Tools used in the U.S. Seasonal Drought Outlook (SDO) included the Climate Prediction Center (CPC) temperature and precipitation outlooks for April through June 2019 (AMJ), 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 AMJ season, and initial conditions such as soil moisture. The oceanic and atmospheric conditions reflect weak El Niño conditions and El Niño is likely to continue through the Northern Hemisphere spring 2019 (~80 percent chance).
Precipitation has averaged at or above normal throughout California, the Great Basin, and the Southwest during the water year to date (WYTD) since October 1, 2018. Also, basin average snow water content (SWC) is above normal across these areas, with parts of Arizona, southern Utah, and the Sierra Nevada Mountains ranging from 150 to 200 percent of average for SWC. The ample precipitation and snowfall this water year to date resulted in major drought reduction throughout much of the Western region. According to the U.S. Drought Monitor, drought coverage in this region decreased from 59 percent at the beginning of October 2018 to 13 percent by mid-March. California became drought-free for the first time since December 2011. The high snow water content and lack of any rapid warmup forecasted through the next month favor continued removal and improvement to drought conditions across the Great Basin and Four Corners region. The seasonal outlook, with its enhanced odds for above normal precipitation also supports drought improvement/removal for these areas. Although drought severity is expected to ease with the onset of the spring snowmelt across northern New Mexico, long-term drought impacts may linger. Drought removal is also probable for southeast Oregon based on above average snowpack. However, persistence and development are forecast for northwest Oregon and parts of Washington. Recent dry weather has resulted in an increase in brush fires across the following counties of western Washington: Whatcom, Mason, Grays Harbor, Cowiltz, and Clark. This is based on below average snow water content, low 28-day streamflows, large precipitation deficits for the WYTD, and enhanced odds for below normal precipitation and above normal temperatures during AMJ. Confidence is tempered for development since impacts related to the drier-than-normal conditions may be slow to occur this spring.
Forecast confidence is high for continued improvement/removal for much of the West but low for the development.
The northern and central Great Plains remain drought-free, and above-average precipitation this winter resulted in major flooding along the lower Missouri River. Drought development is not anticipated during the outlook period at this time, but these areas are climatologically vulnerable to fast-developing drought with multiple weeks of insufficient rainfall and above average temperatures during the late spring and summer. Major drought improvement occurred across the central Rockies this winter. Snow water content ranges from 125 to 175 percent of normal for mid-March across southern Colorado. The climatology tends to be slightly wetter across the high Plains of southeast Colorado during AMJ. These factors along with a seasonal outlook favoring above normal precipitation support continued improvement or removal of drought across Colorado and western Wyoming.
Forecast confidence is low for the High Plains region.
Excessive wetness continues across parts of the lower Mississippi and Tennessee Valleys, while scattered areas of abnormal dryness and moderate drought are present from the Texas Panhandle south to the lower Rio Grande Valley. Confidence is high for the excessively wet areas to remain drought-free during the outlook period. Drought removal is most likely for the D1 areas of Texas based on the 7-day precipitation forecast and seasonal precipitation tools that indicate a slight tilt in the odds for above normal precipitation.
Forecast confidence is high for the lower Mississippi Valley and low for the southern Great Plains.
Major flooding continues across parts of the Midwest region, especially across Iowa, Missouri, southern Wisconsin, and Illinois. During the past 90 days, precipitation surpluses exceeded 4 inches across much of the Midwest with soil moisture ranking in the 99th percentile for this time of year. Given such wet initial conditions, drought development is unlikely during the outlook period.
Forecast confidence is high for the Midwest Region.
Above-average rainfall during late January and early February resulted in drought elimination across the Florida Peninsula. Abnormal dryness (D0) and small areas of moderate short-term drought (D1) have recently developed across parts of Georgia and South Carolina where 30-day precipitation deficits of 1 to 3 inches were observed. Since the seasonal outlook favors above normal precipitation across the Southeast, removal is most likely for these new D1 areas. Meanwhile, heavy rainfall of 5 to 10 inches or more has resulted in saturated soils across northern Alabama northeast to the southern Appalachians, where development of drought is unlikely due to these wet initial conditions.
Forecast confidence is moderate for the Southeast Region.
The Northeast region has remained drought-free since early November. Based on wet initial conditions and the absence of any dry signal among precipitation tools at any time scale, drought development is unlikely through the end of June.
Forecast confidence is high for the Northeast Region.
Moderate to severe drought coverage remained nearly steady along the southern Alaska Panhandle this past winter. Since AMJ is relatively a drier time of year, persistence of this long-term drought is forecast.
Forecast confidence is high for Alaska.
Although much of Hawaii became drought-free during February, drier conditions consistent with a weak El Niño have returned. Drought persistence is most likely for lingering drought on Kauai, while an early start to the dry season is expected to result in development in leeward areas from Oahu to the Big Island. Rainfall associated with the trade winds is expected to be sufficient to keep windward areas of these islands drought-free.
Forecast confidence is moderate for Hawaii.
Drought coverage across Puerto Rico peaked at 42.66 percent at the beginning of March, but decreased to 30.38 percent as of March 12. Since the climatology becomes increasingly wet during AMJ and without a strong dry signal in the seasonal precipitation tools, removal of drought is anticipated by the end of June.
Forecast confidence is low for Puerto Rico.
Forecaster: Brad Pugh
Next Seasonal Drought Outlook issued: April 18, 2019 at 8:30 AM EDT