Tools used in the U.S. Seasonal Drought Outlook (SDO) included the Climate Prediction Center (CPC) temperature and precipitation outlooks for July and July through September 2020 (JAS), 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 JAS season, and initial conditions such as soil moisture. The oceanic and atmospheric conditions reflect ENSO neutral conditions which are most likely (60 percent chance) to persist through the summer.
Short-term drought rapidly expanded and intensified across eastern New Mexico during early to mid-June, due to little or no rainfall (less than 0.5 inch) and above normal temperatures. Soil moisture has decreased below the 5th (20th) percentile across northeast (southeast) New Mexico. Although drought is unlikely to improve through the beginning of July, an increasing wet climatology associated with the Southwest Monsoon favors a 1-category improvement to short-term drought across eastern New Mexico by the end of September. During July-August-September (JAS), eastern New Mexico typically receives 45 to 65 percent of its annual precipitation. Persistence is the more likely outcome in areas farther to the west where long-term drought exists. Drought is likely to persist across the Great Basin and California due to a relatively dry climatology.
Long-term drought continues across the Pacific Northwest where water-year-to-date (since Oct 1, 2019) precipitation has averaged less than 50 percent of normal in parts of Oregon and Washington. Since mid-May, precipitation has averaged 150 to 400 percent across much of the Pacific Northwest. This anomalous wetness along with cooler-than-normal temperatures have prompted slight improvements to drought where the heaviest precipitation occurred. Although the JAS outlook calls for increased chances of above normal temperatures and below normal precipitation, the wet end to spring precludes a larger area of drought development across the Pacific Northwest. This region will be closely monitored in the monthly drought outlooks this summer.
Short-term drought and abnormal dryness has recently developed across parts of Montana. Persistence and development through the southern tier of Montana is generally consistent with the JAS precipitation and temperature outlook, but predicted rainfall during the latter half of June lowers forecast confidence. Persistence and slight expansion of the drought in northeast Montana is favored due the lack of strong wet signal among tools along with likelihood of above-normal temperatures during the summer.
Forecast confidence for the Western Region is high for California and moderate elsewhere.
Colorado has experienced rapidly worsening conditions for much of the state. Since precipitation associated with the Southwest Monsoon typically accounts for less of its annual precipitation, persistence is favored for all of the ongoing drought across Colorado. Increased chances of below normal precipitation and above normal temperatures during JAS favor an expansion of drought northward across the central Rockies. Extreme drought (D3) exists across southwest Kansas, while eastern Kansas remains drought-free. Based on 7-day precipitation amounts (1 to 3 inches) and a continuation of a relatively wet pattern through the final week of June, improvement or removal is favored for central Kansas. Pockets of abnormal dryness and short-term moderate drought have developed across parts of the northern to central Great Plains west to Wyoming. Based on the Jul-Aug-Sep outlook calling for increased chances of above normal temperatures and below normal precipitation, drought is likely to persist and expand across Wyoming. May and June are typically the wettest two months of the year for North Dakota and precipitation gradually declines later through August and September. This drying climatology with time, the absence of a wet signal among the tools, and elevated chances of above normal temperatures during JAS favor persistence and slight expansion of drought across North Dakota. Although short-term drought may develop at times across South Dakota and Nebraska, forecast confidence is too low to designate a development area at this time. The Northern and Central Great Plains will be closely monitored in the monthly drought outlooks this summer.
Forecast confidence is moderate for the High Plains Region.
Rapid drought development and intensification occurred across much of Oklahoma, northwest Texas, and the Texas Panhandle since late May due to a lack of rainfall along with above normal temperatures and high evapotranspiration rates. According to the USDA's National Agricultural Statistics Service, topsoil moisture rated as short to very short increased from 23 percent to 69 percent during the first two weeks of June. A more favorable pattern for much needed rainfall is expected to develop as an upper-level trough develops over the central U.S. during mid to late June. Based on a trend towards a wetter pattern during the latter half of June along with a lack of a dry signal among the seasonal tools, improvement is favored for parts of Oklahoma and the Texas Panhandle. In addition, 7-day rainfall amounts of 1 to 3 inches could reduce 30 to 90-day deficits across much of Oklahoma. Tropical Storm Cristobal along with above-normal precipitation preceding it resulted in widespread improvement and elimination of drought along the Gulf Coast during May into early June. Continued removal of any lingering drought is likely during the outlook period. Although short-term deficits have developed across western Tennessee, increased chances of above normal precipitation during Week-2 and through the seasonal time scale preclude any development for this area.
Forecast confidence is low to modeate for the Southern Region.
Much of the Midwest remains drought-free with only small areas of short-term moderate drought across parts of Minnesota. Based on 7-day rainfall amounts and lack of a dry signal at the seasonal time scale, removal is forecast for those small D1 areas. Since the CPC seasonal outlooks call for slightly elevated chances of above normal precipitation for the eastern two-thirds of the Corn Belt, no development is forecast at the seasonal time scale. However, scattered areas of short-term dryness across Iowa, Illinois, Indiana, and Kentucky will have to be closely monitored for development with the July drought outlook.
Forecast confidence is moderate for the Midwest Region.
During the past 90 days, near to above normal precipitation was observed throughout the Southeast with the largest surpluses (8 inches or more) observed across parts of the Carolinas and Florida. Tropical Storm Cristobal brought heavy rainfall (2 to 6 inches, locally more) to Florida's Big Bend and west along the Gulf Coast. As of mid-June, there is only a small area of long-term drought designated for parts of the Mobile, Alabama area. Based on a wet summertime climatology and the seasonal outlook, removal is likely for lingering drought area. Given the increased chances of above normal precipitation during Jul-Aug-Sep along with the antecedent wetness for much of the Southeast, broad areas of development are unlikely through the end of September.
Forecast confidence is high for the Southeast Region.
Abnormal dryness continues to expand across New England where 30-day deficits exceed 3 inches in parts of Massachusetts, New Hampshire, and Maine. In addition, numerous 28-day streamflows have fallen below the 10th percentile. Although drought development remains favored in the short-term (see the June monthly outlook), it is highly uncertain that drought would persist through the end of September. Therefore, no development is forecast at the seasonal time scale.
Forecast confidence is low for the Northeast Region.
Alaska has remained drought-free since March. Since the seasonal outlook calls for increased chances of above normal precipitation across much of Alaska, development is unlikely to occur during the summer.
Forecast confidence is high for Alaska.
Ongoing drought across Hawaii is likely to persist through the end of September. Abnormal dryness (D0) expanded to all the Hawaiian Islands during May and drought development is favored for the leeward sides. However, removal is more likely along the Kona slopes region on the Big Island where it is their wet season.
Forecast confidence is moderate for Hawaii.
Moderate to severe drought recently developed across Puerto Rico. Since the North American Multi-Model Ensemble depicts increased chances of above normal precipitation across the Caribbean region, improvement or removal of drought are most likely by the end of September.
Forecast confidence is low for Puerto Rico.
Forecaster: Brad Pugh
Next Seasonal Drought Outlook issued: July 16, 2020 at 830am EDT