Freeze Ends Crop Season in Western Nebraska; Eastern Areas Escape — For Now

Freeze Ends Crop Season in Western Nebraska; Eastern Areas Escape — For Now

October 17, 2008

U.S. map showing 30-day precipitation forecast
The 30-day temperature outlook shows above normal temperatures for the shaded area with the highest probability in the darkened area.
U.S. map showing 90 day precip forecast
The 90-day outlook shows equal likelihood of normal, above normal or blow normal precipitation in the Central High Plains.
U.S. map showing 90-day temperature outlook
The 90-day outlook shows above normal temperatures for much of the central U.S. with the darker areas having the highest likelihood.

Just as producers were beginning harvest in many areas of Nebraska, an active storm pattern dropped 0.5 to 3.5 inches of rain, delaying field work for several days.

The first system moved into the central Plains October 6-7 and dropped 0.5 to 2.0 inches of moisture from south central through northeast Nebraska. Areas east of this line received 0.25-0.50 inches, while areas west of it did not receive measurable moisture.

The second of these systems brought the first major snowstorm of the season to the northern Rockies during October 10-14 period. Areas of central and northern Wyoming, as well as southern Montana. received up to four feet of snow at elevations over 7000 feet. Heavy snows were also reported across the western quarter of North and South Dakota.

Nebraska received widespread rain October 11-14. Storm totals exceeded 1.50 inches over eastern Nebraska, with isolated areas approaching three inches. Precipitation totals in western Nebraska generally were in the 0.75-1.50 inch range.

Soil Moisture

Soil moisture readings from the High Plains Regional Climate Center indicate all locations east of North Platte are above normal. In fact, south central through northeast Nebraska could use an extended warm dry period to ease muddy surface conditions.

Across the western third of the state, soil moisture readings are within an inch of normal and should promote good wheat emergence and growth. Platte River flows have increased with the recent moisture and stream flows entering Lake McConaughy double those reported at this time last year.

Season-ending Freeze

The Rocky Mountain snowstorm also brought a season-ending freeze October 13-14 across the Nebraska Panhandle. Low temperatures were consistently below 28ºF, with 20ºF reported at Alliance. Further east and west of North Platte, temperatures dropped below freezing, but failed to reach the killing freeze level of 28ºF.

Cloud cover associated with the October 14 rain delayed the first frost of the fall in other areas, as temperatures bottomed out in the upper 30s and low 40s. Skies cleared as the storm moved east, allowing temperatures to approach or drop below 32ºF across eastern Nebraska. Few locations dropped to 28ºF and it will be at least a week before there is the potential for a hard freeze.

Warmer temperatures from September 20 to October 10 allowed the crop to progress rapidly and the recent freeze likely did little damage.

One of the major complaints frequently cited across the Corn Belt has been the high moisture content of the corn crop.  Dry down has been slow, so the recent freeze should help speed up the drying process.  The primary question now is how active the weather pattern will be going forward.

Forecasts

In the short term, weather models indicate that an upper air ridge will build into the central U.S. through October 21, allowing harvest activity to resume. Precipitation could return to the Central Plains as early as October 22 and last through 24. Current models indicate that low temperatures on the backside of this even will drop to hard freeze (28ºF) levels across eastern Nebraska..

After a brief drying pattern after the next low-pressure system, weather models indicate that a significant upper air trough will enter the western U.S. by the end of the month.  A considerable amount of uncertainty exists with the speed, intensity, and movement of this upper air low.  If the models are correct, another significant snowstorm can be expected across the central and northern Rockies with the potential for accumulating snows across the western half of the central High Plains.

In the long term, the Climate Prediction Center indicates that above normal temperatures are likely across the Central Plains from November through January.  The Center assigns equal chances for above normal, normal, or below normal moisture during this period. If the current trend for robust storm activity continues, their forecast may well prove to be overly optimistic on temperature while underplaying the potential for precipitation.

Al Dutcher
State Climatologist