Drought coverage across the country has progressively declined over the past several months, as assessed by the Drought Monitor. At the end of November 2016, drought encompassed more than one-quarter of the nation. That number dropped below 12 percent at the end of March 2017, and to 4.2 percent in early May, the least coverage since Drought Monitor statistics were first calculated at the beginning of 2000.
In the last four weeks, drought was alleviated in substantial parts of the Northeast, Middle Atlantic States, and south-central Plains. However, latent long-term moisture shortages remain across the Northeast, and drought could re-develop quickly should any substantial period of abnormal heat and dryness occur.
Currently, drought covers much of Florida, Georgia, and eastern Alabama, with extreme drought affecting the central Florida Peninsula and portions of both southern and northern Georgia. Scattered areas of drought exist elsewhere across the southern tier of states from South Carolina to central Texas.
Farther west, drought covers isolated spots in central Colorado and northeastern Wyoming, portions of southwestern California, a swath from southernmost California eastward into southwestern New Mexico, and western parts of the Big Island of Hawaii.
In the contiguous states, drought is expected to persist or intensify in southern California and southwestern Arizona, where above-normal temperatures and seasonably dry conditions are expected. Drought persistence is also favored from west-central Georgia into central and northeastern South Carolina due to seasonal topsoil decline, and less rainfall expected through the rest of the month than in neighboring areas.
At least some improvement is expected in other drought areas.
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In Hawaii, drought on western parts of the Big Island should persist, except along the lower Kona Slopes in the northwesternmost reaches of the Big Island, where summer is a markedly wet time of year.
Forecast confidence is high across the Florida Peninsula, and moderate elsewhere in the Southeast.
- Currently, the Nation’s most substantial broad-scale drought is affecting the Southeast, the only part of the country where extreme drought exists. Rainfall was 3 or more inches below normal for the last three months from central Georgia southward through much of the Florida Peninsula, and six-month deficits of 8 to 12 inches covered the central Florida Peninsula, where a fairly broad area of extreme drought exists.
- From these areas drought on the Drought Monitor extends into portions of South Carolina, southeastern and northwestern Alabama, and northeastern Mississippi.
- Summer is a relatively wet time of year across central and southern South Carolina, southeastern Georgia, and the Florida Peninsula (particularly later in the period) while farther west, summer does not lean dry nor wet relative to the rest of the year. Typically 40 to 50 percent of annual precipitation falls during JJA across the Florida Peninsula.
- Moderate to heavy rains of 1.5 to locally 3.5 inches are forecast through May 24 from western South Carolina and central Georgia westward across Mississippi, with lesser amounts expected closer to the Atlantic Coast and across the Florida Peninsula.
- Odds favor above-normal precipitation for the 6- to 10-day period, and extends through the 8- to 14-day forecast period from the northwestern half of Georgia westward. Thereafter, odds do not particularly favor either wetness nor dryness for the summer as a whole.
- As a result, drought is expected to persist from much of central and southwestern Georgia northeastward through central and northeastern South Carolina, with improvement or removal expected elsewhere (due to wetness in the short-term in western parts of the area, and the marked climatological increase in rainfall in southeastern Georgia and the Florida Peninsula).
- It should be noted that drought will likely expand into some areas not presently affected, especially in central Georgia, but no areas of development are forecast because no specific regions seem especially vulnerable relative to others, and what development occurs is not expected to be widespread.
Forecast confidence is generally moderate to high, but low in Deep South Texas.
- Drought covers scattered areas across the southern Great Plains and some adjacent parts of the westernmost Lower Mississippi Valley.
- Outside Deep South Texas, some relief is anticipated within the next week as 2.0 to locally 4.5 inches of precipitation forecast across central and northeastern Texas, Oklahoma, and adjacent parts of Arkansas and Louisiana.
- Enhanced chances for above-normal precipitation continue through the last week of May (again, outside Deep South Texas) and the summer outlook indicates an increased likelihood for above-normal rainfall through all the drought regions except in western Arkansas and northwestern Louisiana.
- Precipitation climatology is not remarkable here during summer, with amounts not markedly higher nor lower than other times of the year.
- The short- and longer-term outlooks all argue for improvement regionwide, though not as vehemently in Deep South Texas.
Forecast confidence is high for the High Plains.
- Small areas of drought exist in central Colorado and northeastern Wyoming.
- For the next seven days, moderate precipitation (about an inch) is forecast in northeastern Wyoming while heavy amounts (2 or more inches) are expected in the drought area of central Colorado, including some accumulating snow. Thereafter, odds favor above-normal precipitation for the last week of May in central Colorado, and in all the areas of drought for the JJA season as a whole.
- Summer is slightly wetter than other seasons, with 30 to 40 percent of annual precipitation expected during JJA. As no areas worse than moderate drought exist, drought removal is the only reasonable forecast given the indicators.
Forecast confidence is high in southern California and across southeastern Arizona and southwestern New Mexico, but lower between these two areas, where climatology is less telling.
- Summer rainfall and soil moisture climatologies vary significantly across the drought areas in the Southwest, which cover parts of southwestern California and a swath from far southern California eastward into southwestern New Mexico.
- Summer is a pronounced dry season in southwestern California, where less than two percent of annual precipitation typically falls during the period.
- Farther east, monsoon-related rainfall increases later in the summer, and JJA usually brings 40 to 45 percent of annual precipitation to southeastern Arizona and southwestern New Mexico.
- Between these two extremes, summer is not a particularly dry nor wet time of the year.
- Negligible precipitation is likely through the end of May, and the JJA 2017 precipitation outlook is nondescript, with neither abnormal dryness nor wetness favored. Therefore, the forecast is based on climatology, with persistence or intensification in the typically-dry areas in southern California and far southwestern Arizona, and removal anticipated from south-central Arizona eastward.
Forecast confidence in the Northeast is low.
- In southern New England and the adjacent Northeast, precipitation for the last 60 to 90 days has been sufficient to remove drought from the region, though some residual dryness lingers in part of Connecticut. However, long-term precipitation totals remain substantially below normal.
- For the last 24 months, amounts were a foot or more below normal across part of eastern Pennsylvania, central and northern New Jersey, southeastern New York, and most of Connecticut and Massachusetts. Two-year deficits exceed 16 inches in part of Connecticut and the western suburbs of New York City.
- Precipitation should be close to normal through May 22, and odds favor above-normal precipitation during the last week of May. Thereafter, the odds favor above-normal temperatures but neither above- nor below-normal precipitation for the summer as a whole.
- Given the expected continuation of near- or above-normal precipitation through the end of the month, and the nondescript precipitation outlook for JJA, no drought development is forecast, but with latent long-term precipitation deficits still in place, this region will need to be closely monitored as summer progresses; drought could re-develop and intensify quickly should a substantial period of heat and dryness occur.
Confidence is moderate for Hawaii.
- In Hawaii, drought should ease along the lower Kona Slopes on the norwestern part of the Big Island, where summer is a pronouncedly wet time of year. This is not the case in the remainder of the moderate drought area on western sections of the Big Island, so drought is expected to persist through summer there.
- Drought neither exists nor is forecast to develop in Alaska and Puerto Rico.
