5 May 2011 Surviving spring in the Midwest
Spring, in the Midwest United States, is an exercise in determination.
The Missouri-Mississippi-Ohio basin is a battleground with no way for humans to win.
The end of winter brings wildly fluctuating temperatures to the region. Humidity, high humidity, is a constant. Spring weather fronts funnel warm, moist Gulf air masses into the drainage basin. Trapped between the Rockies and the Appalachians, the moist air stays there and provides an increase in the misery quotient.
The rivers that drain the interior U.S. are primarily mountain born and snow fed. Good weather for the ski industry yields an increased risk of spring floods. There are always spring floods. The only uncertainty is where, compounded by when and for how long. One of the three great rivers, often all three, will flood every spring. In addition to the snow melt and ice break up, the potential for flood is increased by the inevitable spring thunderstorms.
The months of spring in the upper Midwest are graced by the season of whirling winds. Tornado season arrives with the spring thunderstorms. The air mass interactions, driven by the shifting jet streams, produce huge squall lines that dump inches of rain on the already saturated ground. Towering thunderstorms forming along the frontal boundaries also bring hail, high line winds, microbursts, and lightning strikes. This pattern can repeat every day for weeks in some springs; preventing access to farm fields for planting, damaging already planted crops, destroying homes, forests, and heralding the worst threat.
Tornado season brings risk to the entire central U.S., from the Gulf of Mexico to the Canadian border. The squall lines spawn tornadoes as they move from West to East. Damage can be next to negligible, or devastating. These are among the most frightening of nature’s anti-personnel devices. There are those fortunately not too common situations when all the factors are primed for super cell thunderstorm formation. These formations can spawn the most powerful tornadoes cataloged. They literally blow towns off the map. This year, we’ve seen a new record for the number of tornadoes in a 24-hour period, 312 now confirmed and a few more may be added to the official count.
This spring we seem to be getting the worst of all options. Strong winter storms and greater than normal snow pack, combined with very heavy rainfall in the region have brought all three great rivers to well over flood stage. The confining levees, 50-foot tall primaries and 30-foot tall secondaries were first constructed in the 1930s by men working for the WPA and other depression –era programs. Many sections were built using mule teams and wagons to haul earth. Now those barriers are insufficient to contain this year’s floods and are being blown apart to control where the floodwaters are flowing; sacrificing cropland to save urban areas.
It seems as if the combined forces of normally cyclic weather are trying to force people out of the Midwest. It isn’t personal, nature doesn’t take notice of our efforts to control it; only the damage we create and leave behind.
By the end of spring, the rivers will have returned to their valleys and much of the storm damage will be cleaned up, or at least, piled up for removal. The fields that were flooded will be dry with cracked mud and weeds to show where the levees were blown apart. And by next spring, someone will be crying for rain.
Linked below, N.E. Tennessee tornado map 27 & 28 April 2011. Entirely too close for our comfort.
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