February Climate Impacts on Agriculture
Just like February 2019, this past February started off with pleasant temperatures and dry conditions. Then the bottom fell out as Arctic surged southward and dominated the Plains region for two consecutive weeks. The culmination of this cold surge occurred February 15-16 when minimum temperatures dropped into the -20’s F and -30’s F. A preliminary state low temperature of -39 F was recorded at Imperial and a large percentage of the state failed to see daytime highs reach 0 F on the 16th.
Prior to entering the month of February, average temperatures for the winter (Dec-Jan) were 3-5 F above normal along the southern border to 7-9 F above normal along the northern border. With temperatures averaging 12-18 F below normal during February, much of this anomalous warmth was eliminated. Figure 1 shows that the cold February resulted in winter temperatures dropping to 1-3 F below normal south to 2 F above normal north.
The cold air was accompanied by periodic rounds of light to moderate snowfall, with some locations receiving over 12 inches of snowfall during this two week stretch. This precipitation across western Nebraska helped to eliminate some of the winter precipitation deficit they had accumulated, but large areas remained below normal for the season (Figure 2).
It is not uncommon to see periods of above and below normal moisture during the winter. The most important aspect of the precipitation events are their cumulative impacts on soil moisture recharge during the non-growing season period. Total accumulated precipitation since October 1 (beginning of soil moisture recharge period) is shown in Figure 3, while accumulated surpluses/deficits are depicted in Figure 4.
The precipitation received during January and February eliminated most of the precipitation deficits accrued since November across eastern Nebraska. Precipitation deficits were generally under 1.50 inches to small pockets of surplus moisture. Precipitation during March and April will need to average 110-120% of normal to eliminate these deficits. Unfortunately, the driest areas of western Nebraska will need 200-300% of normal moisture over the next two months to eliminate moisture deficits incurred since the end of last September. Highly unlikely.
Nebraska Agricultural Statistics Service (NASS) issued their monthly crops update on February 22 for conditions through the 21st. NASS indicted that 22% of the wheat crop was in poor to very poor condition, 44% fair, 33% good, and 1% excellent. Air temperatures were certainly cold enough to cause concerns for winterkill injury, but until temperatures warm up, the extent of injury will likely remain unknown.
Top soil moisture ratings improved from the January release, due in large part to the heavy snow event January 25th that brought 12 inches or greater snowfall to central and eastern Nebraska. NASS reports that top soils are 14% very short, 32% short, 51% adequate, and 3% surplus. Subsoil moisture values have seen little improvement and stand at 20% very short, 40% short, 37% adequate, and 1% surplus.
Both topsoil and subsoil moisture ratings should improve with the next crops report issued by NASS at the end of March. Much of the snowpack had yet to melt when NASS released their report and it still contained 1-2 inches of liquid equivalent water from central through eastern Nebraska. Furthermore, the deep snowpack prior to the Arctic air intrusion protected soils from freezing which will allow more moisture to infiltrate instead of running off into watersheds.
The start of calving season was likely challenging because of the intense cold. Thankfully, no major snowstorms or blizzards occurred during this stretch and the dry nature of the snow likely help reduce death losses. Feed requirements increased due to the cold and cattle on stalks likely required additional feeding supplements due to the deep snow cover making stalk grazing difficult The return to above normal temperatures the last week of February should help alleviate these short term problems.
March Weather Outlook
The Climate Prediction Center (CPC) issued their official March temperature and precipitation outlooks on February 28. CPC’s temperature outlook (Figure 5) calls for above normal temperatures across east of the Rocky Mountains, with below normal temperatures confined to the west coast. Nebraska is included in this above normal temperature area, with eastern Nebraska having the highest probabilities of experiencing these conditions.
CPC’s official March precipitation outlook (Figure 6) calls for a high probability of below normal moisture for New Mexico, Colorado, and western Texas. Probabilities are slightly lower for southern Wyoming, western Nebraska, western Kansas, western Oklahoma, and the central third of Texas. Slight odds of drier than normal weather is predicted for northern Wyoming,
By all appearances, CPC’s temperature and precipitation outlook should come to fruition through the first third of the month as high pressure aloft dominates the central and southern Plains. Average temperatures are expected to be in the range of 15-20 F above normal across Nebraska. The very dry conditions and dormant surface vegetation will create high fire danger conditions when temperatures push into the 70’s and are combined with moderate to high winds.
Both the GFS and European models indicate that a broad upper air trough will push out of the western United States during the February 10-16 period. Model consistency has been terrible between daily runs, but both models indicate that active weather will return to the High Plains region. They are just having a difficult time resolving where the surface lows will track as the entire trough pushes eastward.
What is consistent in the models is that the upper air ridge responsible for the gorgeous start to March will shift to the eastern United States. This will allow energy to move into the central and southern Rockies, which results in the development of a surface low near southeastern Colorado. This solution would lead to significant snows across the southern Rockies, but there is more uncertainty for the central Rockies.
If this storm system comes out in pieces, the first wave would eject into the northern Plains, with the second piece of energy ejecting eastward through the central Plains. This solution would bring colder and wetter weather to western Nebraska. If the upper air trough comes out in one piece, then it will be far enough southward that western Nebraska would be north and west of the precipitation shield that would likely target eastern Kansas and Nebraska.
After this period of inclement weather, the GFS model hints at an upper air ridge building back into the central United States and a return to above normal temperatures. It also produces a couple of cutoff upper air lows of the west coast and begins to move them eastward at the very end of the model runs on the 20th. If this verifies, these lows would move through the southern Rockies and into the southern Plains the final week of the month, increasing the chances for precipitation across the central Plains.
Al Dutcher, Agricultural Extension Climatologist with the Nebraska State Climate Office