Tools used in the U.S. Seasonal Drought Outlook (SDO) included the official Climate Prediction Center (CPC) temperature and precipitation outlooks for May 2016 and May-July 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, May and MJJ climatology, the AMJ16 (most recently available) Caribbean Regional Climate Center (Caricof) Climate Outlooks (for Puerto Rico), and initial conditions. With the current El Nino winding down, no ENSO composites were considered for this Outlook.

The May-July season is climatologically a wet time of year for the northern Great Plains states. The Dakotas typically receive about 40-50 percent of their annual precipitation during the late spring and early summer. This is due, in large part, to passing low pressure systems and overnight thunderstorm clusters (MCS's). For the northern High Plains and adjacent eastern foothills of the Rockies, the climatological percentages for MJJ are less, ranging between 20-40 percent. The North American Land Data Assimilation System (NLDAS) ensemble mean soil moisture anomalies (current, top 1-meter of soil) in North Dakota and northern South Dakota range from 1-3 inches below normal. Up to 1-2 inches of precipitation is forecast across this region during the next 7-days. The Week-2 and experimental Weeks 3 and 4 precipitation outlooks indicate the best chances for above-median precipitation is for southern portions of this region. CPC's 30-day outlook for May, and 90-day outlook for May-July, do not favor any particular category, so Equal Chances (EC) is indicated. Considering these factors, a one-category improvement is forecast in this region, resulting mostly in drought removal.
Forecast confidence for the Northern Plains is moderate.

MJJ climatology also favors wetness across the south-central Plains, extending into Missouri. Approximately 30-45 percent of the annual precipitation received in this region usually falls during the MJJ season. This is also attributed to, in large part, to passing low pressure systems and MCS's. Up to an inch of rain is forecast during the next 7-days across this area, with Week-2 and Weeks 3,4 precipitation outlooks tilting toward the wetter-than-median tercile. Probabilities for above-median precipitation are higher across the south-central Plains than they are for the northern Plains. CPC's monthly and seasonal outlooks also favor above-median precipitation. Based on the above factors, a one-category improvement is anticipated, warranting drought removal for nearly all areas.
Forecast confidence for the south-central Plains is moderate to high.

Across the West, the wet season and the El Nino are beginning to wind down. During the past 30-days, AHPS Percent of Normal Precipitation (PNP) values range from 25-75 percent in Utah, 10-75 percent in Arizona, 150-400 percent in southwestern New Mexico, 25-75 percent in southern and western Nevada, 10-75 percent in California, and 25-75 percent in southern interior Oregon. According to the Western Regional Climate Center in Reno, Nevada, SNOTEL basin-wide Snow Water Content (SWC) values range from about 50-75 Percent of Average (POA) in Utah, less than 50 POA in Arizona and southern New Mexico, 75-90 POA in northwestern Nevada and the California Sierras, and 50-75 percent in southern interior Oregon. For the upcoming 7-day period, moderate to heavy precipitation (0.5-3.0 inches) is expected across northern portions of California (including the Sierras), 0.25-0.50 inch for northwestern Nevada and the southern interior of Oregon, with little to no rainfall forecast across remaining portions of the Western drought area. The Week-2 precipitation outlook from CPC favors a tilt in the odds towards above-median precipitation, while the Weeks 3,4 outlook favors above-median precipitation for the Four Corner states, and EC elsewhere. The May 2016 and May-Jul 2016 precipitation outlooks favor above-median precipitation across much of this region. Though above-median precipitation is favored for most time periods out to 90-days, it is not expected to be enough to warrant at least a one-category improvement in the U.S. Drought Monitor depiction. One possible exception is the southern portion of the Persistence area in Utah, which may get enough rainfall to justify a one-category improvement. The northern portion of this Persistence area is also less likely to receive significant monsoonal moisture in July, increasing support for drought persistence.
Forecast confidence for The West is moderate to high.

The return of the trade winds and the resulting shower activity to the east- and northeast-facing slopes of the Hawaiian Islands signals a more typical circulation pattern, now that the El Nino is fading away. Any residual areas of moderate drought (D1 on the U.S. Drought Monitor depiction) are ripe for removal along the eastern slopes. Drought persistence is predicted along the lee (western) slopes of the Hawaiian Islands.
Forecast confidence for Hawaii is moderate.

There is currently no drought in Alaska.

In Puerto Rico, the rainy season is approaching. This is largely due to the annual return of the Inter-Tropical Convergence Zone (ITCZ), with its surface trough of low pressure and related convective rainfall patterns. It is also connected with the start of the Atlantic hurricane season on June 1st. The Caribbean Regional Climate Outlook Forum (cariCOF) Climate Outlook for Apr-Jun 2016 (latest available) predicts a 45 percent chance of above-median rainfall in Puerto Rico, a 35 percent chance of near-median rainfall, and a 20 percent chance of below-median rainfall. Considering these factors, a one-category improvement in drought conditions is expected across Puerto Rico.
Forecast confidence for Puerto Rico is moderate.

Forecaster: Anthony Artusa

Next Seasonal Drought Outlook issued: May 19, 2016 at 8:30 AM EDT