 Figure 1. Temperature forecast for August 2012 (Source: National Weather Service Climate Prediction Center) |
 Figure 2. Precipitation forecast for August 2012 (Source: National Weather Service Climate Prediction Center) |
| A indicates above normal, B indicates below normal, and EC indicates equal changes of above normal, normal, or below normal conditions. (All figures link to larger versions.) | |
July 20, 2012
Early Models Indicate September and October Could Bring Much-Needed Moisture
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Figure 3. This week the National Drought Monitor showed severe drought moving further east in Nebraska (indicated by gold), with an area of central Nebraska now moving into extreme drought status (indicated in red). An area of eastern Nebraska remained in moderate drought. (Source: U.S. Drought Monitor. See larger version with historical data.)
Figure 4. Temperature forecast for August through October.
Figure 5. Precipitation forecast for August through October.
Is there any relief from the drought in sight? Al Dutcher discusses the forecast for next week on Market Journal. |
Crops continue to suffer from hot temperatures and a lack of significant rainfall. It seems this opening statement has been the norm for the past month. This week the National Drought Monitor designated a second area in Nebraska in extreme drought (Figure 3). Unfortunately, the latest models and extended forecasts offer little evidence of a pattern change that will end this nightmare scenario.
The extended outlooks for August, just released by the Climate Prediction Center (CPC), indicate above normal temperatures are likely for the entire state (Figure 1). They indicate a tendency for below normal moisture across eastern Nebraska, but equal likelihood of above normal, normal, or below normal precipitation for the remainder of the state (Figure 2).
The Climate Prediction Center’s outlook for August-October continues the bias toward above normal temperatures for the entire state (Figure 4). However, only extreme eastern Nebraska is assigned a tendency for below normal moisture; the remainder of the state has equal chances of above normal, normal, or below normal precipitation (Figure 5).
On a positive note, the movement away from drier conditions in the three-month forecast could indicate that better moisture may occur in September and October. How can I come to this conclusion? August represents approximately 40% of the moisture that normally falls in this three-month period. With a dry August forecast for eastern Nebraska, the three-month map may be indicating that enough moisture could fall in the latter two months to compensate for the below normal moisture projected for August.
In the short term, further crop stress will not be avoided through the middle of next week as high temperatures should remain in the upper 90s or above. In fact, the entire state could easily see 100-110°F readings from Monday through Wednesday. The hottest temperatures are likely to occur across south central, southwest, and west central Nebraska.
If the heat isn’t bad enough, models indicate that wind speeds of 20+ mph are likely across the western two-thirds of the state during the first part of next week. This will be in response to an upper air trough trying to move along the periphery of the upper air ridge firmly established over the central Plains. If this upper air trough can dig far enough south, it may be able to flatten the ridge and allow for thunderstorm development in response to monsoon moisture being pulled around the north side of the ridge.
The models also hint that a few days of cooler weather may return to eastern Nebraska by the end of next week as the upper air trough digs southward into the eastern Corn Belt. Depending on the weather model, the cool down may last two to five days with highs dropping 5-15 degrees. This is a large temperature range and indicates considerable uncertainty regarding the strength and longevity of the projected event.
Models indicate that the heat will return after next week’s brief cool down, but also indicate that monsoon moisture may become a more significant contributor to thunderstorm development across western Nebraska. Although confidence is low that these models have correctly identified this scenario, at least there is a glimmer of hope that some welcome moisture may make its way into the state during the latter half of next week.
Al Dutcher
Extension State Climatologist
