Tools used in the U.S. Seasonal Drought Outlook (SDO) included the official Climate Prediction Center (CPC) temperature and precipitation outlooks for June 2016 and June-August 2016, various short- and medium-range forecasts and models such as the forecast 5-day and 7-day precipitation totals from the Weather Prediction Center (WPC), the 6-10 day, 8-14 day, and weeks 3-4 CPC forecasts, the NAEFS precipitation outlooks, the soil moisture tools based on the Constructed Analog on Soil Moisture (CAS), dynamical models (CFSv2, NMME, IMME, IRI, and IMME), the 384-hour total precipitation forecasts from several runs of the GFS, the four-month Palmer drought termination and amelioration probabilities, June and JJA climatology, the AMJ16 (most recently available) Caribbean Regional Climate Center (Caricof) Climate Outlooks (for Puerto Rico), and initial conditions. A transition from El Nino to ENSO neutral is anticipated over the next few months, with a transition to La Nina conditions favored beyond the forecast period. Therefore, climate anomalies associated with ENSO events are not expected to play a significant role in the overall Northern Hemisphere summertime pattern.

During the past 60 days, temperature anomalies ranged between 4 and 8 degrees (F) above normal across the Pacific Northwest. The unseasonable warmth promoted rapid melting of the mountain snowpacks, removing a critical source of reservoir recharge during the drier summer months. Abnormal dryness accompanied the heat, with most locations accumulating less than 75 percent of normal precipitation over the same period, and parts of north-central Oregon, north-central Washington, and the Olympic Peninsula receiving less than 50 percent of normal precipitation. Streamflow conditions are poor across western Washington and northwestern Oregon. Accordingly, abnormal dryness (D0) expanded northward across much of the Pacific Northwest. During the next two weeks, forecasts from WPC and CPC favor cooler temperatures and above-median precipitation. While such a pattern would yield some relief to these expanding impacts, the benefits will likely prove ephemeral, since the prime snowpack building season has passed. Both the CPC monthly and seasonal outlooks favor a return to above-normal temperatures, with equal chances for below-, near-, or above-median precipitation. Therefore, based on climatology and the very low snow water content values at the start of the summer dry season, drought development is favored for central and eastern Oregon, far southwestern Idaho, and western and central Washington. Persistence of existing drought conditions is forecast for southeastern Oregon.
Forecast confidence for the Northwest is moderate to high.

Streamflow conditions are better across central and northern California compared to the Northwest, and with the core of the above-normal temperatures during the spring centered to the north, snow water content values across the Sierras remain near normal. Reservoir levels across northern California are generally near their historical average levels, with the high volume Lake Shasta and Lake Oroville reservoirs at 92 and 96 percent of capacity (108 and 115 percent of normal), respectively. Due to these conditions at the start of the dry season, significant improvements to the USDM drought depictions were made across northern California and northwestern Nevada. Conditions are poorer across southern California, with low streamflow values and most reservoir levels below their historical averages. Therefore, extreme (D3) to exceptional (D4) drought continues to be depicted on the USDM. The summer months are a climatologically dry time of year across California, so water availability is largely dictated by snowmelt into the reservoirs. Outside of small adjustments due to snowmelt and reservoir levels, it is unlikely that drought conditions will change substantially during this period. Therefore, persistence of existing drought areas is forecast for California and the Great Basin. 
Forecast confidence for California and the Great Basin is moderate to high.

Widespread above-normal precipitation resulted in drought reductions across Utah, Wyoming, and parts of Montana during the past several months. Temperatures across the northern Rockies were well above-normal during the spring, resulting in early melting of the mountain snowpacks. The summer months are a wet time of year across much of Montana, and neither a wet nor dry period for Wyoming. During the short range, WPC forecasts favor widespread heavy precipitation across the northern Rockies and adjacent high plains, which should continue the drought improvement trend in this region. The CPC monthly outlook for June favors above-median precipitation for the northern Rockies, while the seasonal outlook maintains the wet signal for southeastern Idaho, Wyoming, and southern Montana.
Forecast confidence for the northern Rockies is moderate.

Little change to the drought depiction was made across the Four Corners states during the past month, with some expansion of abnormal dryness (D0) across southern Utah, and improvements across northeastern New Mexico. Temperatures were near to below average during the past two months, and snowpack conditions across the central and southern Rockies are above average. The summer months are a wet time of year across much of Arizona and New Mexico as the Monsoon ramps up. Due to the discrete convective nature of the precipitation, however, it is difficult to pinpoint which areas will realize improvement and which areas will miss out on the Monsoon moisture. Additionally, the climatological peak of the Monsoon is during the latter part of this forecast period, and therefore significant improvements may not be fully realized until September. Therefore, while localized drought reduction is likely, drought persistence is maintained as the most likely outcome across Arizona. Removal of drought is favored across most of New Mexico due to widespread precipitation forecast in the shorter term.
Forecast confidence for the Four Corners States is low to moderate.

The spring months have been very wet across the Plains, with widespread drought reductions occurring over the previous four weeks across both the northern and central Plains. A small area in the eastern Texas Panhandle and western Oklahoma consistently missed out on this rainfall, so a small sliver of moderate drought (D1) remains. Abnormal dryness (D0) persisted over parts of the upper Midwest and North Dakota. During the next week, additional moderate to heavy rainfall is forecast to overspread much of the Plains, and the CPC 8-14 day outlook maintains a wet pattern across the central and southern Plains, with drier conditions overspreading the northern Plains. The CPC monthly outlook for June maintains a similar pattern, with enhanced chances for above-median precipitation across the Plains and the central and lower Mississippi Valley, and a tilt towards drier conditions across northeastern North Dakota through the western Great Lakes. The seasonal forecast depicts no regions favoring below-median precipitation, and has enhanced chances for above-median precipitation across the central Plains. Based on the wet initial conditions, a wet summer climatology, and the generally wet forecast guidance, drought removal is anticipated for the small D1 area in the southern Plains. Widespread drought development is not anticipated across the central and southern Plains and Midwest this summer. However, drier conditions during the spring have left eastern North Dakota, and northern Minnesota vulnerable to drought development. Although short range wetness is forecast and could temporarily increase soil moisture, guidance for the Week 3-4 period favors a return to drier and warmer conditions. June is the climatological wettest month of the year for North Dakota and Minnesota, so given the drier June outlook, drought development is favored by the end of August for eastern North Dakota, far northeastern South Dakota, and northern Minnesota.
Forecast confidence for the Plains and Midwest is low to moderate.

Much of the Northeast has experienced a dry spring, with precipitation deficits ranging from 2 to 6 inches across much of Pennsylvania, New York, northern New Jersey, and southeastern New England. Consequently, streamflow values are low for this time of year. Temperatures over the past 60 days were generally below normal, which helped to delay drought onset by keeping evapotranspiration (ET) rates low. Still, abnormal dryness (D0) expanded across much of this region during the past month, and moderate drought (D1) developed just east of the Allegheny Plateau across southern Pennsylvania and western Maryland. The Northeast typically receives generous precipitation with an even distribution throughout the year, and drought conditions are therefore typically difficult to maintain at long time scales. During the next week, heavy precipitation is forecast to overspread the Mid-Atlantic region as a wave of low pressure moves up the coast, but a sharp rainfall cutoff near the Mason Dixon Line is anticipated. The CPC 8-14 day outlook favors below-median precipitation and above-normal temperatures, which will increase ET rates towards the beginning of June. Both the CPC monthly outlook for June and the seasonal outlook favor above-median temperatures. Based on these outlooks and the dry initial conditions, short term drought development is likely across much of Pennsylvania, northern New Jersey, southern New York, and southern New England, but there is lower confidence that the drought will last through the end of the outlook period. The CPC seasonal outlook favors above-median precipitation across northern New England, so no drought development is depicted there.
Forecast confidence for the Northeast is low to moderate.

During the past 90 days, parts of Tennessee, northern Georgia, and the far western Carolinas received less than 70 percent of normal precipitation, resulting in short term moderate drought (D1) development. During the next week, WPC QPF forecasts depict widespread rainfall accumulations exceeding two inches across these drought areas. The CPC monthly outlook for June favors above-median precipitation across much of the Southeast, while the seasonal outlook maintains equal chances for below-, near-, or above-median rainfall. Based on the wet short range and monthly forecasts and the lack of a clear dry signal later in the summer, removal of the short term drought conditions is favored.
Forecast confidence for the Southeast is moderate.

Moderate drought conditions continue to linger across the southwestern facing portions of the Hawaiian islands. The summer months are a climatologically dry time of year for Hawaii, and the JJA seasonal outlook maintains equal chances for below-, near-, or above-median precipitation, so persistence of these drought areas is favored. During the past 30 days, widespread rainfall across Puerto Rico resulted in drought reduction. A continued wet pattern is anticipated over the next month, so removal of the remaining drought areas is anticipated. There are currently several areas of abnormal dryness across Alaska, but the CPC monthly and seasonal outlooks generally favor a wet signal, so no drought development is indicated on this outlook.
Forecast confidence is moderate for Hawaii, Alaska, and Puerto Rico.

Forecaster: Adam Allgood

Next Seasonal Drought Outlook issued: June 16, 2016 at 8:30 AM EDT