During late Spring, multiple shortwave troughs ejecting over the Plains and interacting with ample Gulf moisture brought widespread, significantly above normal rainfall to the central and southern Plains.  Additionally, heavy snowfall (1 to 2 feet) fell across parts of the northern Plains.  This precipitation resulted in widespread drought reduction and removal across the Plains.  Above normal rain and mountain snowfall also fell over the central and southern Rockies, resulting in more localized drought improvements.  In contrast, abnormal dryness coupled with unseasonable May warmth resulted in declining streamflows and drought development across parts of the Northeast.  Drought conditions also worsened across the northwestern quadrant of the Nation, where below normal precipitation provided no boosts to extremely low mountain snowpack conditions.  Although there is not a clear climate anomaly signal favoring below normal precipitation for the Northeast, current conditions are likely to continue to degrade as evapotranspiration increases during the Summer months.  Therefore, drought persistence and further expansion is forecast for the Northeast where streamflows are already low, although periodic summer thunderstorms may erode drought conditions in many areas before the end of August.  A continuation of above normal precipitation is favored across the central Rockies, central and southern Plains, and southeastern U.S. during the Summer months, which would favor further drought reductions.  Additionally, the onset of the Summer rainy season is likely to remove the lingering drought area over South Florida.  Seasonal dryness, a potential for abnormal warmth, and poor snowpack conditions are likely to result in drought persistence and intensification across the West, with additional development possible over the Pacific Northwest.  Over the Southwest, monsoonal thunderstorms are likely to bring highly localized relief, but climate anomalies associated with El Nino favor below normal monsoonal rainfall, making persistence the most likely outcome for Arizona and southeastern California.  Suppressed convection is also favored during El Nino summers over the Caribbean, which favors further drought expansion across Puerto Rico.  For Hawaii, although El Nino conditions favor above normal dry season precipitation, it is unlikely to significantly benefit the lingering leeward drought areas.  

Forecaster: A. Allgood

Next Seasonal Outlook issued: June 18, 2015 at 8:30 AM EST