Ag Weather Forum

Drought Outlook Mostly Favorable

Bryce Anderson
By  Bryce Anderson , Ag Meteorologist Emeritus
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Following are highlights of the seasonal drought forecast from NOAA, which are favorable in terms of crop moisture for most areas except -- again -- the far West. -- Bryce

Twitter @BAndersonDTN

Precipitation deficits have been growing from northern Maryland through New England during the spring, with 60-day anomalies exceeding 5 inches from northern New Jersey across southeastern New England. Longer-term deficits are also becoming apparent, with year-to-date percent of normal precipitation values between 50 and 70 percent across much of the region. Unseasonably cold weather slowed snowmelt and evapotranspiration rates during March and April, which limited impacts; however, recent warmth has accelerated plant growth and soil moisture loss, and streamflow values have been steadily decreasing. Accordingly, moderate drought (D1) conditions developed across parts of eastern Pennsylvania, New York, and southeastern New England, while abnormal dryness (D0) was indicated for the remainder of the Northeast. Due to a fairly even distribution of generous climatological rainfall throughout the year, which mitigates the effects of subseaonal dry spells, prolonged drought conditions are more difficult to maintain across the Northeast than regions with long dry seasons such as California. Average soil moisture content usually decreases during the summer months across the Northeast, however, which makes the region vulnerable to the incipient conditions coming out of the spring months. CPC 6-10 and 8-14 day outlooks show enhanced chances for above-median precipitation across the mid-Atlantic and southern New England. While this forecasted precipitation during the remainder of May would boost moisture locally, it is unlikely to be sufficient to overturn increasing moisture deficits on a large scale. Additionally, temperature forecasts for the remainder of May and June depict a climate signal favoring above-median temperatures, which would continue to promote high evapotranspiration rates. At the seasonal time scale, there is little signal for climate anomalies, as ENSO impacts are less apparent during the summer months over the Northeast than in winter months. Therefore, the CPC monthly and seasonal outlooks maintain equal chances for below, near, or above median precipitation. Some dynamical models, such as the CFS, do depict a dry signal across the Northeast during JJA, and the ECMWF forecast indicates abnormal dryness during the Weeks 3 and 4 period. Based primarily on current conditions, climatological precipitation, and the prospects for above normal temperatures early in the forecast period, additional drought development is favored for eastern Pennsylvania, northern New Jersey, eastern New York, and eastern Maine, with persistence favored for existing drought areas. There is reduced confidence for existing or newly developing drought conditions to persist through the entire summer period, however. Additionally, recent heavy thunderstorm activity across parts of far south-central Pennsylvania and north-central Maryland make short term drought development there less likely than areas further north and east, so no development was indicated.

Forecast confidence in the Northeast is low.

Drought Index values have been increasing across South Florida, where short term moderate drought conditions remain across primarily the Everglades. The rainy season begins during late May in southern Florida, which should begin to improve the dry Spring conditions. CPC 8-14 day outlooks maintain near normal precipitation for southern Florida, while the monthly and seasonal outlooks favor near to above median precipitation. Climate anomalies associated with ENSO conditions also favor enhanced precipitation across Florida. Based on both climatology and these outlooks, drought removal is anticipated for South Florida.

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Forecast confidence in South Florida is high.

Thirty-day surpluses of 5-10 inches are common across the eastern two thirds of Texas and much of Oklahoma. Further north, heavy snowfall (1 to 2 feet) fell across parts of Nebraska and the Dakotas, easing drought conditions there as well. Spring precipitation events have also improved long term drought conditions across the Great Plains, with surpluses now observed on the 12 month time scale across Texas, Oklahoma, and western Kansas. Widespread deficits on the 3-year time scale are still present, however, and reservoirs have been slower to recover than soils and rivers. Climate Prediction Center (CPC) 8-14 day, monthly, and seasonal outlooks all indicate enhanced chances for above median precipitation across the central and southern Plains. Below median precipitation is favored across the far northern Plains during the 8-14 day period, with equal chances for below, near, or above median precipitation thereafter. The summer months are a relatively wet time of year across the northern Plains, which favors further drought reductions. Based on these outlooks, further improvements or removal of remaining drought areas are expected.

Forecast confidence in the Plains is moderate to high.

During the past 30 days, above average precipitation fell across much of Minnesota, while below average rainfall persisted across much of Wisconsin. The summer months are climatologically wet across the upper Midwest, particularly across Minnesota, which would favor drought reduction. Precipitation accumulations generally under 0.5 inches are forecast during the upcoming week, while the CPC 8-14 day outlooks favor below median precipitation. The monthly and seasonal outlooks indicate no anomalous climate signals during the summer. El Nino-Southern Oscillation (ENSO) precipitation composites are fairly noisy across the upper Midwest during the summer months. Based primarily on climatology, therefore, drought removal is anticipated across western and central Minnesota, where the percent of annual precipitation and positive soil moisture change values are the greatest. Drought persistence is slightly more favored across eastern Minnesota and Wisconsin, where soil moisture is more likely to decrease during the summer.

Forecast confidence in the upper Midwest is low to moderate.

Recent cool weather and above normal rainfall resulted in drought improvements across Colorado, eastern Utah, and southeastern Wyoming. In fact, SNOTEL snow water content (SWE) values across central Colorado are now above normal. In contrast, drier weather promoted expansion of abnormal dryness across much of Idaho, Montana, and western Wyoming, where snow water content values are considerably lower. The CPC 8-14 day outlook indicates enhanced chances of above median precipitation during Week-2 across the northern and central Rockies. The wet signal is persisted in the CPC monthly and seasonal outlooks as well. Based on these outlooks, drought improvement or removal is favored for much of the central and northern Rockies, including all of Colorado, eastern Utah, and eastern Idaho. Drought persistence is maintained across the remainder of the Intermountain West, where current SWE values are much lower and climatological precipitation is less.

Forecast confidence in the northern and central Rockies is moderate.

The Southwest Monsoon season presents difficulties for this outlook when drought is in place, since improvements under a convective regime tend to be spotty and difficult to pinpoint. CPC monthly and seasonal outlooks indicate enhanced chances for above median precipitation across New Mexico, and equal chances for below, near, or above median precipitation for Arizona. ENSO composites depict a statistically significant dry climate anomaly across Arizona and New Mexico during the summer months, corresponding to the early monsoon period. Gulf surges due to tropical cyclone activity over the eastern Pacific may mitigate this dry signal later in the monsoon season. Based on the ENSO composites and CPC outlooks, drought persistence is forecast for southeastern California and most of Arizona. Drought improvement or removal is forecast for New Mexico and far northeastern Arizona, although these improvements will be spotty in nature.

Forecast confidence in the Southwest Monsoon region is moderate.

The dry season is in full swing across the Western U.S., although a series of troughs have brought some moisture to the Cascades, northern Sierras, and Great Basin. SNOTEL SWE values remain extremely low across the West. The CPC 8-14 day outlook persists this wet pattern for the Great Basin region, while the monthly and seasonal outlooks both maintain equal chances for below, near, or above median precipitation across the West. While the short term rainfall may result in localized ephemeral drought relief, the summer climatology favors persistence. Since streams and reservoirs largely rely on snowmelt for maintenance during the dry season, further drought degradations are also likely throughout the western states. Additional drought expansion is likely across the Pacific Northwest.

Forecast confidence in the West is high.

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Jerome Fitzgerald
5/25/2015 | 4:37 PM CDT
beautiful weather for salmon fishing in southeast Alaska .raining in Idaho still 3 pivots of corn left to plant