The upper air pattern, which drives the movement of air masses and weather systems, will feature a significant onshore orientation of the jet stream in to the Pacific Northwest, a drop southeastward on to the central and southern Plains, with a curl back then to the northeast and into southeastern Canada via the Ohio Valley and Midwest. This in turn should allow rather dominate ridges of high pressure aloft to set-up in the southwestern and southeastern U.S.
As a result, look for warmer- than-average weather in parts of the Southwest and West, as well as far across the southeastern U.S.
Meanwhile, temperatures will average below-normal to occasionally well-below normal throughout the nation's heartland and at times across the Northeast and New England. A wide-range of temperatures will be from the Pacific Northwest to much of the Corn Belt.
Active precipitation pattern
The precipitation outlook for early to mid-spring suggests an active pattern for the northern and central Plains, the Midwest, the Great Lakes region, the Northeast, New England and the mid-Atlantic region. Storminess is forecast to build early in the season the Pacific Northwest. Drier-than-usual weather is forecast across much of the Southwest, the central and southern Rockies and parts of the Deep South.
Specifically, across the Pacific Northwest, the northern Rockies and south throughout the inter-Mountain West and Southwest, outbreaks of cold-wave weather will be on the wane early in the season. Temperatures will show an upwards trends toward moderation later in the spring season. As for precipitation, above to well-above normal amounts are expected through mid-Spring in the Northwest and northern Rockies as a dry pattern tightens its hold in the Southwest. At least adequate levels of run-off moisture should finally materialize.
As for the Dakotas, Minnesota and points southward through the central Plains, a cold, active (wet) pattern will continue into mid-Spring. However, while there will be bouts of more seasonal temperatures, these will be few and far between, and most likely will occur from the lower Missouri Valley, and points southwestward. A higher than average frequency of severe weather outbreaks are expected on southern and eastern areas of the Plains. Do look for a drier late spring weather pattern except from the Missouri Valley, and areas northward as storm systems continue to frequent the region. Late-season snow cover and average to above-average amounts of precipitation may lead to low-land flooding and spring fieldwork delays. One benefit of this will be a steady and beneficial rise on regional steams and rives and their associated water sheds.
Continued wide swings
Elsewhere across the nation, it was a winter season of wide-ranging temperatures, as well as precipitation patterns across the Deep South, Southeast and mid-Atlantic region; and from Texas eastward through the mid-South and southeastern U.S. There's more of this to come, too.
While milder, more seasonal air masses may, on occasion, visit parts of the Southeast, a frequency of weather systems and their attendant cold air intrusions will likely keep barn thermometers on a wild ride into early spring. Thereafter, a welcome return to longer-lasting spells of more seasonal warmth and even a warmer-than-average pattern.
The warmer weather will improve crop growth and development. Dryness and drought areas have seen some improvement. However, this short-term tendency will yield to worsening soil moisture levels and expanding drought-related issues along the Gulf coast and extreme Southeast. Farther north, prospects for excessive rainfall totals may result in periodic flooding centered in Tennessee Valley and parts of the Ohio Valley.
Winter won't give up
As for the Northeast and New England, an active pattern continues this early this spring season, including bouts of winter-like weather. Upper level winds forecast to frequently ride-in from the southwest which typically generates expansive precipitation. Cold air masses, while prevalent in frequency may be short-lived. Not until late in the season will the area experience longer-lasting spells of seasonal temperatures. As for precipitation, normal to above-normal amounts, including late season snowfall is ahead. Fieldwork and planting delays are likely well into the season, along with an increase in spring snowmelt and run-off (flooding) issues.
Finally, across the Midwest and Great Lakes region, southward to the Ohio Valley, a far different winter season compared to that of 2011-2012 generated a wild-ride and range of temperatures and weather, too. This included a wide-range of temperatures as well as no shortage of precipitation, particularly in the eastern Corn Belt. This active pattern will continue, not only regarding the frequency of cold air outbreaks, but the number of weather systems, too. Temperatures will range to below-normal to well below normal, but with some fluctuations from the Mississippi Valley to the lower Ohio Valley. As for precipitation, normal to above-average frequency and amounts are in the offing. The frequency of severe weather outbreaks will also be on the rise across much of the Midwest and Ohio Valley. The recent melting of a sizeable snow cover in parts of the Midwest, along with early through mid-Spring moisture will raise the specter of low-land flooding, fieldwork and planting delays. However, a benefit of this wet pattern will be that of further rises in the Ohio and Mississippi Rivers. Over the remainder of spring, there are signs of a general trend warmer to hotter than-usual conditions, but not necessarily drier.
Potential for long term moisture
Looking ahead briefly into the 2013 late spring and summer season, there is cause for concern as increased dryness and drought issues in the deep southern states, while a re-intensification of drought may be possible on the southern Plains. Meanwhile, a recovery to more seasonal temperatures should improve crop development across the Corn Belt, a trend towards hotter-than-average temperatures will be concern to producers. As for timely rainfall, that looks likely, along with some potential for an ongoing wet pattern, too.