude areas in the vicinity of the top of the 72 degree jet curves. In figure 4 this is the area to the east of the 72 degree jet curves from the western pair of eclipse points ((western Canada) and the area to the west of the eastern pair of 72 degree jet curves (Bering Sea). The eclipse diamond is active in this chart maintaining high-pressure across the saddle between the mid-Pacific and the inter-Mountain areas.


Fig.5


Fig.5

5 extended eclipse grid

In figure 5 the 45 degree jet curves from the eclipse grid are accentuated. It can be seen from the chart that the eastern pair supports high-pressure over the inter-Mountain areas and the western pair supports high-pressure over the Mid-Pacific. Taken together the eclipse lines and the 45 degree jet curves and the 72 degree jet curves area in perfect position to support high-pressure dominance from the China sea to the Bermuda high if the eclipse points in the east and west were aspected to high-pressure by planetary motion. It turns out that in 1988 the planetary motion was very much in support of sustained high-pressure values on both sets of eclipse points for long periods during the spring and early summer of that year. This meant that high pressure would dominate most of the areas depicted in the preceding charts, supporting the high-pressure phase of the North Pacific Index. The reason for this overwhelming high-pressure influence can be seen in the next chart.


Fig.6


Fig.6

6 mars and the lunar node

In this image the position of Mars and the Lunar Node are put into the eastern pair of eclipse points. In Doc Weather the placement of the eclipse points creates a series of harmonic relationships http://www.docweather.com/2show/13/ that have a strong influence on the weather. In this sequence the flow between Mars and the Lunar Node was such that the motions of the planets between the eclipse points stimulated high-pressure values almost at every motion in arc event. This means that when Mars moved to a high-pressure aspect between both points high-pressure values were generated on both of the eastern points. In 1988 the mathematical relationship between the two eclipse points supported the formation of high-pressure on each point for extended periods. This rhythmic phenomenon kept high-pressure values on the two eclipse points for most of the early summer of 1988. In the eclipse grid system of Doc Weather this was a strong signal for drought in the Midwest at that time. It is a highly unusual cadence for the movements of the planets and the unusual nature of the extended drought is linked to this anomaly. If the eclipse points were at an angle of 14 degrees between them then the chances for both points to register high-pressure values at the same time is greatly reduced. For this reason the space between the eclipse points is designated with a red arrow and labeled 15 degrees. This spread between the points is a second factor that is related to extended high-pressure in the eastern Pacific and the inter-Mountain west. The third element that supports the high-pressure anomaly is that two planets were stationed between the two eclipse points for an extended period during the Midwest summer. In 1988 these planets were the lunar node and Mars. These two planets are shown in the chart in blue to designate their predominantly high-pressure influences.


Fig.7


Fig.7

7 summer 2007

In figure 7 the chart for the summer of 2007 is depicted. Between 1988 and 2007 the lunar node has transited the entire zodiac and is approximately in the position it was in during the summer of 1988. In Doc Weather this return positioning constitutes an analog year and is the source of the 19- year rhythm of the High Plains drought cycle. This means that the return of the nodal positions is the same as it was approximately two decades ago. In Doc Weather this nodal return forms the rhythmic basis for the choosing of an analog pattern for a particular year. This method attempts to explain the well-known climatic phenomenon of decadal or inter-decadal influences. That is the return of particular climatic phenomenon in a ten or twenty year cycle. In Doc Weather these decadal cycles are linked to the retrograde motion of the lunar nodes. In 1988 the eclipse points were placed at 15 degrees from each other. During years that have that degree of separation there is an enhanced frequency of high-pressure values placed onto the eclipse grid by planets that are transiting the eclipse points. Similarly to the chart in 1988 the chart of 2007 reveals the placement of planets between the eclipse points during the summer months. This should prove to be a consistent feature in the establishment of long- lived high-pressure areas that should evolve into an NPI pattern across the Pacific. This should most likely end in a blocking high over the High Plains for the early summer. Mars and the lunar node and Uranus will be found within the two eclipse points promising a prolonged blocking pattern for the Midwest monsoon. The dryness should be in place early as Mars transits the points in the early spring. Later in July there is a strong series of high-pressure relationships between Uranus and the lunar node that should bring memories of 1988 into the minds of older growers in the High Plains and the Midwest.