U.S. Plains Heat Sink Remains; Expansion North, East Possible
By Drew Lerner
Kansas City, July 8 (World Weather Inc.) – The southwestern U.S. Plains have become a “heat sink” with hot temperatures expanding and intensifying a little more each day this week. The source of the heat will not be going away and the sink will remain. Concern is rising that when high pressure begins building stronger in the Plains (after July) 15 the heat will become even more oppressive and expand much further to the north and slightly further to the east for a short period of time. Livestock stress is already becoming an issue and declining unirrigated crop conditions are expected to prevail in the region for a while. The southern Plains are expected to remain very warm to hot during much of the summer, but northern areas should see some periodic relief.
Temperatures in the southern Plains have been slowly heating up this week. Most of the market place has been focused on the Midwest and all of 
the rain and improvement that has occurred to crops. But, at the same time the building heat in the southern Plains is indicative of changing atmospheric and soil conditions. Temperature extremes Thursday afternoon were 100 to 110 degrees Fahrenheit throughout the west half of Texas, eastern New Mexico, western Oklahoma and in a few counties into southern Kansas and southern Colorado. Most of the hottest conditions have been confined to the southwestern Plains, but temperatures in the middle and upper 90s have occurred often in the remainder of Texas and have been evolving in eastern and central Oklahoma, Kansas and portions of the Delta in recent days.
The building heat is occurring right in line with our analog years of 1980 and 1998. In both of those summers rain that had been occurring frequently earlier in the summer and spring suddenly stopped and the region went into a period of significant heat and dryness. This year’s heat has been slower evolving than in the past analog years because of the moisture abundance that the southern Plains had acquired during the past year or frequent precipitation. The region needed to dry out before it could accommodate excessive heat and dryness and the time has come for the heat and dryness to begin to build on itself.
Dryness in the southern Plains has been a key part of our summer outlook and seeing the heat and dryness beginning to fester reinforces our summer outlook and we see no reason to back down off of our outlook at this point time because of rain that fell in the past week.
World Weather, Inc. has been suggesting that a high pressure ridge would return to the Plains during the July and even though it has not really materialized in a significant manner thus far we are now seeing more evidence that such an event will soon evolve. The heat sink in the southern Plains is expected to prevail over the next full week with only a short term period of slight cooling expected late this weekend into middle part of next week when temperatures will be a little less hot. By this time next week some ridge building is expected in the Great Plains and immediate neighboring areas of the western Corn Belt and Delta and the heat will be building up once again.
The developing ridge of high pressure will evolve without any changes to the southern Plains heat which suggests the heat will be allowed to not only persist beyond the end of next week, but there is a relatively good chance the heat will be allowed to intensify and expand norward with the developing ridge aloft. The situation should be closely monitored because it has been a long time since temperatures occurred over well 100 degrees Fahrenheit in the central and southern Plains over a several day period. Having such an event occur now might put a much larger percentage of livestock and unirrigated crops under stress.
While there is still potential for this heat wave to become significant in the Plains and westernmost corn belt for several days from July 16 to July 22 it is important to note that the ridge of high pressure is not likely to prevail over the entire Plains for very long. This year’s high pressure ridge will extend far to the north only infrequently. Cool air that will pool occasionally in the U.S. Pacific Northwest and western Canada will set the stage for showers and thunderstorms to evolve up the back side of the high pressure ridge. Monsoon moisture from Mexico will then stream northward to the northern Plains on the back of the ridge and the combination of the moisture feed, hot temperatures in the Plains and cool air in the northwestern U.S. and western Canada will generate a series of storm systems that will frequently knock down the top of the high Pressure ridge.
The storm systems that will evolve in late July and August across the northern Plains and southern Canada will then move across the northern and eastern Midwest keeping those areas a little milder than the southwestern Corn Belt and allowing some rain to fall periodically in those areas. The southwestern Corn Belt and the central and southern Plains will have to deal with some warmer than usual temperatures and less frequent rainfall more often than any other crop area in the nation.
In the meantime, as noted previously the heat sink in the southern Plains will not likely go away – at least not for very long because the base of the high pressure ridge will be very comfortable over the region where very little influence from the mid-latitude jet stream is expected. It is for that reason World Weather, Inc. has suggested the southern Plains, Delta and southwestern Corn Belt would endure a summer of heat and dryness.
The bottom line this discussion is that the heat in the southern Plains will help to reinforce some ridge building in the Plains and the ridge building will reinforce the heat. However, World Weather, Inc. does not expect the heat to prevail very long in the northern Plains or in the Corn Belt because of the pattern described above that should bring periodic bouts of relief to northern and eastern parts of the Midwest later in the summer. Our long term expectations remain the same with the southwestern Corn and Soybean belt suffering from periodic heat and dryness while a more significant bout of stress occurs in the southern half of the Plains and parts of the Delta. Northern and eastern portions of the Midwest will experience some declining rainfall and soil moisture with “some” warmer weather, but there will be opportunities for relief that should maintain a favorable crop outlook in those areas in the long run.
World Weather, Inc. forecasts and comments pertaining to present, past and future weather conditions included in this report constitute the corporation’s judgment as of the date of this report and are subject to change without notice. Comments regarding damage or the impact of weather on agricultural and energy as well as comments made regarding the impact of weather on the commodity and financial markets are the explicit opinions of World Weather, Inc. World Weather, Inc. cannot be held responsible for decisions made by users of the Corporation’s information in any business, trade or investment decision.
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