The reporting period covers the middle of the growing season of winter crops (winter wheat, rye, oats, canola) and contitutes the early sowing season of maize, soybean, wheat spring and rice. In general, NDVI development graph indicate the condition of current winter crops is more favorable than last year's. 

The winter cereals are distributed over the States of Kansas, Oklahoma, Texas, Colorado, Nebraska, Washington, California, Montana and South Dakota. Canola has been planted in North Dakota. In Kansas, South Dakota, Nebraska, North Dakota, California precipitation was well above average by 16%, 41%, 22%, 24%, and 67%, respectively. Among the major winter crop production zones, Oklahoma and Washington suffered precipitation deficits reaching -16% and -12%; both states should be watched for water stresses in the coming months. Below average temperature and RADPAR occurred in all agricultural States, with the coldest weather in North Dakota (-3.0℃ below average), Montana (-3.5℃), and South Dakota (-3.5℃). 

The favorable crop condition was observed in Abilene in Texas, and Sacramento and Bakersfield of California. Oklahoma City to Wichita is the most important winter wheat producing area in the United States, where crop condition is still below average although it improved since March. Another important winter crop region with far below crop condition before April due to drought covers Spokane to Kennewick in Washington, and the Great Falls region in Montana. Crops have been recovering recently in the area but the most important canola region, North Dakota, remains below average.

The regional differences in crop condition are also confirmed by the maximum VCI (VCIx). Nationwide, VCIx reached to 0.86 in the United States. The highest values (above 1) occur in Abilene (Texas), and Sacramento and Bakersfield (California). Low values were recorded in North Dakota, Montana, and Washington States. The fraction of actually cultivated arable land was average.

In summary, the crop condition in Washington, Montana, North Dakota and Oklahoma still needs close monitoring; good crop production can be expected in California, Texas and Kansas. 

报告期涵盖冬季作物（冬小麦，黑麦，燕麦，油菜）生长季节的中期，并构成玉米，大豆，小麦春和稻米的早播季节。一般来说，NDVI发展图表明当前冬季作物的状况比去年更为有利。

冬季谷物分布在堪萨斯州，俄克拉荷马州，德克萨斯州，科罗拉多州，内布拉斯加州，华盛顿州，加利福尼亚州，蒙大拿州和南达科他州。油菜已在北达科他州种植。在堪萨斯州，南达科他州，内布拉斯加州，北达科他州，加利福尼亚州的降水量远高于平均值16％，41％，22％，24％和67％。在主要的冬季作物生产区中，俄克拉荷马州和华盛顿州的降水量差异达到-16％和-12％;在接下来的几个月里，应该关注两个州的水资源压力。低于平均温度和RADPAR发生在所有农业州，北达科他州最低气温（低于平均值-3.0℃），蒙大拿州（-3.5℃）和南达科他州（-3.5℃）。

在德克萨斯州的阿比林和加利福尼亚的萨克拉门托和贝克斯菲尔德观察到有利的作物条件。俄克拉荷马市至威奇托是美国最重要的冬小麦产区，虽然自3月份以来有所改善，但作物长势仍低于平均水平。另一个重要的冬季作物区域，由于干旱，4月份之前远远低于作物长势，包括华盛顿的斯波坎到肯纳威克和蒙大拿州的大瀑布地区。该地区的农作物最近一直在恢复，但北达科他州最重要的油菜地区仍低于平均水平。

作物长势的区域差异也由最大VCI（VCIx）确定。在全国范围内，VCIx在美国达到0.86。最高值（大于1）出现在Abilene（德克萨斯州）和Sacramento和Bakersfield（加利福尼亚州）。北达科他州，蒙大拿州和华盛顿州的记录值较低。实际耕种的耕地比例是平均的。

总之，华盛顿，蒙大拿州，北达科他州和俄克拉荷马州的作物状况仍需密切监测;加利福尼亚州，德克萨斯州和堪萨斯州的作物产量预计良好。

图.X 1_4  Crop phenology of major crops in United States 

图.X Crop condition development graph of winter wheat based on NDVI_United States

图.X Winter crops and canola distribution of United States(red color: winter crops, green color: canola)

图.X Spatial distribution of NDVI profiles

图.X Maximum VCI

Regional analysis

The regional analysis focuses on winter crop producing regions of United States, including California, the Northwest, Northern Plains, and Southern Plains. 

区域分析侧重于美国冬季作物产区，包括加利福尼亚州，西北部，北部平原和南部平原。

Table 1: Agro-climatic indicators by sub-national regions, current season's values and departure from 15YA, January - April 2019

Table 2: Agronomic indicators by sub-national regions, current season's values and departures, January - April 2019

The main agricultural area between Sacramento and Bakersfield had significantly above average crop condition, as indicated by the NDVI development graph. In California temperature was close to average (-0.3℃) and precipitation exceeded average by 82%, which replenished much needed soil moisture reserves. The potential biomass is up 38% over average and CALF increased by 9%. VCIx at 0.99 confirms the favourable crop condition.

如NDVI发展图所示，萨克拉门托和贝克斯菲尔德之间的主要农业区域的作物长势明显高于平均水平。 在加利福尼亚，气温接近平均值（-0.3℃），降水量超过平均值82％，补充了大量需要的土壤水分储备。 潜在生物量比平均水平高38％，CALF增加9％。 VCIx为0.99证实了有利的作物状况。

图.X Crop condition development graph based on NDVI, California

The Southern Plains are the most important winter crops producing zone of the United States; they include Texas, Oklahoma and Kansas. Crop condition reached the 5 year maximum at the end of the monitoring period, in April 2019. CropWatch agro-climatic indicators show average weather condition: precipitation and temperature were 2% and 1.2℃ below average. Precipitation was 12% below average in Oklahoma but average or above average in other States. It is worth noting that the CALF in the region has increased significantly, by 10% above the 5YA. The good crop condition was confirmed by VCIx of 0.92 and winter crop production prospects are favorable.

南部平原是美国最重要的冬季作物生产区; 他们包括德克萨斯州，俄克拉荷马州和堪萨斯州。 在2019年4月监测期结束时，作物长势达到最大值5年.CropWatch农业气候指标显示平均天气条件：降水和温度分别低于平均值2％和1.2℃。 俄克拉荷马州的降水量比平均水平低12％，但其他州的平均降雨量高于平均水平。 值得注意的是，该地区的CALF显着增加，比5YA高出10％。 VCIx确认良好的作物长势为0.92，冬季作物产量前景良好。

图.X Crop condition development graph based on NDVI, Southern Plains

The Northern Plains are another important winter crops producing zone of United States, including South Dakota, North Dakota, and Montana. Crop condition was below the 5-year average during the current monitoring period. Precipitation was up 10% compared with average while temperature and RADPAD were significantly lower than average by 3.2°C and 13%, respectively. The sowing, growth and development of crops in this region was blocked by the cold wave and abnormally low RADPAR that resulted in a significant reduction in CALF of 56%.  The 0.72 VCIx confirmed the poor crop growth in this monitoring period. Production prospects are unfavorable.

北部平原是美国另一个重要的冬季作物生产区，包括南达科他州，北达科他州和蒙大拿州。 在目前的监测期内，作物长势低于5年平均值。 与平均值相比，降水量增加了10％，而温度和RADPAD分别显着低于平均值3.2°C和13％。 该地区作物的播种，生长和发育被冷波和异常低的RADPAR阻断，导致CALF显着降低56％。 0.72 VCIx证实了本监测期间作物生长不良。 生产前景不利。

图.X Crop condition development graph based on NDVI, Northern Plains

Crop condition was significant below the average in the North-West, the fourth major winter crop production  zone of the United States. Precipitation was close to average, only slightly higher than average by 4%, while the temperature dropped 1.2℃ below average. Washington, the major State of the Northwest region suffered insufficient precipitation (12% below average) The drought led to an 11% reduction in CALF while VCIx was just fair (0.75). Crop prospects are average at best.

作物状况显着低于美国第四大冬季作物生产区西北部的平均水平。 降水接近平均值，仅略高于平均值4％，而气温比平均值低1.2℃。 华盛顿是西北地区的主要州，降雨量不足（低于平均水平12％）干旱导致CALF减少11％，而VCIx仅为公平（0.75）。 作物前景充其量只是平均值。

图.X Crop condition development graph based on NDVI_Northwest