Tools used in the U.S. Seasonal Drought Outlook (SDO) included the Climate Prediction Center (CPC) temperature and precipitation outlooks for June and June through August 2021 (JJA), 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 and seasonal time scales, the 384-hour total precipitation forecasts from several runs of the GFS, climatology for the JJA season, and initial conditions such as soil moisture. The USDM, valid on May 18, was used for initial drought conditions. ENSO-neutral conditions are likely during this outlook period. 

Short-term and long-term drought remains entrenched throughout a majority of the West with D2 (severe) to exceptional (D4) drought designated for parts of Washington, Oregon, California, Nevada, Idaho, Montana and the Southwest. As of mid-May, snow water equivalent remains below normal for California, the Great Basin, and the Four Corners region. Farther to the north across Washington, short-term drought expanded due to a lack of precipitation during the past 30 to 60 days. June-July-August is a dry time of year for Washington, Oregon and California. The Southwest is typically dry during June until monsoon rainfall begins later in July. Based on below normal precipitation during the past 30 to 60 days, low soil moisture conditions, and elevated monthly and seasonal probabilities of near to below normal precipitation and above normal temperatures for June and JJA, drought is expected to persist over the south-central West and to expand northward across parts of the Pacific Northwest and northern Rockies  

Forecast confidence for the Western Region is high for persistence and moderate for development. 

Soil moisture continues to decline across the Dakotas where drought continues to intensify due to precipitation deficits during the past 30 days. Due to the lack of wet signal among precipitation tools during the seasonal time scale along with the likelihood of above normal temperatures, persistence is forecast for a majority of the long-term drought across the central to northern High Plains with potential development over those D0 areas in the central High Plains. However, this region is entering their wettest time of year when 40 to 50 percent of its annual precipitation occurs from June through August. This wet climatology reduces forecast confidence of persistence or development. 

Forecast confidence is moderate to low for the High Plains Region.
 
Drought varies in intensity across Oklahoma and Texas with the lowest soil moisture (below the 5th percentile) affecting western and southern Texas. Heavy rainfall during the past 30 days brought major improvements across much of Texas and predicted heavy rainfall in the next two weeks favors further improvement in these areas. Monthly to seasonal tools support elevated probabilities of below normal precipitation and above normal temperatures only across west Texas and the Texas Panhandle. Persistence is favored in parts of western Texas. Since June and JJA are one of the wettest months and seasons of the year across the western Southern Plains, this wet climatology reduces prediction confidence. The Southern Plains will be closely monitored in the monthly drought outlooks through the summer. Recent heavy rainfall and saturated soils make drought development unlikely throughout the lower Mississippi Valley and Tennessee Valley. 

Forecast confidence is low for the Southern Region.

The severe long-term drought across the Midwest remains centered across northwest Iowa, based on 6 to 12-month SPI values. Given the long-term duration of this drought area, persistence is most likely but forecast confidence is low since June-July-August is a relatively wet time of year. Drought persistence is more likely across the Corn Belt, Upper Mississippi Valley, and Great Lakes areas based on: lack of wet signals and near to above normal temperatures at both monthly and seasonal time scales, while a wet climatology reduces the forecast confidence. The Corn Belt will be closely monitored in the monthly drought outlooks through the summer. 

Forecast confidence is low for the Midwest Region.

The short-term moderate drought (D1) expanded for parts of the Carolinas due to precipitation deficit during the past 30 days. Due to the lack of a strong wet signal and likelihood of above normal temperatures among forecast tools from extended range forecasts to seasonal outlooks, drought persistence is likely for the Carolinas. Also, worsening drought conditions are anticipated in the short-term. For the short-term moderate drought (D1) over a small area in southern Florida, the onset of the convective season during June-July-August and a wet pattern from the monthly to seasonal outlook tools strongly favor removal of short-term drought across south Florida. 

Forecast confidence is moderate for the Carolinas and high for southern Florida.

Moderate drought (D1) is ongoing across small parts of the Northeast, where soil moisture and streamflows are below the 20th percentile. Since the monthly and seasonal outlooks calls for elevated probabilities of above normal temperatures and it is a favorable time of year for soil moisture discharge, drought persistence is forecast through the end of August. 

Forecast confidence is moderate for the Northeast Region.

Due to a lack of snowfall this past winter, abnormal dryness (D0) is designated for parts of northern and eastern Mainland Alaska. Based on an increasingly wet climatology for June-July-August, development is unlikely. Alaska is predicted to remain drought-free through August. 

Forecast confidence is high for Alaska.

Abnormal dryness (D0) and moderate drought (D1) expanded across the leeward slopes of the Hawaii Islands. Since the Islands already enter its dry season, the monthly and seasonal outlooks favor below normal precipitation, drought is forecast to persist or develop for leeward parts of the Hawaii Islands.

Forecast confidence is moderate for Hawaii.

Drought (D1) coverage expanded across Puerto Rico, due to below normal rainfall during the past month. The North American Multi-Model Ensemble forecasts favor below normal precipitation from monthly to seasonal precipitation outlooks. Drought persistence is favored. Since June-July-August is its wetter season of the year, this reduces forecast confidence.  
 
Forecast confidence is low to moderate for Puerto Rico.


Forecaster: Yun Fan
 
Next Seasonal Drought Outlook issued: June 17, 2021 at 830am EDT