Tools used in the U.S. Monthly Drought Outlook (MDO) include the Climate Prediction Center (CPC) temperature and precipitation outlooks for May, various short- and medium-range forecasts and models such as the 7-day quantitative precipitation forecast (QPF) totals from the Weather Prediction Center (WPC), the 6-10 day and 8-14 day CPC extended-range forecasts (ERFs), dynamical models at the monthly time scale, climatology for May, and initial conditions such as soil moisture. The U.S. Drought Monitor valid on April 23, 2024 was used for initial drought conditions.

Drought currently covers slightly more than 20 percent of the Western Region, primarily along the northern and southern tiers of the region. May precipitation climatology relative to other times of the year is highly variable across the region. April climatological dryness carries through May in the southern Rockies, with less than 2 percent of the annual total typically recorded during May in the southern half of Arizona, and under 5 percent typical in the rest of the southern Rockies. Less than 5 percent is also typical across most of California and the Pacific Northwest from the Cascades to the Pacific Coast, where May continues the seasonal decline in precipitation that usually carries through the summer. In contrast, May rainfall climatology in central and eastern Montana is more similar to the Plains States, where this is one of the wettest months of the year. Central and eastern Montana on average record 14 to 20 percent of their annual precipitation total during May. Interior parts of the west region are either neutral compared to most other times of the year, or lean slightly dry during May. Most areas of drought in the West Region are expected to persist or intensify during the month, with the exception of a few high-elevation locations in western Montana and central Washington, where the 7-day forecast from the Weather Prediction Center on April 30 calls for 1.3 to 2.5 inches of precipitation, which is considerably higher than other parts of the West Region. Some drought development is forecast in parts of southeastern Montana, central New Mexico, and northeastern New Mexico where there are antecedent precipitation deficits, with subnormal precipitation expected through at least the first several days of May. Due to dry climatology and the official May monthly outlook showing enhanced chances for drier than normal conditions, the persistence/intensification and development forecasts across the southern tier of the Western Region are highly confident. In contrast, increased chances for above-normal precipitation during the 6-10 day period and the wetter climatology make the similar forecasts across the northern tier of the Western Region considerably more uncertain.

Forecast confidence is high across the southern tier of the Western Region, moderate in central Rockies and Pacific Northwest, and low from the northern Intermountain West through most of Montana.

In late April, drought covered about 21.5 percent of the High Plains Region. May is a wet time of year for most of the High Plains Region. Locations from the eastern Rockies eastward across the northern and central Great Plains typically record 12 to 18 percent of their annual precipitation during May. The western half of Colorado and western one-third of Wyoming are the only exceptions in the High Plains Region; May is neither particularly wet nor dry compared to other times of the year. The wet climatology can be a double-edged sword, statistically increasing the odds for drought-impacting precipitation, but also allowing for precipitation deficiencies to increase quickly if observed totals are considerably below normal. For May 2024, improvement or removal is forecast for drought areas in the Great Plains (most of Kansas, southeast Nebraska, and northeast North Dakota) due to heavy rainfall in late April and early May, in combination with the official May outlook favoring above-normal precipitation in most of these areas, except southeast Nebraska. Farther west, drought is expected to persist or intensify in drought areas across far western sections of Kansas and the Dakotas, northern Wyoming, and parts of southern and western Colorado. Late April and early May precipitation is expected to be considerably lighter in these areas, and the official monthly precipitation outlook favors neither higher- nor lower-than-normal totals. Antecedent dryness has southeastern Colorado on the cusp of drought conditions, and with subnormal precipitation expected to continue into at least the second week of May, drought development is forecast there by the end of the month.

Forecast confidence in the High Plains Region is high in Kansas and southern Colorado, and moderate elsewhere.

Drought covers a little under 20 percent of the Southern Region, primarily in the western and northern areas. May is a relatively wet month across Oklahoma and the central tier of Texas from the Red River through Deep South Texas, where 12 to 18 percent of the annual precipitation total typically falls during May. The month leans only slightly wetter than most other months of the year in eastern New Mexico, eastern Texas, and the northern and western sections of Arkansas while other parts of the Southern Region are neither wet nor dry compared to other months. Similar to areas farther north, a line can be drawn along the western edge of the Great Plains, with drought areas in western Texas and parts of the Oklahoma Panhandle expected to persist or intensify while drought eases or is removed from areas farther east. Heavy rainfall in late April and early May are expected to bring improvement to central Texas. Farther north, across drought areas in most of Oklahoma, northern Arkansas, and southeastern Tennessee, the official May outlook shows enhanced chances for above-normal precipitation for the month as a whole, justifying a similar forecast in those areas. The May outlook does not favor wet weather in drought areas along the western tier of the Southern Region, and in fact calls for enhanced chances for below-normal May precipitation in the Big Bend and part of extreme west-central Texas. Warmer than normal conditions are also expected during May in this area, increasing the odds for drought persistence and intensification in western parts of the Southern Region. Some drought development is forecast in the northwestern Texas Panhandle and the adjacent Oklahoma Panhandle, where short-term precipitation deficits have been increasing.

Forecast confidence is moderate to high for the Southern Region.

Drought covers over 23 percent of the Midwest Region, primarily along and west of the Mississippi Valley. Little or no drought exists from Michigan and Illinois eastward across the northern Ohio Valley. May is somewhat wetter than most other times of the year in the drought-affected parts of the Midwest Region, especially along the western tier adjacent to the High Plains Region. Moderate to heavy precipitation in late April and early May is anticipated in areas affected by drought, and the monthly outlook for May has enhanced chances for wetter-than-normal weather across the drought areas in most of Missouri, Illinois, Minnesota, and most of Wisconsin. The 8- to 14-day outlook also favors above-normal precipitation for most drought areas in the Midwest Region. With above-normal precipitation expected on most or all time frames, drought improvement or removal (depending on initial intensity) is forecast for all drought areas in the Midwest Region.

Forecast confidence is moderate to high in the Midwest Region.

Currently, no drought exists in the Southeast Region, but that is expected to change. Most of the region is expected to remain in a pattern of near- to above-normal rainfall through most of May, with the exception of the Florida Peninsula. The May outlook favors subnormal rainfall in this region, as do the shorter-term forecasts (through the next 2 weeks). A spell of hot weather is also expected after the first week of May, with record or near-record highs of 90 to 95 deg. F forecast for at least a few days. The combination of high temperatures and subnormal precipitation should allow drought to develop across a large part of the Florida Peninsula by the end of May, and probably earlier. 20 to 30 percent of the state could slip into drought during the next few weeks.

Forecast confidence is high in the Southeast Region.

No drought currently exists in the Northeast Region, as determined by the U.S. Drought Monitor, and none is expected to develop. Subnormal precipitation during the first week of May is expected to give way to wetter conditions later in the month, with near- or above-normal rainfall favored in most areas for the 6- to 10-day and 8- to 14-day periods. The May outlook for the month as a whole shows enhanced chances for surplus rainfall in the southernmost states (Maryland and West Virginia) with no tilt of the odds in either direction farther north. Given the lack of any compelling reason to expect drought development, the Northeast Region is expected to be drought free through the end of the month, although the inherent unpredictability of spring precipitation in the region, along with a lack of a strong wet signal, reduces confidence.

Forecast confidence is moderate in the Northeast Region.

Alaska is forecast to remain drought-free by the end of May. Somewhat below normal precipitation, along with a deficient snowpack, has affected the southeasternmost part of the state for a few months (about 2.5 percent of the state). Although no drought development is forecast, this area is at a slightly enhanced risk and will need to be monitored closely.

Forecast confidence is high in most of Alaska, but moderate in southeasternmost sections.

With subnormal precipitation favored during May, the areas of drought in Hawaii, now covering about one-third of the state, are expected to persist or intensify. In addition, abnormal dryness not yet reaching drought intensity over portions of the southeastern half of the state are expected to slide into drought by the end of the month, given the drier than normal weather anticipated. If all areas of expected drought development occur, about half of the state will be experiencing drought by the end of May.

Forecast confidence is moderate in Hawaii.

In Puerto Rico, heavy rainfall in late April and early May are expected to remove the small area of drought in the northwestern part of the Commonwealth early in the month.

Forecast confidence is high in Puerto Rico.

The U.S. Virgin Islands are forecast to remain drought-free through the end of May. A pattern of above-normal rainfall has been observed over the last several weeks, and there is no compelling guidance to indicate that this trend should sharply reverse by the end of the month.

Forecast confidence is moderate in the U.S. Virgin Islands.

Forecaster: Rich Tinker

Next Monthly Drought Outlook issued: May 31, 2024 at 3:00 PM EDT