What’s the Real Wildcard in the Summer Forecast?

Ranchers, farmers and others are preparing for a continuation of a largely wetter than normal summer especially in the Plains, and the Rockies.  Just released Thursday, June 20th, the Climate Prediction Center’s latest outlook for July-August-September (JAS) calls for a tilt towards a continuation of the below normal temps and above normal rainfall in the nation’s heartland. 

3-Mo. Temperature Outlook

3-Mo. Precipitation Outlook

Temperature Breakdown

“Bulls-eye for cooler than normal weather over the Central Plains into Wyoming with the strongest signal in Kansas, and – increased chances for above normal over the same area.  Despite the possibility of cooler than normal temperatures, warm periods are still likely (in fact the 8-14-day outlook ending July 3rd favors (some) warmer than normal temperatures,” said Mary Knapp, Assistant State Climatologist, located at Kansas State University in Manhattan, Kan.

“Some possible weather-related problems for agricultural interests: high humidity plus warm temperatures equal high stress on cattle; high temperatures when corn is pollinating will reduce the kernel set, reducing yield; and poor root development could result in plant stress with only a short period of dry weather,” noted Knapp.

Right on the heels of a vastly challenging relentlessly cold, icy winter that morphed immediately into a soggy (and in some cases turbulent) spring, the summer weather is also a critical time for the health of livestock.  It’s also wheat harvest season, and the transitional period leading into the all-important fall harvest.

Bottom line, if the models are correct, significantly warmer temperatures are on tap for the beginning of July

According to the latest monthly outlook for July (maps below) from the Climate Prediction Center (CPC), a significant portion of the central corn belt is expecting a continuation of having the highest probabilities for below normal temperatures, with an extension of the current upper atmospheric pattern (jet stream.)

“Meanwhile, much of the central Plains, western corn belt and northern half of the southern Plains (IA, NE, SD, KS, and MO) is projected to receive above normal moisture. “However, I would caution that last month’s forecast for June saw two polar opposite forecasts for the northern Plains temperatures from the mid-month release compared to the end of the month release, and I am seeing the same potential for the month of July,” said Allen Dutcher, Associate State Climatologist; Nebraska State Climate Office in Lincoln, Neb.

July Temperature Outlook

July Precipitation Outlook

Dutcher points out that the below normal forecast is from the Climate Prediction Center (CPC), but other models like the GFS indicate a substantial ridge building into the southern/central U.S. by the end of this month. “If this occurs, this CPC forecast will likely be a bust for temperatures and I would expect a much warmer forecast to be issued at the end of the month (remember, this is their two week long lead, and will be updated at the end of the month,)” said Dutcher.  “This is the same pattern that happened during last month when the 30-day changed dramatically from the mid-month release of the 30 day – compared to the revised end of the month 30-day forecast.”

The current forecasts for the rest of June includes development of the mean trough position over the northwest U.S. through the central Rockies.  “Downstream, the subtropical ridge across the southeastern U.S. appears to re-develop by the end of the month, placing much of the central U.S. under high pressure aloft.  Bottom line, if the models are correct, significantly warmer temperatures are on tap for the beginning of July,” analyzed Dutcher, adding, “The longer the ridge holds across the southeastern U.S., the longer the period of above normal temperatures will hold on to open up the month of July.

Precipitation: The Real Wildcard

Regarding precipitation, Dutcher acknowledges that will be the difficult forecast for the next 30 days.  “Snowpack is over 1800% of normal (Yes; 1,800 percent) for the Colorado river basin (southern and central Rockies). This goes to show the influence of the huge snowpack across the southern Rockies coupled with the persistent trough across the western U.S. for much of April and May. This kept conditions colder than normal and slowed down the (eventual) melt period,” Dutcher said.  Therefore, there’s great opportunity for much moisture and also for it to feed into systems to produce heavier than normal rain; courtesy of this larger than normal amount of snow (moisture.)

Longer term, the three-month forecast calls for below normal temperatures from the northern Plains southward through the northern one-third of Texas. “Precipitation is forecasted to be above normal for a majority of the U.S., with the highest probabilities assigned to the northern/central Rockies east/southeast through the central/southern Plains,” said Dutcher.   Again, temperatures will be influenced by whether the ridging pattern shown to develop by months end is transitory or begins to lock into place.

With so many planting issues and with a national corn/soybean crop that is well behind its normal growth pattern (especially the eastern half of the corn belt), warmer temperatures during July have the potential for crops to catch up a bit, but heat stress conditions will be elevated due to pollination occurring later in July closer to the statistical peak of summer heat.  However, Dutcher notes that a warm September would be an important factor for crop growth.

There’s also a possibility of cool and moist conditions returning, since El Niño conditions are forecast through at least through this fall.  

“The real wild card in this entire forecast is the area of the Pacific Northwest eastward through the northern Plains.  Drought conditions have developed, intensified, and shifted slightly southward.  This area has been consistently projected to see above normal moisture, which has failed to materialize,” said Dutcher. Temperatures the past couple of weeks have been above normal (dryness supporting surface warming).  “If this area intensifies, then it would help support building the central Plains ridging pattern further northward by month’s end, weakening the ability of the western U.S. trough to progress eastward (expanding early July dryness south and eastward across the western/central corn belt),” added Dutcher.  If this pattern holds long enough, the upper air pattern could lock in place right during the period when our national corn crop begins to enter pollination (then we will see whether the continuous rainfall has compromised corn rooting structure: shallow rooting syndrome leading to flash drought conditions.

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Amy G. Hadachek

Hadachek is a freelance writer who lives on a farm and cow-calf operation with her husband in north central Kansas and is also a meteorologist and storm chaser. She can be contacted at: rotatingstorm2004@yahoo.com