Tools used in the U.S. Monthly Drought Outlook (MDO) included the Climate Prediction Center (CPC) temperature and precipitation outlooks for June, 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), the Week 3-4 outlooks and tools from CPC, dynamical models at the monthly time scale, the 384-hour total precipitation forecasts from several runs of the GFS, and climatology for June. Initial conditions such as soil moisture, 28-day streamflows, and Snow Water Content (SWC) were also considered. The May 28 USDM was used for the initial drought conditions.
The Advanced Hydrologic Prediction Service (AHPS) Percent of Normal Precipitation (PNP) values for the past 30-days range from 200-600 percent of normal in central and southern Clalifornia eastward to parts of the northwestern Southwest and parts of central Montana, down to 5-25 percent of normal in far southeastern California, Southwestern Arizona, and southern portions of New Mexico. SWC is well above average in California, the Central Great Basin and the Central Rockies, and below average in the Cascade Mountains (7% to 78%). Across the West, 28-day streamflows from the U.S. Geological Survey depict values in the lowest quartile of the historical distribution for this time of year in western Washington, north central Colorado, and in other very scattered locations. June precipitation climatology favors increasing dryness across the West Coast states and the Southwest (pre-monsoon), and relatively wet conditions in the Rockies and adjacent High Plains. Precipitation outlooks for the next 30-days favor relatively wet conditions across the Four Corners drought area (including southeastern New Mexico) and the Central Great Basin, and relatively dry conditions for the Pacific Northwest. Accordingly, drought conditions are likely to be improved or removed across the southern Rockies/Four Corners region during June, though drought conditions are likely to persist and expand in southern Washington state.
Forecast confidence is moderate to high for improvement/removal for the southern Rockies/Four Corners region, moderate for Washington State.
The High Plains region is currently drought-free. Precipitation forecasts for nearly all time-scales out to a month is expected to be above normal in most of the region. With these precipitation outlooks, soil moisture ranks above the 90th percentile from South Dakota into Kansas, and with a wet June climatology, drought development is unlikely by the end of June. An exception is for development in northern North Dakota and adjacent areas where D0 currently exists. 60-day precipitation has averaged between 40-70 percent of normal and near to below normal precipitation and above normal temperatures in all time ranges out to a month are expected.
Forecast confidence is high for most of the High Plains region, but low to moderate for northern North Dakota.
Only one small lingering area of moderate drought remains in southwestern Texas. With a somewhat wet June climatology, and above normal precipitation, and near to below normal temperature forecasts at most time ranges out to a month, all point to drought removal in this region. The remaining portion of the South are wet, and no development is expected by June 30.
Forecast confidence is moderate to high for the South.
Widespread flooding continues across parts of the Midwest region, especially along the banks of the Missouri and Mississippi Rivers and the Red River of the North. During the past 30 days, precipitation surpluses range from 2 to 8 inches throughout much of the Midwest, with soil moisture ranking in the 95th-99th percentiles for this time of year. Based on a wet June climatology, wet initial conditions, and the expectation of near normal precipitation at all timescales out to a month, drought development is unlikely during the outlook period.
Forecast confidence is moderate to high for the Midwest Region.
Abnormal dryness (D0) and moderate drought (D1) affected the area from Alabama and northern Florida eastward to the Carolinas during May. 60-day precipitation deficits range from 1 to 4 inches in these D0 and D1 areas, and 28-day streamflows fall within the lowest quartile. June precipitation climatology favors a slight tilt toward wetness, especially in Florida. Climatologically, sea-breeze induced and/or pulse convective activity in this area ramps up significantly by about mid-June. June precipitation forecasts were mixed, included dry weather in the QPF (Days 1-7) and slight odds for subnormal rainfall for Weeks 3-4, but above normal rainfall during the extended range (Days 6-10 and 8-14). Despite this, the predicted ERF precipitation amounts are not expected to be enough to erase longer-term deficits, plus most temperature outlooks out to a month favor above normal temperatures over the region. Therefore, drought persistence (and even some development) is considered more likely.
Forecast confidence is moderate for much of the Southeast Region; but low along and near the South Atlantic Coast.
The Northeast region has remained drought-free since early November 2018. During the last 60-days, widespread precipitation surpluses have been observed across most of the Northeast, and soil moisture ranks above the 80th percentile for nearly all of this region. Based on these initial soil moisture conditions, June climatology favoring a slightly tilt toward wetness, and near to slightly below normal rainfall and near normal (EC) temperatures for all time ranges out to the end of June, drought development is unlikely to occur.
Forecast confidence is moderate to high for the Northeast Region.
Moderate to extreme drought (D1 to D3) coverage remained nearly steady along the southeastern Alaska Panhandle this past month. Since June is a normally dry month, along with favorable odds of below normal precipitation and above normal temperatures at all scales, drought should continue across the southeastern Alaska Panhandle and drought development is likely for western sections of the southeastern Alaska Panhandle.
Forecast confidence is moderate to high for Alaska.
With unseasonable warmth and subnormal rainfall, abnormal dryness (D0) expanded while extreme drought (D3) returned to the southern Big IslandHawaii during the last 30 days. The CPC's monthly outlooks indicate near normal precipitation and slightly above normal temperatures during June, and the archipelago is entering its dry season with a weak El Niño in progress. These factors support drought persistence for the leeward slopes of the Hawaiian Islands.
Forecast confidence is high for Hawaii.
Drought coverage dropped from 32.51 percent three months ago to 15.54 percent across Puerto Rico. The large reduction in drought and abnormal dryness occurred over the western third of the Commonwealth in early to mid-April. In contrast, conditions have been deteriorating farther southwest. Thirty-day precipitation deficits range from 2 to 8 inches in the interior portion of central Puerto Rico, and dryness/drought is expanding towards the southwest coast. Monthly forecast tools favor below normal precipitation in this region. Although climatology becomes increasingly wet from late spring, it may not be enough to erase the longer-term deficits noted above. Therefore, drought persistence is expected in Puerto Rico.
Forecast confidence is moderate for Puerto Rico.
Forecaster: Yun Fan
Next Monthly Drought Outlook issued: June 30, 2019 at 3 PM EDT