April 2001

WEATHER BRIEFS

China: Warm Weather Promotes Wheat Growth Across The North China Plain

The North China Plain was unseasonably dry during March, but soil moisture levels and irrigation supplies were adequate for emerging and vegetative winter wheat. March temperatures were mostly above normal across the North China Plain, promoting good vegetative growth. Temperatures were also above normal in Manchuria for most of March, and soils were becoming warm enough to encourage early spring wheat and summer crop field preparation. Cooler temperatures during the last 10 days of March slowed crop development in northern China, but near to above-normal temperatures returned in early April. On average, winter wheat on the North China Plain reaches the heading stage by early May, with the crop advancing from south to north. Southern China received frequent rain during March, especially in the southernmost provinces. While much-needed rain fell across the Yangtze Valley during the week of March 18 - 24, seasonal precipitation has been below normal. Additional rainfall will be needed to support summer crops, including rice, as the growing season progresses.

Middle East: Winter Grains Nearing Harvest

Wheat harvesting typically begins in April for the warmer growing areas in the southern portion of the Middle East. This year’s unseasonable warmth has pushed crop development ahead of schedule. During January-March 2001, warmer-than-normal weather dominated the region, eliminating snow cover in winter wheat areas of central Turkey and western Iran and inducing crops to break dormancy earlier than normal. Rainfall was near to above normal from southeastern Turkey to Israel, but below-normal precipitation elsewhere raised concern for spring development of winter wheat, especially in the northwestern wheat growing region of Iran. Iran had been exhibiting a favorable growing season after two years of consecutive drought, but below rainfall was recorded in western Iran for 2001. During the first 10 days of March, light showers swept across Turkey, but temperatures where well above normal and increased evaporation rates and crop moisture demands. Further south, mostly dry and warm weather covered Israel and western Syria, and beneficial rains extended from eastern Syria to western Iran, increasing soil moisture for winter wheat development. During the remainder of March, Eastern Turkey and neighboring areas in Syria received moderate rainfall, but temperatures remained 4 to 8 degrees C above normal across much of the region, increasing moisture demands of vegetative to heading winter wheat. Precipitation was somewhat lighter in western Turkey with the heaviest amounts, around 25 millimeters, falling during the week of March 18 - 24 across the Anatolian Plateau. During the week of March 25 - 31, scattered showers (5 - 25 millimeters or more) brought localized relief to winter wheat areas of Iran, while above normal temperatures maintained high rates of crop-water usage and evaporation.

Northwest Africa: Winter Grains Enter the Heading Stage With Limited Moisture Reserves

During early April, winter grains are in or entering the moisture-critical heading stage across northwestern Africa. The 2001 winter grain growing season has been highlighted by moderate rain occasionally easing dryness in key growing areas of Tunisia and northern Morocco, while pernicious drought affects production in southern Morocco and much of Algeria. In December 2000, the first substantial rains of the growing season fell on winter grain areas in southern Morocco during the last half of the month. This prompted widespread planting which had been slowed by previous dryness. Winter grains in northern Morocco received intermittent showers throughout the month, aiding winter grain emergence and early plant establishment. Farther east, below-normal precipitation fell over winter grain areas in Algeria and Tunisia, with crop areas in western Algeria receiving less than 50 percent of normal rainfall. Although the dryness in these areas favored fieldwork for winter grain planting, it reduced moisture needed for crop emergence and establishment. In January 2001, near- to above-normal precipitation improved moisture conditions for winter grain development in northern Morocco, Algeria, and Tunisia. A drying trend since early January in southern Morocco has severely limited moisture for vegetative crops. During the first 10 days of February, only light and widely scattered showers fell across Morocco and Algeria, providing limited moisture for vegetative winter grains. In Tunisia, heavy showers fell across the winter grains area, increasing soil moisture for developing crops. From February 11 - 24, dry weather continued for the most part across the region. Soil moisture was becoming more critical as winter grains approached the heading stage. During February 25 through March 3, light to moderate showers eased dryness and increased soil moisture in northern Morocco. This rain again missed southern Morocco. Western Algeria received light showers that week, further aiding soil moisture reserves, as did eastern Algeria and Tunisia. The heaviest rains were limited to the coast. Some stations in southern Morocco did not receive any rainfall for the entire month of February. Also, during the month of February, average temperatures in northwest Africa were 1- 3 degrees C above normal, thereby increasing evaporative losses to already low soil moisture. Rains did return to northern Morocco on March 7^th and some areas in southern Morocco saw some badly needed showers as a low pressure system moved in from the west. Rainfall was practically non-existent across all of Northwestern Africa during March 11 - 24. From March 25 - 31, light showers provided little relief for winter grains in northern Morocco, and in northern-most and eastern Algeria. That week, more significant rain fell in Tunisia helping to ease recent dryness. Winter grains in southern Morocco, and central and western Algeria again saw the lowest amounts of rainfall. As of April 10, with a significant portion of the crop in the heading stage, increased rainfall is critically needed across the region in the next several weeks to prevent further declines in yield potential. The month of March recorded precipitation as below average across all of northwest Africa. Some cumulative precipitation totals for the month of March are: Casablanca, Morocco, 24 mm of precipitation, half its normal March total of 49 mm. Marrakech, in southern Morocco received only 6 millimeters (out of a normal 32 mm in March); Algiers, Algeria received 1mm (avg. 59 mm). Eastward and inland, Batna, Algeria, saw 6 mm (43 mm avg.), and Tunis, Tunisia had 27 mm (avg. 45 mm) during the month of Mach.

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