This monitoring period lasts from October, 2019 to January, 2020. It covers the late harvesting season of summer crops in 2019 and the sowing period of winter crops in 2020. In the last bulletin, growing situation of the 2019 summer crops had been reported. This analysis will focus on agroclimatic conditions and their potential impact on the 2020 winter crops. In general, the crop condition of winter wheat was mixed.

(a) Phenology of major crops

(b) Crop condition development graph based on NDVI

In this monitoring period, cloudy-rainy weather was sweeping through most parts of the United States. The precipitation was 18% above average, temperature was 0.1 ℃ below average, and RADPAR was 4% below average. In the key winter wheat production zones, significantly above average precipitation occurred in the southern Plains covering Kansas, Oklahoma, and Texas, and the precipitation was 19%, 66% and 9% above average respectively at state level. Abundant rainfall replenished soil moisture for growth of winter crops. In contrast, the other important winter crop zones of the United States, the Pacific Northwest and California received below average precipitation, including Washington (-4%), Oregon (-19%), Montana (-10%), Idaho (-13%) and California (-22%). Due to limited water demand in the early-growth stage and dormancy period, the shortage of precipitation has limited impact on growth of winter wheat in this reporting period.

(c) Time series temperature profile

(d) Time series rainfall profile

The positive influence of agro-climatic condition on winter crops in the southern Plains was captured by the map of potential biomass departure, compared to the 15 year average. The potential biomass of the southern Plains was 10% to 20% above the average. Due to the deficit of precipitation, a negative potential biomass departure was widely observed in the northwest of United States and in California where the potential biomass was 20% below the average. The spatial pattern of NDVI departure clusters represented variations of crop condition. It is interesting to note that slightly below average crop conditions occurred in the southern Plains with better agro-climatic condition. This could be attributed to the uncropped land fraction during the current stage as shown on the cropped and uncropped arable land map. Due to the rainfall deficit, NDVI departures indicated that crop condtions in eastern Washington state deteriorated greatly. Although suffering precipitation shortage, the crop condition in California fluctuated up and down but was generally close to average due to irrigation.  

In short, CropWatch estimated that the growth situation of winter wheat was acceptable in the southern Plains, while the situation of winter crops in the northwest and California should be watched in the next bulletin.

(e) Potential biomass departure from 5YA

(f) Spatial distribution of NDVI profiles

(g) Maximum VCI

(h) Cropped and uncropped arable land

Regional Analysis

In this section, only the three agro-ecological zones (AEZs) dominated by winter crops were analyzed, they are the Southern Plains, Northwest, and California.

1. Southern Plains

As the top winter crop producing zone of United States, precipitation of the southern Plains was 25% above average, the temperature was  0.2 ℃ below, and RADPAR was 3% below average. The significant above average precipitation can replenish soil moisture and stimulate the growth of winter wheat after wintering period. Compared to the 5 year average, the fraction of cropped arable land was 4% below the average.

(i) Crop condition development graph based on NDVI

2. Northwest

In this monitoring period, the Northwest was short of precipitation. It was 13% below average compared to the 15 year average. Other agro-climatic indices were close to average, such as temperature (-0.4℃) and RADPAR(1%).  Due to the shortage of precipitation the crop condition converted from above average to below average. Crop condition in this region should be watched closely considering the increase of water demand in next reporting period.

(j) Crop condition development graph based on NDVI

3. California

In this reporting period, California suffered severe shortage of precipitation. Compared to the 15 year average, precipitation was significantly 22% below the average. In this Mediterranean climate, this period is critical because of the predominantly cool and rainy weather. Due to a shortage of water, the crop condition was below average at the early growing stage before wintering, while it recovered to the 5 year average at the end of January. This  could be attributed to the positive effects of irrigation. In summary, CropWatch estimated that the crop growth would be near average.

(k) Crop condition development graph based on NDVI

Table **:  Agro-climatic indicators of major winter crops zones, current season's values and departure from 15YA, October 2019 to January 2020

Table ** Agronomic indicators of major winter crops zones, current season's values and departure from 5YA, October 2019 to January 2020