Highlights: Generally mild weather from the Plains to the Atlantic Seaboard contrasted with colder-than-normal weather in the West. Relative to normal, February was the coldest month of the winter of 2012-13 for locations east of the Rocky Mountains. Frigid conditions in December and January eased somewhat across the Intermountain West toward the end of winter.
Winter precipitation eradicated drought across much of the lower Southeast. Even as heavy rain triggered lowland flooding across the Deep South, including Florida's panhandle, showers largely bypassed Florida's citrus belt. As a result, producers across Florida's peninsula had to rely on irrigation as warm weather pushed citrus into an early bloom during February. Farther west, above-normal winter precipitation provided some limited relief to drought-stressed rangeland, pastures, and winter wheat on the Plains. Beneficial winter precipitation also fell across the upper Midwest; however, subsoil moisture shortages persisted across the Nation's midsection as producers prepared for spring planting. In contrast, drought was mostly eliminated before or during winter in the eastern Corn Belt.
Elsewhere, the Western wet season got off to a good start, especially in December; however, unfavorably dry conditions developed as 2013 began and persisted through January and February. As a result, water-supply prospects -especially from California to the central and southern Rockies - dimmed by the end of winter.
Historical Perspective: The winter of 2012-13 was overall warm and wet. The Nation's average temperature of 34.3 degrees Fahrenheit was 1.9 degrees above the long-term mean, while the average precipitation of 7.10 inches was 110 percent of normal. These numbers represented the 19th-warmest, 25th-wettest December to February during the 118-year period of record.
Winter warmth was most prevalent east of the Rockies, while chilly conditions were the rule from California to the southern Rockies. State temperature rankings ranged from the 20th-coldest February in Utah to the fifth-warmest February in Delaware. Meanwhile, most of the eastern half of the United States experienced a wet winter, while pockets of dryness dotted the West. State rankings varied from the 21st-driest December to February period in California to the fourth-wettest winter in Alabama, Louisiana, and Michigan. Top-ten values for winter wetness were also noted in Georgia, Mississippi, Illinois, and Wisconsin.
December: Despite occasional December precipitation across the Nation's midsection, hard red winter wheat conditions remained mostly steady or declined due to poor crop establishment and acute soil moisture shortages. In addition, drought intensified across southern portions of the Plains, especially from southern Texas into eastern Kansas. By December 30, the portion of the Plains' wheat rated in very poor to poor condition included 61 percent in Oklahoma, 49 percent in Nebraska, and 31 percent in Kansas. However, enough snow fell across the northern and central Plains to provide some degree of insulation from temperatures that locally and periodically fell to -10 degrees Fahrenheit or lower.
In contrast, significant precipitation fell in much of the soft red winter wheat belt, particularly across the Ohio Valley. As a result, most of the wheat continued to thrive across the Mid-South and lower Midwest. By month's end, 70 percent of the Illinois wheat crop was rated good to excellent. In both the Ohio Valley and the upper Midwest, enough of December's precipitation fell in the frozen form to establish a substantial snow cover. Meanwhile, widespread precipitation also fell in much of the East, although rain was spotty across Florida. Some of the heaviest precipitation, relative to normal, fell across the Northeast and from the central Gulf Coast into the southern Appalachians.
Elsewhere, much of the West experienced unsettled weather during December. Precipitation was especially heavy from northern California into the Intermountain West. For example, the average water content of the high-elevation Sierra Nevada snow pack increased by 10 inches during the month, reaching 14 inches (approximately 140 percent of normal) by the end of December.
The Nation's winter agricultural regions escaped significant freezes during December, although there were several chilly mornings - particularly from December 19-21 - in California and the Desert Southwest. Florida's coldest morning, for the most part, occurred on December 23. Overall, December temperatures were highly variable in the West but mostly above normal across the eastern half of the Nation. Western temperatures were influenced by snow cover, mainly in parts of the Intermountain region.
January: Despite sporadic January precipitation on the Plains, drought remained entrenched across the Nation's midsection. By month's end, at least half of the winter wheat was rated very poor to poor in Oklahoma (69 percent), South Dakota (66 percent), and Nebraska (50 percent). In Kansas, 39 percent of the winter wheat and 85 percent of the rangeland and pastures were rated very poor to poor on January 27. Precipitation was a little heavier on the northern Plains, where snow provided wheat with some protection from weather extremes.
The southern Plains also received moisture from time to time, helping to offset the effects of mostly above-normal temperatures. In fact, above-normal monthly temperatures prevailed in nearly all areas from the Plains to the East Coast, despite a late-month cold outbreak that resulted in the coldest weather in 2 years in parts of the Midwest and Northeast. January readings averaged more than 5 degrees Fahrenheit above normal in much of the Southeast. In contrast, frigid weather blanketed the Intermountain region, while near- to below-normal temperatures covered the remainder of theWest. Chilly weather that struck winter agricultural regions in California and Arizona at mid-month represented the area's most severe cold wave since a similarly timed event in mid-January 2007.
Meanwhile, abundant January precipitation fell from the Mississippi Valley to the Appalachians, as well as in the Mid-Atlantic States. Lowland flooding affected several areas, primarily from the central Gulf Coast northeastward into the Ohio Valley. In contrast, very little moisture spilled across the mountains into New England or the southern Atlantic States. In the latter region, the combination of warm, dry conditions led to heavy irrigation demands in Florida's winter agricultural belt.
Elsewhere, disappointingly dry weather accompanied generally cool conditions in the West. For example, the average water content of the high-elevation Sierra Nevada snow pack stood at 16 inches (about 90 percent of average) at month's end, compared to 14 inches (140 percent) on January 1. However, late-month storms provided some drought relief in the Southwest.
February: For many areas east of the Rockies, particularly across the Midwestern and Mid-Atlantic States, February was the coldest month during the winter of 2012-13. Conversely, warmth continued across the Deep South, from southern Texas to Florida's peninsula, where some early planting activities and blooming were noted by the end of February.
February precipitation highlights included heavy rain in the lower Southeast and several late-winter storms across the Plains and Midwest. Southeastern storms led to some record-high February precipitation totals and lowland flooding; however, rainfall largely bypassed Florida's peninsula, where producers continued to irrigate citrus and other crops.
Across the Plains and Midwest, the highest-impact storms struck during the second half of the month, from February 20-22 and 25-27. Both late-month storms produced heavy, wind-driven snow in various parts of the central and southern Plains and Midwest, stressing livestock and disrupting travel, but providing beneficial topsoil moisture and insulation for drought-stressed rangeland, pastures, and winter wheat. Still, by late February, roughly one-third to two-thirds of the hard red winter wheat was rated very poor to poor - a list headed by South Dakota (66 percent very poor to poor), Oklahoma (54 percent), Nebraska (50 percent), Texas (45 percent), and Kansas (36 percent).
Elsewhere, drier-than-normal weather dominated during February across southern Texas and nearly all areas west of the Rockies. In fact, disappointing amounts of precipitation fell across much of the West in January-February 2013, diminishing the prospects for spring and summer runoff and increasing water-supply concerns from California to the central and southern Rockies. By winter's end, the water content of the high-elevation Sierra Nevada snow pack stood at 16 inches, about two-thirds of normal for the end of February.