Tools used in the U.S. Monthly Drought Outlook (MDO) included the Climate Prediction Center (CPC) temperature and precipitation outlooks for July, 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 outlooks , the Week 3-4 outlooks and tools from CPC, dynamical models at the monthly time scale, the 384-hour total precipitation forecasts from several runs of the GFS, climatology for July, and initial conditions such as soil moisture. The U.S. Drought Monitor, valid on June 22 at 12Z, was used for the initial drought conditions.

Drought conditions blanketed 98 percent of the Western Region, with 56 percent reported as extreme to exceptional drought (D3 to D4). Drought conditions continued to worsen across the Pacific Northwest towards the end of the month as a massive heat dome promoted dry weather and much above-normal temperatures. Many locations likely set new all time record high temperatures and subsequently broke those new records on following days. Further south, a trough drawing tropical moisture northward brought locally heavy rainfall to parts of the Desert Southwest and New Mexico, relieving drought conditions. Some of this moisture worked northwards across the Rockies, but drought relief was scant. A similar pattern is forecast for the first week of July, with the remnants of Hurricane Enrique aiding a new surge of moisture from the Gulf of California into southern and eastern New Mexico, which should bring additional drought relief. Locally heavy rainfall is also possible across the Central Rockies, but lighter amounts are forecast across Wyoming, the Great Basin, and the Northwest where drought conditions are entrenched. The updated CPC July temperature and precipitation outlooks favor above-normal temperatures across most of the Western Region, with the highest probabilities (more than 70 percent) for above across the Northwest. Below-average precipitation is also favored for the Northwest, and extremely dry soils will allow hot temperatures to develop and persist for extended periods of time, creating drought sustaining feedback. In contrast, above-normal monsoon rainfall is favored for the southern Four Corners region, which may help promote continued drought reductions in regions where climatological precipitation is highest.

Forecast confidence is high for the Western Region.

During June, rainfall eased drought conditions across eastern Colorado, and localized convection brought spotty relief to parts of Kansas and the western Dakotas. On a broad scale, however, below-average precipitation and hot weather caused drought conditions to expand across the High Plains Region. During early June, heavy rainfall is forecast for the Colorado Plains and southern Kansas, but there is a sharp decreasing gradient to the north. Below-average rainfall is favored during Week-2, and the updated CPC monthly precipitation outlook favors below-average precipitation from Nebraska northward. Given forecasts for persistent hot weather during July, there is a potential for flash drought development during July in areas where 30-day rainfall deficits are present. Based on soil moisture conditions and the hot, dry forecasts, drought expansion and intensification is most likely across Wyoming, the Dakotas, Nebraska, and northern Kansas. Early period rainfall will likely stave off drought expansion into eastern Colorado and southern Kansas.

Forecast confidence is low to moderate for the High Plains Region.

During June, copious rains fell across the central Gulf Coast states, and towards the end of the month a trough pulling tropical moisture from the Pacific generated heavy rainfall across western Texas. Due to these wet conditions, only 7 percent of the Southern Region remains in drought conditions, mostly small areas in western Texas and central Oklahoma. Widespread heavy rainfall is favored during the first week of July across most of the south-central U.S., which favors continued drought reductions for most locations where drought is still extant. Model guidance indicates that a small region of the Texas Big Bend area may receive lighter accumulations during this time. While the updated July precipitation outlook also favors above-normal precipitation and near to below-normal temperatures across the majority of the Southern Region, equal chances for below-, near-, and above-average rainfall is maintained for the southern portion of the Big Bend region of Texas. Therefore, drought reductions are favored across the entire Southern Region, except for the southern Texas Big Bend region, where persistence is maintained.

Forecast confidence is moderate to high for the Southern Region.

During June, hot, mostly dry weather promoted widespread drought expansion across the upper Midwest and western Corn Belt. Towards the end of the month, a narrow swath of heavy rainfall brought localized relief to southern Iowa and parts of Michigan, but most of this rainfall fell south of the core drought areas. During early July, forecasts from WPC show additional widespread heavy rainfall across the mid-Mississippi Valley and Ohio Valley, but accumulations decrease sharply to the north where drought conditions remain entrenched. The updated monthly temperature and precipitation outlooks for July favor below-average precipitation and above-normal temperatures for the upper-Midwest. These conditions favor continued drought expansion across northern Minnesota, northern Wisconsin, and the western upper-peninsula of Michigan. The CPC 8-14 day outlook slightly favors above-normal precipitation for Michigan, and given the recent heavy rainfall, no further drought expansion is favored during July. Improvements across Michigan, northern Illinois, and far southern Iowa are based on the ongoing response to recent rainfall, with many streams experiencing above-normal flow and flooding. Additional precipitation during July should help to maintain these improvements.

Forecast confidence is moderate for the Midwest Region.

Across the Northeast, an unusually protracted drought continued to expand and intensify during June across northern New York and northern New England. A wet climatology typically makes drought events in this region relatively short lived, but record low streamflow conditions in many areas show the extent of the impacts, and it would take a long period of generous rainfall (more than a month outside of near record rains) to alleviate these conditions. Widespread rainfall depicted on the WPC 7-day QPF across much of the East during early June has a sharp cutoff north of Massachusetts, and the updated CPC July outlooks favor below-average rainfall and above-normal temperatures across northern New England. Therefore, drought relief is unlikely to come during July, and additional degradations and drought expansion across Maine are favored.

Forecast confidence is moderate for the Northeast Region.

Across the Southeast, only small areas of moderate drought remain across the coastal Carolinas and the southern Virginia piedmont. Widespread heavy rainfall is favored during early July, and the updated July precipitation outlook favors equal-chances for below-, near-, and above-normal rainfall across the regions where drought remains. Based on the forecasts for heavy rainfall early in the month and a wet summer climatology, removal of remaining drought across the Southeast Region is the favored outcome.

Forecast confidence is high for the Southeastern Region. 

No drought is anticipated to develop across Alaska, with near to below-normal temperatures favored during July. Dynamical models generally favor below-normal rainfall across Hawaii, which would promote additional drought expansion. Small drought areas remain across eastern Puerto Rico, which should continue to decrease under the summer convective regime. The National Hurricane Center is monitoring a disturbance that has a high potential for development in early July, and dynamical models bring this potential system into the Caribbean. This potential tropical cyclone introduces increased uncertainty, as a track near Puerto Rico could result in copious rainfall, but a track further south may result in a period of decreased convection due to subsidence surrounding the storm.

Forecast confidence is high for Alaska, moderate for Hawaii, and low to moderate for Puerto Rico.

Forecaster: Adam Allgood
 
Next Monthly Drought Outlook issued: July 31, 2021 at 3pm EDT