Ranchers and farmers in Colorado and Wyoming, as well as eastward into parts of the central Plains states will be closely monitoring precipitation forecasts this summer, with drought an increasing concern.

The Climate Prediction Center released its official forecast for June, July and August on Thursday, May 21, and precipitation is forecast to be below normal from northern New Mexico into the western half of Colorado, into Wyoming and Montana. Eastern Colorado has slightly more favorable chances for normal precipitation.

“Then, above normal precipitation is forecast for most of the eastern half of the United States, with the highest probabilities assigned to eastern Nebraska, eastern Kansas, Iowa, and areas east-southeast through much of the southeastern U.S.,” said Al Dutcher, agricultural Extension climatologist in the Nebraska State Climate Office in Lincoln.

Temperature-wise, above-normal summer warmth is predicted from Colorado into Wyoming and Montana, with even warmer temperatures expected for southwest Colorado.

“Above normal temperatures are also forecast for the western High Plains region and the southern Plains (Texas and Oklahoma),” Dutcher said. Closer to average temperatures are expected in the eastern half of the central and northern High Plains region.

COLORADO

Southern Colorado (including the San Luis Valley, and the Plains south of I-70) is seeing drought continuing to expand, while areas north of I-70 are holding steady due to better rainfall.

“The drought conditions were brought on by a couple of factors. Freezing temperatures in April (many locations in the teens and 20s for several days), after which plants already started to leaf out due to a warm February through March. The peach crop on the western Colorado slope suffered greatly from these freeze conditions. The second factor was lack of rainfall, and February through April was the 15th driest period on record for Colorado,” said Kyle Mozley, meteorologist for the National Weather Service in Pueblo, Colo.

Additionally, snowfall, which was near average for much of the winter, melted rapidly this spring with snowpack in the Rio Grande and Arkansas drainages now under 50 percent of normal. The good news is that areas to the north are near normal, Mozley said.

El Nino Southern Oscillation (ENSO) is currently neutral.

“Summer months are the tough period for forecasting trends with ENSO. Currently model projections are trending more towards La Nina by fall, which usually leads to drier and windier conditions across much of Colorado. The exception would be the Central Mountains where orographic northwest flow is favored,” Mozley said. “Areas over the southwest part of the state (San Juan Mountains) miss out on snow.”

Mozley observed a rather bland monsoon season (seasonal reversal of the wind pattern which typically brings thunderstorm activity northward into the Rockies).

“The Outgoing Longwave Radiation (OLR) model I use to track Equatorial Rossby Waves (ERs) off the African Coast are virtually nonexistent. The ERs are a primary monsoon trigger, especially for eastern Colorado. These waves move off the African Coast, and into the Gulf of Mexico, allowing moisture to move northward into the eastern Colorado Plains,” said Mozley, although he acknowledged, “There may be a hint of one around July 20-24, about two weeks late from its normal starting date.”

Regarding agricultural concerns, Grass-Cast, a fairly new tool, can assist ranchers and grassland managers in the Colorado Plains with forage planning and productivity.

“It takes the current rangeland conditions and projects how rangeland would react to above, at or below normal expected precipitation. Even if we had above normal precipitation (which is not forecast), drought would be forecast to persist,” Mozley said.

WYOMING

Conditions in southwest Wyoming are deteriorating, and north-central regions are becoming a bit dry. The Evaporative Demand Drought Index shows eastern Wyoming doing fairly well, but dryness in the southwest is being reflected in the index.

“The entire state of Wyoming is expecting dryer than normal conditions looking out about two weeks and the three-month outlooks indicate below normal precipitation for most of the state, except far eastern parts where the signal is not clear enough to make a determination,” said Tony Bergantino, interim director for the Water Resources Data System in the Wyoming State Climate Office and Wyoming CoCoRaHS state coordinator.

“Southwest Wyoming should expect above-normal temperatures which will only worsen the (current drought) situation there. The rest of the state will be in a similar pattern,” Bergantino said.

Most Wyoming reservoirs are running fairly full with a few exceptions: Fontenelle, Palisades, Boysen and Buffalo Bill. There is still some snow yet to come off at the higher elevations so that indicates good reservoir capacity in most places, the unfortunate exception being the southwest where Fontenelle is only at 54 percent.

KANSAS AND NEBRASKA

“Odds for above normal precipitation are forecast for central and eastern Nebraska and most of Kansas. Although the Nebraska panhandle and far western Kansas are expected to be near normal, the above normal precipitation favors the early summer (June) with near normal precipitation more likely in July and August,” said Michael L. Moritz, warning coordination meteorologist with the National Weather Service in Hastings, Neb.

Near-normal temperatures are expected across eastern Kansas and central and eastern Nebraska for June, July and August. Odds favor slightly above normal temperatures across the Nebraska panhandle and the western third of Kansas. The greatest likelihood for warm temperatures is in southwest Kansas.

AGRICULTURAL IMPACT

Regarding the agricultural impact heading into the summer of 2020, there is a large variability in moisture conditions across the Great Plains. The latest U.S. Drought Monitor (https://droughtmonitor.unl.edu/) indicates a large area of moderate to extreme drought (D1 to D3) broadly centered over southeastern Colorado and southwestern Kansas. Drought there and in the Northwest has left 20 percent of the U.S. winter wheat production area in drought,” said Brad Rippey, USDA meteorologist in the Office of the chief economist for the World Agricultural Outlook Board in Washington, D.C. (https://www.usda.gov/oce/weather/Drought/AgInDrought.pdf; slides 14-16).

The latest Crop Progress report from USDA/NASS (https://usda.library.cornell.edu/concern/publications/8336h188j) showed 16 percent of the U.S. winter wheat crop rated in very poor to poor condition, Rippey said.

“Colorado led major production states with 44 percent of its winter wheat rated very poor to poor, followed by Kansas (23 percent) and Oregon (22 percent). Drought was also adversely affecting some rangeland and pastures across southern sections of the Rockies and High Plains. On May 17, nearly one-third of the rangeland and pastures were rated in very poor to poor condition in New Mexico (33 percent), Colorado (32 percent), and Oregon (31 percent),” Rippey said.

“Looking forward, odds are tilted toward a hot, dry summer across the northern High Plains (including Montana and Wyoming), which could lead to diminishing soil moisture reserves and an increase in pasture and rangeland stress,” he said.

In recent weeks, the most important factor driving U.S. weather patterns has been the persisting high-pressure system over eastern Canada.

“This high-pressure system, which effectively formed an atmospheric block, diverted cool air southward across the Plains and Midwest, especially from mid-April to mid-May. As a result, late-season freezes resulted in freeze injury to a variety of commodities, including fruit crops and winter wheat,” Rippey said. “However, freeze damage in individual locations was highly dependent on observed minimum temperatures, stage of crop development and effectiveness of freeze protection, where applicable.”

Neither La Nina nor El Nino conditions are expected to significantly influence the summer conditions either. “There’s a great deal of uncertainty about where (this climate pattern) will be six months from now, as the computer simulations are all over the place, while the official forecast indicates roughly equal likelihood of La Nina and neutral conditions by end of 2020.”

The latest ENSO advisory (El Nino Southern Oscillation), can be found at https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.html. ❖

— Hadachek is a freelance writer who lives on a farm with her husband in north central Kansas and is also a meteorologist and storm chaser. She can be reached at rotatingstorm2004@yahoo.com.